Characteristics and largest manufacturers of high-power LEDs for flashlights. Technical characteristics of high-power CREE LEDs

When purchasing or assembling new LED flashlights, you should definitely pay attention to the LED used. If you are purchasing a lantern only to illuminate a dark street, then there is a huge choice - choose any one with a bright white LED. But if you want to buy a portable lighting device with characteristics for more complex tasks, the important point here is the choice of the appropriate luminous flux, that is, the ability of the device to illuminate a large space with a powerful beam.

Main characteristics

LEDs are responsible for the quality of light that the flashlight emits. The stability of lighting depends on many characteristics, including current consumption, light flux and color temperature. Among the trendsetters, it is worth noting the company Cree; in its assortment you can find very bright LEDs for flashlights.

Modern pocket models are created using a single LED, the power of which reaches 1, 2, or 3 W. The indicated electrical characteristics are the properties of various LED models from well-known brands. The intensity of the light rays or luminous flux is an indicator that depends on the type of LED and the manufacturer. The manufacturer also indicates the number of lumens in the specifications.

This indicator directly correlates with the color temperature of the light. Light-emitting diodes can produce up to 200 lumens per watt and are produced today in different temperatures to glow: warm yellowish or cool white.

Lanterns with a warm white tint produce a pleasant light to the human eye, but they shine less brightly. Light with a neutral color temperature effectively allows the smallest elements to be seen. Cool white lighting is usually typical for models with a huge beam range, but can irritate the eyes during prolonged use.

If the temperature reaches approximately 50 °C, the lifetime of the crystal can be up to 200,000 hours, but this is not justified from an economic point of view. For this reason, many companies produce products that can withstand operating temperatures of up to 85 °C, while saving on cooling costs. If the temperature exceeds 150 °C, the equipment may completely fail.

The color rendering index is a qualitative indicator that characterizes the ability of an LED to illuminate a space without distorting the actual shade. LEDs for flashlights with a color rendering source characteristic of 75 CRI or more are a good option. An important element of the LED is the lens, thanks to which the angle of dispersion of the light fluxes is set, that is, the range of the beam is determined.

In any technical specification of an LED, the emission angle must be noted. For any of the models, this characteristic is considered individual and usually varies in the range from 20 to 240 degrees. High-power LED flashlights have an angle of approximately 120°C and generally include a reflector and an additional lens.

Although today we can see a strong leap in the production of high-power LEDs consisting of multiple crystals, global brands are still producing LEDs with lower power. They are produced in a small case that does not exceed 10 mm in width. In a comparative analysis, one can notice that one such powerful crystal has a less reliable circuit and dispersion angle than a pair of similar elements simultaneously in a single housing.

It would not be amiss to recall the four-pin “SuperFlux” LEDs, the so-called “piranha”. These flashlight LEDs have improved specifications. The piranha LED has the following main advantages:

1. the light flux is distributed evenly;
2. no need to remove heat;
3. lower price.

Types of LEDs

There are many flashlights with improved features available in the market today. The most popular LEDs are from Cree Inc.: XR-E, XP-E, XP-G, XM-L. Today the latest XP-E2, XP-G2, XM-L2 are also popular - they are mainly used in small flashlights. But, for example, Cree MT-G2 and MK-R LEDs from Luminus are widely used in huge models of search lights that can operate simultaneously from a pair of batteries.

In addition, LEDs are usually distinguished by brightness - there is a special code thanks to which you can sort LEDs by this parameter.

When comparing some diodes with others, it is worth paying attention to their dimensions, or rather, to the area of ​​the light-emitting crystals. If the area of ​​such a crystal is small, then it is easier to concentrate its light into a narrow beam. If you want to get a narrow beam from XM-L LEDs, you will need to use a very large reflector, which negatively affects the weight and dimensions of the housing. But with small reflectors on such an LED, a fairly effective pocket flashlight will come out.

Application area of ​​LEDs

Mostly, when choosing flashlights, consumers choose models with the maximum beam of light, but in many cases they do not need this option. In many cases, such equipment is used to illuminate a nearby area or an object that is located at a distance of no more than 10,000 m. A long-range flashlight shines at 100 m, although in many cases with a rather narrow beam that poorly illuminates the surrounding area. As a result, when illuminating a distant object with such lighting devices, the user will not notice those objects that are located in close proximity to him.

Let's look at a comparison of the tonality of light produced by LEDs: warm, neutral and cold. When selecting the appropriate flashlight light temperature, the following important points must be taken into account: LEDs with a warm glow can minimally distort the color of the illuminated objects, but they have lower brightness than neutral-spectrum LEDs.

When choosing a powerful search or tactical flashlight, where the brightness of the device is an important point, it is recommended to select an LED with a cold spectrum of light. If a flashlight is needed for everyday life, tourism purposes, or for use in a head-mounted model, then proper color rendering is important, which means LEDs with warm light will be more advantageous. A neutral LED is the golden mean in all respects.

Not taking into account the cheapest flashlights, which only have a single button, many flashlights have a couple of operating modes, including strobe and SOS modes. The non-brand model has the following operating options: the highest power rating, medium power and “strobe”. In addition, the average power is basically equal to 50% of the highest brightness of the light, and the lowest is 10%.

Branded models have a more complex structure. Here you can control the operating mode using a button, rotating the “head”, turning the magnetic rings and a combination of all of the above.

Boruit heavy duty headlamp. For lighting during fishing, hunting and household work.

The modern lighting market offers a huge selection of lighting devices with narrow scattering angles and a long range. These are general purpose floodlights, floodlights for transport, theater stages, studios, construction sites, airfields and many others. Such lighting devices also include powerful battery-powered flashlights.

When choosing the most suitable, modern and effective flashlight, you may immediately become confused, since with all the variety of their designs, types of light sources used, range and beam scattering angle and other parameters, it is difficult to immediately settle on a specific model.

In this article we will try to understand the most important technical features of flashlights that influence the correctness of their choice.

The purpose of powerful flashlights

Powerful flashlights are designed for use in difficult conditions where a stable, bright luminous flux is required, the maintenance of which is ensured over a long period of time. Most often they are used in their work by rescue services, employees of the Ministry of Internal Affairs, speleologists and tourists. Typical representatives of this class of lighting devices are search or tactical flashlights. Also powerful are under-barrel flashlights, which are attached under the barrel of a weapon using special fasteners, camping flashlights or those that have a long operating time, headlamps or headlamps, the fastening of which allows you to attach them to your head. Therefore, when choosing a powerful flashlight, you should always pay attention to what purpose it is intended for.

The special conditions in which powerful flashlights are usually used dictate special requirements for their design and light characteristics. Namely:

• shock resistance and moisture resistance of the case;
• the presence in lanterns of materials with high thermal conductivity, ensuring effective heat removal from the light source;
• battery capacity, the value of which directly affects the duration of the flashlight and the stability of its luminous flux;
• universal design of the container for installing batteries;
• possibility of adjusting the angle of dispersion of the light flux;
• the reliability of special fastenings, the effectiveness of anti-slip inserts or notches on the flashlight handle, the presence of a strap for carrying the flashlight on the shoulder and other nuances.

Body material and handle design

Since it so happens that search lights are the most popular on the market, we will take a look at them as an example.

For the manufacture of the body of modern powerful search lamps, anodized duralumin is often used, lightweight, durable and corrosion-resistant, on the outer surface of which either anti-slip polyurethane coating is applied, resistant to scratches and impacts, or longitudinal, transverse and diagonal notches. The body of such flashlights is mostly made in the form of a tube that simultaneously performs two functions - a handle and a container for batteries. But there are flashlights with a remote handle. Examples of cases and handles can be seen in the images below.

The images also clearly show the radiator fins, which increase the efficiency of heat removal from the light source. The ribs are made by turning the body metal mass closer to the optical part of the flashlight.

Waterproof

Flashlights have different degrees of protection against foreign objects and moisture getting inside their housing. Since all flashlights have minimal protection capable of trapping dust particles, but are not able to work when they are exposed to drops and splashes of water for a long time, they can be divided into two groups: non-moisture-resistant and moisture-resistant flashlights. According to the classification system for degrees of protection (IP - Ingress Protection Rating), non-moisture resistant ones can be assigned the value IP50, that is, dust-proof and moisture-permeable. Housings for moisture-resistant flashlights are usually produced with the ability to immerse all flashlights under water. Therefore, their degree of protection starts from IP67 and ends with IP69. Sometimes the number indicating the penetration of foreign objects is omitted and the letter “X” is placed instead of the first number (IPХ7 - IPХ9).

Let's decipher the meaning of numbers 7 - 9. Number 7 indicates the possibility of briefly immersing the flashlight to a depth of up to 1 meter. The number 8 indicates the possibility of long-term immersion of the flashlight to a depth of more than 1 meter. The number 9 indicates the possibility of long-term immersion of the flashlight to a very great depth, where there is high fluid pressure.

Sources of light

The light source is perhaps the most important element that characterizes the consumer and operational parameters of flashlights. Conventional incandescent lamps are becoming a thing of the past and are no longer used in modern powerful flashlights. Modern high-power flashlights use halogen incandescent lamps, xenon discharge lamps (HID) and light-emitting diodes (LED) as light sources.

Halogen lamps

This is an improved type of incandescent lamps and we can only talk about their advantages in comparison with traditional options. Filling the bulb of an incandescent lamp with halogen additives made it possible to increase its luminous efficiency at the same power and extend its service life by half (up to 2000 hours) by reducing tungsten burnout.

The lamps have an average light output of 22 Lm/W. This is almost twice as high as a conventional incandescent lamp, but it is still very low considering that the lamp must be operated in a portable flashlight and the energy source has a limited resource. Lamps are very sensitive to frequent switching on, during which they mostly burn out.

Like conventional incandescent lamps, they are becoming a thing of the past, because it is difficult for them to compete with durable and energy-efficient LED and xenon light sources.

Xenon lamps

A characteristic feature of xenon lamps is that the electrical discharge of the lamp occurs in the inert gas xenon, at high pressure and high current densities. For this reason, the lamps have very high brightness and a visible emission spectrum close to sunlight with a color temperature of 6100 - 6300 K.

Xenon lamps have a high ignition voltage and therefore require the use of special ignition devices. After ignition, the lamps light up within approximately 15 seconds.

Xenon lamps are very sensitive to changes in supply voltage. When the supply voltage changes by ±5%, the lamp power changes by ±20%. For this reason, when using lamps of this type, it is necessary to use stabilizing devices that maintain the voltage at the same level as the battery discharges.

The light output of a xenon lamp ranges from 80 to 100 Lm/W. Xenon discharge has the highest brightness. According to theoretical estimates, its maximum brightness can reach 2000 MKd/m².

The bright, powerful luminous flux of the daytime spectrum allows you to evenly illuminate a large area, which makes such flashlights an indispensable tool for search work in accident sites, in conditions of heavy dust and gas contamination in mines, deep wells and caves. The light of a xenon flashlight is noticeable even during the day at a great distance, which is very important during rescue operations in the mountains and taiga.

This type of light source confidently replaces incandescent lamps and gas-discharge lamps from modern flashlight models. This fact is easily explained by the following advantages of LEDs:

• the LED, unlike a xenon lamp, is inertia-free and when a supply voltage is applied to it, it instantly reaches the nominal glow mode, just like a halogen lamp;
• the heating temperature of the LED is much lower than the heating temperature of halogen and xenon lamps;
• Since when the LED lights up, less energy is spent on heating, LEDs today have the highest efficiency - up to 45%. By comparison, a halogen lamp has an efficiency of about 5%, a xenon lamp - up to 30%;
• The maximum luminous efficiency of LEDs used in industrial production is 120 Lm/W. The average luminous efficiency of LEDs used in battery-powered flashlights is 80 - 95 Lm/W, that is, comparable to the luminous efficiency of xenon lamps.

Light distribution

Powerful flashlights can be classified both by the type of light source and by the direction of the light flux. Speaking about the direction of the light flux, we can distinguish two types of powerful flashlights:

• spotlights. The beam of light from such lanterns has a wide front and is capable of illuminating objects located at a fairly large distance, more than five hundred meters;
• long-range flashlights. The beam of light from such lanterns has a very narrow focus so that one bright spot is projected on the illuminated object, but the range of such a beam reaches one and a half kilometers. For information: the range of the flashlight is determined by the distance at which the illumination level is equivalent to the light intensity of the full moon, which is taken equal to 0.25 lux and is optimal for safe movement.

Spotlights are most effective at short and medium distances up to five hundred meters. Their most important characteristic is not the range, but the brightness of the light flux over a maximum area without deep shadow. This is ensured thanks to the special design of the reflectors. Spotlights are an ideal option for outdoor activities, hunting and fishing.

Long-range flashlights have a completely different purpose. Long-range flashlights are used by speleologists, searchers, and miners.

Long-range flashlights usually include flashlights with a lighting range of 500 meters or more. This is also ensured by the design of reflectors and optics, which allow the light beam to be focused. What is important here is not the scattering of light, but its concentration at one point, the formation of a bright light spot.

Very often, the functions of spotlights and long-range flashlights are combined in one flashlight. Structurally, such lanterns have a movable (in the axial direction) diffuser and a lens installed at the outlet. By adjusting them, they achieve the creation of a light spot of the required diameter. When adjusted, the angle of light redistribution and the focal distance between the lamp (LED) and the illuminated object change.

Rechargeable batteries

Powerful flashlights with search-type LEDs for power supply mainly use two types of replaceable batteries, these are 26650 and 18650, with an output voltage of 3.7 V. Such batteries are produced by many companies, have different prices, declared capacity values, discharge and charge times. Batteries of these types are widely used not only for powering flashlights, but also, for example, for making laptop batteries. Therefore, there should not be any difficulties in purchasing such batteries.

Different flashlight models have different numbers of batteries installed. Basically these are 2, 3 elements. There are a large number of flashlight models that have a universal container designed to install 1, 2 or 3 elements by adding a special insert supplied with the flashlight to the handle.

Since 18650 and 26650 batteries have the same length, 65 mm, some flashlight models can use batteries of both types. To prevent the 18650 elements from “dangling” inside the container, a plastic adapter sleeve is included with the flashlight.

In small lanterns it is possible to install 1 element. It happens that instead of 1 18650 element, 2 CR123A elements are used.

More powerful battery-powered LED flashlights can be equipped with D-type cells with a capacity of 10,000 mAh and a voltage of 1.2 V.

In general, when choosing a flashlight, you should definitely be interested in what batteries are used in them, and what they can be replaced with. To assess the possibility of such a replacement, see the tables of standard sizes of galvanic cells.

If you decide on the model of search flashlight, remember that for its successful, reliable and long-term operation you need high-quality batteries. I think that if you are going to spend a significant amount of money on a flashlight, you should not skimp on its most important element.

In the case of flashlights that work with a xenon lamp, from the point of view of choosing a power element, everything is much simpler. All flashlights have their own batteries, which are supplied with the flashlight. Therefore, when choosing a flashlight, you don’t need to think about anything. However, if you look at this from an operational point of view, then over time there may be problems with replacing them.

Although there are exceptions. For example, the flashlight shown in the photo below is powered by four 18650 batteries.

Operating modes

The operating modes of flashlights with a xenon lamp, due to the inertia of turning on the lamp and the limited number of its on-off cycles, as a rule, have three operating modes, namely these are the modes in which the lamp operates at different powers. Each lantern has an operating mode at minimum power, at which the lamp glows stably, an operating mode at rated power, and a forced mode, at which maximum brightness is created. When operating in the latter mode, the battery capacity is naturally consumed very quickly.

A powerful LED rechargeable flashlight, in addition to the listed operating modes of xenon flashlights, has two additional operating modes, these are:

• stroboscopic mode. This mode is intended for self-defense from an attacking enemy, by disorienting him in space with very bright and frequent light pulses;
• SOS mode or beacon to attract the attention of strangers to you.

To summarize, we can conclude that powerful flashlights with halogen incandescent lamps have faded into the background. The leadership is shared by flashlights with xenon lamps and flashlights with LEDs. However, LED high-power flashlights have characteristics comparable to flashlights equipped with xenon lamps, and therefore are increasingly used.

And finally, we invite you to watch a video review of two portable, powerful rechargeable LED flashlights made in China and Germany.

Many people wonder why a diode of the same power (for example 50W) costs 100 rubles in a Chinese online store, but 500 rubles in Russia. Chinese sellers and manufacturers wisely use the characteristics of LEDs, which cannot be measured without special equipment. In addition, they have learned to produce very cheap and low-quality ones. 99% of buyers do not understand them and encounter them for the first time. A large difference in price gives a good reason for deception; you can always sell junk at the price of a branded one, which they skillfully do.

• 1. Chip size
• 2. Current strength on the crystal
• 3. Parameters of ultra-bright LEDs from 10W
• 4. Specifications 5050, 2835, 5730, 5630, 3528
• 5. Characteristics of LEDs for flashlights
• 6. Main characteristics
• 7. Detailed description

Chip size

You've probably seen that sometimes the seller writes the crystal size in the specifications, indicating it in “mil”. This is how thousandths of an inch are designated; in millimeters it is 0.0254 mm. A typical crystal has dimensions of 30*30mil and 45*45mil. In millimeters 0.762*0.762mm and 1.143*1.143mm. It is not very easy to measure, but you can compare it by eye if you have a standard. I use a digital caliper, accurate to 0.01mm. For measurements, you need a tool with sharp ends; a regular micrometer is not suitable, since the crystal is recessed in the body.

Matching size and power:

1. 1W - 45*45mil;
2. 1W - 30*30mil;
3. 0.75W - 24*40mil;
4. 0.5W - 24*24mil.

Current strength on the crystal

On LED matrices, the power can be determined by the number of installed LEDs. They are visible in the form of dots under the yellow phosphor. Color and RGB do not have phosphor, they are clearly visible.

On high-power LEDs, 1 KR has a power of 1W and a rated current of 300mA. At this current, normal long-term operation is ensured. If 50 KR are visible, then they will be equal to 50W.

Parameters of ultra-bright LEDs from 10W

Let's look at the features of powerful LED white light matrices. To reduce the cost, the Chinese decided to install smaller and worse crystals at 0.5W and 0.75W, for which the rated current is 150mA and 220mA. For them, 300mA will be too much, they will degrade and overheat. Good ones should have a length and width between 30*30mil and 45*45mil.

When making a choice in the store, use this information to calculate the actual parameters of powerful matrices from 10W, 20W, 30W, 50W, 70W, 100W.

To visually determine the quality of a high-power LED, use geometric parameters. It is best if the chips under the phosphor are square. Rectangular ones are practically a guarantee of inflated performance.

Specifications 5050, 2835, 5730, 5630, 3528

..

The numbers in the marking indicate only the size of the SMD case. And this has nothing to do with its power. For example, for SMD5050 the dimensions will be 5.0mm by 5.0mm.

In large packages SMD5630, SMD 5730, European and American brands Samsung, LG, Philips produce 0.5W ice chips. The Chinese skillfully take advantage of this and put a weak 0.01W power supply into the standard 5630 and 5730 case, selling them as 0.5W. That's why Chinese corn lamps are studded with weak diodes.

Technical characteristics of Chinese

Characteristics of LEDs for flashlights

In addition to producing low-quality LEDs, the Chinese have learned to produce counterfeits of ultra-bright LEDs for flashlights, LED beams, and bicycle lights. They copy the appearance 95-99%, but the parameters still remain Chinese, 30-40% worse than the originals.

This explains the low cost of rechargeable LED flashlights on Cree Q5, Cree XML T6, Cree XHP50. The cheapest ones are 100% fake. I checked it myself, having bought 10 different flashlights on Kriya Q5 and T6. They all turned out to be fake CRIs made by LatticeBright.

The characteristics of bright LEDs for flashlights are described in detail at the following links:

Main characteristics

There are many options to reduce the cost and replace expensive materials with cheap ones. The most important feature is that such a replacement does not affect the appearance in any way, which is why such questions arise.

List of differences affecting the price:

1. base material, copper or aluminum;
2. the number of conductors going to the crystal;
3. conductor material;
4. LED mass;
5. service life according to standard L70 or L80;
6. maximum operating temperature;
7. number of Lumens per 1 Watt;
8. phosphor quality;
9. color rendering index CRI;
10. crystal size;
11. crystal quality;
12. variation in technical characteristics;
13. precision soldering and assembly.

Some parameters can only be determined after 5000 hours. works:

• CD degradation rate;
• effective service life;
• quality of yellow phosphor.

I believe that the effective service period according to the L80 and L70 standards plays a primary role in payback. For outdoor LED lamps, secondary parameters do not play a special role.

Detailed description

1. On cheap LEDs, the base is made of aluminum; its thermal conductivity is worse than that of copper. This significantly affects the mass. The rate of heat removal from the radiators decreases, and during operation their temperature becomes higher.

2. The crystal has a very small size; to supply power, it is connected by thin conductors to external contacts. It's best if there are 4 of them, the worst is 2 pieces.

3. In branded diodes, the conductors are made of thin gold threads; they can withstand current surges, especially in a car. Gold is replaced with copper or gilded copper. Conductivity deteriorates, reducing reliability. Probably many of you have seen daytime running lights or LED lamps that blink. When heated, contact with K is lost, and when cooled it appears again.

4. Copper is much heavier than aluminum or other alloys based on it. Therefore, a good LED should be heavy. For low-power 1W, 3W, 5W the difference will be small. And starting from 10W to 100W, the difference in weight will be 2-3 times.

5. Standard L70 and L80 determine the number of hours that it will work before the luminous flux decreases to 70% and 80% of the original. The Chinese write a standard value of 30,000 hours for everyone. and 50,000h.

6. According to the characteristics, LEDs have a maximum operating temperature of 60°. Already 70° is critical for them; a large cooling system is required. Good ones will work for the required time of 50-70 thousand hours at 110°.

7. The worst ones give 50 lm/W, the good ones up to 130 lm/W, the best ones up to 200 lm/W. When buying from the Chinese, do not expect more than 100 lm/W.

8. All white ice chips without phosphor glow blue. To give it a warm white or neutral white color, yellow phosphor is applied. It comes in different varieties; inexpensive ones quickly burn out. This leads to a color shift towards blue and a change in the color rendering index. A CRI below 80 is not suitable for residential use.

9. Color rendition is responsible for the accuracy of the color reproduction of an object that we see under LED lighting. At low CRI<80 цвета будут сильно искажены, поэтому светодиодные светильники и лампы с CRI <80 используют в уличном освещении, в подсобных и нежилых помещениях.

10.The current strength that can be supplied to it depends on the size of the CD. Square LED COB matrices (assemblies, modules) consist of ordinary 1W and 3W crystals. For them the standard is 30mil, 45mil. For high power COB LEDs at 10W, 20W, 30W, 50W, 100W the sizes can be 24*24mil, 24*44mil, 44*44mil.

For low-power LEDs, they can be of different sizes, even 2-3 LEDs in one housing, connected in series or parallel.

11. The same applies to high-power RGB LEDs. In terms of size, 1W and 3W CDs can be the same. The bad ones are labeled as 1W, which are better labeled 3W.

12. Indirectly, quality can be determined by the spread of parameters of the used RCs. They are turned on to glow slightly. Some will shine much brighter than others, there is a wide range. The more evenly they shine, the better.

13. The quality of assembly and installation of the CD affects the service life. All elements are subjected to strong heating and cooling, materials expand and contract. If heat dissipation deteriorates, then the phosphor around it begins to turn black.

For safety and the ability to continue active activities in the dark, a person needs artificial lighting. Primitive people pushed back the darkness by setting fire to tree branches, then they came up with a torch and a kerosene stove. And only after the invention of the prototype of a modern battery by the French inventor Georges Leclanche in 1866, and the incandescent lamp in 1879 by Thomson Edison, did David Mizell have the opportunity to patent the first electric flashlight in 1896.

Since then, nothing has changed in the electrical circuit of new flashlight samples, until in 1923, Russian scientist Oleg Vladimirovich Losev found a connection between luminescence in silicon carbide and the p-n junction, and in 1990, scientists managed to create an LED with greater luminous efficiency, allowing them to replace a light bulb incandescent The use of LEDs instead of incandescent lamps, due to the low energy consumption of LEDs, has made it possible to repeatedly increase the operating time of flashlights with the same capacity of batteries and accumulators, increase the reliability of flashlights and practically remove all restrictions on the area of ​​their use.

The LED rechargeable flashlight that you see in the photograph came to me for repair with a complaint that the Chinese Lentel GL01 flashlight I bought the other day for $3 does not light, although the battery charge indicator is on.

The external inspection of the lantern made a positive impression. High-quality casting of the case, comfortable handle and switch. The plug rods for connecting to a household network for charging the battery are made retractable, eliminating the need to store the power cord.

Attention! When disassembling and repairing the flashlight, if it is connected to the network, you should be careful. Touching unprotected parts of your body to uninsulated wires and parts may result in electric shock.

How to disassemble the Lentel GL01 LED rechargeable flashlight

Although the flashlight was subject to warranty repair, remembering my experiences during the warranty repair of a faulty electric kettle (the kettle was expensive and the heating element in it burned out, so it was not possible to repair it with my own hands), I decided to do the repair myself.

It was easy to disassemble the lantern. It is enough to turn the ring that secures the protective glass a small angle counterclockwise and pull it off, then unscrew several screws. It turned out that the ring is fixed to the body using a bayonet connection.

After removing one of the halves of the flashlight body, access to all its components appeared. On the left in the photo you can see a printed circuit board with LEDs, to which a reflector (light reflector) is attached using three screws. In the center there is a black battery with unknown parameters; there is only a marking of the polarity of the terminals. To the right of the battery there is a printed circuit board for the charger and indication. On the right is a power plug with retractable rods.

Upon closer examination of the LEDs, it turned out that there were black spots or dots on the emitting surfaces of the crystals of all LEDs. It became clear even without checking the LEDs with a multimeter that the flashlight did not light due to their burnout.

There were also blackened areas on the crystals of two LEDs installed as backlight on the battery charging indication board. In LED lamps and strips, one LED usually fails, and acting as a fuse, it protects the others from burning out. And all nine LEDs in the flashlight failed at the same time. The voltage on the battery could not increase to a value that could damage the LEDs. To find out the reason, I had to draw an electrical circuit diagram.

Finding the cause of the flashlight failure

The electrical circuit of the flashlight consists of two functionally complete parts. The part of the circuit located to the left of switch SA1 acts as a charger. And the part of the circuit shown to the right of the switch provides the glow.

The charger works as follows. The voltage from the 220 V household network is supplied to the current-limiting capacitor C1, then to a bridge rectifier assembled on diodes VD1-VD4. From the rectifier, voltage is supplied to the battery terminals. Resistor R1 serves to discharge the capacitor after removing the flashlight plug from the network. This prevents electric shock from capacitor discharge in the event of your hand accidentally touching two pins of the plug at the same time.

LED HL1, connected in series with current-limiting resistor R2 in the opposite direction with the upper right diode of the bridge, as it turns out, always lights up when the plug is inserted into the network, even if the battery is faulty or disconnected from the circuit.

The operating mode switch SA1 is used to connect separate groups of LEDs to the battery. As you can see from the diagram, it turns out that if the flashlight is connected to the network for charging and the switch slide is in position 3 or 4, then the voltage from the battery charger also goes to the LEDs.

If a person turns on the flashlight and discovers that it does not work, and, not knowing that the switch slide must be set to the “off” position, about which nothing is said in the flashlight’s operating instructions, connects the flashlight to the network for charging, then at the expense If there is a voltage surge at the output of the charger, the LEDs will receive a voltage significantly higher than the calculated one. A current that exceeds the permissible current will flow through the LEDs and they will burn out. As an acid battery ages due to sulfation of the lead plates, the battery charge voltage increases, which also leads to LED burnout.

Another circuit solution that surprised me was the parallel connection of seven LEDs, which is unacceptable, since the current-voltage characteristics of even LEDs of the same type are different and therefore the current passing through the LEDs will also not be the same. For this reason, when choosing the value of resistor R4 based on the maximum permissible current flowing through the LEDs, one of them may overload and fail, and this will lead to an overcurrent of parallel-connected LEDs, and they will also burn out.

Rework (modernization) of the electrical circuit of the flashlight

It became obvious that the failure of the flashlight was due to errors made by the developers of its electrical circuit diagram. To repair the flashlight and prevent it from breaking again, you need to redo it, replacing the LEDs and making minor changes to the electrical circuit.

In order for the battery charge indicator to actually signal that it is charging, the HL1 LED must be connected in series with the battery. To light an LED, a current of several milliamps is required, and the current supplied by the charger should be about 100 mA.

To ensure these conditions, it is enough to disconnect the HL1-R2 chain from the circuit in the places indicated by red crosses and install an additional resistor Rd with a nominal value of 47 Ohms and a power of at least 0.5 W in parallel with it. The charge current flowing through Rd will create a voltage drop of about 3 V across it, which will provide the necessary current for the HL1 indicator to light. At the same time, the connection point between HL1 and Rd must be connected to pin 1 of switch SA1. In this simple way, it will be impossible to supply voltage from the charger to the LEDs EL1-EL10 while charging the battery.

To equalize the magnitude of the currents flowing through the LEDs EL3-EL10, it is necessary to exclude resistor R4 from the circuit and connect a separate resistor with a nominal value of 47-56 Ohms in series with each LED.

Electrical diagram after modification

Minor changes made to the circuit increased the information content of the charge indicator of an inexpensive Chinese LED flashlight and greatly increased its reliability. I hope that LED flashlight manufacturers will make changes to the electrical circuits of their products after reading this article.

After modernization, the electrical circuit diagram took the form as in the drawing above. If you need to illuminate the flashlight for a long time and do not require high brightness of its glow, you can additionally install a current-limiting resistor R5, thanks to which the operating time of the flashlight without recharging will double.

LED battery flashlight repair

After disassembly, the first thing you need to do is restore the functionality of the flashlight, and then start upgrading it.

Checking the LEDs with a multimeter confirmed that they were faulty. Therefore, all the LEDs had to be desoldered and the holes freed from solder to install new diodes.

Judging by its appearance, the board was equipped with tube LEDs from the HL-508H series with a diameter of 5 mm. LEDs of type HK5H4U from a linear LED lamp with similar technical characteristics were available. They came in handy for repairing the lantern. When soldering LEDs to the board, you must remember to observe polarity; the anode must be connected to the positive terminal of the battery or battery.

After replacing the LEDs, the PCB was connected to the circuit. The brightness of some LEDs was slightly different from others due to the common current-limiting resistor. To eliminate this drawback, it is necessary to remove resistor R4 and replace it with seven resistors, connected in series with each LED.

To select a resistor that ensures optimal operation of the LED, the dependence of the current flowing through the LED on the value of the series-connected resistance was measured at a voltage of 3.6 V, equal to the voltage of the flashlight battery.

Based on the conditions for using the flashlight (in case of interruptions in the power supply to the apartment), high brightness and illumination range were not required, so the resistor was chosen with a nominal value of 56 Ohms. With such a current-limiting resistor, the LED will operate in light mode, and energy consumption will be economical. If you need to squeeze out maximum brightness from the flashlight, then you should use a resistor, as can be seen from the table, with a nominal value of 33 Ohms and make two modes of operation of the flashlight by turning on another common current-limiting resistor (in the diagram R5) with a nominal value of 5.6 Ohms.

To connect a resistor in series with each LED, you must first prepare the printed circuit board. To do this, you need to cut any one current-carrying path on it, suitable for each LED, and make additional contact pads. The current-carrying paths on the board are protected by a layer of varnish, which must be scraped off with a knife blade to the copper, as in the photograph. Then tin the bare contact pads with solder.

It is better and more convenient to prepare a printed circuit board for mounting resistors and soldering them if the board is mounted on a standard reflector. In this case, the surface of the LED lenses will not be scratched, and it will be more convenient to work.

Connecting the diode board after repair and modernization to the flashlight battery showed that the brightness of all LEDs was sufficient for illumination and the same brightness.

Before I had time to repair the previous lamp, a second one was repaired, with the same fault. I didn’t find any information about the manufacturer or technical specifications on the flashlight body, but judging by the manufacturing style and the cause of the breakdown, the manufacturer is the same, Chinese Lentel.

Based on the date on the flashlight body and on the battery, it was possible to establish that the flashlight was already four years old and, according to its owner, the flashlight worked flawlessly. It is obvious that the flashlight lasted a long time thanks to the warning sign “Do not turn on while charging!” on a hinged lid covering a compartment in which a plug is hidden for connecting the flashlight to the mains for charging the battery.

In this flashlight model, the LEDs are included in the circuit according to the rules; a 33 Ohm resistor is installed in series with each one. The resistor value can be easily recognized by color coding using an online calculator. A check with a multimeter showed that all the LEDs were faulty, and the resistors were also broken.

An analysis of the cause of the failure of the LEDs showed that due to sulfation of the acid battery plates, its internal resistance increased and, as a result, its charging voltage increased several times. During charging, the flashlight was turned on, the current through the LEDs and resistors exceeded the limit, which led to their failure. I had to replace not only the LEDs, but also all the resistors. Based on the above-mentioned operating conditions of the flashlight, resistors with a nominal value of 47 Ohms were chosen for replacement. The resistor value for any type of LED can be calculated using an online calculator.

Redesign of the battery charging mode indication circuit

The flashlight has been repaired, and you can begin making changes to the battery charging indication circuit. To do this, it is necessary to cut the track on the printed circuit board of the charger and indication in such a way that the HL1-R2 chain on the LED side is disconnected from the circuit.

The lead-acid AGM battery was deeply discharged, and an attempt to charge it with a standard charger was unsuccessful. I had to charge the battery using a stationary power supply with a load current limiting function. A voltage of 30 V was applied to the battery, while at the first moment it consumed only a few mA of current. Over time, the current began to increase and after a few hours increased to 100 mA. After fully charging, the battery was installed in the flashlight.

Charging deeply discharged lead-acid AGM batteries with increased voltage as a result of long-term storage allows you to restore their functionality. I have tested the method on AGM batteries more than a dozen times. New batteries that do not want to be charged from standard chargers are restored to almost their original capacity when charged from a constant source at a voltage of 30 V.

The battery was discharged several times by turning on the flashlight in operating mode and charged using a standard charger. The measured charge current was 123 mA, with a voltage at the battery terminals of 6.9 V. Unfortunately, the battery was worn out and was enough to operate the flashlight for 2 hours. That is, the battery capacity was about 0.2 Ah and for long-term operation of the flashlight it is necessary to replace it.

The HL1-R2 chain on the printed circuit board was successfully placed, and it was necessary to cut only one current-carrying path at an angle, as in the photograph. The cutting width must be at least 1 mm. Calculation of the resistor value and testing in practice showed that for stable operation of the battery charging indicator, a 47 Ohm resistor with a power of at least 0.5 W is required.

The photo shows a printed circuit board with a soldered current-limiting resistor. After this modification, the battery charge indicator lights up only if the battery is actually charging.

Modernization of the operating mode switch

To complete the repair and modernization of the lights, it is necessary to resolder the wires at the switch terminals.

In models of flashlights being repaired, a four-position slide-type switch is used to turn on. The middle pin in the photo shown is general. When the switch slide is in the extreme left position, the common terminal is connected to the left terminal of the switch. When moving the switch slide from the extreme left position to one position to the right, its common pin is connected to the second pin and, with further movement of the slide, sequentially to pins 4 and 5.

To the middle common terminal (see photo above) you need to solder a wire coming from the positive terminal of the battery. Thus, it will be possible to connect the battery to a charger or LEDs. To the first pin you can solder the wire coming from the main board with LEDs, to the second you can solder a current-limiting resistor R5 of 5.6 Ohms to be able to switch the flashlight to an energy-saving operating mode. Solder the conductor coming from the charger to the rightmost pin. This will prevent you from turning on the flashlight while the battery is charging.

Repair and modernization
LED rechargeable flashlight "Foton PB-0303"

I received another copy of a series of Chinese-made LED flashlights called the Photon PB-0303 LED spotlight for repair. The flashlight did not respond when the power button was pressed; an attempt to charge the flashlight battery using a charger was unsuccessful.

The flashlight is powerful, expensive, costs about $20. According to the manufacturer, the luminous flux of the flashlight reaches 200 meters, the body is made of impact-resistant ABS plastic, and the kit includes a separate charger and a shoulder strap.

The Photon LED flashlight has good maintainability. To gain access to the electrical circuit, simply unscrew the plastic ring holding the protective glass, rotating the ring counterclockwise when looking at the LEDs.

When repairing any electrical appliances, troubleshooting always starts with the power source. Therefore, the first step was to measure the voltage at the terminals of the acid battery using a multimeter turned on in mode. It was 2.3 V, instead of the required 4.4 V. The battery was completely discharged.

When connecting the charger, the voltage at the battery terminals did not change, it became obvious that the charger was not working. The flashlight was used until the battery was completely discharged, and then it was not used for a long time, which led to a deep discharge of the battery.

It remains to check the serviceability of the LEDs and other elements. To do this, the reflector was removed, for which six screws were unscrewed. On the printed circuit board there were only three LEDs, a chip (chip) in the form of a droplet, a transistor and a diode.

Five wires went from the board and battery into the handle. In order to understand their connection, it was necessary to disassemble it. To do this, use a Phillips screwdriver to unscrew the two screws inside the flashlight, which were located next to the hole into which the wires went.

To detach the flashlight handle from its body, it must be moved away from the mounting screws. This must be done carefully so as not to tear the wires off the board.

As it turned out, there were no radio-electronic elements in the pen. Two white wires were soldered to the terminals of the flashlight on/off button, and the rest to the connector for connecting the charger. A red wire was soldered to pin 1 of the connector (the numbering is conditional), the other end of which was soldered to the positive input of the printed circuit board. A blue-white conductor was soldered to the second contact, the other end of which was soldered to the negative pad of the printed circuit board. A green wire was soldered to pin 3, the second end of which was soldered to the negative terminal of the battery.

Electrical circuit diagram

Having dealt with the wires hidden in the handle, you can draw an electrical circuit diagram of the Photon flashlight.

From the negative terminal of the battery GB1, voltage is supplied to pin 3 of connector X1 and then from its pin 2 through a blue-white conductor it is supplied to the printed circuit board.

Connector X1 is designed in such a way that when the charger plug is not inserted into it, pins 2 and 3 are connected to each other. When the plug is inserted, pins 2 and 3 are disconnected. This ensures automatic disconnection of the electronic part of the circuit from the charger, eliminating the possibility of accidentally turning on the flashlight while charging the battery.

From the positive terminal of battery GB1, voltage is supplied to D1 (microcircuit-chip) and the emitter of a bipolar transistor type S8550. The CHIP performs only the function of a trigger, allowing a button to turn on or off the glow of EL LEDs (⌀8 mm, glow color - white, power 0.5 W, current consumption 100 mA, voltage drop 3 V.). When you first press the S1 button from the D1 chip, a positive voltage is applied to the base of the transistor Q1, it opens and the supply voltage is supplied to the LEDs EL1-EL3, the flashlight turns on. When you press button S1 again, the transistor closes and the flashlight turns off.

From a technical point of view, such a circuit solution is illiterate, since it increases the cost of the flashlight, reduces its reliability, and in addition, due to the voltage drop at the junction of transistor Q1, up to 20% of the battery capacity is lost. Such a circuit solution is justified if it is possible to adjust the brightness of the light beam. In this model, instead of a button, it was enough to install a mechanical switch.

It was surprising that in the circuit, LEDs EL1-EL3 are connected in parallel to the battery like incandescent light bulbs, without current-limiting elements. As a result, when turned on, a current passes through the LEDs, the magnitude of which is limited only by the internal resistance of the battery and when it is fully charged, the current may exceed the permissible value for the LEDs, which will lead to their failure.

Checking the functionality of the electrical circuit

To check the serviceability of the microcircuit, transistor and LEDs, a 4.4 V DC voltage was applied from an external power source with a current limiting function, maintaining polarity, directly to the power pins of the printed circuit board. The current limit value was set to 0.5 A.

After pressing the power button, the LEDs lit up. After pressing again, they went out. The LEDs and the microcircuit with the transistor turned out to be serviceable. All that remains is to figure out the battery and charger.

Acid battery recovery

Since the 1.7 A acid battery was completely discharged, and the standard charger was faulty, I decided to charge it from a stationary power supply. When connecting the battery for charging to a power supply with a set voltage of 9 V, the charging current was less than 1 mA. The voltage was increased to 30 V - the current increased to 5 mA, and after an hour at this voltage it was already 44 mA. Next, the voltage was reduced to 12 V, the current dropped to 7 mA. After 12 hours of charging the battery at a voltage of 12 V, the current rose to 100 mA, and the battery was charged with this current for 15 hours.

The temperature of the battery case was within normal limits, which indicated that the charging current was not used to generate heat, but to accumulate energy. After charging the battery and finalizing the circuit, which will be discussed below, tests were carried out. The flashlight with a restored battery illuminated continuously for 16 hours, after which the brightness of the beam began to decrease and therefore it was turned off.

Using the method described above, I had to repeatedly restore the functionality of deeply discharged small-sized acid batteries. As practice has shown, only serviceable batteries that have been forgotten for some time can be restored. Acid batteries that have exhausted their service life cannot be restored.

Charger repair

Measuring the voltage value with a multimeter on the contacts of the output connector of the charger showed its absence.

Judging by the sticker pasted on the adapter body, it was a power supply that outputs an unstabilized DC voltage of 12 V with a maximum load current of 0.5 A. There were no elements in the electrical circuit that limited the amount of charging current, so the question arose, why in the quality charger, did you use a regular power supply?

When the adapter was opened, a characteristic smell of burnt electrical wiring appeared, which indicated that the transformer winding had burned out.

A continuity test of the primary winding of the transformer showed that it was broken. After cutting the first layer of tape insulating the primary winding of the transformer, a thermal fuse was discovered, designed for an operating temperature of 130°C. Testing showed that both the primary winding and the thermal fuse were faulty.

Repairing the adapter was not economically feasible, since it was necessary to rewind the primary winding of the transformer and install a new thermal fuse. I replaced it with a similar one that was on hand, with a DC voltage of 9 V. The flexible cord with a connector had to be resoldered from a burnt adapter.

The photo shows a drawing of the electrical circuit of a burnt-out power supply (adapter) of the Photon LED flashlight. The replacement adapter was assembled according to the same scheme, only with an output voltage of 9 V. This voltage is quite sufficient to provide the required battery charging current with a voltage of 4.4 V.

Just for fun, I connected the flashlight to a new power supply and measured the charging current. Its value was 620 mA, and this was at a voltage of 9 V. At a voltage of 12 V, the current was about 900 mA, significantly exceeding the load capacity of the adapter and the recommended battery charging current. For this reason, the primary winding of the transformer burned out due to overheating.

Finalization of the electrical circuit diagram
LED rechargeable flashlight "Photon"

To eliminate circuit violations in order to ensure reliable and long-term operation, changes were made to the flashlight circuit and the printed circuit board was modified.

The photo shows the electrical circuit diagram of the converted Photon LED flashlight. Additional installed radio elements are shown in blue. Resistor R2 limits the battery charging current to 120 mA. To increase the charging current, you need to reduce the resistor value. Resistors R3-R5 limit and equalize the current flowing through the LEDs EL1-EL3 when the flashlight is illuminated. The EL4 LED with a series-connected current-limiting resistor R1 is installed to indicate the battery charging process, since the developers of the flashlight did not take care of this.

To install current-limiting resistors on the board, the printed traces were cut, as shown in the photo. The charge current-limiting resistor R2 was soldered at one end to the contact pad, to which the positive wire coming from the charger had previously been soldered, and the soldered wire was soldered to the second terminal of the resistor. An additional wire (yellow in the photo) was soldered to the same contact pad, intended to connect the battery charging indicator.

Resistor R1 and indicator LED EL4 were placed in the flashlight handle, next to the connector for connecting the charger X1. The LED anode pin was soldered to pin 1 of connector X1, and a current-limiting resistor R1 was soldered to the second pin, the cathode of the LED. A wire (yellow in the photo) was soldered to the second terminal of the resistor, connecting it to the terminal of resistor R2, soldered to the printed circuit board. Resistor R2, for ease of installation, could have been placed in the flashlight handle, but since it heats up when charging, I decided to place it in a freer space.

When finalizing the circuit, MLT type resistors with a power of 0.25 W were used, except for R2, which is designed for 0.5 W. The EL4 LED is suitable for any type and color of light.

This photo shows the charging indicator while the battery is charging. Installing an indicator made it possible not only to monitor the battery charging process, but also to monitor the presence of voltage in the network, the health of the power supply and the reliability of its connection.

How to replace a burnt out CHIP

If suddenly a CHIP - a specialized unmarked microcircuit in a Photon LED flashlight, or a similar one assembled according to a similar circuit - fails, then to restore the flashlight's functionality it can be successfully replaced with a mechanical switch.

To do this, you need to remove the D1 chip from the board, and instead of the Q1 transistor switch, connect an ordinary mechanical switch, as shown in the above electrical diagram. The switch on the flashlight body can be installed instead of the S1 button or in any other suitable place.

Repair and alteration of LED flashlight
14Led Smartbuy Colorado

The Smartbuy Colorado LED flashlight stopped turning on, although three new AAA batteries were installed.

The waterproof body was made of anodized aluminum alloy and had a length of 12 cm. The flashlight looked stylish and was easy to use.

How to check batteries for suitability in an LED flashlight

Repair of any electrical device begins with checking the power source, therefore, despite the fact that new batteries were installed in the flashlight, repairs should begin with checking them. In the Smartbuy flashlight, the batteries are installed in a special container, in which they are connected in series using jumpers. In order to gain access to the flashlight batteries, you need to disassemble it by rotating the back cover counterclockwise.

Batteries must be installed in the container, observing the polarity indicated on it. The polarity is also indicated on the container, so it must be inserted into the flashlight body with the side on which the “+” sign is marked.

First of all, it is necessary to visually check all contacts of the container. If there are traces of oxides on them, then the contacts must be cleaned to a shine using sandpaper or the oxide must be scraped off with a knife blade. To prevent re-oxidation of the contacts, they can be lubricated with a thin layer of any machine oil.

Next you need to check the suitability of the batteries. To do this, touching the probes of a multimeter turned on in DC voltage measurement mode, you need to measure the voltage at the contacts of the container. Three batteries are connected in series and each of them should produce a voltage of 1.5 V, therefore the voltage at the terminals of the container should be 4.5 V.

If the voltage is less than specified, then it is necessary to check the correct polarity of the batteries in the container and measure the voltage of each of them individually. Perhaps only one of them sat down.

If everything is in order with the batteries, then you need to insert the container into the flashlight body, observing the polarity, screw on the cap and check its functionality. In this case, you need to pay attention to the spring in the cover, through which the supply voltage is transmitted to the flashlight body and from it directly to the LEDs. There should be no traces of corrosion on its end.

How to check if the switch is working properly

If the batteries are good and the contacts are clean, but the LEDs do not light, then you need to check the switch.

The Smartbuy Colorado flashlight has a sealed push-button switch with two fixed positions, closing the wire coming from the positive terminal of the battery container. When you press the switch button for the first time, its contacts close, and when you press it again, they open.

Since the flashlight contains batteries, you can also check the switch using a multimeter turned on in voltmeter mode. To do this, you need to rotate it counterclockwise, if you look at the LEDs, unscrew its front part and put it aside. Next, touch the body of the flashlight with one multimeter probe, and with the second touch the contact, which is located deep in the center of the plastic part shown in the photo.

The voltmeter should show a voltage of 4.5 V. If there is no voltage, press the switch button. If it is working properly, then voltage will appear. Otherwise, the switch needs to be repaired.

Checking the health of the LEDs

If the previous search steps failed to detect a fault, then at the next stage you need to check the reliability of the contacts supplying the supply voltage to the board with LEDs, the reliability of their soldering and serviceability.

A printed circuit board with LEDs sealed into it is fixed in the head of the flashlight using a steel spring-loaded ring, through which the supply voltage from the negative terminal of the battery container is simultaneously supplied to the LEDs along the flashlight body. The photo shows the ring from the side it presses against the printed circuit board.

The retaining ring is fixed quite tightly, and it was only possible to remove it using the device shown in the photo. You can bend such a hook from a steel strip with your own hands.

After removing the retaining ring, the printed circuit board with LEDs, which is shown in the photo, was easily removed from the head of the flashlight. The absence of current-limiting resistors immediately caught my eye; all 14 LEDs were connected in parallel and directly to the batteries via a switch. Connecting LEDs directly to a battery is unacceptable, since the amount of current flowing through the LEDs is limited only by the internal resistance of the batteries and can damage the LEDs. At best, it will greatly reduce their service life.

Since all the LEDs in the flashlight were connected in parallel, it was not possible to check them with a multimeter turned on in resistance measurement mode. Therefore, the printed circuit board was supplied with a DC supply voltage from an external source of 4.5 V with a current limit of 200 mA. All LEDs lit up. It became obvious that the problem with the flashlight was poor contact between the printed circuit board and the retaining ring.

Current consumption of LED flashlight

Just for fun, I measured the current consumption of LEDs from batteries when they were turned on without a current-limiting resistor.

The current was more than 627 mA. The flashlight is equipped with LEDs of type HL-508H, the operating current of which should not exceed 20 mA. 14 LEDs are connected in parallel, therefore, the total current consumption should not exceed 280 mA. Thus, the current flowing through the LEDs more than doubled the rated current.

Such a forced mode of LED operation is unacceptable, as it leads to overheating of the crystal, and as a result, premature failure of the LEDs. An additional disadvantage is that the batteries drain quickly. They will be enough, if the LEDs do not burn out first, for no more than an hour of operation.

The design of the flashlight did not allow soldering current-limiting resistors in series with each LED, so we had to install one common one for all LEDs. The resistor value had to be determined experimentally. To do this, the flashlight was powered by pants batteries and an ammeter was connected to the gap in the positive wire in series with a 5.1 Ohm resistor. The current was about 200 mA. When installing an 8.2 Ohm resistor, the current consumption was 160 mA, which, as tests showed, is quite sufficient for good lighting at a distance of at least 5 meters. The resistor did not get hot to the touch, so any power will do.

Redesign of the structure

After the study, it became obvious that for reliable and durable operation of the flashlight, it is necessary to additionally install a current-limiting resistor and duplicate the connection of the printed circuit board with the LEDs and the fixing ring with an additional conductor.

If previously it was necessary for the negative bus of the printed circuit board to touch the body of the flashlight, then due to the installation of the resistor, it was necessary to eliminate the contact. To do this, a corner was ground off from the printed circuit board along its entire circumference, from the side of the current-carrying paths, using a needle file.

To prevent the clamping ring from touching the current-carrying tracks when fixing the printed circuit board, four rubber insulators about two millimeters thick were glued onto it with Moment glue, as shown in the photograph. Insulators can be made from any dielectric material, such as plastic or thick cardboard.

The resistor was pre-soldered to the clamping ring, and a piece of wire was soldered to the outermost track of the printed circuit board. An insulating tube was placed over the conductor, and then the wire was soldered to the second terminal of the resistor.

After simply upgrading the flashlight with your own hands, it began to turn on stably and the light beam illuminated objects well at a distance of more than eight meters. Additionally, the battery life has more than tripled, and the reliability of the LEDs has increased many times over.

An analysis of the causes of failure of repaired Chinese LED lights showed that they all failed due to poorly designed electrical circuits. It remains only to find out whether this was done intentionally in order to save on components and shorten the life of the flashlights (so that more people would buy new ones), or as a result of the illiteracy of the developers. I am inclined to the first assumption.

Repair of LED flashlight RED 110

A flashlight with a built-in acid battery from the Chinese manufacturer RED brand was repaired. The flashlight had two emitters: one with a beam in the form of a narrow beam and one emitting diffused light.

The photo shows the appearance of the RED 110 flashlight. I immediately liked the flashlight. Convenient body shape, two operating modes, a loop for hanging around the neck, a retractable plug for connecting to the mains for charging. In the flashlight, the diffused light LED section was shining, but the narrow beam was not.

To make the repair, we first unscrewed the black ring securing the reflector, and then unscrewed one self-tapping screw in the hinge area. The case easily separated into two halves. All parts were secured with self-tapping screws and were easily removed.

The charger circuit was made according to the classical scheme. From the network, through a current-limiting capacitor with a capacity of 1 μF, voltage was supplied to a rectifier bridge of four diodes and then to the battery terminals. The voltage from the battery to the narrow beam LED was supplied through a 460 Ohm current-limiting resistor.

All parts were mounted on a single-sided printed circuit board. The wires were soldered directly to the contact pads. The appearance of the printed circuit board is shown in the photograph.

10 side light LEDs were connected in parallel. The supply voltage was supplied to them through a common current-limiting resistor 3R3 (3.3 Ohms), although according to the rules, a separate resistor must be installed for each LED.

During an external inspection of the narrow beam LED, no defects were found. When power was supplied through the flashlight switch from the battery, voltage was present at the LED terminals, and it heated up. It became obvious that the crystal was broken, and this was confirmed by a continuity test with a multimeter. The resistance was 46 ohms for any connection of the probes to the LED terminals. The LED was faulty and needed to be replaced.

For ease of operation, the wires were unsoldered from the LED board. After freeing the LED leads from the solder, it turned out that the LED was tightly held by the entire plane of the reverse side on the printed circuit board. To separate it, we had to fix the board in the desktop temples. Next, place the sharp end of the knife at the junction of the LED and the board and lightly hit the knife handle with a hammer. The LED bounced off.

As usual, there were no markings on the LED housing. Therefore, it was necessary to determine its parameters and select a suitable replacement. Based on the overall dimensions of the LED, the battery voltage and the size of the current-limiting resistor, it was determined that a 1 W LED (current 350 mA, voltage drop 3 V) would be suitable for replacement. From the “Reference Table of Parameters of Popular SMD LEDs,” a white LED6000Am1W-A120 LED was selected for repair.

The printed circuit board on which the LED is installed is made of aluminum and at the same time serves to remove heat from the LED. Therefore, when installing it, it is necessary to ensure good thermal contact due to the tight fit of the rear plane of the LED to the printed circuit board. To do this, before sealing, thermal paste was applied to the contact areas of the surfaces, which is used when installing a radiator on a computer processor.

In order to ensure a tight fit of the LED plane to the board, you must first place it on the plane and slightly bend the leads upward so that they deviate from the plane by 0.5 mm. Next, tin the terminals with solder, apply thermal paste and install the LED on the board. Next, press it to the board (it’s convenient to do this with a screwdriver with the bit removed) and warm up the leads with a soldering iron. Next, remove the screwdriver, press it with a knife at the bend of the lead to the board and heat it with a soldering iron. After the solder has hardened, remove the knife. Due to the spring properties of the leads, the LED will be pressed tightly to the board.

When installing the LED, polarity must be observed. True, in this case, if a mistake is made, it will be possible to swap the voltage supply wires. The LED is soldered and you can check its operation and measure the current consumption and voltage drop.

The current flowing through the LED was 250 mA, the voltage drop was 3.2 V. Hence the power consumption (you need to multiply the current by the voltage) was 0.8 W. It was possible to increase the operating current of the LED by decreasing the resistance to 460 Ohms, but I did not do this, since the brightness of the glow was sufficient. But the LED will operate in a lighter mode, heat up less, and the flashlight’s operating time on a single charge will increase.

Checking the heating of the LED after operating for an hour showed effective heat dissipation. It heated up to a temperature of no more than 45°C. Sea trials showed a sufficient illumination range in the dark, more than 30 meters.

Replacing a lead acid battery in an LED flashlight

A failed acid battery in an LED flashlight can be replaced with either a similar acid battery or a lithium-ion (Li-ion) or nickel-metal hydride (Ni-MH) AA or AAA battery.

The Chinese lanterns being repaired were equipped with lead-acid AGM batteries of various sizes without markings with a voltage of 3.6 V. According to calculations, the capacity of these batteries ranges from 1.2 to 2 A×hours.

On sale you can find a similar acid battery from a Russian manufacturer for the 4V 1Ah Delta DT 401 UPS, which has an output voltage of 4 V with a capacity of 1 Ah, costing a couple of dollars. To replace it, simply re-solder the two wires, observing the polarity.

After several years of operation, the Lentel GL01 LED flashlight, the repair of which was described at the beginning of the article, was again brought to me for repair. Diagnostics showed that the acid battery had exhausted its service life.

A Delta DT 401 battery was purchased as a replacement, but it turned out that its geometric dimensions were larger than the faulty one. The standard flashlight battery had dimensions of 21x30x54 mm and was 10 mm higher. I had to modify the flashlight body. Therefore, before buying a new battery, make sure that it will fit into the flashlight body.

The stop in the case was removed and a part of the printed circuit board from which a resistor and one LED had previously been soldered off was cut off with a hacksaw.

After modification, the new battery installed well in the flashlight body and now, I hope, will last for many years.

Replacing a lead acid battery
AA or AAA batteries

If it is not possible to purchase a 4V 1Ah Delta DT 401 battery, then it can be successfully replaced with any three AA or AAA size AA or AAA pen-type batteries, which have a voltage of 1.2 V. For this, it is enough connect three batteries in series, observing polarity, using soldering wires. However, such a replacement is not economically feasible, since the cost of three high-quality AA-size AA batteries may exceed the cost of purchasing a new LED flashlight.

But where is the guarantee that there are no errors in the electrical circuit of the new LED flashlight, and it will not have to be modified either. Therefore, I believe that replacing the lead battery in a modified flashlight is advisable, as it will ensure reliable operation of the flashlight for several more years. And it will always be a pleasure to use a flashlight that you have repaired and modernized yourself.

To move or work in the dark, you need a flashlight. They come in different types ranging from small pocket ones to large military or search ones. The design and power of a flashlight depends on its purpose, for example, in order to illuminate a keyhole in a dark entrance, a low-power pocket flashlight is enough, while tourists need a camping flashlight that can shine in all directions, like a kerosene lamp, and a waterproof, impact-resistant flashlight to move around in poor visibility conditions. In this article, we'll look at how to choose a powerful LED rechargeable flashlight for your needs.

Criterias of choice

To make the right choice of LED flashlight, you need to consider a number of factors, including:

1. Type and power of LEDs. Brightness and energy consumption depend on them.
2. Colorful temperature. Comfort during use depends on it.
3. Capacity and type of batteries. Affects the duration of work.
4. Reflector and optical system. It depends on them how focused the light flux will be.
5. Design features. They affect impact resistance, resistance to water and dust, ease of use, carrying and holding in hands.

Types of LEDs

Flashlights can use various LEDs, and every year more and more powerful and brighter models are released. However, this does not prevent us from dividing them into the main types used:

1. 5 mm LEDs. Previously used in all LED flashlights, now this is an outdated type of LEDs, the reason for this is their low brightness and significant energy consumption. To get a strong luminous flux from a flashlight, you have to install many of these LEDs, which is not always possible, since such a flashlight will not fit in your pocket.

The photo below shows an example of flashlights with 5 mm LEDs 5 mm LEDs in flashlights

1. SMD LEDs.

Various types can be used - 5050, 3528, 5730 and others. They have two advantages - high power and small dimensions. This allows you to achieve good luminous flux for small lanterns. Matrixes of such LEDs are installed on camping lanterns and other types of lanterns with a diffused light mode function. It allows you to illuminate a large area from one flashlight with a diffuse beam, albeit with losses of illumination, rather than a focused bright beam.

Panel with diffused light on the flashlight

1. Powerful LEDs 1, 3, 5 Watt. Two groups can be distinguished here:

• Noname LEDs.
• Branded LEDs, for example, the CREE brand and its popular XM-l models and others.

high-power LED flashlight

Accordingly, cheap Chinese LEDs are installed in products in the budget price segment, and branded LEDs are installed in more expensive flashlight models. The differences lie in the specific luminous flux - the number of Lumens per 1 Watt of power, in other words, the efficiency. This determines not only how brightly the flashlight will shine, but also how long it will operate on a single battery charge. It is also observed that cheap high-power LEDs fail faster, like any noname products.

What kind of LEDs are installed in powerful flashlights?

As already mentioned, the most common LEDs are from CREE; we have prepared a summary table with the characteristics of popular LED models for flashlights.

Name	Cree XM-L T6	Cree XM-L2	Cree XP-G2	Cree XR-E
Photo
U, V	2,9	2,85	2,8	3,3
I, mA	700	700	350	350
P, W	2	2	1	1
Operating temperature, °C	<150	<85	<85	<85
Luminous flux, Lm	280	320	145	100
Illumination angle, °	125	125	115	90
Color rendering index, Ra	80-90	70-90	80-90	70-90

And more powerful.

Name	Cree MT-G2	Cree MK-R	Luminus SST-50	Luminus SBT-90
Photo
U, V	5,7; 8,55; 34,2;	6; 12;	3,6	3,5
I, mA	1100; 735; 185;	2500; 1250	5000	9000…13500
P, W	6,3	8,5	18	20…40
Operating temperature, °C	<85	<150	<85	<85
Luminous flux, Lm	440	510	1250	2000…2500
Illumination angle, °	115	120	100	90
Color rendering index, Ra	<70	70-90	80-90	80-90

But LEDs can be designated in a different way, with a more concise marking, for example:

• XM-L: T5, T6, U2.
• XP-G: R4, R5, S2.
• XP-E: Q5, R2, R.
• XR-E: P4, Q3, Q5.

This video shows the process of replacing such an LED.

For flashlights, color temperature is not as important as color temperature for indoor lighting. However, it is worth paying attention to it. is perceived as softer to the eye, and neutral and cool shades make you more alert and focused.
Color temperature of flashlights

Batteries

Now the leading place in sales is occupied by Li-ion batteries. The reason for this is their large capacity with small dimensions, good current output, and almost complete absence of memory effect. There are also disadvantages that should be remembered - in the cold, lithium-ion batteries discharge faster than in the heat, and if a lithium can is short-circuited without protection, a reaction will occur with a large release of heat, even leading to an explosion.
18650 battery

Powerful LED flashlights are most often equipped with lithium batteries; in addition to them, there are also other types of batteries:

• Ni-Cd – nickel-cadmium.
• Ni-Mh – nickel metal hydride.
• Pb – lead.

But recently they are used in flashlights less and less.

Reflector and optical system

The design of the reflector and the presence of lenses affect the shape of the light spot. Some models have the ability to move the lens, which allows you to focus the light beam. The lenses collect the light flux, as a result you get a more illuminated space, but a smaller area than without focusing.

Focusing the light beam

But different tasks require a light beam of different sizes. For example, if the flashlight will be used to repair a car, then in most cases, a model with the ability to focus will be better suited to illuminate a large area when searching for a problem, and then narrow the beam of light to a small but bright point when eliminating it or studying it in detail. At the same time, a focused spot is not needed to move in the dark; flashlights that widely illuminate the space in front of you are better suited.

Types by purpose

In addition to the elements used and their features, when choosing flashlights, they are also distinguished by their purpose. To choose the right LED flashlight for specific tasks, you need to clearly understand what you will use it for, because there are no universal models as such.

Military and special devices

The main feature of military flashlights and special-purpose lighting devices is, first of all, the high strength of the housing and its resistance to moisture. Such devices also include search lights that shine brightly and far away, which allows you to find something in difficult conditions, for example, in a forest or in large rooms.

Models for technical personnel

Flashlights for technical personnel must be compact and have a long operating time. Their size and weight should not complicate the movement of the worker, who already carries tools and parts with him. An excellent addition to such a device would be the ability to focus the light beam and a head mount.
Headlamp

For outdoor recreation and tourism

Search and camping lanterns, as well as those used for military purposes, are suitable for tourists, since the conditions in which they will work are similar - humidity, the possibility of bumps and falls, etc. A camping lantern resembles a kerosene lamp and is a broad-directional or all-directional lighting fixture. It is convenient to use, for example, when preparing for an overnight stay and dinner. You should also pay attention to flashlights with a built-in generator. They can either work without batteries or be recharged by operating the generator lever (rotation or rhythmic pressing on the handle, depending on the design).
Camping lantern

How to convert an ordinary flashlight into an LED one

Let's look at how to make an LED flashlight with your own hands. To do this you will need the following set of parts and tools:

1. Frame. You can take it from an old lantern or make it yourself, or print it on a 3D printer.
2. LEDs. Selected individually.
3. or resistors to limit their current.
4. Battery.
5. A charge controller for batteries or a charger suitable for the type of battery used.
6. Power button or toggle switch.

If you use high-power LEDs, you will need a circuit board on an aluminum substrate.

LED substrate

To improve heat dissipation, you need to use a radiator, you can take it from the motherboard. Small radiators are installed on chipsets, northbridge, power switches and other board elements.
LEDs on the heatsink from the motherboard. Don't forget to coat everything with thermal paste!

To charge and protect the 18650 battery, you can use the TP4056 board with protection, it can be ordered on Aliexpress or bought at a radio store, it costs 20-50 rubles.
Lithium battery charging board based on tp4056

Interesting: This board can be used to replace disposable batteries in a flashlight or to convert any device to batteries.

We pack this in the flashlight body, if it is iron, as in the photo, do not forget to provide insulation for all boards.

To power the LEDs, you can use a specialized driver or a switching boost converter, for example, MT3608. The output voltage is set using a multi-turn potentiometer; in the photo below it can be recognized by its blue housing.

Expert opinion

Alexey Bartosh

Specialist in repair and maintenance of electrical equipment and industrial electronics.

Ask a question to an expert

If you use a driver for power, its main characteristics are the output current and power; it determines how many LEDs you can connect in series.

It is necessary to select a voltage such that the current is 10-30% lower than the rated current. For 1 W LEDs, the rated current is in the range of 300-350 mA.
Boost converter in a flashlight

A less complicated way is to select the operating mode for heating the LEDs. That is, gradually increase the voltage, testing the radiator by touch; it should not heat up, or its temperature should be less than 50 degrees Celsius, this is the temperature when your hand still tolerates it when you touch it and you don’t want to pull it back. This is an imprecise method, so it is better to focus on both current and heating.

Homemade flashlight assembly

The second option is simpler. To replace an incandescent lamp with an LED, you need to take an old light bulb, break the bulb, remove all the insides so that only the base remains. Next, an insulated LED lead with a soldered resistor selected for the appropriate voltage is placed inside the base.
DIY LED light bulb for a flashlight from an ordinary one