A simple indicator of the discharge of Li-ion batteries. Discharge controller Li-Ion on discrete elements About the built-in protection circuit in Li-ion batteries
Everyone knows the advantages of lithium batteries - first of all, this is a high energy density, low weight and the absence of a "memory effect". It is also worth noting that the potential of one lithium battery. (3.6V) is three times that of a single NiCd or NiMH battery (1.2V).
However, lithium batteries have a number of features that do not allow their safe use without special control systems. These systems are called charge and discharge controllers. In today's industry, there are highly integrated microcircuits ready to perform these functions. But, as it turned out, they are not available for mass use. They are not sold in radio parts stores by the piece. They must be ordered from companies specializing in the supply of electronic components for enterprises and repair shops. And the minimum lot in this case is from 10 pieces (this is at best).
All this prompted us to develop our controller on discrete elements available in any provincial radio store.
When discharging a lithium battery. you need to control its voltage and current strength in the circuit.
The voltage on a charged lithium battery. is 4.2V, not 3.6V as it says on it. Up to 3.6V, it drops under a load close to the capacity of the battery. Voltage control is not to give the battery. discharge below 3V. This threshold varies within 0.5 V depending on the chemical composition and geometric shape of the battery. Battery discharge. below 3V, leads to irreversible chemical processes inside the battery, which makes it unsuitable for further use.
To control the current strength in the circuit, it is necessary to provide a shutdown mechanism similar to the machine that is in the electrical panel in each apartment. Those. it must protect against short circuits and turn off when a certain current in the circuit is exceeded. AT general case The maximum discharge current that the battery can deliver. equal to its capacity. For example, accum. with a capacity of 2A h can safely deliver a current of 2A. Battery work at currents exceeding its capacity, it is possible in short-term modes, or in normal mode, if this is indicated in the documentation by the battery manufacturer. In the event of a short circuit, the lithium battery might explode! Be careful!
More about chemical processes, charge and discharge modes of lithium batteries. can be read here Panasonic Lithium Ion Handbook (in English).
It all started with the fact that the battery in my laptop turned off. The laptop was two years old, from the battery. it almost did not work - it was always connected to the network. As I was later told, this could be the cause of the battery failure. Those. it was not a slow dying battery. with a decrease in capacity, on the contrary, the laptop worked from it for five hours, just one fine day, it did not turn on from the battery and that's it. The battery is no longer detected in Windows, and I concluded that the built-in battery controller burned out. batteries. Having disassembled the battery, we saw 6 elements, combined 2 into 3 cells with a series-parallel connection.
By measuring the voltage on each cell, we made sure that they were charged. This once again confirmed the version of the controller failure. During external inspection of the controller, no visible damage was found. I rejected the idea of \u200b\u200brepairing the controller as difficult (on the forums, people wrote about soldering and programming the controller processor). In general, the complexity of this controller made a strong impression. Who knows what really burned out there?
So I ordered a new battery, and I decided to deal with this one later. But in vain!
I took care of them two months later. I tore the elements out of the case, disconnected them from the controller, measured the voltage on them and was very surprised - 4 elements were completely discharged! And on the other two, the voltage was about 1V. Apparently the damaged controller completely discharged 2 cells through itself.
According to the instructions, battery. discharged below 3V, it was necessary to charge with a current of 0.1 from the capacity. These 4 elements could not be charged. No tambourine dancing, freezing and thawing, tapping, etc. didn't help. I had to throw them out. This is the deep overdischarge that kills lithium batteries. The remaining two elements were charged successfully.
The elements were labeled Sanyo UR18650FM 2.6AH. It is immediately clear that the capacity of the element is 2.6 Ah and it is produced by the Japanese corporation Sanyo. Searching the corporation's website led us to a document called . Only the letter M at the end is missing. The document turned out to be very interesting. It contained specifications battery with a capacity of 2.5 Ah, the dimensions coincided with ours.
Deciding to use this document as a guide to action, we set about designing our discharge controller.
From the “Discharge rate characteristics” graph (characteristics of the discharge dynamics), it became clear that the element allows a discharge of up to 2.7V and a current of 2C, i.e. double capacity. Accordingly, our element with a capacity of 2.6A h can produce 5.2A.
discharge controller
Having comprehensively analyzed this document and other reference literature, Skvortsov Vladimir Nikolaevich (not to be confused with Starling) created a controller to work with one or two lithium cells. The controller protects the cells from short circuits and overdischarge.
The controller circuit shown in the figure provides load disconnection when the battery voltage drops to 6V (3V for each element). A short circuit is considered a current strength above 4A.
To use a controller with one element (shutdown at 3V), you need to select (increase) the resistor R1 - it is responsible for the response threshold when the voltage drops. You also need to take into account the individual characteristics of the transistor VT1 (tolerance% deviation).
To control the current strength, a resistor R7 is selected. The smaller its value, the more current the controller passes.
As a transistor VT3, you can use any powerful field-effect transistor with a current margin of 3 times the battery capacity, for example 15N03.
The principle and modes of operation of the controller
Power on, normal mode
When a battery of two charged batteries (8.4V) is connected, the VT4 transistor opens. Due to the base current through R4, the voltage at the VT4 emitter becomes about 0.7V. Also, resistor R4 keeps VT2 closed.
When VT4 is opened, a current begins to flow through the R1-R2 divider, which creates a voltage drop across R1, and VT1 opens. The voltage on its drain becomes close to the voltage on the battery. Through the resistor R3, it is fed to the gate VT3 and it opens. In this case, the "-" battery through R7 and open VT3 is connected to the output terminal "-". The controller turned on.
Overdischarge protection
When the battery voltage the battery reaches 6V (3V on each element), the voltage at the R1-R2 divider decreases, the voltage at the VT1 gate also decreases to the closing threshold, VT1 closes. The shutter VT3 is connected through R5 to the "-" battery. batteries, so VT3 also closes. The load is turned off. To bring the controller to its original state, you need to disconnect the load and charge the battery.
When testing assembled circuit you need to connect at least some minimum load to it, for example, LEDs. The protection mechanism works only with the connected load, in addition, the LEDs will clearly indicate the disconnection of the load.
Short circuit protection
The short circuit current is set by R7. The smaller its value, the more current the controller passes. The circuit in Figure 1 uses a 0.1 ohm resistor. With such a resistor, the controller allows current up to 4A, more current is considered a short circuit. When working at high currents, the resistor R7 must be of sufficient power - at least 1W.
When the permissible current is exceeded, the voltage drop across R7 + the voltage drop at the source - the drain of VT3 increases to the opening level of VT2. Open VT2 connects the VT3 gate to the "-" battery, VT3 closes. The drain VT3 as well as the base VT4 and the gate VT2 are connected to the “+” of the battery through the load. VT4 closes, the voltage on the divider R1-R2 is about 0, VT1 also closes. The load is turned off. To bring the controller to its original state, you need to disconnect the load.
Printed circuit board
The printed circuit board in Sprint-Layout 4 format can be downloaded in rar, 5Kb.
If you do not have this program, you can download it in rar, 1Mb.
The dimensions of the device (30 x 16mm) were chosen for the possibility of its installation in the end of the battery. batteries.
Device photos
Please note that the base of the transistor VT4 (KT3107) and the gate VT2 (2SK583) are conductors on the reverse side of the printed circuit board.
Battery preparation
Do not use batteries in the same device different types and stamps. It is better and safer to find identical elements.
When using two elements, you need to balance their initial potential - i.e. they should have the same voltage. To do this, connect their negative poles (minuses) directly, and the positive ones through a 30 Ohm resistor. The power of the resistor is 1 or 2 watts. Then you need to measure the voltage at the terminals of the resistor. If it is more than 10 millivolts, you need to wait. You have to wait about a day. It turns out that a more charged battery is slowly discharged through a resistor to a less charged one. That. voltage equalizes. Balanced elements can be connected directly without a resistor - in series or in parallel.
A little clarification about the serial connection. Factory integrated controllers discharge monitor the voltage on each of the series-connected elements. Our controller only controls the total output voltage. Measurements have shown that when using balanced cells, the voltage difference across the cells is 5 - 8 millivolts. This is perfectly acceptable. Therefore, there is no need to install a separate controller on each element.
charge theory
Factory charge controllers control voltage, current and charge time, select normal or gentle mode. If the voltage on the cell is above 3V, it is charging normally. The charging process in this case goes in 2 stages:
Stage 1 - charging with direct current (Constant current - CC);
Stage 2 - charging with constant voltage (Constant voltage - CV).
The maximum charge current depends on the capacity (C) of the battery, as a rule it is 0.7C or 1.0C. For our cells, the charge current was indicated in the document, and was equal to 0.7C. Charge voltage 4.2V (for one cell).
The power supply for charging one battery must have a voltage of 4.2V and provide a current of 0.7C (where C is the battery capacity, in our case 2.6 0.7 \u003d 1.82A). If the elements are connected in series, then the charge voltage doubles - 8.4V. If in parallel, the current strength doubles 2 0.7C \u003d 1.4C, and the voltage remains 4.2V.
The Charge characteristics graph shows both stages of charging. At the first stage, through the battery. pass a current of 0.7C. The main thing here is not to let the current rise above this value. At the same time, the voltage on the element gradually increases from 3 to 4.2V. The stage is called D.C.(CC), this means that while the voltage is increasing, the current remains constant.
The first stage ends when the voltage on the element reaches 4.2V. This is indicated by the red number 1 on the graph. From this moment, the second stage begins - constant pressure(CV). This means that the voltage remains constant at 4.2V, and the current gradually decreases to a vanishingly small value. The moment of the beginning of the decrease in the current strength is indicated on the graph by the red number 2.
As can be seen from the graph, 80% of the capacity gain falls on the first stage.
Factory controllers consider charging complete when the current drops to set value- as a rule, it is 0.1C. In our graph, this is 50 milliamps. Also, some factory controllers monitor charging time. If for certain time the battery is not fully charged (the current has not dropped to desired value), the controller also stops charging. The charge time depends on the capacity and charge current, and is indicated in the documentation. For our battery, this is 3 hours at a current strength of 0.7C.
The gentle charge mode is selected by the controller if the voltage on the battery was below 3V. Such an element is considered to be deeply discharged, and it must be charged carefully. In this case, charging starts from the Precharge stage. At this stage, the charge current is set to 0.1 of the capacity (0.1C). With this current, the voltage on the element is slowly raised to 3V. And then everything is as usual.
If you use serviceable elements and do not discharge them below 3V, you can completely get by with improvised means. To do this, you need a power supply with a voltage of 4.2 or 8.4V and current limiting. The end of the charge can be tracked by current strength or not tracked at all, but turn off the power supply after 2 or 3 hours.
In the near future, we will publish ways to refine conventional power supplies to meet the above characteristics.
To be continued…
Development of the device and printed circuit board - Skvortsov Vladimir Nikolaevich
Statement of the problem, submission and design of the material - Ugreninov Vitaly
Tyumen-Kosmopoisk, 2009
Sources used
Mini - USB charging Joint technical group TEGIR. expeditionary energy.
Lithium Ion Handbook Panasonic industrial
UR18650F Specifications SANYO Mobile Energy Company
Lithium ion Battery lineup SANYO Mobile Energy Company
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This is how the charge controller board looks like, removed from the NOKIA BL-6Q battery and its circuit diagram.
Let's see how it works. The battery is connected to two pads located on the sides of the controller (B- and B+). There are two microcircuits on the printed circuit board - TPCS8210 and HY2110CB.
The task of the controller is to maintain the voltage on the battery within 4.3 - 2.4 volts to protect it from overcharging and overdischarging. In the normal discharge (or charge) mode, the HY2110CB chip outputs voltage to the OD and OS pins high level, which is slightly less than the battery voltage.
This voltage keeps the FETs of the TPCS8210 chip constantly open, through which the battery is connected to the load (your device).
When the battery is discharged, as soon as the voltage on the battery drops below 2.4 volts, the overdischarge detector of the HY2110CB chip will work and voltage will no longer be output to the OD output. The upper (according to the diagram) transistor of the TPCS8210 chip will close and thus the battery will be disconnected from the load.
When charging the battery, as soon as the voltage on the battery reaches 4.3 volts, the overcharge detector of the HY2110CB chip will work and the voltage will no longer be output to the OC output. The lower (according to the diagram) transistor of the TPCS8210 chip will close and the battery will also be disconnected from the load.
Alternative replacement method
As you can see from the diagram, none of the microcircuits has any output for transmitting information about the battery status to your device. The output of the controller "K" is simply connected through a resistor of a certain value to the negative terminal of the battery. Therefore, no "secret" information is received from the battery controller. In some models of controllers, instead of a fixed resistor, a thermistor is installed to control the temperature of the battery.
By the value of this resistor, your device can determine the type of battery, or turn off if this value does not match the desired values.
This means that to replace such a battery with a battery from another manufacturer, it is not necessary to change the charge controller, just measure the resistor between the "-" and "K" terminals and connect the "K" terminal of the device to the battery minus through an external resistor of the same value.
The documentation for the HY2110CB chip used in the controller can be downloaded, and for the TPCS8210 chip -.
Let's take an example e-book LBOOK V5, how to most accurately make an analogue of a battery using knowledge about the charge controller device. All work is carried out in the following sequence:
- Finding a battery cell phone, closest to the native in size and capacity. In our case, this is NOKIA BL-4U. (Right in picture)
- We bite off the wire from the native battery in such a way that the remaining part on the connector is enough to solder a new battery, and the remaining part on the old battery is enough to strip the conductors and measure with a tester.
- We take any digital tester and set the resistance measurement mode on it, the measurement limit is 200 Kom. We connect it to the negative terminal and the output of the controller of the native battery. We measure the resistance.
- We turn off the device. We are looking for the nearest resistor value. In our case, this is 62 Kom.
- Solder a resistor between the negative terminal of the new battery and the controller output wire on the connector. (Yellow wire in the picture).
- Solder the terminals of the "+" and "-" connectors, respectively, to the positive and negative terminals of the new battery. (Red and black wires in the picture).
How tightly Li-ion batteries have entered our lives. The fact that they are used in almost all microprocessor electronics is already the norm. So radio amateurs have long adopted them and use them in their homemade products. Contribute to this significant advantages Li-ion batteries, such as small size, large capacity, a wide range of designs of various capacities and shapes.
The most common battery is 18650, its voltage is 3.7 V. For which I will make a discharge indicator.
Probably, it’s not worth telling how low their discharge is harmful to the crane batteries. And for batteries of all varieties. Proper operation batteries will extend their life several times and save you money.
Charging indicator circuit
The circuit is quite versatile and can operate in the range of 3-15 volts. The response threshold can be adjusted with a variable resistor. So the device can be used for almost any battery, be it acid, nickel-cadmium (nicd) or lithium-ion (Li-ion).
The circuit monitors the voltage and as soon as it falls below a predetermined level, the LED will light up, signaling a low battery discharge.
The circuit uses an adjustable one (link where I took it). In general, this zener diode is a very interesting radio element that can make life easier for radio amateurs when building circuits based on stabilization or threshold operation. So take it into service, especially when building power supplies, current stabilization circuits, etc.
The transistor can be replaced by any other NPN structure, the domestic analogue of KT315, KT3102.
R2- adjusts the brightness of the LED.
R1 is a variable resistor with a rating of 50 to 150 kOhm.
The value of R3 can be added up to 20-30 kΩ to save power if a high gain transistor is used.
If you do not have an adjustable TL431 stabilizer, then you can use a proven Soviet two-transistor circuit.
The operating threshold is set by resistors R2, R3. Instead, one variable can be soldered to allow adjustment and reduce the number of elements. Soviet transistors can be replaced with BC237, BC238, BC317 (KT3102) and BC556, BC557 (KT3107).
The circuit can be assembled on the board or surface-mounted. Put on a heat shrink tube and blow it with a hot air gun. Attach with double sided tape to the back of the case. I personally installed this fee into a screwdriver and now I don’t drive its batteries to a critical discharge.
You can also connect a buzzer (tweeter) in parallel with a resistor with an LED, and then you will definitely know about critical thresholds.
It will be about very convenient fee with charge controller based on TP4056. The board additionally has protection for li-ion 3.7V batteries.
Suitable for reworking toys and household appliances from batteries to accumulators.
This is a cheap and efficient module (charging current up to 1A).
Although a lot has already been written about modules on the TP4056 chip, I will add a little from myself.
More recently, I learned about, which cost a little more, are slightly larger in size, but additionally include a BMS module () to control and protect the battery from overdischarge and overcharge based on the S-8205A and DW01, which turn off the battery when the voltage on it is exceeded . 
The boards are designed to work with 18650 cells (mainly due to the charging current of 1A), but with some alteration (soldering the resistor - reducing the charging current) they are suitable for any 3.7V batteries.
The layout of the board is convenient - there are solder pads for input, output and for the battery. Modules can be powered by Micro USB. The charging status is displayed by the built-in LED.
Dimensions are approximately 27 by 17 mm, the thickness is small, the “thickest” place is the MicroUSB connector 
Specifications:
Type: Charger module
Input Voltage: 5V Recommended
Charge Cut-off Voltage: 4.2V (±)1%
Maximum Charging Current: 1000mA
Battery Over-discharge Protection Voltage: 2.5V
Battery Over-current Protection Current: 3A
Board Size: Approx. 27*17mm
Status LED: Red: Charging; Green: Complete Charging
Package Weight: 9g
The link in the header sells a lot of five pieces, that is, the price of one board is about $0.6. It's slightly more expensive than a single charging board on the TP4056, but without protection - these are sold in packs for a dollar and a half. But for normal operation, you need to buy a separate BMS. 
Briefly about adjusting the charging current for TP4056
TP4056 charge controller module + battery protection
Provides overcharge, overdischarge, triple overload and short circuit protection.
Max Charging Current: 1A
Maximum continuous discharge current: 1A (peak 1.5A)
Charging voltage limit: 4.275 V ±0. 025 V
Limitation (cutoff) of discharge: 2.75 V ±0. 1 V
Battery protection, chip: DW01.
B+ connects to the positive terminal of the battery
B- connects to the negative terminal of the battery
P- is connected to the negative terminal of the load and charge connection point.
There is R3 on the board (marking 122 - 1.2 kOhm), to select the desired charging current for the element, select the resistor according to the table and solder it. 
Just in case typical inclusion TP4056 from specification. 
The lot of TP4056 + BMS modules is taken not for the first time, it turned out to be very convenient for hassle-free alterations of household appliances and toys to batteries.
The dimensions of the modules are small, just less than two AA batteries in width, flat - they are great for installing old batteries from cell phones.
For charging, a standard 5V source from USB is used, the input is MicroUSB. If the boards are used in cascade, you can solder to the first one in parallel, the photo shows the minus and plus contacts on the sides of the MicroUSB connector.
There is nothing on the reverse side - this can help when attaching to glue or tape.
MicroUSB connectors are used for power supply. Old boards on the TP4056 had MiniUSB.
You can solder the boards together at the input and only connect one to USB - this way you can charge 18650 cascades, for example, for screwdrivers.
Outputs - extreme pads for connecting the load (OUT +/-), in the middle BAT +/- for connecting the battery cell.
The fee is small and convenient. Unlike just modules on the TP4056, there is battery cell protection here.
For cascading, you need to connect the load outputs (OUT +/–) in series, and the power inputs in parallel.
The module is ideal for installation in various Appliances and toys that are powered by 2-3-4-5 AA or AAA cells. This, firstly, brings some savings, especially with frequent replacement of batteries (in toys), and, secondly, convenience and versatility. You can use for power elements taken from old batteries from laptops, cell phones, disposable electronic cigarettes, and so on. In case there are three elements, four, six and so on, you need to use the StepUp module to increase the voltage from 3.7V to 4.5V/6.0V, etc. Depending on the load, of course. Also convenient is the option on two battery cells (2S, two boards in series, 7.4V) with a StepDown board. As a rule, StepDown are adjustable, and you can adjust any voltage within the supply voltage. This is an extra volume to place instead of AA / AAA batteries, but then you don’t have to worry about the electronics of the toy.
Specifically, one of the boards was designed for an old IKEA mixer. Very often it was necessary to replace the batteries in it, and it worked poorly on batteries (in NiMH 1.2V instead of 1.5V). The motor doesn't care if it is powered by 3V or 3.7V, so I did without StepDown. It even turned a little more vigorously.
The 08570 battery from an electronic cigarette is almost ideal for any alterations (capacity is about 280mAh, and the price is free).
But in this case, it's a bit long. The length of the AA battery is 50 mm, and this battery is 57 mm, did not fit. You can, of course, make a “superstructure”, for example, from polymorph plastic, but ...
As a result, I took a small model battery with the same capacity. It is highly desirable to reduce the charging current (up to 250 ... 300 mA) by increasing the resistor R3 on the board. You can heat the regular one, bend one end, and solder any available 2-3 kOhm.
On the left, I brought a picture according to the old module. On the new module, the placement of the components is different, but all the same elements are present. 
We connect the battery (Solder) to the terminals in the middle of BAT +/–, solder the motor contacts from the contactor plates for AA batteries (we remove them altogether), solder the motor load to the board output (OUT +/–).
You can cut a USB hole in the lid with a Dremel. 
I made a new cover - the old one was completely thrown out. The new slots are thought out for placing the board and a hole for MicroUSB. 
Gif of the mixer from the battery - it spins briskly. The 280mAh capacity is enough for a few minutes of work, you have to charge it in 3-6 days, depending on how often you use it (I rarely use it, you can plant it at once if you get carried away.). Due to the decrease in charging current, it charges for a long time, a little less than an hour. But any charging from a smartphone. 
If you use a StepDown controller for RC cars, then it's better to take two 18650 and two boards and connect them in series (and the charging inputs in parallel), as in the picture. Where the common OUT is placed any step-down module and adjusted to the desired voltage (for example, 4.5V / 6.0V) In this case, the machine will not drive slowly when the batteries run out. In the event of a discharge, the module will simply turn off abruptly.
The module on the TP4056 with built-in BMS protection is very practical and versatile.
The module is designed for a charging current of 1A.
If you connect in a cascade, take into account the total current when charging, for example, 4 cascades to power the batteries of a screwdriver will “ask” 4A for charging, and this charger from a cell phone will not stand it.
The module is convenient for remaking toys - radio-controlled cars, robots, various lamps, remote controls ... - all possible toys and equipment where you have to change batteries often.
Update: if the minus is through, then everything is more complicated with parallelization.
See comments.
The product was provided for writing a review by the store. The review is published in accordance with clause 18 of the Site Rules.
I plan to buy +57 Add to favorites Liked the review +29 +62The article “Repair and modernization of LED lights” discusses in detail the issue of repairing and refining the electrical circuits of Chinese LED lights, replacing a failed acid battery with an analog.
But there is another option for replacing the battery when repairing a flashlight - replacing it with a lithium-ion battery from faulty electronic devices. For example, a cell phone, camera, laptop or screwdriver. Batteries are also suitable, which no longer provide the required duration of the device, but are still operational.
The first lithium-ion battery was released in 1991 by the Japanese corporation Sony. The nominal voltage of one battery cell is 3.7 V. The minimum allowable is 2.75 V. The charge voltage should not exceed 4.2 V at a charge current of 0.1 to 1 battery capacity (C). Lithium-ion batteries practically do not have a memory effect and have a low self-discharge current, at room temperature no more than 20% per year. At the moment, in terms of technical characteristics, they are the best.
Previously, I had to repair and upgrade an LED flashlight in which all the LEDs burned out. After repair, after several years of operation, it stopped shining due to the failure of the lead battery. As you can see in the photo, his body was swollen.
So the flashlight was gathering dust on the shelf until the lithium-ion battery from the camera failed. The analysis showed that the balance and charge controller failed in the battery. Two battery cells were in good technical condition, which I decided to install in a flashlight instead of an acid battery.
Standard charger for the flashlight lithium ion battery was not suitable, as it provided a constant charge current with an uncontrolled voltage. And for a lithium-ion battery, when charging, it is necessary to provide a charging current of 0.1-1C at a voltage not exceeding 4.2 V per cell.
Controller selection
for charging a lithium-ion battery
You can make the controller yourself, but on sale, for example, on Aliexpress, ready-made ones are sold at a price of 0.2-0.3 cents, assembled on the TP4056 chip or its analogues (ACE4054, BL4054, CX9058, CYT5026, EC49016, MCP73831, LTC4054, LC6000 , LP4054, LN5060, TP4054, SGM4054, U4054, WPM4054, IT4504, PT6102, PT6181, Y1880, VS6102, HX6001, Q7051).
Aliexpress bought the simplest controller module, the technical characteristics of which fully meet the requirements for charging a lithium-ion battery installed in a flashlight. His appearance shown in the photo.
The controller is assembled according to the above electrical diagram. By changing the value of the resistor coming from the second output of the microcircuit to the common wire, you can limit the maximum charging current.
The choice of Li-ion battery charging current is determined based on two restrictions. The current value should be within 0.1-1 of the battery capacity (usually denoted by the letter C). For example, for a battery with a capacity of 600 mAh, the current should not exceed 0.6 A. Therefore, it is necessary that the value of the current-setting resistor be 2 kOhm (the resistor should be marked 202). And do not exceed the amount of current that the charger can provide. For this case, the current must be more than 0.6 A. The current is always indicated on the charger label.
| TP4056 Controller Specifications | ||
|---|---|---|
| Name | Meaning | Note |
| Input voltage, V | 4,5-8,0 | More than 5.5 V is not recommended |
| Output voltage, V | 4,2 | |
| Maximum charge current, A | 1,0 | Can be changed by R value from pin 2 |
| Minimum charge current, A | 0,03 | With less current, it will go to sleep |
| Auto power off | there is | At charging current |
| Operation indicator | there is | Red-charge, blue-charged |
| Voltage monitoring, V | 4,0 | If lower, then charging is turned on. |
| Reverse polarity protection | No | Battery reversal is not allowed |
| input connector | Micro USB | Has pins for soldering |
| output connector | No | Has pins for soldering |
| Overall dimensions, mm | 19×27 | |
| Module weight, gr | 1,9 | |
It is worth noting that if you confuse the polarity of connecting the battery to the output of the controller, then the chip will immediately break through and the voltage supplied to the controller will begin to flow to the battery terminals, which can damage it.
After charging Li-ion, the battery from the controller does not need to be disconnected. In sleep mode or when the controller is not powered, it does not drain the battery.
In this controller circuit, the shutdown function is not enabled when the battery is heated above the permissible temperature. But it can be turned on if the output 1 of the microcircuit is disconnected from the common wire and connected to the output of the battery temperature sensor (these are in the batteries of all cell phones).
If there is a need to use a controller that has protection against polarity reversal when connecting the battery and short circuiting the output, then you can use the controller shown in the photo.
In addition to the TP4056 chip, a DW01A (protection circuit) and a chip with two key field-effect transistors SF8205A are installed. The protection time is several minutes at a current of 3A. The rest of the specifications have not changed.
In the flashlight, the batteries are connected to the controller by soldering. Therefore, a controller without a protection scheme was chosen, which was presented first in the article.
Installing the lithium-ion battery
in LED lantern
Before starting work, you need to check the performance of the controller and battery.
The controller can be energized without load. In this case, the output voltage is set to 4.2 V and the blue LED on the board is lit. Next, you need to check the battery by connecting it to the output of the controller and fully charging it. During charging, the red LED will shine, and when the battery is charged, it will turn blue.
It is advisable to carry out sea trials of the battery after charging, connect it instead of the acid one and see how long the flashlight will shine. I worked for 10 hours and continued to shine. I did not wait any longer, since this time is quite enough for my tasks.
New electrical circuit of the LED lamp
The next step is to develop a new electric circuit diagram lantern. The negative wire is common to all nodes and the battery. In the left position of the SA1 switch, its common contact connects the battery to the positive terminal of the controller. When connecting the middle pin to pin 3, voltage is supplied to the narrow beam board, and with pin 4 to the ambient light LED bar.
The SA2 toggle switch is used to select the battery from which the LEDs will work. Since there were two batteries available, I decided to install both in the flashlight. There is no unequivocal answer to the question of the admissibility of parallel connection of lithium-ion batteries without a special controller. Therefore, I decided to go the proven route and provided the ability to connect the batteries separately.
A separate connection of each battery made it possible not only to ensure their operation and charging in optimal conditions, but also to know how long it will work during the operation of the flashlight. Knowing how much time was enough to work from one battery, it will be known how much more the flashlight can illuminate.
In addition, if one of the batteries fails, this will not lead to loss of flashlight performance. Two separate LED arrays and two batteries ensure that you are never left in the dark.
Assembling a flashlight on a lithium-ion battery
Now everything is ready and you can start upgrading the flashlight - altering its circuit to work with a lithium-ion battery.
First, all wires are soldered from the switch and the old board is removed. charger.
In the body of the upgraded flashlight there was a compartment designed for a short power cord, which was closed with a folding bar with diffused light LEDs. The lever of the toggle switch SA2 for selecting the battery was brought into it.
To fix the batteries, double-sided tape was used, in the form of two strips. Batteries can also be fixed with silicone.
Before fixing the batteries and the controller board, wires of the required length were pre-soldered to them with a soldering iron. Due to the fact that two batteries in one half of the body of the flashlight were not conveniently placed, I installed them one by one in each half of the body. The controller board was fixed to the case with two screws with M2 nuts.
When soldering wires to the battery terminals, care must be taken so that the free ends of the wires do not accidentally touch and short-circuit its terminals.
The photo shows the lantern after installation. It remains to check its operation of the nodes and collect.
It is impossible to measure the charging current by including an ammeter in the open circuit after the controller, since internal resistance instrument is large and the measurement results will be incorrect. I have a USB tester available, with which you can find out the voltage supplied from the charger, the current charge current, charge time and the energy capacity that the battery has received. The tester showed that the controller charges the battery with a current of 0.42 A. Therefore, the controller charges the battery normally.
After assembling the flashlight, it turned out that its red body does not transmit blue light, and it is impossible to find out about the end of charging.
I had to disassemble the lantern and make a slotted hole in the area where the indicator LEDs are located.
Now that the battery is charged, the blue LED is clearly visible.
About choosing a lithium-ion battery for a flashlight
Any lithium-ion battery is suitable for upgrading the flashlight, regardless of the material from which its positive electrode is made and the form factor (shape and geometric dimensions). The capacity of the battery (expressed in Ah) does not matter either, just the larger it is, the longer the flashlight will shine.
It should be noted that if a battery that has been in use for a long time is installed in the flashlight, then its actual capacity, as a rule, is much less than indicated on its label.
You can check the feasibility of installing an old battery in a flashlight by measuring its capacity when charging, which will require the presence of measuring instruments, at least a USB tester. Or charge the battery completely, connect it to the lamp's LED board and check the sufficiency of its operation time.
If the battery is insufficient in capacity, you will have to purchase a new one. The most suitable for the flashlight is the popular Li-ion battery type 18650.
About the built-in protection circuit in Li-ion batteries
There are lithium-ion batteries that have a built-in protection circuit board (PCB - power control board) against short circuit, overcharge and deep discharge. Such protection is mandatory installed in batteries of expensive equipment, such as cell phones, cameras, laptops.
The round-shaped protection board can also be installed at the end of the AA battery. In this case, the battery is somewhat longer and has the inscription “Protected” on its body.
The photo shows the opened case of a cell phone battery. It has printed circuit board protection scheme. When used to install a cell phone battery in a flashlight, this circuit will serve as additional protection, therefore, if it is serviceable, then it should not be deleted.
Solder the wires, observing the polarity, to the extreme contacts, next to which the polarity marking is applied.
The protection circuit, unlike the controller, does not limit the charging current, but only protects the battery. This is the difference between these nodes.
How to restore a Li-ion battery
after deep discharge
If a Li-ion battery quickly charges and discharges, then it has exhausted its resource and cannot be restored.
If the battery does not have a protection circuit and the voltage at its terminals is zero, then the battery cannot be restored either.
If a protection circuit is built into the battery and it does not accept a charge, and the voltage at its terminals is zero, then you can try to restore it.
The reason for this behavior may be a deep discharge resulting from long-term storage of the battery in a discharged state. If the voltage at the terminals of the can becomes less than 2.8 V, then the protection system regards this as an internal short circuit and, for safety, blocks the possibility of charging it.
To understand the reason, you need to measure the voltage at the battery terminals with a voltmeter. If the value is less than 2.8 V, then apply from the controller, observing the polarity, a voltage of 4.2 V directly to the battery terminals. The battery protection circuit does not need to be disabled, it is safe for it.
If the charging current has started, then after ten minutes, disconnect the controller from the battery and again measure the voltage at its terminals. If it has become more than 2.8 V, then try charging through the protection circuit. If the voltage is close to zero and does not increase, then the battery is faulty and cannot be further used. If the voltage increased, but did not reach 2.8 V, then continue charging directly.
If the battery begins to charge through the protection circuit, then it is working. AT otherwise the diagram needs to be deleted. To use the battery for a flashlight, a protection circuit is not required.
In this simple way, you can test a LI-ion battery and, if possible, restore its performance.
Conclusion
Replacing the acid battery in led lamp lithium-ion allows to solve the main issue - the performance of the flashlight for a long time with its rare use, since the self-discharge of the battery does not exceed 2% of its capacity per month.
In addition, in the presence of a lithium-ion battery from any failed electronic device, you can save money and the flashlight will become much easier.
