How to charge rechargeable batteries. How to properly charge batteries. By type of chemical reaction

Did the battery from your camera, flashlight, children's toy or other necessary device suddenly run out? Such an eventuality cannot be foreseen. Unless you use special batteries with indicators. Or be careful not to carry a replacement with you. How to charge batteries at home? We will share with you useful instructions and recommendations.

What batteries can be charged?

Not every AA battery can be filled with energy using a homemade method. What batteries can be charged? Only finger alkaline (alkaline). But under no circumstances should you eat salt! The possibility of leakage or explosion of the product cannot be ruled out.

Method 1: Charger

We figured out whether the battery can be charged. If you constantly use such AA batteries, then the easiest way for you is to buy a special Charger for them. Such a device will help to “breathe life” into the battery without unnecessary hassle.

However, the method also has significant drawbacks. Each charge reduces battery life by one third. In addition, the procedure may cause leakage of its composition.

Method 2: Power Supply

Let's look at how to charge batteries at home. For this method, you will need a power supply and wires to connect to it. Everything is in place? Here are the instructions for action:

When receiving a rechargeable AA battery using this method, pay attention to these recommendations:

• The process will not work if you reverse the polarity when connecting the wires. Moreover, in this way you will destroy the remaining charge in the element.
• Using the described method, the battery can be charged 1-2 times.
• The method is only suitable for finger-type alkaline cells!
• The procedure can be performed in any environmental conditions (with the exception of the freezer stage).

Method 3: Heating

You can also restore the battery charge by regular heating. But be careful - this method can cause the product to explode!

The simplest thing is this:

Method 4: Volume reduction

The method is quite incomprehensible and exotic at first glance. We need to reduce the size of the battery so that the charge in it is restored on its own.

What should you do for this? Mechanically reduce and make the body volume thinner. To do this, the battery is hit against something hard - asphalt, wall, stone, brick, etc. Or they simply trample on it with thick shoes. You can try to flatten it with a handy tool - for example, pliers.

This method will charge all AA batteries. It must be said that such a “barbaric” method helps restore the charge in some cases even to 100%!

Method 5: exposure to solutions

We continue to look at how to charge batteries at home. Within this method, two methods can be distinguished.

Instructions for the first:

How to charge batteries at home in another way:

1. Use an awl or similar tool to make holes in the battery caps next to the carbon rod. The depth of each should be within 3/4 of the height of the entire battery.
2. Pour liquid into the hole. You can take not ordinary water, but a solution of double vinegar or hydrochloric acid (no more than 8-10%).
3. To sufficiently saturate the base, you need to repeat the pouring procedure several times, maintaining time intervals so that the composition has time to be absorbed.
4. Finally, be sure to seal the holes. For these purposes, it is best to use resin or plasticine.
5. Now you can use the battery - its charge should be restored to 70-80%.

Now you know how to charge a AA alkaline battery. Choose any method convenient for you. And, most importantly, be extremely careful! Careless actions may cause the battery to explode!

IN modern world There are many devices and rechargeable batteries are already a necessity. While some people change one battery after another, others simply charge the battery. In order for the product to last as long as possible, it is necessary to follow the recommendations for charging and operation and select them in accordance with the requirements of the devices.

Contents

What batteries can be charged?

You can only charge rechargeable batteries that are marked as such on the case. It is forbidden to insert the most ordinary models into the memory, no matter what type they are - AA or smaller.

Battery AA NiСd

If you violate safety rules, be prepared for:

• Nothing will happen, then you can be considered lucky;
• The battery will hiss and deteriorate;
• Overheating, fire and even explosion are possible;
• Short circuit in the network.

Depending on the materials, batteries are of the following types:

1. Nickel metal hydride;
2. Nickel-cadmium;
3. Nickel-zinc;
4. Lithium-ion;
5. Lithium polymer.

The nickel-cadmium battery has a memory effect, so it must be fully discharged and recharged. Nickel metal hydride also has a memory effect, but it is kept to a minimum.

Rechargeable batteries have standard sizes similar to classic models:

• Little finger (AAA)
• Finger (AA).
• Thumbelina type C.
• Keg or D battery.
• Crown or Corundum.
• 1/2 AA.
• Large square.

There can be both batteries and accumulators of such standard sizes, because of this it is very important not to confuse them. It's worth noting that there are no coin cell batteries, with the exception of a limited edition for hearing aids.

There are also Li-Ion batteries in the following sizes, and they can be charged:

The type of battery is selected according to specific devices. Cameras will accept AA, but some toys will require a barrel. The most popular are still 10440 and AAA.

Battery capacity can vary from 150 mAh to 6000 mAh. The larger the capacity, the more expensive device. The capacity size is indicated on the case in large letters. The larger the capacity, the longer the device can work.

Why can't you charge regular batteries?

Disposable cells have a completely different operating principle - ions flow from the electrolyte to the electrodes. Over time, their supply runs out, and then the battery runs out. If you pass current through a conventional model, the recovery process simply will not occur. For example, during operation of zinc-manganese batteries, the zinc electrode will dissolve.

The batteries are designed in such a way that the indicators of electrolytes and electrodes can be returned to the original version. When such a battery is connected to a charger, oxygen and hydrogen ions are converted from the electrolyte. The reduction process begins, where hydrogen acts as a catalyst for converting the cathode into lead, and oxygen – the anode into lead dioxide.

How to determine if it is a battery or an accumulator

Before purchasing, you should know a few nuances that will allow you to determine regular batteries from rechargeable ones:

1. Pay attention to the inscription on the case. If there is a capacity, then it is a battery; it is indicated in mah (milliamps) per hour. The higher this indicator, the longer it will last.
2. If there is a rechargeable inscription on the case, then it is rechargeable. If the inscription sounds like do not recharge, then recharging is prohibited.
3. Please pay attention to the cost of the product. Regular batteries are cheaper than rechargeable batteries. The price directly depends on power indicators and recharge cycles.
4. Rechargeable batteries have a greater safety margin. They last a long time and charge gradually, but ordinary batteries stop functioning when connected to more powerful devices.
5. The battery boasts a voltage of ~1.5 V, but the battery has a voltage of ~1.2v, ~3.7v. The crown will have 9 volts in both cases.
6. If the markings on the case contain the letters: R, CR, LR and FR, then this is a battery.
7. If the case is marked with: NiCd, Ni-MH, Ni-Zn, HR, ZR, KR, li-ion or li-pol, then this is a battery.

By following simple steps, everyone can determine the necessary batteries for themselves.

In the picture on the left there is a battery, as it is written on the case: 850 mAh, rechargeable and nickel metal hydride. On the right is the battery, as it only says Alkaline.

How to properly charge a battery

1. Before charging at home, read the instructions for the device and recommendations from the manufacturer.
2. Modern batteries do not have a memory effect, so there is no need to pump up the battery. With the exception of nickel-cadmium (Ni-Cd) batteries.
3. Observe temperature conditions, do not insert into the charger at temperatures below 5 degrees and above 50 degrees Celsius.
4. Select a charger specifically for batteries; it’s good if this was done right away. Keep in mind that the slower the energy charge is delivered, the better.
5. Do not leave the battery in the charger for more than a day. If they are not charged, then there is no point in continuing.

Important! When charging, the battery will heat up, this is normal, but it should not be very hot; if it seems to you that it is overheating very much in the charger, then stop the procedure.

How long does it take to charge batteries?

To correctly determine the battery charging time, use the standard formula:

X (hours) = 1.4 * Y (mAh) / Z (mA), where 1, 4 is the coefficient used, because not all the current goes into the battery charge, you can call this a discount on heat transfer.

Some of the current turns into heat, so the battery overheats.

If the capacity is 2400 mAh, and the charger current is 150, then the formula turns out: 1.4 * 2400 / 150 = 22.4

To charge a battery with a capacity of 2400 mAh with an incoming charge of 150 mAh it will take up to 22 and a half hours. Some chargers do not detect the battery charge; voltage is supplied constantly, even if the battery is already fully charged. This approach can harm the battery by shortening its shelf life or rendering it unusable due to overheating.

In order to make your life easier, it is recommended to use modern smart chargers that are equipped with a charge indicator. They can provide information on how many milliamps (mA) were transferred to the battery, and since the capacity is indicated on the case, using a simple subtraction method you can find out how many percent the battery is charged. Also, after charging is complete, the device will turn itself off.

Still have questions or have something to add? Then write to us about it in the comments, this will make the material more complete and accurate.

For normal operation of any battery, you must always remember "The Three P's Rule":

1. Don't overheat!
2. Do not recharge!
3. Do not overdischarge!

You can use the following formula to calculate the charging time for a NiMH or multi-cell battery:

Charging time (h) = Battery capacity (mAh) / Charger current (mA)

Example:
We have a battery with a capacity of 2000mAh. The charging current in our charger is 500mA. We divide the battery capacity by the charging current and get 2000/500=4. This means that at a current of 500 milliamps, our battery with a capacity of 2000 milliamp hours will charge to full capacity in 4 hours!

And now in more detail about the rules that you need to try to follow for the normal operation of a nickel-metal hydride (Ni-MH) battery:

1. Store Ni-MH batteries with a small amount of charge (30 - 50% of its rated capacity).
2. Nickel-metal hydride batteries are more sensitive to heat than nickel-cadmium (Ni-Cd) batteries, so do not overcharge them. Overloading can negatively affect the battery's current output (the battery's ability to hold and release its accumulated charge). If you have a smart charger with " Delta Peak"(interrupting the battery charge when the voltage peak is reached), then you can charge the batteries with virtually no risk of overcharging and destruction of them.
3. Ni-MH (nickel metal hydride) batteries can (but not necessarily!) be “trained” after purchase. 4-6 charge/discharge cycles for batteries in a high-quality charger allows you to reach the limit of capacity that was lost during the transportation and storage of batteries in questionable conditions after leaving the manufacturing plant. The number of such cycles can be completely different for batteries from different manufacturers. High-quality batteries reach their capacity limit after only 1-2 cycles, while batteries of questionable quality with artificially high capacity cannot reach their capacity limit even after 50-100 charge/discharge cycles.
4. After discharging or charging, try to let the battery cool to room temperature (~20 o C). Charging batteries at temperatures below 5 o C or above 50 o C can significantly affect battery life.
5. If you want to discharge a Ni-MH battery, do not discharge it to less than 0.9V for each cell. When the voltage of nickel batteries drops below 0.9V per cell, most chargers with "minimal intelligence" cannot activate the charge mode. If your charger cannot recognize a deeply discharged cell (discharged less than 0.9V), then you should resort to using a “dumb” charger or connect the battery for a short time to a power source with a current of 100-150mA until the battery voltage reaches 0.9V.
6. If you constantly use the same battery assembly in electronic device in recharging mode, then sometimes it is worth discharging each battery from the assembly to a voltage of 0.9V and fully charging it in an external charger. This complete cycling procedure should be performed once every 5-10 battery recharging cycles.

Charging table for typical Ni-MH batteries

The data in the table is valid for completely discharged batteries

Assessing the characteristics of a particular charger is difficult without understanding how an exemplary charge of a li-ion battery should actually proceed. Therefore, before moving directly to the diagrams, let's remember a little theory.

What are lithium batteries?

Depending on what material the positive electrode of a lithium battery is made of, there are several varieties:

• with lithium cobaltate cathode;
• with a cathode based on lithiated iron phosphate;
• based on nickel-cobalt-aluminium;
• based on nickel-cobalt-manganese.

All of these batteries have their own characteristics, but since these nuances are not of fundamental importance for the general consumer, they will not be considered in this article.

Also, all li-ion batteries are produced in various sizes and form factors. They can be either cased (for example, the popular 18650 today) or laminated or prismatic (gel-polymer batteries). The latter are hermetically sealed bags made of a special film, which contain electrodes and electrode mass.

The most common sizes of li-ion batteries are shown in the table below (all of them have a nominal voltage of 3.7 volts):

Internal electrochemical processes proceed in the same way and do not depend on the form factor and design of the battery, so everything said below applies equally to all lithium batteries.

How to properly charge lithium-ion batteries

Most the right way Lithium batteries are charged in two stages. This is the method used Sony company in all of its chargers. Despite a more complex charge controller, this ensures a more complete charge of li-ion batteries without reducing their service life.

Here we are talking about a two-stage charge profile for lithium batteries, abbreviated as CC/CV (constant current, constant voltage). There are also options with pulse and step currents, but they are not discussed in this article. You can read more about charging with pulsed current.

So, let's look at both stages of charging in more detail.

1. At the first stage A constant charging current must be ensured. The current value is 0.2-0.5C. For accelerated charging, it is allowed to increase the current to 0.5-1.0C (where C is the battery capacity).

For example, for a battery with a capacity of 3000 mAh, the nominal charge current at the first stage is 600-1500 mA, and the accelerated charge current can be in the range of 1.5-3A.

To ensure a constant charging current of a given value, the charger circuit must be able to increase the voltage at the battery terminals. In fact, at the first stage the charger works as a classic current stabilizer.

Important: If you plan to charge batteries with a built-in protection board (PCB), then when designing the charger circuit you need to make sure that the open circuit voltage of the circuit can never exceed 6-7 volts. Otherwise, the protection board may be damaged.

At the moment when the voltage on the battery rises to 4.2 volts, the battery will gain approximately 70-80% of its capacity (the specific capacity value will depend on the charging current: with accelerated charging it will be a little less, with a nominal charge - a little more). This moment marks the end of the first stage of charging and serves as a signal for the transition to the second (and final) stage.

2. Second charge stage- this is charging the battery with a constant voltage, but a gradually decreasing (falling) current.

At this stage, the charger maintains a voltage of 4.15-4.25 volts on the battery and controls the current value.

As the capacity increases, the charging current will decrease. As soon as its value decreases to 0.05-0.01C, the charging process is considered complete.

An important nuance of the operation of a proper charger is its complete shutdown from the battery after charging is complete. This is due to the fact that for lithium batteries it is extremely undesirable for them to remain under high voltage for a long time, which is usually provided by the charger (i.e. 4.18-4.24 volts). This leads to accelerated degradation of the chemical composition of the battery and, as a consequence, a decrease in its capacity. Long-term stay means tens of hours or more.

During the second stage of charging, the battery manages to gain approximately 0.1-0.15 more of its capacity. The total battery charge thus reaches 90-95%, which is an excellent indicator.

We looked at two main stages of charging. However, coverage of the issue of charging lithium batteries would be incomplete if another charging stage were not mentioned - the so-called. precharge.

Preliminary charge stage (precharge)- this stage is used only for deeply discharged batteries (below 2.5 V) to bring them to normal operating mode.

At this stage the charge is ensured DC reduced value until the battery voltage reaches 2.8 V.

The preliminary stage is necessary to prevent swelling and depressurization (or even explosion with fire) of damaged batteries that have, for example, an internal short circuit between the electrodes. If a large charge current is immediately passed through such a battery, this will inevitably lead to its heating, and then it depends.

Another benefit of precharging is pre-heating the battery, which is important when charging at low ambient temperatures (in an unheated room during the cold season).

Intelligent charging should be able to monitor the voltage on the battery during the preliminary charging stage and, if the voltage does not rise for a long time, draw a conclusion that the battery is faulty.

All stages of charging a lithium-ion battery (including the pre-charge stage) are schematically depicted in this graph:

Exceeding the rated charging voltage by 0.15V can reduce the battery life by half. Lowering the charge voltage by 0.1 volt reduces the capacity of a charged battery by about 10%, but significantly extends its service life. The voltage of a fully charged battery after removing it from the charger is 4.1-4.15 volts.

Let me summarize the above and outline the main points:

1. What current should I use to charge a li-ion battery (for example, 18650 or any other)?

The current will depend on how quickly you would like to charge it and can range from 0.2C to 1C.

For example, for a battery size 18650 with a capacity of 3400 mAh, the minimum charge current is 680 mA, and the maximum is 3400 mA.

2. How long does it take to charge, for example, the same 18650 batteries?

The charging time directly depends on the charging current and is calculated using the formula:

T = C / I charge.

For example, the charging time of our 3400 mAh battery with a current of 1A will be about 3.5 hours.

3. How to properly charge a lithium polymer battery?

All lithium batteries charge the same way. It doesn't matter whether it is lithium polymer or lithium ion. For us, consumers, there is no difference.

What is a protection board?

The protection board (or PCB - power control board) is designed to protect against short circuit, overcharge and overdischarge of the lithium battery. As a rule, overheating protection is also built into the protection modules.

For safety reasons, it is prohibited to use lithium batteries in household appliances unless they have a built-in protection board. That's why all cell phone batteries always have a PCB board. The battery output terminals are located directly on the board:

These boards use a six-legged charge controller on a specialized device (JW01, JW11, K091, G2J, G3J, S8210, S8261, NE57600 and other analogues). The task of this controller is to disconnect the battery from the load when the battery is completely discharged and disconnect the battery from charging when it reaches 4.25V.

Here, for example, is a diagram of the BP-6M battery protection board that was supplied with old Nokia phones:

If we talk about 18650, they can be produced either with or without a protection board. The protection module is located near the negative terminal of the battery.

The board increases the length of the battery by 2-3 mm.

Batteries without a PCB module are usually included in batteries that come with their own protection circuits.

Any battery with protection can easily turn into a battery without protection; you just need to gut it.

Today, the maximum capacity of the 18650 battery is 3400 mAh. Batteries with protection must have a corresponding designation on the case ("Protected").

Do not confuse the PCB board with the PCM module (PCM - power charge module). If the former serve only the purpose of protecting the battery, then the latter are designed to control the charging process - they limit the charge current at a given level, control the temperature and, in general, ensure the entire process. The PCM board is what we call a charge controller.

I hope now there are no questions left, how to charge an 18650 battery or any other lithium battery? Then we move on to a small selection of ready-made circuit solutions for chargers (the same charge controllers).

Charging schemes for li-ion batteries

All circuits are suitable for charging any lithium battery; all that remains is to decide on the charging current and the element base.

LM317

Diagram of a simple charger based on the LM317 chip with a charge indicator:

The circuit is the simplest, the whole setup comes down to setting the output voltage to 4.2 volts using trimming resistor R8 (without a connected battery!) and setting the charging current by selecting resistors R4, R6. The power of resistor R1 is at least 1 Watt.

As soon as the LED goes out, the charging process can be considered completed (the charging current will never decrease to zero). It is not recommended to keep the battery on this charge for a long time after it is fully charged.

The lm317 microcircuit is widely used in various voltage and current stabilizers (depending on the connection circuit). It is sold on every corner and costs pennies (you can take 10 pieces for only 55 rubles).

LM317 comes in different housings:

Pin assignment (pinout):

Analogues of the LM317 chip are: GL317, SG31, SG317, UC317T, ECG1900, LM31MDT, SP900, KR142EN12, KR1157EN1 (the last two are domestically produced).

The charging current can be increased to 3A if you take LM350 instead of LM317. It will, however, be more expensive - 11 rubles/piece.

The printed circuit board and circuit assembly are shown below:

The old Soviet transistor KT361 can be replaced with a similar one pnp transistor(for example, KT3107, KT3108 or bourgeois 2N5086, 2SA733, BC308A). It can be removed altogether if the charge indicator is not needed.

Disadvantage of the circuit: the supply voltage must be in the range of 8-12V. This is due to the fact that for normal operation of the LM317 chip, the difference between the battery voltage and the supply voltage must be at least 4.25 Volts. Thus, it will not be possible to power it from the USB port.

MAX1555 or MAX1551

MAX1551/MAX1555 are specialized chargers for Li+ batteries, capable of operating from USB or from a separate power adapter (for example, a phone charger).

The only difference between these microcircuits is that MAX1555 produces a signal to indicate the charging process, and MAX1551 produces a signal that the power is on. Those. 1555 is still preferable in most cases, so 1551 is now difficult to find on sale.

A detailed description of these microcircuits from the manufacturer is.

The maximum input voltage from the DC adapter is 7 V, when powered by USB - 6 V. When the supply voltage drops to 3.52 V, the microcircuit turns off and charging stops.

The microcircuit itself detects at which input the supply voltage is present and connects to it. If the power is supplied via the USB bus, then the maximum charging current is limited to 100 mA - this allows you to plug the charger into the USB port of any computer without fear of burning the south bridge.

When powered by a separate power supply, the typical charging current is 280 mA.

The chips have built-in overheating protection. But even in this case, the circuit continues to operate, reducing the charge current by 17 mA for each degree above 110 ° C.

There is a pre-charge function (see above): as long as the battery voltage is below 3V, the microcircuit limits the charge current to 40 mA.

The microcircuit has 5 pins. Here is a typical connection diagram:

If there is a guarantee that the voltage at the output of your adapter cannot under any circumstances exceed 7 volts, then you can do without the 7805 stabilizer.

The USB charging option can be assembled, for example, on this one.

The microcircuit does not require either external diodes or external transistors. In general, of course, gorgeous little things! Only they are too small and inconvenient to solder. And they are also expensive ().

LP2951

The LP2951 stabilizer is manufactured by National Semiconductors (). It provides the implementation of a built-in current limiting function and allows you to generate a stable charge voltage level for a lithium-ion battery at the output of the circuit.

The charge voltage is 4.08 - 4.26 volts and is set by resistor R3 when the battery is disconnected. The voltage is kept very precisely.

The charge current is 150 - 300mA, this value is limited by the internal circuits of the LP2951 chip (depending on the manufacturer).

Use the diode with a small reverse current. For example, it can be any of the 1N400X series that you can purchase. The diode is used as a blocking diode to prevent reverse current from the battery to the LP2951 chip when the input voltage is turned off.

This charger produces a fairly low charging current, so any 18650 battery can charge overnight.

The microcircuit can be purchased both in a DIP package and in a SOIC package (costs about 10 rubles per piece).

MCP73831

The chip allows you to create the right chargers, and it’s also cheaper than the much-hyped MAX1555.

A typical connection diagram is taken from:

An important advantage of the circuit is the absence of low-resistance powerful resistors that limit the charge current. Here the current is set by a resistor connected to the 5th pin of the microcircuit. Its resistance should be in the range of 2-10 kOhm.

The assembled charger looks like this:

The microcircuit heats up quite well during operation, but this does not seem to bother it. It fulfills its function.

Here's another option printed circuit board with SMD LED and micro USB connector:

LTC4054 (STC4054)

Very simple circuit, great option! Allows charging with current up to 800 mA (see). True, it tends to get very hot, but in this case the built-in overheating protection reduces the current.

The circuit can be significantly simplified by throwing out one or even both LEDs with a transistor. Then it will look like this (you must admit, it couldn’t be simpler: a couple of resistors and one condenser):

One of the printed circuit board options is available at . The board is designed for elements of standard size 0805.

I=1000/R. You shouldn’t set a high current right away; first see how hot the microcircuit gets. For my purposes, I took a 2.7 kOhm resistor, and the charge current turned out to be about 360 mA.

It is unlikely that it will be possible to adapt a radiator to this microcircuit, and it is not a fact that it will be effective due to the high thermal resistance of the crystal-case junction. The manufacturer recommends making the heat sink “through the leads” - making the traces as thick as possible and leaving the foil under the chip body. In general, the more “earth” foil left, the better.

By the way, most of the heat is dissipated through the 3rd leg, so you can make this trace very wide and thick (fill it with excess solder).

The LTC4054 chip package may be labeled LTH7 or LTADY.

LTH7 differs from LTADY in that the first can lift a very low battery (on which the voltage is less than 2.9 volts), while the second cannot (you need to swing it separately).

The chip turned out to be very successful, so it has a bunch of analogues: STC4054, MCP73831, TB4054, QX4054, TP4054, SGM4054, ACE4054, LP4054, U4054, BL4054, WPM4054, IT4504, Y1880, PT6102, PT6181, VS61 02, HX6001, LC6000, LN5060, CX9058, EC49016, CYT5026, Q7051. Before using any of the analogues, check the datasheets.

TP4056

The microcircuit is made in a SOP-8 housing (see), it has a metal heat sink on its belly that is not connected to the contacts, which allows for more efficient heat removal. Allows you to charge the battery with a current of up to 1A (the current depends on the current-setting resistor).

The connection diagram requires the bare minimum of hanging elements:

The circuit implements the classical charging process - first charging with a constant current, then with a constant voltage and a falling current. Everything is scientific. If you look at charging step by step, you can distinguish several stages:

1. Monitoring the voltage of the connected battery (this happens all the time).
2. Precharge phase (if the battery is discharged below 2.9 V). Charge with a current of 1/10 from the one programmed by the resistor R prog (100 mA at R prog = 1.2 kOhm) to a level of 2.9 V.
3. Charging with a maximum constant current (1000 mA at R prog = 1.2 kOhm);
4. When the battery reaches 4.2 V, the voltage on the battery is fixed at this level. A gradual decrease in the charging current begins.
5. When the current reaches 1/10 of the one programmed by the resistor R prog (100 mA at R prog = 1.2 kOhm), the charger turns off.
6. After charging is complete, the controller continues monitoring the battery voltage (see point 1). The current consumed by the monitoring circuit is 2-3 µA. After the voltage drops to 4.0V, charging starts again. And so on in a circle.

The charge current (in amperes) is calculated by the formula I=1200/R prog. The permissible maximum is 1000 mA.

A real charging test with a 3400 mAh 18650 battery is shown in the graph:

The advantage of the microcircuit is that the charge current is set by just one resistor. Powerful low-resistance resistors are not required. Plus there is an indicator of the charging process, as well as an indication of the end of charging. When the battery is not connected, the indicator blinks every few seconds.

The supply voltage of the circuit should be within 4.5...8 volts. The closer to 4.5V, the better (so the chip heats up less).

The first leg is used to connect the temperature sensor built into the lithium-ion battery (usually the middle terminal of the battery cell phone). If the output voltage is below 45% or above 80% of the supply voltage, charging is suspended. If you don't need temperature control, just plant that foot on the ground.

Attention! This circuit has one significant drawback: the absence of a battery reverse polarity protection circuit. In this case, the controller is guaranteed to burn out due to exceeding the maximum current. In this case, the supply voltage of the circuit directly goes to the battery, which is very dangerous.

The signet is simple and can be done in an hour on your knee. If time is of the essence, you can order ready-made modules. Some manufacturers of ready-made modules add protection against overcurrent and overdischarge (for example, you can choose which board you need - with or without protection, and with which connector).

You can also find ready-made boards with a contact for a temperature sensor. Or even a charging module with several parallel TP4056 microcircuits to increase the charging current and with reverse polarity protection (example).

LTC1734

Also a very simple scheme. The charging current is set by resistor R prog (for example, if you install a 3 kOhm resistor, the current will be 500 mA).

Microcircuits are usually marked on the case: LTRG (they can often be found in old Samsung phones).

A transistor will do just fine any p-n-p, the main thing is that it is designed for a given charging current.

There is no charge indicator on the indicated diagram, but on the LTC1734 it is said that pin “4” (Prog) has two functions - setting the current and monitoring the end of the battery charge. For example, a circuit with control of the end of charge using the LT1716 comparator is shown.

The LT1716 comparator in this case can be replaced with a cheap LM358.

TL431 + transistor

It is probably difficult to come up with a circuit using more affordable components. The hardest part here is finding the TL431 reference voltage source. But they are so common that they are found almost everywhere (rarely does a power source do without this microcircuit).

Well, the TIP41 transistor can be replaced with any other one with a suitable collector current. Even the old Soviet KT819, KT805 (or less powerful KT815, KT817) will do.

Setting up the circuit comes down to setting the output voltage (without a battery!!!) using a trim resistor at 4.2 volts. Resistor R1 sets the maximum value of the charging current.

This circuit fully implements the two-stage process of charging lithium batteries - first charging with direct current, then moving to the voltage stabilization phase and smoothly reducing the current to almost zero. The only drawback is the poor repeatability of the circuit (it is capricious in setup and demanding on the components used).

MCP73812

There is another undeservedly neglected microcircuit from Microchip - MCP73812 (see). Based on it, a very budget charging option is obtained (and inexpensive!). The whole body kit is just one resistor!

By the way, the microcircuit is made in a solder-friendly package - SOT23-5.

The only negative is that it gets very hot and there is no charge indication. It also somehow doesn’t work very reliably if you have a low-power power source (which causes a voltage drop).

In general, if the charge indication is not important for you, and a current of 500 mA suits you, then the MCP73812 is a very good option.

NCP1835

A fully integrated solution is offered - NCP1835B, providing high stability of the charging voltage (4.2 ±0.05 V).

Perhaps the only drawback of this microcircuit is its too miniature size (DFN-10 case, size 3x3 mm). Not everyone can provide high-quality soldering of such miniature elements.

Among the undeniable advantages I would like to note the following:

1. Minimum number of body parts.
2. Possibility of charging a completely discharged battery (precharge current 30 mA);
3. Determining the end of charging.
4. Programmable charging current - up to 1000 mA.
5. Charge and error indication (capable of detecting non-chargeable batteries and signaling this).
6. Protection against long-term charging (by changing the capacitance of the capacitor C t, you can set the maximum charging time from 6.6 to 784 minutes).

The cost of the microcircuit is not exactly cheap, but also not so high (~$1) that you can refuse to use it. If you are comfortable with a soldering iron, I would recommend choosing this option.

More detailed description is in .

Can I charge a lithium-ion battery without a controller?

Yes, you can. However, this will require close control of the charging current and voltage.

In general, it will not be possible to charge a battery, for example, our 18650, without a charger. You still need to somehow limit the maximum charge current, so at least the most primitive memory will still be required.

The simplest charger for any lithium battery is a resistor connected in series with the battery:

The resistance and power dissipation of the resistor depend on the voltage of the power source that will be used for charging.

As an example, let's calculate a resistor for a 5 Volt power supply. We will charge an 18650 battery with a capacity of 2400 mAh.

So, at the very beginning of charging, the voltage drop across the resistor will be:

U r = 5 - 2.8 = 2.2 Volts

Let's say our 5V power supply is rated for a maximum current of 1A. The circuit will consume the highest current at the very beginning of the charge, when the voltage on the battery is minimal and amounts to 2.7-2.8 Volts.

Attention: these calculations do not take into account the possibility that the battery may be very deeply discharged and the voltage on it may be much lower, even to zero.

Thus, the resistor resistance required to limit the current at the very beginning of the charge at 1 Ampere should be:

R = U / I = 2.2 / 1 = 2.2 Ohm

Resistor power dissipation:

P r = I 2 R = 1*1*2.2 = 2.2 W

At the very end of the battery charge, when the voltage on it approaches 4.2 V, the charge current will be:

I charge = (U ip - 4.2) / R = (5 - 4.2) / 2.2 = 0.3 A

That is, as we see, all values ​​do not go beyond the permissible limits for a given battery: the initial current does not exceed the maximum permissible charging current for a given battery (2.4 A), and the final current exceeds the current at which the battery no longer gains capacity ( 0.24 A).

The main disadvantage of such charging is the need to constantly monitor the voltage on the battery. And manually turn off the charge as soon as the voltage reaches 4.2 Volts. The fact is that lithium batteries tolerate even short-term overvoltage very poorly - the electrode masses begin to quickly degrade, which inevitably leads to loss of capacity. At the same time, all the prerequisites for overheating and depressurization are created.

If your battery has a built-in protection board, which was discussed just above, then everything becomes simpler. When a certain voltage is reached on the battery, the board itself will disconnect it from the charger. However, this charging method has significant disadvantages, which we discussed in.

The protection built into the battery will not allow it to be overcharged under any circumstances. All you have to do is control the charge current so that it does not exceed the permissible values ​​for a given battery (protection boards cannot limit the charge current, unfortunately).

Charging using a laboratory power supply

If you have a power supply with current protection (limitation), then you are saved! Such a power source is already a full-fledged charger that implements the correct charge profile, which we wrote about above (CC/CV).

All you need to do to charge li-ion is set the power supply to 4.2 volts and set the desired current limit. And you can connect the battery.

Initially, when the battery is still discharged, the laboratory power supply will operate in current protection mode (i.e., it will stabilize the output current at a given level). Then, when the voltage on the bank rises to the set 4.2V, the power supply will switch to voltage stabilization mode, and the current will begin to drop.

When the current drops to 0.05-0.1C, the battery can be considered fully charged.

As you can see, the laboratory power supply is an almost ideal charger! The only thing it can’t do automatically is make a decision to fully charge the battery and turn off. But this is a small thing that you shouldn’t even pay attention to.

How to charge lithium batteries?

And if we are talking about a disposable battery that is not intended for recharging, then the correct (and only correct) answer to this question is NO.

The fact is that any lithium battery (for example, the common CR2032 in the form of a flat tablet) is characterized by the presence of an internal passivating layer that covers the lithium anode. This layer prevents a chemical reaction between the anode and the electrolyte. And the supply of external current destroys the above protective layer, leading to damage to the battery.

By the way, if we talk about the non-rechargeable CR2032 battery, then the LIR2032, which is very similar to it, is already a full-fledged battery. It can and should be charged. Only its voltage is not 3, but 3.6V.

How to charge lithium batteries (be it a phone battery, 18650 or any other li-ion battery) was discussed at the beginning of the article.

One of the most important criteria correct operation For good efficiency and long service life of a battery, proper charging is considered. This applies to all batteries, be they massive industrial batteries of rather large capacity, or tiny batteries in your tablets or phones.

Most of batteries have the so-called “memory effect” to varying degrees. It is expressed in the fact that the batteries “remember” the limits of the used capacity.
For this reason, in fact, preparatory training of batteries is being carried out. Due to the above result, it is not recommended to charge batteries that have not yet run out completely.
In this case, the batteries will, among other things, “remember” the limits to which they are given the opportunity to reach.
The result will be a reduction in the physical capacity of the batteries, their rapid discharge, and short service life.

When purchasing new batteries, it is recommended to “train” them. It consists of completely discharging/charging the batteries themselves. To put it simply, you need to discharge the batteries, then charge them “all the way”. The process is repeated 3-4 times.
As a result of this procedure, the batteries will last much longer. With all this, you seem to be “overclocking” them, increasing the potential capacity to the limits.

The fewer times the battery is discharged and the shallower each individual discharge, the longer its service life will be.

How can I charge the battery?

• The best option is charging with direct current 0.1 - 0.2 C for 6-8 hours.

• Fast charge - within 3-5 hours. current is about a third of the rated current.

• Accelerated charging - is carried out with a current equal to the nominal capacity of the battery itself; heating and destruction of the element is possible.

A newer type of lithium-ion batteries with higher energy density and smaller size (cell thickness from 1mm! with significant flexibility). Use down to minus 20 degrees. And the complete absence of “memory effect”.
Batteries of this type are explosive and fire hazardous if they are overcharged, quickly discharged or short circuited. Therefore, all elements are equipped with a built-in charge and discharge controller board.
The number of operating cycles is 900 full charge-discharge. It should be noted that a deep discharge can completely damage the battery. It is recommended to discharge such batteries to no more than 40% of their maximum capacity.
Charging is carried out with a voltage of 4.2 volts per cell, a current of 1C and the charging process is completed at a current of 0.1-0.2C. Charging time is approximately 2 hours.

Most come in the form AA batteries and small-sized disk batteries (tablets)
The supply voltage of one element is 1.37 volts
Self-discharge of this type is approximately 10% per month.
They are subject to the “memory effect” and such batteries are not recommended for use in buffer mode. After a long period of inactivity of such a battery, it is necessary to perform a charge-discharge cycle with a current of approximately the nominal capacity. Discharge cycle from 1.36 volts to 1 volt, lower is not recommended.
The rated charging current is within 0.1-1 of the rated capacity of the element.
Can be used at temperatures down to minus 50 degrees.

Pb (lead acid) battery

AGM battery