How to charge AA batteries. How to charge a car battery at home. Is it possible to charge a lithium-ion battery without a controller?
Assessing the characteristics of a particular charger is difficult without understanding how an exemplary charger should actually operate. charge li-ion battery 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 everyone li-ion battery They 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):
| Designation | Standard size | Similar size |
|---|---|---|
| XXYY0, Where XX- indication of diameter in mm, YY- length value in mm, 0 - reflects the design in the form of a cylinder |
10180 | 2/5 AAA |
| 10220 | 1/2 AAA (Ø corresponds to AAA, but half the length) | |
| 10280 | ||
| 10430 | AAA | |
| 10440 | AAA | |
| 14250 | 1/2 AA | |
| 14270 | Ø AA, length CR2 | |
| 14430 | Ø 14 mm (same as AA), but shorter length | |
| 14500 | AA | |
| 14670 | ||
| 15266, 15270 | CR2 | |
| 16340 | CR123 | |
| 17500 | 150S/300S | |
| 17670 | 2xCR123 (or 168S/600S) | |
| 18350 | ||
| 18490 | ||
| 18500 | 2xCR123 (or 150A/300P) | |
| 18650 | 2xCR123 (or 168A/600P) | |
| 18700 | ||
| 22650 | ||
| 25500 | ||
| 26500 | WITH | |
| 26650 | ||
| 32650 | ||
| 33600 | D | |
| 42120 |
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
The most correct way to charge lithium batteries is to charge in two stages. This is the method Sony uses 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 the battery charge constant voltage, but with 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 correct charger operation is its complete disconnection 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 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 LM317 microcircuit, 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 into 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:
- Monitoring the voltage of the connected battery (this happens all the time).
- 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.
- Charging with a maximum constant current (1000 mA at R prog = 1.2 kOhm);
- 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.
- 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.
- 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). On its basis it turns out very a budget option charging (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. 
From undeniable advantages I would like to note the following:
- Minimum number of body parts.
- Possibility of charging a completely discharged battery (precharge current 30 mA);
- Determining the end of charging.
- Programmable charging current - up to 1000 mA.
- Charge and error indication (capable of detecting non-chargeable batteries and signaling this).
- 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.
At first, when the battery is still discharged, laboratory block 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.
1. Recharging of secondary batteries (batteries) must be carried out only when charger, which is intended for this!
The ideal option is when charging is specially selected for battery power sources in the store.
2. Fast recharging (30 minutes - 2 hours) with modern powerful chargers is not supported by all types of batteries. The slower the energy charge is delivered, the better.
3. Before you begin recharging, it is important to carefully read all included operating manuals and instructions in advance.
Moreover, such instructions must be attached to both the charger and direct rechargeable batteries.
4. Any new or old rechargeable battery must undergo so-called “training”. In fact, “training” is 3-4 full “discharge/charge” cycles.
Those. new rechargeable batteries must be recharged to the maximum and discharged to the minimum possible level (in this case, the battery charge should not be reduced to “zero”).
If your charger is really high-quality, then the “training” function is pre-installed in it. Such a charger is capable of independently carrying out the “training” process when selecting the appropriate option in the menu (read the instructions for the charger).
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If the “training” option is not provided in the memory, this process must be performed in manual mode, controlling all its stages. Three or four full cycles (automatically or manually) will be enough.
5. When recharging batteries, it is important to monitor the temperature of the batteries. This indicator (temperature) should not exceed 55 degrees Celsius (very hot to the touch).
Important nuance!
IMPORTANT: modern “smart” and programmable chargers that perform “fast” charging of batteries are able to automatically monitor the temperature of the charged elements, turning on the overheating protection system in time!
The battery should warm up, but not “boil”, which can lead to electrolyte leakage.
Those. Having plugged the batteries into the cheapest charger, the temperature must be controlled manually, periodically checking the heating level with the back of your hand.
6. If the battery has undergone “training”, it can be recharged without waiting for it to “go to zero”. In this case, it is worth talking about partial recharging during operation.
When working with lithium batteries, it is worth knowing that recharging is a natural procedure for them. And even lithium batteries are stored in a fully charged state.
Partial recharging is insurance against caking of the chemical composition of the battery!
7. There are no between nickel-cadmium and nickel-metal hydride battery chargers. Older models of Ni-Cd chargers are quite suitable for modern Ni-MH batteries, although the duration of the energy supply will increase slightly.
As for recharging Ni-Cd secondary current sources in a Ni-MH specification charger, this is possible, but not advisable, because High charging currents can reduce the service life of older battery models.
At the same time, old chargers are unlikely to be able to supply a modern battery with the required supply in less than 3-4 hours.
Autonomous power sources - rechargeable batteries, are seen in modern technologies an integral element of almost any project. For automotive vehicles, the battery is also a structural part, without which full operation of the vehicle is unthinkable. The universal usefulness of batteries is obvious. But technologically these devices are still not completely perfect. For example, obvious imperfection is indicated by frequent charging of batteries. Of course, the relevant question here is what voltage to charge the battery in order to reduce the frequency of recharging and maintain all its operating properties for a long time. long term operation?
Determining the basic battery parameters will help you thoroughly understand the intricacies of the charging/discharging processes of lead-acid batteries (car batteries):
- capacity,
- electrolyte concentration,
- discharge current strength,
- electrolyte temperature,
- self-discharge effect.
The battery capacity receives the electricity given off by each individual battery bank during its discharge. As a rule, the capacity value is expressed in ampere hours (Ah).
On the body battery for a car, not only the rated capacity is indicated, but also the starter current when starting the car when cold. An example of marking - a battery produced by the Tyumen plant The battery discharge capacity, indicated on the technical label by the manufacturer, is considered a nominal parameter. In addition to this figure, the charge capacity parameter is also significant for operation. The required charge value is calculated by the formula:
Сз = Iз * Тз
where: Iз – charging current; Тз – charging time.
The figure indicating the discharge capacity of the battery is directly related to other technological and design parameters and depends on operating conditions. Among the design and technological properties of the battery, the discharge capacity is influenced by:
- active mass,
- the electrolyte used,
- electrode thickness,
- geometric dimensions of electrodes.
Among the technological parameters, the degree of porosity of the active materials and the recipe for their preparation are also significant for the battery capacity.
Internal structure of lead acid car battery, which includes the so-called active materials - plates of minus and plus fields, as well as other components Operational factors are not left out either. As practice shows, the strength of the discharge current paired with the electrolyte can also influence the battery capacity parameter.
Effect of electrolyte concentration
Excessive electrolyte concentrations will shorten battery life. Operating conditions of a battery with a high concentration of electrolyte lead to an intensification of the reaction, which results in the formation of corrosion on the positive electrode of the battery.
Therefore, it is important to optimize the value, taking into account the conditions in which the battery is used and the requirements set by the manufacturer in relation to such conditions.
Optimizing the concentration of battery electrolyte seems to be one of the important aspects of operating the device. Monitoring the concentration level is mandatory For example, for conditions with a temperate climate, the recommended level of electrolyte concentration for most car batteries is adjusted to a density of 1.25 - 1.28 g/cm2.
And when the operation of devices in relation to hot climates is relevant, the electrolyte concentration should correspond to a density of 1.22 - 1.24 g/cm2.
Batteries - Discharge Current
The battery discharge process is logically divided into two modes:
- Long.
- Short.
The first event is characterized by a discharge at low currents over a relatively long period of time (from 5 to 24 hours).
For the second event (short discharge, starter discharge), on the contrary, large currents are characteristic in a short period of time (seconds, minutes).
An increase in discharge current provokes a decrease in the capacity of the battery.
Teletron charger, which is successfully used to work with lead-acid car batteries. Uncomplicated electronic circuit, but high efficiency Example:
There is a battery with a capacity of 55 A/h with an operating current at the terminals of 2.75 A. Under normal environmental conditions (plus 25-26ºС), the battery capacity is in the range of 55-60 A/h.
If the battery is discharged with a short-term current of 255 A, which is equivalent to increasing the rated capacity by 4.6 times, the rated capacity will drop to 22 A/h. That is, almost double.
Electrolyte temperature and battery self-discharge
The discharge capacity of batteries naturally decreases if the temperature of the electrolyte drops. A drop in the temperature of the electrolyte entails an increase in the degree of viscosity of the liquid component. As a result, the electrical resistance of the active substance increases.
Disconnected from the consumer, completely inactive, it has the ability to lose capacity. This phenomenon is explained by chemical reactions inside the device, which take place even under conditions of complete disconnection from the load.
Both electrodes – negative and positive – are affected by redox reactions. But to a greater extent, the process of self-discharge involves the electrode of negative polarity.
The reaction is accompanied by the formation of hydrogen in gaseous form. With an increase in the concentration of sulfuric acid in the electrolyte solution, there is an increase in the density of the electrolyte from a value of 1.27 g/cm 3 to 1.32 g/cm 3 .
This is commensurate with a 40% increase in the rate of self-discharge effect on the negative electrode. An increase in the self-discharge rate is also provided by metal impurities included in the structure of the negative polarity electrode.
Self-discharge of a car battery after prolonged storage. With complete inactivity and no load, the battery has lost a significant part of its capacity. It should be noted: any metals present in the electrolyte and other components of batteries enhance the self-discharge effect.
When these metals come into contact with the surface of the negative electrode, they cause a reaction that results in the release of hydrogen.
Some of the existing impurities act as a charge carrier from the positive electrode to the negative electrode. In this case, reactions of reduction and oxidation of metal ions take place (that is, again the process of self-discharge).
There are also cases when the battery loses its charge due to dirt on the case. Due to contamination, a conductive layer is created that short-circuits the positive and negative electrodes In addition to internal self-discharge, external self-discharge of a car battery cannot be ruled out. The reason for this phenomenon may be a high degree of contamination of the surface of the battery case.
For example, electrolyte, water or other technical liquids have been spilled on the housing. But in this case, the self-discharge effect is easily eliminated. You just need to clean the battery case and keep it clean at all times.
Charging car batteries
Let's start from the situation when the device is inactive (turned off). What voltage or current should I use to charge a car battery when the device is in storage?
Under battery storage conditions, the main purpose of charging is to compensate for self-discharge. In this case, charging is usually performed with low currents.
The range of charge values is usually from 25 to 100 mA. In this case, the charge voltage must be maintained within the range of 2.18 - 2.25 volts in relation to a single battery bank.
Selecting battery charging conditions
The battery charging current is usually adjusted to a certain value depending on the specified charging time.
Preparation car battery batteries for recharging in a mode that needs to be determined taking into account the technological properties and technical parameters when operating the battery So, if you plan to charge the battery for 20 hours, the optimal charge current parameter is considered to be 0.05 C (that is, 5% of the nominal capacity of the battery).
Accordingly, the values will increase proportionally if one of the parameters is changed. For example, with a 10-hour charge, the current will already be 0.1C.
Charging in a two-stage cycle
In this mode, initially (the first stage) a charge is carried out with a current of 1.5 C until the voltage on a separate bank reaches 2.4 volts.
After this, the charger is switched to a charge current mode of 0.1 C and continues to charge until the capacity is full for 2 - 2.5 hours (second stage).
The charge voltage in the second stage mode varies between 2.5 - 2.7 volts for one can.
Forced charge mode
The principle of forced charging involves setting the charging current value at 95% of the nominal battery capacity - 0.95C.
The method is quite aggressive, but it allows you to charge the battery almost completely in just 2.5-3 hours (in practice 90%). Charging up to 100% capacity in a forced mode will take 4 – 5 hours.
Control training cycle
The practice of operating automobile batteries shows a positive result when the control and training cycle is applied to new batteries that have not yet been used. For this option, charging with parameters calculated by a simple formula is optimal:
I = 0.1 * C20;
Charge until the voltage on a single bank is 2.4 volts, after which the charging current is reduced to the value:
I = 0.05 * C20;
With these parameters, the process is continued until fully charged.
The control and training cycle also covers discharge practice, when the battery is discharged with a small current of 0.1 C to a total voltage level of 10.4 volts.
In this case, the degree of electrolyte density is maintained at 1.24 g/cm 3 . After discharge, the device is charged according to standard methods.
General principles for charging lead-acid batteries
In practice, several methods are used, each of which has its own difficulties and is accompanied by different amounts of financial costs.
Deciding how to charge the battery is not difficult. Another question is what result will be obtained from using this or that method The most accessible and simple method A DC charge is considered to be at a voltage of 2.4 - 2.45 volts/cell.
The charging process continues until the current remains constant for 2.5-3 hours. Under these conditions, the battery is considered fully charged.
Meanwhile, the combined charging technique has gained greater recognition among motorists. In this option, the principle of limiting the initial current (0.1C) until the specified voltage is reached.
The process then continues at a constant voltage (2.4V). For this circuit, it is permissible to increase the initial charge current to 0.3 C, but no more.
It is recommended to charge batteries operating in buffer mode at low voltage. Optimal charge values: 2.23 – 2.27 volts.
Deep discharge - eliminating the consequences
First of all, it should be emphasized: restoring the battery to its nominal capacity is possible, but only under the condition that no more than 2-3 deep discharges have occurred.
The charge in such cases is performed with a constant voltage of 2.45 volts per jar. It is also allowed to charge with a current (constant) of 0.05C.
The battery restoration process may require two or three separate charge cycles. Most often, to achieve full capacity, charging is carried out in 2-3 cycles. If the charge is carried out with a voltage of 2.25 - 2.27 volts, it is recommended to perform the process twice or three times. Since at low voltages it is not possible to achieve the nominal capacity in most cases.
Of course, the influence of ambient temperature should be taken into account during the restoration process. If the ambient temperature is within the range of 5 – 35ºС, the charge voltage does not need to be changed. Under other conditions, the charge will need to be adjusted.
Video on the control and training cycle of the battery
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In this article we will answer the burning question of our customers, whether it is possible to charge regular batteries.
So, allow a little theory. What is the difference between a battery and an accumulator? In a battery, the chemical reaction is irreversible; they are most often alkaline. In the battery, the reaction is reversible; they are acidic and nickel-cadmium, if modern. From the definition itself it is clear that the chemical reaction in the battery is irreversible, chemical substances and elements are produced and are not restored.
What's the little secret? In power supplies of old models, or of low quality, not all substances that are poured at the factory participate in the reaction. Why? ... As a result of the operation of the battery, chemical compounds with dielectric properties, salts, oxides, are formed on the conductive elements, which in simple language, prevent the passage of electric current in the circuit. Therefore, the formation of a crust of salts and oxides, powerful dielectrics, is the main reason for battery failure. Often, in many battery models, forty to seventy percent of the chemicals do not even react.
In the Soviet Union, famous physicists and chemists solved the problem of regeneration (restoration) of batteries and batteries. The methodology and principles of the basic solutions are based on “passing” a high electric current through the battery. As a result of the passage of high currents, crusts of dielectrics (salts and oxides) were destroyed. The contacts were cleaned and the reaction continued. It is important to understand that in this way efficiency was increased, but the battery was not charged in any way.
It is important to understand that the methodology used to regenerate batteries is radically different from the solutions on which household chargers are built.
In modern expensive batteries, manufacturers do their best to combat the problem of salt formation. After all, the amount of chemicals that are poured into the battery cannot be increased. Therefore, the battery life is influenced by the design and the most complete use of reagents. Here regeneration gives less effect, because salts are almost not formed and the reagent is produced by 90 percent; they cannot be restored
What happens if you charge a battery in a standard household charger? When a reverse current is passed, the element will begin to heat up, regeneration processes will begin, the effect of which depends on the volume of remaining reagents and the amount of salts formed. This process needs to be controlled, and the batteries should not be allowed to heat above 40 C. In other words, if they become hot, we stop the charging process. The duration should not exceed 15 minutes. This regeneration will extend the life of the battery by 5-10 minutes.
Under no circumstances should batteries be left on the charger for a long time. When charging for a long time, the alkali will begin to boil and gases will begin to be released inside. After an hour, the batteries will swell, swell, and chemicals, bubbles, and stench will begin to leak from the cracks. After two or three hours, if the case is strong enough to hold the contents inside, an explosion will occur and the alkali will scatter throughout the apartment.
The answer to the question is it possible to charge regular batteries - No!!! It's better to buy batteries. In addition, in our company you can get wholesale prices with home delivery. I hope this article was useful to you.
The car battery is charged using special chargers. To correctly carry out this process, you need to know the type of car battery, its characteristics, and also choose the right type of charger.
Car battery device
Most cars have lead acid batteries. The design consists of six jars, which are placed in an insulating housing made of material. A special plastic that is resistant to sulfuric acid is selected for the housing.
The jars are connected in series. They contain positive and negative electrodes, which are designed as lead grids coated with an active mass. The electrodes are placed in an electrolyte. Over time, during operation, the plates fail, which leads to a decrease in battery capacity. The smaller the capacity, the faster the battery discharges.
Battery types
There are two types of batteries.
- Serviced.
- Maintenance free.
The serviceable batteries have caps on the jars that you can unscrew yourself. In such batteries it is possible to check the electrolyte level, its quality and, if necessary, it is possible to top it up. But it is not recommended to do this on your own, without experience in this procedure. All operations to check the quality of the electrolyte, its level and topping up should be entrusted to a specialist. This work is not expensive, but in some cases it can revive the battery.
The maintenance-free battery has no caps and is completely solid. Its repair and resuscitation are not possible.
Also, motorists often add distilled water to the battery, thereby diluting the electrolyte. This can be done, but only if necessary. If you unscrew the caps on the jars, the electrolyte level will be visible; if it is below the electrodes, then topping up is needed. The level should be the same in all six jars.
Do not add water or electrolyte to the battery yourself. Before doing this, you should measure the quality of the electrolyte with a special device. But if you still decide to add water, then add only distilled water and in small portions.
Types of chargers
Based on the type of charge, devices are divided into:
- Charger with constant voltage. In these chargers, the charging voltage is constant, and the current can be adjusted using a regulator.
- Charger with constant current. In such devices, the current is constant, and the voltage is changed by the regulator. Using this type of charging, you can fully charge the battery, but you need to carefully monitor the process. At long-term use the electrolyte may boil, and this may cause the battery to short-circuit and even catch fire.
- Automatic (combined). These modern chargers first charge the battery with a constant constant current at a varying voltage, but then, as the battery is gradually charged, the voltage is fixed and the current gradually decreases. When the battery is fully charged, the device turns off automatically.
There are several ways to check the condition of the battery.
- Using a regular tester. The tester is set to voltmeter mode and the voltage is measured with the car turned off. If this procedure is done with the engine running, you will find out whether the generator is charging. The voltage when the car is turned off should be close to 12 V.
- Load coil. By design, it represents a resistance of 0.018 - 0.020 Ohms with a voltmeter connected in parallel. This unit is connected for 5 - 7 seconds and then readings are taken from the voltmeter.
- According to the indicator on the battery. Some types of batteries have a hydrometric indicator, which is a small peephole. In this eye, the colors of the indicator change. If the color is green, then the battery is charged. If it is white, the battery needs to be charged, and if it is dark, the charge is at a minimum and the electrolyte may need to be topped up.
You can find out how the car works in the detailed material of our specialist.
When is battery charging necessary?
Since a car generator is not able to fully charge the battery, but only 60%, it is recommended to charge the battery at least once a season, before the cold weather. You should also monitor the readings of the hydrometric indicator, if there is one.
The first sign that the battery needs charging is when the car starts. If the starter spins quickly, then everything is fine. If it is slow and the rotation speed seems to be fading, this indicates a low charge.
What to pay attention to and precautions
Since the battery uses sulfuric acid, you need to be careful and follow safety precautions. Charging should be done in a ventilated non-residential area at an ambient temperature of +10 degrees Celsius.
The question is often asked: is it possible to charge the battery without removing it? Yes, you can. But at above-zero temperatures. If you charge at negative temperatures, the charging efficiency decreases. In addition, when the battery is left in the cold for a long time, the electrolyte may freeze. That is why the battery should be brought into a warm room, where it will “defrost” and only then should charging begin.
Preparing the battery for charging, removing it from the car
Before charging, it is advisable to wipe the battery with a soda solution, this will make it possible to remove acid residues from the surface. The solution is simple to prepare: one tablespoon of baking soda per glass of water. If the solution begins to hiss when rubbed, then acid residues are present.
After removing the battery from the car, you need to unscrew the caps from the jars and put them on top. This will allow the electrolyte to evaporate when heated and not splash out of the jars. You should also check the electrolyte level.
It can be determined by eye. If all the plates are completely immersed in the electrolyte by 0.5 cm, then the level is normal. It is also worth paying attention to the levels in neighboring jars, they should be the same everywhere. If the level is less than required, you can add distilled water.
If the battery is maintenance-free (that is, there are no caps), we ignore this procedure.
Connecting the charger
When connecting the charger, observe the correct polarity. The positive terminal of the charger must be connected to the positive terminal (“+”) on the battery. To the negative (“-”) we connect exactly the negative of the charger. Reversing the polarity will result in short circuit and failure of the charger and battery. Therefore, you should be careful. The terminals are marked on both the battery and the charger.
On most chargers, the positive terminal is painted red and the negative terminal black.
Charging duration, process control
It is recommended to charge the battery with low currents; this will allow all plates to distribute the charge evenly and prevent the electrolyte from overheating. You should use no more than 1/10 of the battery capacity. It is indicated on the body and designated “A/hour”.
If the charger is automatic and does not have control levers, then it is impossible to make your own settings. Typically, such devices are equipped with indicator lamps indicating at what stage the battery is charging. And when fully charged, the green light comes on.
If the charger has a built-in ammeter, then charging will be considered completed when the device's needle reaches zero.
The time directly depends on the charging current. If the battery needs to be charged urgently, the process can be carried out using high currents, but this reduces the battery's operating reserve. If there is no rush, then charge with low currents. With such charging, the process usually does not take more than 8 hours.
Monitor the electrolyte; if it begins to boil, reduce the current.
Completion of charging, installation of the battery on the car
After charging is complete, disconnect the charging wires, screw on the caps on the jars and wipe the battery with soda solution again. When charging, droplets of electrolyte evaporate from the jars and settle on the body. If you do not remove the electrolyte from the surface, current may leak through the case and the battery will quickly discharge. This problem is very common, since 80% of car enthusiasts simply do not know this. The electrolyte on the body is not particularly visible; it lies in a thin film, but this is enough for the current to pass through the body of the device.
When connecting, pay attention to the condition of the terminals and their tight press to the battery terminals. They should not be oxidized and should fit tightly.
How to charge a car battery when there is no charge
If the charger is missing and you urgently need to charge it, you can use the following methods:
- Using a portable jump starter. It resembles a small battery, the charge of which is enough to start the engine.
- Assemble a homemade charger if you have the necessary elements on hand. This requires a diode bridge, a resistor, a multimeter and a light bulb, as well as some knowledge of electrical engineering and skill with a soldering iron.
- If the battery does not show signs of life in the cold, it should be removed and placed in a warm room for 30 minutes. The electrolyte will warm up and you can start the car.
- Use the device to charge your laptop. At the output it produces 18 V. You need to insert a light bulb from the headlight in series into the circuit, it will act as a resistor. Then the current will not exceed 2 A, but it will take about 20 hours to fully charge the battery in this way.
Conclusion
When charging the battery, use all the tips given above and do not forget about safety precautions. Protect your eyes from getting acid from the battery, wash your hands thoroughly after contact with battery caps and jars. Charging should be done in a warm room with good ventilation, away from children. Choose a charger only from trusted brands based on the characteristics of your battery, and then it will serve you faithfully for a long time.
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