From this article you will understand how to properly charge a Li-Ion (lithium-ion) battery, and also learn how to use it and how to use it properly. Such knowledge will extend the life of your battery.
The lithium-ion battery is so widespread due to the simplicity of production, low cost and a large number of charge-discharge cycles. But in order to appreciate these advantages, you need to properly use a Li-Ion battery.
Operating instructions vary depending on the type of battery. For example, Ni-MH and Ni-Cd batteries must be fully discharged before charging. Otherwise, the elements are enlarged, and the battery capacity is reduced. However, the rule "bought a phone - discharge it to" zero, and then charge and repeat the cycle several times "is not universal and does not apply to Li-Ion.
Therefore, before applying the following recommendations, look at the battery. It should be written on it that it is lithium-ion (Li-Ion). Only in this case, use the following operating rules.
Do not discharge the battery to zero too often.
It is still impossible to completely discharge the battery. The protection board turns off the device when a certain minimum is reached. Full discharge is possible only if you disassemble the battery and remove the protective board. Li-Ion and Li-Pol batteries do not tolerate frequent full discharge. Therefore, they are sold charged at 2/3.
Put the device in charge when 10-20% remains on the battery
A message like “Please connect the charger” appears when the charge reaches 10-20% for a reason. Follow the manufacturers recommendations and connect the charger.
But it is not necessary to wait for such a fall. If you can charge your phone or laptop, do it. Regular recharging is not a panacea, but the more often you charge Li-Ion, the longer it will work.
Calibrate the battery periodically
Calibration involves the complete discharge and subsequent charging of the device. There is no contradiction with the first rule: calibration must be done about once every three months.
Calibration does not extend the battery life directly, but only helps the controller correctly determine the battery capacity. If the controller determines the amount of charge incorrectly, the device has to be charged more often. Charging and discharging cycles are spent, the battery crashes faster.
Use original charger
Originality in the context of the problem is needed to protect themselves from the use of low-quality products. If you are sure that the technical characteristics of the third-party device correspond to the characteristics of the original charger, then no problems will arise.
Try not to use “frogs”
If possible, refuse to charge the batteries with a frog. Using non-certified devices is unsafe, there are cases that “frogs” are ignited during charging.
Lithium-ion batteries are not as "finicky" as their nickel-metal hydride counterparts, but still require some care. Adhere to five simple rules, you can not only extend the life cycle of lithium-ion batteries, but also increase the operating time of mobile devices without recharging.
Do not allow a full discharge. Lithium-ion batteries lack the so-called memory effect, so they can and, moreover, need to be charged without waiting for discharge to zero. Many manufacturers calculate the life of a lithium-ion battery by the number of full charge cycles (up to 0%). For high-quality batteries, this 400-600 cycles. To extend the life of your lithium-ion battery, charge your phone more often. Optimally, as soon as the battery charge drops below 10-20 percent, you can put the phone on charge. This will increase the number of discharge cycles to 1000-1100
.
Experts describe this process with such an indicator as Depth Of Discharge. If your phone is discharged to 20%, then the Depth of Discharge is 80%. The table below shows the dependence of the number of discharge cycles of a lithium-ion battery on the Depth of Discharge:
Discharge once every 3 months. For a long time, a full charge is also harmful to lithium-ion batteries, as is continuous discharge to zero.
Due to the extremely unstable charging process (we often charge the phone as necessary, and from where, from USB, from a wall outlet, from an external battery, etc.), experts recommend that once every 3 months the battery be completely discharged and after that charge up to 100% and hold on charging 8-12 hours. This helps reset the so-called upper and lower battery charge flags. You can read more about this.
Store partially charged. The optimal condition for long-term storage of a lithium-ion battery is a charge level of 30 to 50 percent at a temperature of 15 ° C. If you leave the battery fully charged, its capacity will decrease significantly over time. But the battery, which for a long time was gathering dust on the shelf discharged to zero, most likely, is no longer a tenant - it's time to send it for recycling.
The table below shows how much capacity remains in a lithium-ion battery, depending on the storage temperature and charge level during storage for 1 year. 
Use the original charger. Few people know that in most cases the charger is built directly inside the mobile devices, and the external network adapter only lowers the voltage and rectifies the current of the household power supply, that is, it does not directly affect the battery. Some gadgets, such as digital cameras, lack a built-in charger, and therefore their lithium-ion batteries are inserted into an external “charger”. It is here that the use of an external charger of dubious quality instead of the original can negatively affect the performance of the battery.
Do not overheat. Well, the worst enemy of lithium-ion batteries is the high temperature - they do not tolerate overheating at all. Therefore, do not expose direct sunlight to mobile devices, and do not leave them in close proximity to heat sources, such as electric heaters. Maximum allowable temperatures at which the use of lithium-ion batteries is possible: –40 ° C to + 50 ° C
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The first experiments on the creation of lithium galvanic cells were recorded back in 1012. A real working model was created in 1940, the first production copies (non-rechargeable!) Appeared in the 70s, and the triumphal procession of this type of battery began in the early 90s, when the Japanese company Sony was able to master their commercial production.
Currently, it is believed that this is one of the most promising directions for the creation of autonomous electrical energy sources despite their rather high (at the existing level) cost.
The main advantage of this type of battery is its high energy density (of the order of 100 W / h per 1 kg of weight) and the ability to perform a large charge / discharge cycle.
The newly created batteries are also characterized by such an excellent indicator as a low self-discharge rate (from 3 to 5% in the first month, with a subsequent decrease in this indicator). This allows for
And this is not all - in comparison with the widespread Ni-Cd, the new circuit with the same dimensions provides three times more performance with virtually no negative memory effect.
Negative characteristics
lithium ion batteries.
First of all, the high cost, the need to preserve the battery in a charged state, and the so-called “aging effect”, which manifests itself even when the galvanic cell was not in operation. The last unpleasant property is manifested in a constant decrease in capacity, which in two years can lead to a complete failure of the product.
Lithium batteries
Lithium or lithium-ion (Li-ion) batteries are mainly present in cell phones, laptops, and camcorders. Products are expensive, batteries, too, and therefore you need to deal with them even more competently than with any other batteries. So what is Li-Yon's strength? There are probably even more rumors and myths. Firstly, it starts to appear on its own, if only because sellers of equipment with Li-ion batteries do not give special parting words, saying that the battery is “smart” and will do everything right. But not myself. After all, how many cases have owners of new laptops worn out a battery in a month and then paid good ones for a new battery. Of course, lithium batteries are expensive because they are crammed with electronics, but, unfortunately, it does not save you from a fool.
Overdischarge
As with nickel batteries, lithium batteries are also very afraid of overcharging and overdischarging. But, since these batteries are used in smart devices and are equipped with their own chargers, their electronics do not allow overcharging - that is, you can not be afraid of him. But overdischarge is more difficult to control, which is why it is the most typical reason for premature battery failure. Of course, in expensive and complex devices, such as laptops, disconnection occurs before the voltage drops to a critical value. But precedents indicate that this emergency shutdown is better considered as an emergency measure, to which, if possible, it is better not to bring. This is the most important rule - to avoid complete discharge, as low voltage can disconnect the emergency protection circuit. It happens that people "kill" the battery, carried away by training. Training is a good thing, but for lithium batteries, 2-3 full cycles are enough.
There is no memory effect for lithium batteries, so they can be recharged at any time, so after training it is better not to discharge the batteries to the end. The recommended lower threshold is 5-10%. The critical lower threshold is 3%.
Many incomplete cycles or one complete
Lithium batteries have a lifespan of approximately 300 cycles. A full cycle is a cycle of full charge and full (i.e., up to about 3% capacity) discharge, or vice versa. If the battery is discharged to 50% and then charged, it will be 1/2 cycle, if up to 75% and charged - 1/4 cycle, etc. So, for phones and laptops, the difference in benefits between full and incomplete cycles is different. The Internet stubbornly claims that a lot of people charged their phones when they were not fully charged (that is, they recharged the phone every day) and, as a result, ditched them. At the same time, for laptops it is reliably known that full cycles wear out the battery faster than incomplete ones. The situation is clarified by a detailed examination of the device Li-ion batteries (see additional materials). It turns out a lot depends on the controller. It is he who controls the charge current, monitors the state of the battery, etc. So, in laptops, the controller is located in the battery itself and is adjusted by system utilities, such as calibration. In cell phones, the controller is located in the phone itself and so simply cannot be adjusted. Although lithium batteries do not have a memory effect, there is a so-called “digital memory" effect. The fact is that the charge-discharge control electronics located in the battery itself works independently of the device that uses the battery. Internal electronics monitors the cell voltage level, interrupts the charge upon reaching the set maximum value (taking into account the voltage change due to the charging current and battery temperature), interrupts the discharge when the critical value is reached and reports this “up” (a large range of specialized chips). The battery monitoring system “above” calculates the charge level based on information about the moments when the charge and discharge from the battery are turned off and the readings of the current measurement system. But if the operating conditions are such that a complete discharge before a hardware shutdown or a full charge does not occur, these calculations after several cycles may not be entirely correct - the battery capacity decreases over time, and the current meter readings may not always correspond to reality. Typically, deviations do not exceed one percent for each cycle, unless serious changes occur during operation, for example, with the failure of one of the battery cells. The monitoring system has the ability to “learn”, that is, to recalculate the value of the total battery capacity, but for this you need to perform at least one full charge-discharge cycle before the hardware circuits of the battery operate. So it turns out that with very frequent cycles, the controller crashes, and, therefore, incorrectly calculates the battery charge and performs incorrect charging, as a result of which the battery deteriorates. Unlike a laptop, you cannot recalibrate the phone. All that remains in this case is to make a couple of complete cycles to bring the controller in order. I recommend, ideally, combining complete and incomplete cycles, adhering to the principle of the “golden mean”. Personally, I did just that with my cell phone - as a result, after 2 years of operation, the drop in capacity was no more than 40%, which is the norm. In part, time also does not spare lithium batteries - they wear out over time, regardless of operation; their age is short and it is reasonable to change the batteries every 2-3 years.
Storage
If the battery is not used, it is recommended to store it at 40% capacity in a cool place. The lower temperature limit for storage and operation is 00 C. In general, lithium batteries like to be charged, i.e. they are better to store and keep in a charged state, unlike nickels. But with prolonged storage, the maximum charge still wears out the battery more, so 40% of the charge is considered the optimal state.
Battery resuscitation
In general, if the battery is dead, it is better to buy a new one, this is the most logical option, although expensive. I have not seen reliable recipes for reanimating batteries. There are real legends here, especially about laptops, that people reanimated their dying laptop battery and everything is fine with them. One of them sounds like this: “You need to completely discharge the battery, leave the laptop for a week; then fully charge the battery and also leave it for a week; after two months, the capacity should be restored. ”
For cell phones: combine full and incomplete cycles (in the proportion of "HZ").
For laptops: as few complete cycles as possible (after training).
For all: it is recommended to do 80% cycles; do not allow a full discharge (below 3%).
The processes of charging the discharge of any rechargeable batteries proceed in the form of a chemical reaction. However, the charge of lithium-ion batteries is an exception to the rule. Scientific studies show the energetics of batteries such as the chaotic movement of ions. The allegations of pundits deserve attention. If lithium-ion batteries are properly charged in science, then these devices should last forever.
Scientists see the facts of loss of useful capacity of batteries in practice as ions blocked by so-called traps.
Therefore, as in the case with other similar systems, lithium-ion devices are not immune from defects in the process of their application in practice.
Chargers for Li-ion structures have some similarities with devices designed for acid-lead systems.
But the main differences between such chargers are seen in the supply of high voltages to the cells. In addition, more stringent current tolerances are noted, plus the exclusion of charge in an intermittent or floating manner when the battery is fully charged.
A relatively powerful power device that can be used as an energy storage device for the construction of alternative energy sources If they differ in some flexibility, in terms of voltage connection / disconnection, manufacturers of lithium-ion systems categorically reject this approach.
Li-ion batteries and the operating rules of these devices do not allow the possibility of unlimited overcharging.
Therefore, there is no so-called “miraculous” charger for lithium-ion batteries that can extend the life of the battery for a long time.
It is impossible to get additional Li-ion capacity due to a pulsed charge or other known tricks. Lithium-ion energy is a kind of “clean” system that takes a strictly limited amount of energy.
Charging cobalt-blended batteries
The classic designs of lithium-ion batteries are equipped with cathodes, the structure of which is composed of materials:
- cobalt,
- nickel,
- manganese,
- aluminum.
All of them are usually charged up to 4.20 V / I. The permissible deviation is not more than +/- 50 mV / i. But there are also certain types of nickel-based lithium-ion batteries that allow a charge of up to 4.10V / i.
Cobalt-blended lithium-ion batteries are equipped with internal protective circuits, but this point rarely saves the battery from exploding in overcharge mode There is also a development of lithium-ion batteries, where the percentage of lithium is increased. For them, the charge voltage can reach a value of 4.30 V / I and above.
Well, an increase in voltage increases the capacitance, but voltage output beyond the specification is fraught with destruction of the battery structure.
Therefore, for the most part, lithium-ion batteries are equipped with protective circuits, the purpose of which is to maintain the established norm.
Full or partial charge
However, practice shows: most powerful lithium-ion batteries can take a higher voltage level if it is supplied for a short time.
With this option, the charging efficiency is about 99%, and the cell remains cold during the entire charge time. True, some lithium-ion batteries still heat up at 4-5C when they reach full charge.
Perhaps this is due to protection or due to high internal resistance. For such batteries, the charge should be stopped when the temperature rises above 10ºC at a moderate charge rate.
Li-ion batteries in the charger on charging. The indicator shows the full charge of the batteries. Further process threatens to damage batteries Full charging of cobalt-blended systems occurs with a threshold voltage value. In this case, the current drops by up to 3 -5% of the nominal value.
The battery will show a full charge and when a certain level of capacity is reached, remaining unchanged for a long time. The reason for this may be increased self-discharge of the battery.
Increase charge current and saturation charge
It should be noted: an increase in the charge current does not accelerate the achievement of a state of full charge. Lithium- reaches the peak voltage faster, but the charge until the tank is fully saturated takes longer. However, charging the battery with high current quickly increases the battery capacity to about 70%.
Lithium-ion batteries do not support mandatory full charge, as is the case with lead-acid devices. Moreover, just such a charging option is undesirable for Li-ion. In fact, it is better not to fully charge the battery, because high voltage “strains” the battery.
The choice of a lower voltage threshold or full removal of the saturation charge helps to extend the life of the lithium-ion battery. True, this approach is accompanied by a decrease in the time of the return of battery energy.
It should be noted here: household chargers, as a rule, operate at maximum power and do not support charging current (voltage) adjustments.
Manufacturers of household chargers for lithium-ion batteries consider the long life less important than the cost of complicating circuit designs.
Li-ion Battery Chargers
Some cheap home chargers often use a simplified technique. Charge a lithium-ion battery for one hour or less, without switching to a saturation charge.
The ready indicator on such devices lights up when the battery reaches the voltage threshold in the first stage. The state of charge in this case is about 85%, which often satisfies many users.
This domestic charger is offered for use with various batteries, including lithium-ion batteries. The device has a voltage and current regulation system, which is already good Professional chargers (expensive) are characterized in that they set the threshold of the charging voltage lower, thereby extending the life of the lithium-ion battery.
The table shows the calculated power when charging such devices at different threshold voltage values, with and without saturation charge:
| Charge voltage, V / per cell | Capacity at high voltage cutoff,% | Charge time, min | Capacity at full saturation,% |
| 3.80 | 60 | 120 | 65 |
| 3.90 | 70 | 135 | 75 |
| 4.00 | 75 | 150 | 80 |
| 4.10 | 80 | 165 | 90 |
| 4.20 | 85 | 180 | 100 |
As soon as the lithium-ion battery begins to charge, a rapid increase in voltage is noted. This behavior is comparable to lifting a load with a rubber band when there is a lag effect.
The capacity will eventually be full when the battery is fully charged. This charge characteristic is typical for all batteries.
The higher the charge current, the brighter the effect of the rubber tape. Low temperature or the presence of a cell with high internal resistance only enhance the effect.
The structure of a lithium-ion battery in its simplest form: 1- minus copper bus; 2 - positive tire made of aluminum; 3 - anode of cobalt oxide; 4- cathode made of graphite; 5 - electrolyte Assessing the state of charge by reading the voltage of a charged battery is impractical. An open circuit voltage measurement (idle) after the battery has been idle for several hours is the best indicator.
As with other batteries, temperature affects idle in the same way that it affects the active material of a lithium-ion battery. , laptops and other devices is estimated by counting pendants.
Lithium-ion battery: saturation threshold
The lithium-ion battery is not capable of absorbing excess charge. Therefore, when the battery is fully saturated, the charge current must be removed immediately.
A constant current charge can lead to metallization of lithium cells, which violates the principle of ensuring the safe operation of such batteries.
To minimize defect formation, you should disconnect the lithium-ion battery as soon as possible when the charge peak is reached.
This battery will not take charge as much as it should. Due to improper charging, he lost his main energy storage properties. As soon as the charge stops, the voltage of the lithium-ion battery begins to drop. The effect of reducing physical stress is manifested.
For some time, the open circuit voltage will be distributed between unevenly charged cells with a voltage of 3.70 V and 3.90 V.
Here, the process is also noteworthy when a lithium-ion battery, which has received a fully saturated charge, begins to charge the neighboring battery (if one is included in the circuit), which has not received a saturation charge.
When lithium-ion batteries are required to be constantly kept in the charger in order to ensure their readiness, bet on chargers that have the function of short-term compensation charge.
The charger with the function of short-term compensation charge turns on if the open circuit voltage drops to 4.05 V / I and turns off when the voltage reaches 4.20 V / I.
Chargers designed for operational readiness or for standby mode often allow you to lower the battery voltage to 4.00V / i and charge lithium-ion batteries only to 4.05V / i, preventing them from reaching the full level of 4.20V / i.
Such a technique reduces physical stress, inherently related to technical stress, and helps to extend battery life.
Charge without cobalt batteries
Traditional batteries have a nominal cell voltage of 3.60 volts. However, for devices that do not contain cobalt, the denomination is different.
So, lithium-phosphate batteries have a nominal value of 3.20 volts (charging voltage of 3.65V). And the new lithium-titanate batteries (made in Russia) have a nominal cell voltage of 2.40V (charging 2.85).
Lithium phosphate batteries are energy storage devices that do not contain cobalt in their structure. This fact slightly changes the charging conditions of such batteries. For such batteries, traditional chargers are not suitable, as they overload the battery with a risk of explosion. Conversely, a charging system for cobalt-free batteries will not provide a sufficient 3.60V charge for a traditional lithium-ion battery.
Excessive Li-ion Battery
The lithium-ion battery operates safely within specified operating voltages. However, the operation of the battery becomes unstable if it is charged above operating standards.
Long-term charging of a lithium-ion battery with a voltage above 4.30V, designed for a working rating of 4.20V, is fraught with metallization of the anode with lithium.
The cathode material, in turn, acquires the properties of an oxidizing agent, loses state stability, and emits carbon dioxide.
The pressure of the battery cell increases and if the charge continues, the internal protection device will operate at a pressure of 1000 kPa to 3180 kPa.
If the pressure increase continues even after this, the protective membrane opens at a pressure level of 3.450 kPa. In this state, the cell of the lithium-ion battery is on the verge of explosion and ultimately this is exactly what happens.
Structure: 1 - top cover; 2 - upper insulator; 3 - steel can; 4 - lower insulator; 5 - anode tab; 6 - cathode; 7 - separator; 8 - anode; 9 - cathode tab; 10 - outlet; 11 - PTC; 12 - gasket The operation of the protection inside the lithium-ion battery is associated with an increase in the temperature of the internal contents. A fully charged battery has a higher internal temperature than a partially charged battery.
Therefore, lithium-ion batteries are seen to be safer on the condition of low-level charging. That is why the authorities of some countries require the use of Li-ion batteries in aircraft, saturated with energy not exceeding 30% of their full capacity.
The threshold of the internal temperature of the batteries when fully loaded is:
- 130-150 ° C (for lithium-cobalt);
- 170-180 ° C (for nickel-manganese-cobalt);
- 230-250 ° C (for lithium manganese).
It should be noted: lithium-phosphate batteries have better temperature stability than lithium-manganese batteries. Lithium-ion batteries are not the only ones that pose a danger in conditions of energy overload.
For example, lead-nickel batteries are also prone to melting, followed by fire, if energy saturation is performed with violations of the passport regime.
Therefore, the use of chargers ideally suited to the battery is of paramount importance for all lithium-ion batteries.
Some conclusions from the analysis
Charging lithium-ion batteries has a simplified technique compared to nickel systems. The charging circuit is straightforward, with voltage and current limitations.
Such a circuit is much simpler than a circuit that analyzes complex voltage signatures that change as the battery is used.
The process of saturation of lithium-ion batteries with energy is interruptible; these batteries do not need to be fully saturated, as is the case with acid-lead batteries.
Controller circuit for low power lithium-ion batteries. A simple solution and a minimum of details. But the circuit does not provide cycle conditions under which a long service life is maintained. The properties of lithium-ion batteries promise the benefits of a renewable energy source (solar panels and wind turbines). As a rule, either a wind generator rarely provides a full battery charge.
For a lithium-ion, the lack of stable charging requirements simplifies the charge controller circuit. The lithium-ion battery does not require a controller that balances voltage and current, as required by lead-acid batteries.
All household and most industrial lithium-ion chargers fully charge the battery. However, the existing devices for charging lithium-ion batteries for the most part do not provide voltage regulation at the end of the cycle.
