Maintenance lithium battery. How to properly charge a lithium-ion battery: instruction manual
If you are interested in how to charge a lithium-ion battery, then you have come to the right place.
Modern mobile devices require an independent power source.
Moreover, this is true for both “ high technology» like smartphones and , and for more simple devices, say, electric drills or multimeters.
There are many different types of batteries. But for portable equipment, Li-Ion is most often used.
To such widespread led by the relative ease of production and low cost.
Excellent performance characteristics, plus low self-discharge and a large reserve of charge-discharge cycles, also contributed to this.
Important! For greater convenience, most of these batteries are equipped with a special monitoring device that prevents the charge from crossing critical levels.
When a critical discharge occurs, this circuit simply stops supplying voltage to the device, and when the permissible charge level is exceeded, it turns off the incoming current.
A phone or tablet with a lithium-ion battery must be charged when the battery level is 10–20%.
Moreover, after reaching the nominal 100%, charging should last another one and a half to two hours.
This is necessary because the battery will actually be charged to 70–80%.
Advice! Approximately once every three months it is necessary to carry out preventive discharge.
When charging from a laptop or desktop computer, it is necessary to take into account that the USB port is unable to provide a sufficiently high voltage, therefore, the process will take more time.
Alternating cycles of full and incomplete (80–90%) charging will extend the life of the device.
Despite such a smart architecture and general unpretentiousness, following some rules for using batteries will help extend their life.
To prevent the device’s battery from “suffering,” it is enough to follow simple recommendations.
Rule 1. No need to completely discharge the battery
Modern lithium-ion batteries do not have a “memory effect”. Therefore, it is better to charge them before the moment of complete discharge comes.
Some manufacturers measure the service life of their batteries by the number of charge cycles from zero.
The highest quality products can withstand up to 600 such cycles. When charging the battery with 10–20% remaining, the number of cycles increases to 1700.
Rule 2. Complete discharge still needs to be done once every three months.
With unstable and irregular charging, the average maximum and minimum charge levels in the previously mentioned controller are lost.
This causes the device to receive incorrect information about the amount of charge.
Preventative discharge will help prevent this. When the battery is completely discharged, the minimum charge value in the control circuit (controller) will be reset to zero.
After this, you need to charge the battery to capacity, keeping it connected to the network for eight to twelve hours.
This will update maximum value. After such a cycle, the battery operation will be more stable.
Rule 3: An unused battery should be stored with a small amount of charge.
Before storage, it is better to charge the battery by 30–50% and store it at a temperature of 15 0 C. In such conditions, the battery can be stored for quite a long time without much damage.
A fully charged battery will lose a significant portion of its capacity during storage.
And completely discharged ones after long-term storage will only have to be sent for recycling.
Rule 4. Charging must be done only with original devices
It is noteworthy that directly charger built into the design of a mobile device (, etc.).
In this case, the external adapter acts as a rectifier and voltage stabilizer.
Cameras are not equipped with such a device. This is why their batteries must be removed and charged externally.
The use of third-party “charging” can negatively affect their condition.
Rule 5. Overheating is detrimental to Li-Ion batteries
High temperatures have an extremely negative impact on the design of batteries. Low ones are also destructive, but to a much lesser extent.
This must be kept in mind when using lithium-ion batteries.
The battery must be protected from direct sun rays and use away from heat sources.
The permissible temperature range is between -40 0 C and +50 0 C.
Rule 6. Charging batteries using a “frog”
Using uncertified chargers is unsafe. In particular, common Chinese-made “frogs” often ignite during charging.
Before using such a universal charger, you must check the maximum permissible values indicated on the packaging.
So, attention must be paid to the maximum capacity.
If the limit is less than the battery capacity, then best case scenario it will not charge completely.
When the battery is connected, the corresponding indicator on the frog body should light up.
If this does not happen, it means the charge is critically low or the battery is faulty.
When the charger is connected to the network, the connection indicator should light up.
Another diode is responsible for achieving maximum charge, which is activated under appropriate conditions.
How to charge and maintain a lithium ion battery: 6 simple rules
Permissible temperature ranges for charging and discharging lithium-ion batteries
Testing Features
Tests for the number of cycles were carried out with a discharge current of 1C; for each battery, discharge/charge cycles were carried out until 80% of the capacity was reached. This number was chosen based on the timing of the test and for possible comparison of results later. The number of full equivalent cycles is up to 7500 in some tests.Life tests were carried out at various levels charge and temperature, voltage measurements were taken every 40-50 days to control discharge, the duration of the tests was 400-500 days.
The main difficulty in the experiments is the discrepancy between the declared capacity and the real one. All batteries have a capacity higher than declared, from 0.1% to 5%, which contributes additional element unpredictability.
NCA and NMC batteries were most commonly used, but lithium cobalt and lithium phosphate batteries were also tested.
A few terms:
DoD - Depth of Discharge - depth of discharge.
SoC - State of Charge - charge level.
Using Batteries
Number of cycles
On at the moment there is a theory that the dependence of the number of cycles that a battery can withstand on the degree of battery discharge in a cycle has the following form (blue indicates discharge cycles, black indicates equivalent full cycles):This curve is called the Wöhler curve. The main idea came from mechanics about the dependence of the number of stretches of a spring on the degree of stretching. Initial value 3000 cycles at 100% battery discharge is a weighted average at a 0.1C discharge. Some batteries show better results, some worse. At a current of 1C, the number of full cycles at 100% discharge drops from 3000 to 1000-1500, depending on the manufacturer.
In general, this relationship, presented in the graphs, was confirmed by the results of experiments, because It is advisable to charge the battery whenever possible.
Calculation of superposition of cycles
When using batteries, it is possible to operate with two cycles simultaneously (for example, regenerative braking in a car):
This results in the following combined cycle:
The question arises, how does this affect the operation of the battery, is the battery life significantly reduced?
According to the results of the experiments, the combined cycle showed results similar to the addition of complete equivalent cycles of two independent cycles. Those. The relative capacity of the battery in the combined cycle fell according to the sum of the discharges in the small and large cycles (the linearized graph is presented below). 
Influence large cycles discharge is more significant, which means it is confirmed that it is better to charge the battery at every opportunity.
Memory effect
The memory effect of lithium-ion batteries was not noted according to the experimental results. Under various modes, its total capacity still did not subsequently change. At the same time, there are a number of works that confirm the presence this effect in lithium phosphate and lithium titanium batteries.Battery storage
Storage temperatures
No unusual discoveries were made here. Temperatures 20-25°C are optimal (in ordinary life) for battery storage, if not used. When storing a battery at a temperature of 50°C, capacity degradation occurs almost 6 times faster.Naturally more low temperatures better for storage, but in everyday life this means special cooling. Since the air temperature in the apartment is usually 20-25°C, storage will most likely be at this temperature.
Charge level
As tests have shown, the lower the charge, the slower the self-discharge of the battery. The capacity of the battery was measured, what it would be during its further use after long-term storage. Best result showed batteries that were stored with a charge close to zero.Generally good results showed batteries that were stored with no more than 60% charge level at the start of storage. The numbers differ from those below for a 100% charge for the worse (i.e. the battery will become unusable earlier than indicated in the figure):
Figure taken from article 5 practical tips for using lithium-ion batteries
At the same time, the figures for small charge are more optimistic (94% after a year at 40°C for storage at 40% SOC).
Since a 10% charge is impractical, since the operating time at this level is very short, It is optimal to store batteries at SOC 60%, which will allow you to use it at any time and will not critically affect its service life.
Main problems of the experimental results
No one has conducted tests that can be considered 100% reliable. The sample, as a rule, does not exceed a couple of thousand batteries out of millions produced. Most researchers cannot provide reliable comparative analyzes due to reasons of insufficient sampling. Also, the results of these experiments are often confidential information. So these recommendations do not necessarily apply to your battery, but can be considered optimal.Results of the experiments
Optimal charging frequency - at every opportunity.Optimal storage conditions are 20-25°C with a 60% battery charge.
Sources
1. Course “Battery Storage Systems”, RWTH Aachen, Prof. Dr. rer. nat. Dirk Uwe SauerLithium-ion batteries are not as finicky as their nickel-metal hydride counterparts, but they still require some care. Sticking to five simple rules, you can not only extend life cycle lithium-ion batteries, but also increase the operating time of mobile devices without recharging.
Do not allow complete discharge. Lithium-ion batteries do not have the so-called memory effect, so they can and, moreover, need to be charged without waiting for them to discharge to zero. Many manufacturers calculate the life of a lithium-ion battery by the number of full discharge cycles (up to 0%). For 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. Fully charging for a long time is just as harmful to lithium-ion batteries as constantly discharging to zero.
Due to the extremely unstable charging process (we often charge the phone as needed, and wherever possible, from USB, from a socket, from an external battery, etc.), experts recommend completely discharging the battery once every 3 months and then charging it to 100% and holding it on charge 8-12 hours. This helps reset the so-called high and low battery flags. You can read more about this.
Store partially charged. The optimal condition for long-term storage of a lithium-ion battery is between 30 and 50 percent charge at 15°C. If you leave the battery fully charged, its capacity will decrease significantly over time. And here is the battery that for a long time it was collecting dust on the shelf, discharged to zero, most likely no longer alive - it’s time to send it for recycling.
The table below shows how much capacity remains in a lithium-ion battery depending on storage temperature and charge level when stored for 1 year. 
Use the original charger. Few people know that in most cases the charger is built directly into mobile devices, and the external network adapter only lowers the voltage and rectifies the current of the household electrical network, that is, it does not directly affect the battery. Some gadgets, such as digital cameras, do not have a built-in charger, and therefore their lithium-ion batteries are inserted into an external “charger”. This is where using an external charger of questionable quality instead of the original one can negatively affect the performance of the battery.
Avoid overheating. Well, the worst enemy of lithium-ion batteries is high temperature– they cannot tolerate overheating at all. Therefore, do not expose your mobile devices to direct sunlight or place them near heat sources such as electric heaters. Maximum permissible temperatures at which lithium-ion batteries can be used: from –40°C to +50°C
Also, you can look
Reading “tips for operating” batteries on forums, you can’t help but think - either people skipped physics and chemistry at school, or they think that the rules for operating lead-acid and ion batteries are the same.
Let's start with the principles of operation of a Li-Ion battery. On the fingers, everything is extremely simple - there is a negative electrode (usually made of copper), there is a positive one (made of aluminum), between them there is a porous substance (separator) impregnated with electrolyte (it prevents the “unauthorized” transfer of lithium ions between the electrodes):
The operating principle is based on the ability of lithium ions to be integrated into crystal lattice various materials - usually graphite or silicon oxide - to form chemical bonds: accordingly, when charging, the ions are built into the crystal lattice, thereby accumulating a charge on one electrode; when discharging, they respectively move back to the other electrode, giving away the electron we need (who is interested in a more accurate explanation of the processes taking place - google intercalation). As an electrolyte, water-containing solutions are used that do not contain a free proton and are stable in wide range stress. As you can see, in modern batteries everything is done quite safely - there is no lithium metal, there is nothing to explode, only ions run through the separator.
Now that everything has become more or less clear about the operating principle, let’s move on to the most common myths about Li-Ion batteries:
- Myth one. The Li-Ion battery in the device cannot be discharged to zero percent.
In fact, everything sounds correct and is consistent with physics - when discharged to ~2.5 V, the Li-Ion battery begins to degrade very quickly, and even one such discharge can significantly (up to 10%!) reduce its capacity. In addition, if the voltage is discharged to such a voltage with a standard charger, it will no longer be possible to charge it - if the battery cell voltage drops below ~3 V, the “smart” controller will turn it off as damaged, and if there are all such cells, the battery can be taken to the trash.
But there is one very important thing that everyone forgets about: in phones, tablets and others mobile devices the operating voltage range on the battery is 3.5-4.2 V. When the voltage drops below 3.5 V, the indicator shows zero percent charge and the device turns off, but it is still very far from the “critical” 2.5 V. This is confirmed by the fact that if you connect an LED to such a “discharged” battery, it can remain on for a long time (maybe someone remembers that they used to sell phones with flashlights that were turned on by a button regardless of the system. So the light there continued to burn even after discharge and turn off the phone). That is, as you can see, during normal use, discharge to 2.5 V does not occur, which means it is quite possible to discharge the battery to zero percent. - Myth two. If Li-Ion batteries are damaged, they explode.
We all remember "explosive" Samsung Galaxy Note 7. However, this is rather an exception to the rule - yes, lithium is a very active metal, and it is not difficult to explode it in the air (and it burns very brightly in water). However, modern batteries do not use lithium, but its ions, which are much less active. So for an explosion to occur, you need to try very hard - either physically damage the charging battery (cause a short circuit), or charge it with a very high voltage (then it will be damaged, but most likely the controller will simply burn out itself and will not allow the battery to charge). Therefore, if you suddenly have a damaged or smoking battery in your hands, don’t throw it on the table and run away from the room shouting “we’re all going to die” - just put it in a metal container and take it out to the balcony (so as not to breathe in the chemicals) - the battery will smolder for some time and then go out. The main thing is not to fill it with water, the ions are of course less active than lithium, but still some amount of hydrogen will also be released when reacting with water (and it likes to explode). - Myth three. When a Li-Ion battery reaches 300 (500/700/1000/100500) cycles, it becomes unsafe and needs to be changed urgently.
A myth, fortunately, that circulates less and less on forums and has no physical or chemical explanation at all. Yes, during operation the electrodes oxidize and corrode, which reduces the battery capacity, but nothing except less time battery life and unstable behavior at 10-20% charge does not threaten you. - Myth four. WITH Li-Ion batteries and you can’t work in the cold.
This is more of a recommendation than a prohibition. Many manufacturers prohibit the use of phones at sub-zero temperatures, and many have experienced rapid discharge and even shutdown of phones in the cold. The explanation for this is very simple: the electrolyte is a water-containing gel, and everyone knows what happens to water at subzero temperatures (yes, it freezes, if anything), thereby rendering some area of the battery unusable. This leads to a voltage drop, and the controller begins to consider this a discharge. This is not beneficial for the battery, but it is not fatal either (after heating, the capacity will return), so if you desperately need to use the phone in the cold (to use it - take it out of a warm pocket, check the time and put it back does not count) then it is better to charge it 100% and turn on any process that loads the processor - this will cool it down more slowly. - Myth fifth. A swollen Li-Ion battery is dangerous and should be thrown away immediately.
This is not exactly a myth, but rather a precaution - a swollen battery can simply burst. From a chemical point of view, everything is simple: during the intercalation process, the electrodes and electrolyte decompose, resulting in the release of gas (it can also be released during recharging, but more on that below). But very little of it is released, and for the battery to appear swollen, several hundred (if not thousands) of recharge cycles must go through (unless, of course, it is defective). There are no problems getting rid of the gas - just pierce the valve (in some batteries it opens itself when there is excess pressure) and bleed it off (I don’t recommend breathing with it), after which you can cover the hole with epoxy resin. Of course, this will not return the battery to its former capacity, but at least now it will definitely not burst. - Myth six. Overcharging is harmful to Li-Ion batteries.
But this is no longer a myth, but a harsh reality - when recharging, there is a high chance that the battery will swell, burst and catch fire - believe me, there is little pleasure in being splashed with boiling electrolyte. Therefore, all batteries have controllers that simply prevent the battery from being charged above a certain voltage. But here you need to be extremely careful in choosing a battery - Chinese handicraft controllers can often malfunction, and I don’t think fireworks from your phone at 3 am will make you happy. Of course, the same problem exists in branded batteries, but firstly, this happens much less often there, and secondly, they will replace your entire phone under warranty. This myth usually gives rise to the following: - Myth seventh. When you reach 100%, you need to remove the phone from charging.
From the sixth myth, this seems reasonable, but in reality there is no point in getting up in the middle of the night and unplugging the device: firstly, controller failures are extremely rare, and secondly, even when the indicator reaches 100%, the battery still charges for some time to the very, very maximum low currents, which adds another 1-3% capacity. So, in reality, you shouldn’t play it safe. - Myth eight. You can charge the device only with the original charger.
The myth takes place due to the poor quality of Chinese chargers - when normal voltage at 5 +- 5% volts they can produce both 6 and 7 - the controller, of course, will smooth out this voltage for some time, but in the future it will, at best, lead to the controller burning out, at worst, to an explosion and (or) failure motherboard. The opposite also happens - under load, the Chinese charger produces 3-4 volts: this will lead to the battery not being able to charge completely.
In this article, by correct operation of lithium-ion batteries, we will understand compliance with such conditions in which the lithium-ion battery portable device will be able to work safely, will last a long time, and the functioning of the device will remain fully functional.
But even if the stress mode was allowed, and the battery became very hot, do not rush to charge it. Wait until it cools down and only then connect it to the charger, then it will be able to accept a charge normally and safely.
During the charging process, the battery should also not overheat; if this happens, it means that too much current is flowing through the electrolyte, and this is harmful.
Low-quality chargers suffer from so-called “fast charging,” like some inductive wireless chargers. It is better not to use such “fast” chargers. The fact is that a safe charger must respond to the current consumed by the battery during charging and quickly change the supplied voltage, if necessary, reduce it, when necessary, increase it.
If the charger is just a transformer with a rectifier, then your battery will most likely overheat due to overvoltage and gradually break down. Not all fast chargers are compatible with lithium batteries.
Most best option- an original charger from the same manufacturer as the device being charged, ideally the charger included in the kit. But if it is not possible to use an original charger, then use one that gives a lower current - this will save the battery from overheating due to the supply of excessive power.
A good alternative to the original charger is a computer USB port. USB 2.0 will give 500mA, USB 3.0 - a maximum of 900mA. This is enough for safe charging.
Some of the “fast” devices are capable of pumping 3-4 amperes into the battery, but this is destructive for small-capacity batteries, such as the batteries of pocket mobile gadgets (see documentation). A small current from USB is a guarantee of the safety of the lithium-ion battery.
Many devices allow you to remove the battery, so having a spare battery is not a problem at all. The operating time of the device will double, deep discharge is eliminated (install a backup battery in advance, without waiting for the main battery to be completely discharged), and the temptation to use a harmful “fast” charger will disappear. 20% discharge of the main battery is a signal to install a backup one.
If the first battery gets very hot from intense load or due to external heating (accidentally left in the sun), insert a spare one, and while the first one cools down, you will continue to use your device, keeping both batteries unharmed. When the one that has warmed up has cooled down, it can be recharged in the original charger (mains or car).
So, in order for a lithium battery to serve for a long time and faithfully, it is necessary:
1. Do not allow the battery to warm up above 30°C, best temperature 20°C.
2. Avoid overcharging the battery and overvoltage at the terminals, optimally 3.6 V.
3. Avoid deep battery discharge - let 20% be the limit.
4. Avoid high current loads during charging and discharging (see documentation), use USB.
5. Have a backup battery.
