How to charge a lithium ion battery

How big is the impact of temperature changes on lithium batteries? Lithium battery cells of different manufacturers and different specifications and models have different temperature and safety characteristics in the overcharge test. At present, most lithium batteries are affected by temperature, and the lower the temperature, the worse the electrochemical reaction activity of the internal charge and discharge of the battery.

How much does temperature change affect lithium batteries?

For lithium batteries, there is currently no clear theory in the industry to support the inevitable connection of internal resistance, discharge platform, life, and capacity under various temperature performance. The relevant calculation formulas and mathematical models are still in the groping stage. In general, lithium batteries are not sensitive to the temperature in the range of 0-40°C, but once the temperature exceeds this range, the life and capacity will be compromised.

Temperature has the greatest impact on the charging and discharging functions of lithium batteries. The electrochemical reaction at the electrode/electrolyte interface is related to the ambient temperature. The electrode/electrolyte interface is regarded as the blood of a lithium battery.

If the temperature drops, the response of the electrode will also decrease: assuming that the voltage of the lithium battery remains stable and the discharge current decreases, the power output of the lithium battery will also decrease. If the temperature rises, the opposite is true, that is, the output power of the lithium battery will rise. Temperature also affects the transfer speed of the electrolyte, which accelerates when the temperature rises, and slows down when the temperature drops: the charging and discharging functions of lithium batteries will also be affected.

The upper and lower limits of the working environment temperature of the lithium battery pack are relatively high, which can meet most of the environmental temperature requirements, but the temperature still has an impact on the working efficiency. The temperature of the lithium battery pack is too low and the capacitance of the lithium battery pack will drop even more. Fast, and the internal resistance will increase.

When the temperature drops from 18°C ​​to 0°C, the internal resistance of the 150Ah lithium battery pack will double. Below 0°C, the discharge capacity of the lithium battery pack decreases faster; when the temperature drops to -10°C, the internal resistance of the lithium battery pack doubles.

Since the chemical reaction inside the lithium battery is closely related to the temperature, the heat consumption rate of the lithium battery pack will be different at different temperatures. The ambient temperature is low, and the lithium battery pack generates more heat by itself during operation.

The working environment temperature of the lithium battery has a certain influence on the internal resistance, heat consumption rate, discharge capacity, cycle life and consistency of the battery state. When we use lithium iron phosphate battery packs, we must try our best to control the working environment under a better temperature environment.

Abnormal temperature will have a huge impact on the performance and life of lithium-ion batteries, and may even cause safety problems such as thermal runaway. Therefore, lithium batteries with excellent heat dissipation are qualified lithium batteries.

How to charge a lithium ion battery? How to charge the lithium battery correctly? There are many ways to construct lithium-ion batteries. Using the correct charging method, the lithium-ion battery can be fully charged. If the charging method is not correct, the lithium-ion battery will be undercharged at the slightest level, and the capacity of the lithium-ion battery will decrease, shorten the lifespan, and cause overcharge.

How to charge a lithium ion battery?

The charging process of lithium-ion batteries can be divided into four stages: trickle charging (low-voltage precharge), constant current charging, constant voltage charging, and charging termination.

Stage 1: Trickle charge—Trick charge is used to precharge (recovery charge) the fully discharged battery cell first.

Stage 2: Constant current charging—When the voltage of the lithium-ion battery rises above the trickle charge threshold, increase the charging current for constant current charging. The current for constant current charging is between 0.2C and 1.0C.

Phase 3: Constant voltage charging—When the battery voltage rises to 4.2V, the constant current charging ends and the constant voltage charging phase begins. According to the saturation of the battery cell, the charging current gradually decreases from the maximum value as the charging process continues. When it decreases to 0.01C, the charging is considered to be terminated.

Stage 4: Charge termination-There are two typical charging termination methods: using the minimum charging current to determine or using a timer (or a combination of the two). The minimum current method monitors the charging current in the constant voltage charging stage, and terminates the charging when the charging current decreases to the range of 0.02C to 0.07C.

How to charge the lithium battery correctly?

①The first time a lithium battery is charged, it does not need to be fully charged for 12 hours. This is something that old Ni-MH batteries only need to do. The batteries used in today's smartphones and laptops are mostly lithium-ion batteries or polymer lithium batteries. The first time you only need to charge it as usual, and the battery full indicator light is on.

②From a safety point of view, do not cover anything on the lithium battery when charging, and do not put it on the bed to avoid fire. In addition, try not to answer the phone when charging, because the electromagnetic radiation of the charging mobile phone will be relatively large.

③The lithium battery does not need to be activated by a special method, and the lithium battery will be naturally activated during the driving of the electric vehicle. Lithium batteries have no memory effect, so there is no need to deliberately deep charge and discharge activation.

④Avoid high-temperature charging. Do not charge in an environment where the temperature exceeds 40°. High temperature will cause the battery capacity to decline. Try to choose a cool and ventilated environment, too hot and humid environment is not conducive to the charging state, but also damage the battery and reduce the life of the charger.

⑤The lithium battery pack should be charged as much as possible to avoid recharging after the battery is under-voltage every time. This can greatly improve the battery life and make the battery in a shallow cycle state, so that the battery life will be prolonged.

⑥ Please use the original charger or the reputable brand charger, the lithium battery should use the lithium battery special charger, and follow the instructions, otherwise the battery will be damaged or even dangerous.