If you want to parallel lithium ion batteries, battery consistency is a very important issue.Because of the poor consistency of parallel lithium-ion battery pack in the process of charging is likely to be charged or overcharged phenomenon.
In this way, there will be great damage to the structure of lithium-ion batteries, which will affect the service life of the whole group of lithium-ion batteries.Therefore, the parallel lithium ion batteries in the lithium ion battery package are mostly produced with the same capacity and batch.
If you want to parallel the lithium-ion battery by yourself, then you should pay attention to maintaining the consistency of the battery, it is best to meet the following requirements: lithium-ion battery core voltage difference ≤10mV, internal resistance difference ≤5m, capacity difference ≤20mA.

Parallel lithium ion battery pack charging features
The overall voltage does not change, the capacity of the lithium-ion battery pack will add up, the internal resistance will be reduced, and the delayed power supply time will be extended.
The core content of parallel charging lies in the current size after parallel and its use effect.According to the parallel theory, the main current is equal to the sum of the branch currents. Therefore, the charging current of n parallel lithium-ion batteries that have been combined into a battery pack should be the sum of the current of n lithium ion batteries to achieve the same charging efficiency as that of a single battery. Under the formula of Ohm's law: I=U/R, this design is reasonable.
However, the internal resistance of the batteries in parallel will also change. According to the parallel internal resistance formula, the total internal resistance of the two parallel lithium ion batteries is equal to the ratio of the product of the internal resistance of the two batteries and the sum of the internal resistance. The parallel resistance will decrease with the increase of the number of parallel batteries.Therefore, the parallel charging efficiency of lithium-ion batteries can be realized on the basis that the current is less than the sum of the current of N parallel lithium-ion batteries.

If you are buying a lithium ion battery pack in parallel, there is not much to pay attention to when charging. As long as you charge it in the normal way, you can do it.
If it is the multiple single lithium-ion battery parallel processing and lithium-ion battery pack, then we should pay attention to the installation of the protection plate, the installation of the protection plate to reduce the harm of the lithium-ion battery when charging as much as possible.