how to test lithium ion battery pack capacity?
Take 18650 li ion battery pack for example.
Firstly, after each battery charged at room temperature, it’s discharged so that you can get the discharged battery capacity. Make sure two points during this period of testing: 1) the charging condition was to set a constant charging voltage with 4.2v; 2) the discharging condition was to set a limit current of 0.01C ( 10mA) and a end voltage with 2.75v
Secondly, since lithium ion battery pack is combined in parallel or series connection. Therefore, the test method should plus parallel or series numbers in the first step, so as to get the battery pack capacity.
Thirdly, as lithium ion battery pack is generally embeded with BMS (Battery Management System), the end voltage should also take BMS protection data into consideration. For example, BMS set up 3.0v to protect lithium ion battery pack from over-discharge, and 4.25v to protect lithium ion battery pack from over-charge. So your testing data should be change end voltage to 3.0v. and charging voltage into 4.25v