A. The multimeter battery power shortage leads to the multimeter measurement of the value is large, fully charged the actual single cell voltage for the normal 4.20V, but the multimeter shows 4.30V or greater, the customer mistakenly thought that the battery is not protected from overcharging.

B. Check whether the C-line welding position is correct, B- and C-line welding is reversed to protect the board without charge and discharge protection; C-line welding in the P-pad is no charge protection function.

C. The charger is abnormal. Charger damage may output more than 100V high voltage, resulting in damage to the protection board and battery overcharge.

D. Protection board charging MOS tube breakdown (protection board power down after measuring the resistance between C- and P-, if it is infinity, M above is OK normal; Ω and K is MOS tube is bad). Protection board charging MOS damage common causes are: 1, the charger, especially high-power charging cabinet in the protection board charging protection moment there is high voltage leads to charging MOS high voltage breakdown; 2, the current is greater than the protection board charging MOS can withstand the maximum current leads to charging MOS overheating damage, such as half a port of the board supports charging maximum current 5A, discharge maximum current 15A, customers connected to the same port use For example, the charging MOS will be over 15A current when discharging 15A.

E. The protection board charging protection control circuit or charging MOS driver circuit damage.