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Home > News > How to repair a lithium battery Pack? (Chapter One)

How to repair a lithium battery Pack? (Chapter One)

2018-02-05

How to repair a lithium battery Pack? (Chapter One)


Malfunctions of lithium - ion batteries usually include: disconnection of the BMS (Battery Management System) or battery cables, 

BMS failure, and some batteries aging faster than others, resulting in voltage differences.


A damaged battery or a series of batteries will cause the voltage of that series to drop compared with other series. 

We should check the appearance of the battery pack for any damage, leakage, charring, or overheating, and then check the voltage of the charging and discharging terminals.


0V Battery Pack Voltage:

First, measure whether there is a voltage between B - and the total positive pole of the battery pack. If there is voltage, check for possible problems such as disconnections.

If the circuit is normal, check whether the temperature sensor of the BMS is damaged, which may cause the battery to stop charging and discharging.

In this way, we can find the fault point on the BMS and replace it or conduct a charging test on the battery pack.

If, without passing through the BMS, the voltage between the total positive and total negative terminals of the battery pack is still 0V,

it may be due to self - discharge during long - term storage. Therefore, you can charge the total positive and negative poles of the battery pack without going through the BMS (or charge individual batteries to activate the battery).


The charging voltage must be correct, and the charging voltage for a single battery should be the maximum operating voltage of the battery.

The charging voltage of the battery pack is:


(LiFePO4) Charging voltage = 3.65V × S (number of series - connected batteries)

(Li - ion) Charging voltage = 4.2V × S (number of series - connected batteries)


When starting to charge, use a small current less than 0.2C. After the voltage rises, we can gradually increase the current, but it is better to be less than 0.2C.

When the voltage exceeds the minimum operating voltage of the battery, we can reconnect the charging through the BMS. Once the battery is activated, 

measure the voltage of each series - connected battery.


If the voltage differences are significant, it indicates that some batteries are damaged and cannot be activated.

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