This is why it’s a good idea to disassemble lithium-ion battery packs for its cells. In most other cases, just a single cell has failed. Remember, battery packs are made of many cells that are grouped in a specific way. So, if one cell dies, it will bring down the cells that it is immediately attached to.
The following steps should be followed in order to reassemble the battery pack correctly: Ensure that all components of the lithium battery pack are present, including cells, wires, terminals, and case cover. Assemble the cells into their respective terminal connections.
The repair process begins with a thorough cell inspection and testing. As battery cells are the essential components of any lithium battery pack, it is important to ensure they are in good condition before continuing with the repair. The first step is to conduct a voltage test on each individual cell.
It generally means that the other cell groups are just fine. Lithium-ion battery packs are spot welded together. So it's no small feat to separate the cells. In fact, breaking down a lithium-ion battery pack is a rather involved process that takes care and patience. You have to be extremely careful when breaking down a lithium-ion battery pack.
In order to remove the cells you will need to carefully insert a mat knife into the space between the blocks and carefully cut the plastic connector tabs off. It’s incredibly important that you don’t cut through the cells while doing this because cutting though a lithium cell is bad (you will have to trust us on this one).
It’s incredibly dangerous and one wrong move can kill you, maim you or leave you blind. If you take apart a Lithium pack you immediately void the warranty, no dealer in their right mind is going to take that battery back. Soldering the end of the lithium cells can cause them to blow up in your face leaving you blind.