How to replace a broken cell

Broken cell replacement

Yes, this will happen eventually for everyone. If you, like me, using 2nd-hand cells we do not know how many cycles they all have done and they may go faulty on you. Today Im showing you how simple it is for me, with my design of bus bars, to replace a broken cell.

The procedure

First of all you need to find the cell. I’m not going to dig deep into how to find it but you need to understand that continuity testing a fuse connection on a pack where you have several cells may not work. Since all cells basically are a big resistor and will let current through (Depending on meter and way you test)

You could also measure the voltage between the cell and the bus bar. With some luck the cell wont hold the same charge as the rest and if so you will see a diff in voltages. If you want to go this route the best way is to test it during 2 different SOC and you will find them.

When the broken cell is found its time to remove it out of the holders. I make sure to mark the cell on both sides and desolder the fuse wire.

Make sure you have enough room to get it out. With proper bus bar design you will have that room.

Then you pop the corners away from the holder on 1 of the sides. This to ensure you can push it out.

I use a pencil to push it out. Don’t use any sharp objects that could potentially destroy your cell.

When you got the cell out its just a matter of replacing it and in with the new one. To help out replacing cells its good if you keep the cells clean from any glue or other stuff before assembling. Or else this will become a night-mare.

When i assemble it again i always crosscheck voltage once more before attaching the last wire.

I don’t do anything regarding the removed corners since my packs will be perfectly still and the cells have no chance of escaping out since there is soldered wires on both sides!

Happy power walling and see you next time!

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