Ebike: Replace cells of a Samsung Ezee kit battery pack
Note: Be aware that working with lithium-ion rechargeable batteries is dangerous. This is not a step by step tutorial. Do not base your work solely on these instructions.
It is time to replace all cells of this Samsung battery pack. Capacity dropped as low as 4.5Ah (50% capacity lost). The arrangement is 13s4p and it is a 3 sections pack. This means it must be folded 2 times.
There are different types of arrangement like 13s5p with a different construction but in the same case.
I went with the 13s4p pack because this is the number of cells I have left.
It's pretty simple; a few screws and you are in like Flynn.
You then carefully cut this black plastic and take everything out. Disconnect the BMS, dissolder all the wires and mark the connections on the pack. You will need this info to rebuild the pack. Remove the temperature sensor.
Marking the connections:
Add cell insulation gaskets on the + terminals. Glue the cells by group of 3. I 3dprinted supports to ease this task. The kapton tape isolates the cells from my hot glue gun.
This has nothing to do with the process of isolating the cells between the groups. That would be done differently and this is not necessary in my case.
I use 8 mm./0.15 mm. nickel strips. I put 2 layers of strips to connect the 2 sections where only one path is available.
While spot welding the cells, isolate the adjacent groups if you don't want to have a bad day...
Add some fish paper or similar (I reused the ones from my old pack) BEFORE folding the 3 sections if you don't want to have another really bad day...
Ressolder everything back and put a new heat shrink tube. Connect the BMS, test your connections, put the lid back and do a complete discharge/charge cycle.
Happy biking