One of my Lectric XP 1.0 batteries jumped from 10.3 Ampere-Hours to around 5 AH. This tells me one or more cells failed. It is out of warranty, so I took it apart to find the bad cells. Along the way, I learned a few things:

1. After removing all screws, I found it difficult to remove the ends. This was because the manufacturer had injected what looked like black RTV into the ends and then closed up the pack.
2. Carefully (foolishly?), using a hacksaw blade, I was able to cut through the RTV on both ends and remove the battery pack.
3. I counted 27 Samsung 18650 cells.

The nominal voltage of the pack is 48V. Given 3.7V per cell, this comes out to 13 cells in series. If there are two series strings in the pack, I get 26 cells. Each string should have a capacity of 5.2 AH. This implies that one of the strings failed open.

However, an 18650 LiPo cell is rated 2.3 to 3.6 AH. That is far from the needed 5.2 AH.

Does anyone have insights as to what is going on here?

Thanks,

Rick