EIG Battery makes two different cells, one based on LiFePO4 chemistry, and the other based on LiNiCoMno2. I think these are the latter cells. They have a steeper discharge curve than lithium phosphate, with a less-pronounced knee in the curve. This makes it much easier to estimate the state of charge from the pack voltage. The cells used in the Bosch 36V litheon power tool packs have a similar chemistry. The Bosch packs don't have any individual cell monitoring, just a pack LVC. I've been using a couple of these packs on my ebike for over a year now without any BMS. As long as you don't push the average cell voltage close to the upper or lower limits these cells stay very closely balanced. The controller provides a low-voltage cutoff for the pack, and the charger sets the high voltage cutoff (around 4.1V). The drawback is a shorter cycle life, typically around 1000 full cycles to 80% of capacity, compared to 2000 or more for lithium phosphate. Personally I'm willing to accept the shorter life in return for eliminating the hassle of a BMS. It would be great to hear feedback from anyone who's used the EIG cells, or any information about sources/cost.
There's loads of information about the Bosch power tool packs on Endless Sphere. Just search for "Bosch fatpack".
