Well, here I go working on more range extension stuff…
Out of the 12 or so laptop batteries, I got about 42-44 good batteries. There are just enough to give me 6 series with 7 cells in parallel (2x Samsung 28A / 2x Sanyo UR18650F / 3x LGABB41865 per parallel group).
I don’t plan on pushing these hard… Only 8-10A max for the whole 6S7P pack, as an input to my boost converter range extender… The cells are rated for around 5A max discharge, so in 7P this should be perfect at 8-10A.
The problem I am having now though is finding a relatively cheap, reliable, stateside 6S BMS that can ship soon, preferably with separate charge / discharge / eswitch and some adjustability / programmability… Or at least reasonable defaults: 3.0v minimum per cell, 4.2 maximum per cell, not balancing start at 4.35v like the cheap cheap-o BMSs.
Can you guys help me out? Once I get this all hooked up, I’d like to be able to rest easy knowing I can just plug this guy in and trust the BMS to do it’s job keeping things balanced and cutting off without over discharging these old cells.