I must be addicted to these batteries. This lot of 4 Bosch Fat Packs BAT836 36V Litheon batteries (BFPs) and a BC830 charger came up on Endless-Sphere for $150. I snapped them up and they arrived the other day. I have to say that I love these batteries. They are bulletproof (I've drained many down to 0V and they just recover completely), dead simple to manage (no BMS is needed), simple to charge (I've used NiMH chargers, LiFEPO4 chargers, and the BC830 which is designed for the packs and they all work fine), built like a tank (the plastic housing is extremely tough and protects the cells extremely well), and last forever (I've had mine for a long time and they seem to never go bad).
I love BFPs!