Due to not having $3000 for one of the commercial BMS setups for my new (well, surplus used) 192 cell pack. (2 strings of 96), I'm going to usse some of the little BMS boards you can get for power tools (18650 cells). I've made a little daughterboard that lets me use their power switching as error detect, and they have 100ma balance current.
Finally doing some detailed testing on the setup, and of course they don't quite match specs they are sold with. Actually, a bit of weirdness in how they work. First, put it in "Charge" mode - where it's looking for over voltage conditions. The slowly ramp up the voltage. 4.3v - over voltage detect triggers 4.45v - regulator turns on. now slowly turn the voltage down 4.2v - regulator turns off 4.1v - error clears Note: If you turn the voltage down before the regulator turns on, the error will clear just under 4.3v. Toggling to Discharge mode doesn't reset the error even if you are velow 4.3v (and above 4.1v) Ok, now for Discharge mode. Slowly turn the voltage down. 2.5v - under voltage detect triggers At this poing, if you switch back to Charge mode - there is no error, switch to Discharge mode - and there is still an error. Slowly turn the voltage back up. If you stay in Discharge mode, the error never clears. Toggling to charge mode and back, the error will clear at 2.95v. Kinda weird. Usable, but not great. -- Worlds only All Electric F-250 truck! http://john.casadelgato.com/Electric-Vehicles/1995-Ford-F-250 -- Bobcats and Cougars, oh my! http://john.casadelgato.com/Pets _______________________________________________ Address messages to ev@lists.evdl.org No other addresses in TO and CC fields HELP: http://www.evdl.org/help/
