Originally posted by TRF512
How'd you manage to pull 20amp per cell... I can only manage 2amperes as the lowest resistor I can find is 0.33 ohms and I'm worried I might burn my relays if I parallel in more resistors....
My homebrewed tray uses op-amps to monitor cell voltage and transistor-driven relays for cutting off the load resistors...
A picture would be appreciated...
My load bank is a bunch of old heating elements from toasters connected in parallel. My DVM won't reliably read below 1 ohm tho, so I can't tell you what the actual R is Judging from my max Iload, probably around 0.03 ohms, give or take a few. The bank itself has a capacity of about 3kW, so I get actual DC resistance, not the heat-dependent kind like toasters and light bulbs use.
I use a tight feedback loop with a very very very high frequency PWM chopper control to maintain the discharge rates, with the current and voltage read in with 16bit ADCs.
Active control is the only way to go for things like that.
I'm currently rebuilding it tho, since there was some latchup that took out a couple of the port pins on my microcontroller, destabilizing the feedback loop and frying a pack. Lucky for me it was a set of 1700SCRs
Pictures will come when my camera starts cooperating again. Right now it's on the fritz.