Michael Ross wrote:
Doubtful you can buy it, but you can make one. I am in the process myself. Sure you want to do this at home? This much power is non-trivial. Be wary.
A single cell isn't too bad. Doing a whole pack gets into high power territory.
Power = volts x amps. For power under 1000 watts, you can make or buy power resistors. 3.6v at 100a is only 360 watts. This will be smaller than your fist. It will get hot, so a good airflow around it is needed (like a fan). Up to 1000 watts or so, you can re-purpose a small ceramic heater. Replace its heating element with your load resistors, and use its fan to cool it.
For high current and high voltage at the same time, the power gets pretty high. Commercial multi-kilowatt power resistors are as big as your arm, and can be found for $20 and up. These need to be cooled with a big fan, or immersed in water.
Jury-rigged resistors can be made out of almost anything, if you're knowledgeable. The resistance is unpredictable, and will change with temperature and how well you connect the wires to it.
For the pack as a whole, you can use your car's motor controller as an adjustable resistor. It can drive a resistive load just as well as an inductive load (the motor). Disconnect the motor, and connect your load resistor in its place. Use the throttle to control the battery current. This has the advantage that your contactors, fuses, and meters are all in the circuit.
-- Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius, and a lot of courage, to move in the opposite direction. -- Albert Einstein -- Lee Hart's EV projects are at http://www.sunrise-ev.com/LeesEVs.htm _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
