There's no need to actually stall the motor to determine the stall current. You can simply measure the winding resistance and divide that into the battery voltage. Beware that, in some motors, stalling, even for a split second, can begin to demagnetize the magnets (if it is a permanent magnet motor). Sean On Wed, Aug 5, 2009 at 8:26 PM, Brent Brown wrote: >> I would like to test with a load, but haven't figured out >> a way to do that yet. (The cart is not ready yet.) >> Anybody know how to put load on a 500W motor sitting on a desk? > > If it's a real problem just skip straight to the stall test, which will l= ikely be highest > current draw. Beware the hazards, but you need to know the stall current = so you > need to do this test. Lock the motor solid with the rotor prevented from = turning in a > suitably secure and safe fashion. Make sure your batteries are new and fu= lly > charged, cables are short, good connections etc. Measure the current with= 100% > direct battery power (for just a few seconds) measure current with a DC c= lamp on > ammeter. Expect more than you were expecting. Spec your controller accord= ingly, > then build it. > > Test with your controller also with the locked motor. Try it for a second= or two, if no > smoke, good. Continue tests at various power settings 0 -100%. Carefully = monitor > heat rise over time, with appropriate cool down periods to avoid damage to > controller or motor. Check heat rise in your MOSFETs and heat sink agrees= with > your calculations. > > -- > Brent Brown, Electronic Design Solutions > 16 English Street, St Andrews, > Hamilton 3200, New Zealand > Ph: +64 7 849 0069 > Fax: +64 7 849 0071 > Cell: +64 27 433 4069 > eMail: =A0brent.brown@clear.net.nz > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- = http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist