A simple 60 to 100 watt incandescent bulb is great for making some basic tests. Get an old fashioned rubber pigtail socket for it. Use a silicone coated rough service bulb for safety. Also wear insulating gloves, remember you're working with high voltage and it can bite you.
First, connect the bulb across your contactor's high voltage contacts with the contactor off. If you get light, turn on the key. Now you should get no light. This is a rough indication that power is getting to the controller (but note that you might get fooled by other stuff on the downstream side of the contactor, such as a DC:DC converter). If you got light with the key both on and off, your contactor is not closing. This could be an open in the key circuit. Check for a safety shutoff like the ones in ICEVs. Check fuses. If your controller has a precharge circuit, make sure it's working. If you get no light either way, key on or key off, it could be an open jumper in the battery, an open fuse or breaker, even an open battery. Time to test those items. Connect your light bulb in parallel with your multimeter set on voltage in the 1000v or so range. (The light loads the battery as a coarse test for high resistance connections that might not show up with a high impedance multimeter alone.) Connect negative meter/light lead to battery negative. Work through the battery (pack) module by module, from most negative to most positive. You should see the voltage increase about 6v with each additional module. If it drops to zero or doesn't increase much when you jump, there's your problem. If the battery tests out OK, continue your trace through fuse, breaker, contactor. Next, disconnect at the least one cable to the motor from the output of the controller (probably stamped M+ and M-). With the key on, put the light across the B+ and B- (traction battery in) terminals of the controller. If no light, you have an open circuit between battery and controller. Check fuses, breakers, connections. If you get a light, now you've pretty well narrowed the problem down to the controller and the motor. Once you have light at B+ and B-, connect the light to M+ and M- (controller output). MOTOR DISCONNECTED! Push on the pedal. The light should brighten as you push. No light? Could be a dead controller, or could be something as simple as the potbox not returning to zero properly (many controllers for example have a high pedal lockout so they won't output anything if powered up with your foot on the pedal, to prevent surprises). Disconnect the potbox from the controller. Using your ohmmeter, check that its resistance gets close to zero (check with your controller manufacturer for the specification here) when the pedal is up. The potbox resistance should vary from close to zero (under 100 ohms or so) with pedal up, to something in the 4000-5000 ohm range with the pedal all the way to the floor. Or, try replacing the potbox with a 5k potentiometer from Radio Shack or whatever. If it seems to be narrowed down to the controller, depending on your controller, it may have diagnostic LEDs on some kind of remote controller or inside. Check with the manufacturer. Light varies with the pedal? Great! The controller is probably OK. Check the motor connections. Check motor brushes. Try CAREFULLY (trans in neutral, wheels jacked up) connecting a single 6v battery to the motor (if series motor it will go to one field terminal and one armature terminal, where the controller was connected). You can use good heavy jumper cables. Be prepared for a spark when you connect. USE ONLY ONE 6v BATTERY! More than that and you can overspeeed the motor. If the motor runs now, and the controller worked right as above, your problem almost has to be between the controller and the motor. Check all connections. If it doesn't, check the field to armature jumper cable and the brushes. The above tests are not foolproof; high resistance connections and logic errors in microprocessor controlled controllers can bite you. But this is a start. I typed this up fast and probably missed something. Others may have further ideas for useful tests and/or may correct anywhere I may have misspoken (mistyped). Good luck. David Roden - Akron, Ohio, USA EVDL Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" and "etpost" addresses will not reach me. To send a private message, please obtain my email address from the webpage http://www.evdl.org/help/ . = = = = = = = = = = = = = = = = = = = = = = = = = = = = = _______________________________________________ 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)
