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Discussion Starter #1
I just converted a 94 Probe to electric, 144V, Curtis 1231C. I was stopped at a light, when trying to go, had loss of power to the motor, then started. I got 1/2 a block away from home and it died again, this time permanently. Later, I found as the main contactor was engaged and power started flowing, the motor hardly turned and I saw electric sparks coming from the contactor going to the contactors plastic case. After shuting it down, I could see the side of the case burned. What would cause the HV to jump to the case and not flow through to the controller / motor?
 

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I am guessing you probably had a loose cable connection or bad crimp that overheated and caused the damage. I melted down a fuse bracket early on with my car because of a bad connection in my car.

Make darn sure all your cable connections are properly tightened and are of sufficient size, and make sure to use some kind of anticorrosive stuff on all the battery terminals.

Also ensure that your contactor has the appropriate voltage and current ratings to handle the load. If it isn't an albright SW200 or something equivalent, it may have fried itself being unable to take the load.

Is there any chance that the contactor was switching under load for some reason? This could mess things up.
 

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...Later, I found as the main contactor was engaged and power started flowing, the motor hardly turned and I saw electric sparks coming from the contactor going to the contactors plastic case....

Do you have a precharge resistor across the main contactor? Are you using an appropriately sized contactor? Sounds like either a bad crimp overheated, as suggested by madderscience, or you've destroyed the contacts by repeatedly closing them into a dead short (ie - from not precharging the capacitors inside the controller).
 

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Discussion Starter #4
It could be a bad contactor. When it was ordered, I went with a 12V coil, when installed, it turned out to be a 48V coil. The tag was torn off, so unreadable. It was also broken, but after opening it and removing the small piece of plastic, it worked. I've had the loose connections before, not a pretty sight.

I have another coil on order, Thanks!!
 

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Discussion Starter #5
Ya, I'm going with a bad contactor. There is a precharge resistor. I'm guessing the contactor is for a 48V system, but the tag had been ripped off, so I'll never know.

Where's the juice trying to go anyways? Seems like it would have tried to jump across the contactor, but instead its going down the plastic side of the contactor to what?
 
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