# Curtis 1239e burning out precharge resistor



## Ozpara (Apr 11, 2016)

Hi
I am running dual Curtis controllers HPEVS dual 35 kit. I have been driving it for a year on 144 volts and recently upped this to 158 volts this worked fine for about 6 weeks but now it looks like I've blown one controller. The master controller now burns out the pre charge resistor when I try and start the car. The slave controller works fine.
It started when I noticed the car running on only one motor. When I pulled off all the covers the following issues were found.
A hot joint on the slave contactor.
The master fuse 400amps was blown.

After fixing the hot joint on the slave side and changing out the fuse on the master side I now find the pre charge resistor heats up and burns out. The relays and contractors all test ok.
Any one out there seen this before and it's all pointing to the Curtis pre charge.
Any advice would me much appreciated.


----------



## kennybobby (Aug 10, 2012)

It sounds like the contact surfaces of the main contactor are frosted and not making good connection, so all the current is being carried thru the precharge resistor. This could happen if the contactor is switched OFF while under a high current load.

Most cars use a separate precharge contactor that is taken offline once the capacitors in the motor controller have filled up, i.e. after about 6 R * C time constants, where R is the precharge resistance and C is the capacitance in the motor controller.


----------



## jacksdad (Apr 13, 2015)

something does not completely make sense though as the hpevs pre charge resistor is on a relay controlled from the curtis controller so i don't understand why this would be open after the first 6 seconds i assume it turns it off once the capacitors are charged - is i possible 158 V is enough to fry the precharge resistor when 144V is not - i would have thought there would be a bigger safety margin than this - i think it sounds more like a controller error - i would contact hpevs


----------



## Ozpara (Apr 11, 2016)

I have now replaced all contactors and pre charge resistors. Was getting a dead shirt on the controller DC side pulled it apart and it looks like I have a fries Mofset. Anyone able to give me info on where to get a IRF54127 mosfet to replace the damaged one. 
As the world is in lockdown I don't think it will get fixed any other way for a awhile. 

Or does anyone able to give me the specs for this mosfet


----------



## JustintheFalcon (Nov 15, 2020)

Ozpara said:


> I have now replaced all contactors and pre charge resistors. Was getting a dead shirt on the controller DC side pulled it apart and it looks like I have a fries Mofset. Anyone able to give me info on where to get a IRF54127 mosfet to replace the damaged one.
> As the world is in lockdown I don't think it will get fixed any other way for a awhile.
> 
> Or does anyone able to give me the specs for this mosfet


Did you get a source/resolution for your controller? I've the same HPEVS setup which ran for 5 years with no issues. I've been using Flight Systems Industrial Products to fix my burnt out primary controller since Oct2020 but not thrilled with the results so far.


----------

