Main HV- contactor not engaging
Posted: Sun Mar 08, 2026 7:05 pm
Hello
I have just finished rewiring my zombieverter into my project car. I had a test setup prior to installing in the car. The setup was a Nissan leaf stack with the leaf batteries. I have experimented with using just the ISA shunt and the leaf BMS and both options worked. I decided to not try and wire the leaf BMS between my split packs and am just using the ISA shunt. When I split the pack I added two contactors to the rear pack that are connected to pin 31 of the VCU, one on the HV- one on HV+. Then I have another HV- contactor on pin 31 in the front pack. I looked up the transistor doing the pull down for this and I seem to remember that it can pull 2 amps which I should be fine. I have not looked up how much current the contactors pull. I did put a 7.5 amp fuse on the power supply for the contractors and it has not blown.
I know that the contactors can work as I tested by grounding the wire connected to pin 31 and they engage. I also know my pre-charge contractor. When I hit start the system triggers the pre-charge relay, then fails as I don't have power to the HV. I also didn't expect to have the precharge turn of if the main HV- contactor was not engaged.
I would like to know if I can tell if the car is in the "ON" state(pin 15 high) and is it trying to pull the HV low. I looked through the web interface spot values and didn't find anything indicating what should be happening. Can anyone point me to something to look at?
I have just finished rewiring my zombieverter into my project car. I had a test setup prior to installing in the car. The setup was a Nissan leaf stack with the leaf batteries. I have experimented with using just the ISA shunt and the leaf BMS and both options worked. I decided to not try and wire the leaf BMS between my split packs and am just using the ISA shunt. When I split the pack I added two contactors to the rear pack that are connected to pin 31 of the VCU, one on the HV- one on HV+. Then I have another HV- contactor on pin 31 in the front pack. I looked up the transistor doing the pull down for this and I seem to remember that it can pull 2 amps which I should be fine. I have not looked up how much current the contactors pull. I did put a 7.5 amp fuse on the power supply for the contractors and it has not blown.
I know that the contactors can work as I tested by grounding the wire connected to pin 31 and they engage. I also know my pre-charge contractor. When I hit start the system triggers the pre-charge relay, then fails as I don't have power to the HV. I also didn't expect to have the precharge turn of if the main HV- contactor was not engaged.
I would like to know if I can tell if the car is in the "ON" state(pin 15 high) and is it trying to pull the HV low. I looked through the web interface spot values and didn't find anything indicating what should be happening. Can anyone point me to something to look at?