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Hi i have a similar setup with emus bms and hpevs ac motors and curtis controller. The emus guide suggested circuits does show controlling the main contactors from the bms. The HPEVS circuits have the main contactors controlled from the curtis and thus it controls the precharge relay etc which makes sense.

I am considering having further contactors within each battery box which only come on when u turn the ignition switch which would then energise the curtis controllers at the same time (as the 12v supply to the curtis is also on the ignition circuit as is the bms). This would mean that normally when the ignition is off no HV cables are live outside of the battery boxes. I did wonder about allowing the bms to control these contactors might be a good idea but actually the risk is higher i think from the bms suddenly cutting power when a voltage sags (this i guess could be likely at full acceleration when current is at full draw and this would surely cut the contactor life) and im not sure any of the BMS alarm states (low voltage high temp etc ) really justify an instant contactor cutoff and just a big red warning light on the dash would be enough for you to slow down and stop as soon as safe and investigate. I do have 2 big emergency stop switches on the dash that either cut the throttle supply for if the throttle cable snaps or sticks on as i have a direct chain drive and no clutch) and one that cuts 12v power to the curtis controller which hpevs reckon was ok to be used in a true emergency and would cut power to the contactors and stop everything. I did consider a third cutoff swith which cut power to my battery pack contactors but left the ignition on these might be helpful if the insulation montor detected a leak from battery pack to chasssis. I also have an internia switch which also cuts power to the curtis controller if there is a crash.

Any views on this would be gratefully received
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