openinverter forum

After some fiddling and testing I just discovered that both my Nissan contactors are closed shut without any activation on them !
I'm reusing the Nissan contactorbox in its original form driven by the simpBMS and using the Nissan LBC. So all in all pretty original.

Strange thing is that both SYSTEM MAIN RELAY1 and SYSTEM MAIN RELAY2 are both shut/closed.
When applying +12V to activate they still 'click' but the contacts keep closed. So they never open after removing +12V.

Any thoughts what could have caused this ??
First thing comes to mind is that they arced but I'm using the pre-charge relay also before closing them..

Yup, I've fused a couple of those myself.
Inrush to a fairly serious filter circuit did mine (Hybrid inverter charger).
I ran it with an without precharge (10A) with the same result after about 3 activations.

They simply do not like being closed before you have the voltage equalised across them. Doesn't seem to take much of a deviation at all to do the damage.

I've replaced the contactors this evening and adjusted the pre-charge to 5 seconds so hopefully they will last a bit longer.,
What pre-charge time does the Leaf orginally have ?

I think the Leaf has quite a short precharge time, but the precharge resistor is really low value. Maybe 30 ohms? That won't leave much voltage at all for the contactors.