I would guess more like a precharge problem (assuming that is how you have the main contactor setup) have you ever done an "Off" then "On" that quickly before? Inrush current to charge the controller caps would be one of few things that could blow the fuse without failing itself, but since you were able to drive home things are obviously working.I just finished upgrade from lead to Li, and changed out my charger and dc-dc because I went from 96v to 120v. I installed a little Elcon 1500 charger... and after the first day driving around I had a really weird thing happen.
I was grabbing an 'opportunity charge' while guest lecturing at the local community college about Electric Vehicles, and we had just moved to going thru the car. About half-way thru walking the class thru the system I wanted to show the contactor open/close, so I quick unplugged the charger, hopped in the car, turned in on - fine, turned it off - fine, turned it right back on to make contacter close again, and BAM.... blew my big ferraz 400amp fuse.
The fuse was installed 'close' (maybe 1/2 inch) to the charger physically, in-line between front pack and rear. I had a 'cover' over exposed lugs/bolts made from bike inner tube slipped over the line.
I am using the charger interlock output running thru to pot-box->KSI. I did NOT use optional key-switch wire on charger, I joined it with the AC power in as instructed...
everything else seems fine, and once I found it after class I was able to just take it out and run home fuse-less. controller, dc-dc, everything seems working fine. Charger seemed fine and charged pack up just dadny last night.
what could have happened? any guesses?
In theory the charger should have no way of sourcing/sinking that kind of current with out having a short circuit failure.