Story Time. Exploding 18650s

I did read your entire post. I made a typo in my first sentence but go back and read the third paragraph. If your VESC had failed and caused a short, then massive amounts of current would also make your switch fail. Your VESC definitely failed first. A failed switch cannot short a VESC but a shorted VESC will short your switch without a fuse. BTW, you don’t need a 40A fuse, even a 100A fuse would have saved your build.

Things to add to your list: #Do your research, you should have known how bad a bursted battery fire is, it should not have been a surprise, there are plenty of youtube videos out there. Same thing with failing FETs, it is common knowledge in the electrical engineering world that FETs fail as a short most of the time, a simple google search would have had you better prepared.

#If you see smoke, do not power things up, That is really where you F’d up. You should have had the patience to check things out thoroughly before ever making that choice. Whether it was a FET or anything else on the board, you should have made an inspection.

#Do NOT throw batteies off a balcony!!! Putting others at risk is seriously not cool. Plus you could have made the fire much much worse! This is more of a having common sense thing but again, knowing how batteries fail would have helped in not making that mistake.

#Check, double check and triple check your VESC settings, Given that this is the second time you’ve had a failed VESC, the odds of them both having manufacturing defects are low unless you purchased them from a non reputable source (in which case the common sense and research arguments apply), I would post all your settings for others to look through, maybe they can spot what was wrong.

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Chassis mounted FETs with through hole legs do exist

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Wait a minute the fets on vesc short battery to motor on fail? It makes sense, feeling pretty dumb. Fuse going in asaply…

FETs commonly fail closed so yes. :slight_smile:

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