Electro drive motor controller blown

[MrAshley23]

Hi guys I really need help to get this motor running again. I bought an old currie lightning fs. Took it home and did some testing.. the motor worked great for a while and when I went to hook everything up I accidentally hooked the battery up backwards when I went to test the motor again it made a small amount of smoke so I pulled the plug quickly but now I can't start the motor with the battery connected correctly.. I opened the motor housing and exploded the controller.. is it just a fuse or diode blown or is this more serious? I'm pretty good with a soldering iron and have worked on and fixed other electronics but never 3 phase bldc controllers. Can anyone give me some knowledge as to how to go about fixing it without unpotting the whole controller and sensors to run fault tests.

 

[amberwolf]

The usual things destroyed by reverse battery polarity are the phase FETs.

The shunt(s) can melt off the board--usually just comes unsoldered, but sometimes they actually blow like fuses.

Polarized capacitors on the battery bus can be damaged; may not be obvious but will have different electrical characteristics than they should, if damaged.

The LVPS that converts battery voltage to the 5v and 12v or 15v / etc the MCU and gate drivers/etc use can also be damaged, usually just the first (higher voltage) stage. Sometimes if that fails in the wrong way it allows battery voltage to the lower voltage stage(s), and if those also fail the wrong way they'll pass battery voltage to the MCU and other low-voltage devices, and at that point the controller is unrepairable unless you have another identical one failed in a different way you can swap those parts from (esp. MCU).

Sometimes when the FETs blow from motor overcurrent, they damage the gate drives too--this doesn't usually happen from reverse polarity, but it can.