I wanted to share some pictures of this ESC failure. I have seen this happen before but I could not explain it until it happened to me.
Failure: Arc formed between the positive battery terminal and a nearby capacitor pin once the unit was anti-sparked and powered. This resulted in an observable flash I could see through my yellow ESC enclosure, which indicated to me that I should un-power and inspect the unit.
Cause: Rough handling caused a capacitor pin adjacent to the positive battery terminal to come loose. This was observed before the failure as a buzzing sound during anti-sparking which would stop after a few seconds. I believe the loose capacitor pin caused minor arcing between the capacitor pin and the PCB board, which charged the air around the pin. This reduces the insulating ability of the local air enough to allow a larger arc between the capacitor pin and the positive battery terminal.
More Details: This is a Little Focer v4 on a 20s battery. I anti-spark every time I power the unit. I tested my anti-spark to make sure it was still working. I tried to solder the capacitor back in place but all the conductor on the PCB is gone. I know that can be repaired but I don’t have the materials needed. It is probably better off because as I removed the capacitor the pin fell off.
Solution: Easier handling and potting material at the base of the capacitors to take stress off the pins would prevent this failure. I imagine some sealing material on the backside of the PCB around the battery terminals also wouldn’t hurt.
