The polarity inversion that costed a lot

What happens when your 3S 2200mA battery is not sufficient for lab test (but can't use a workbench power supply)? Well you upgrade to a better one just for the test duration. We got a 12V motorcycle battery, couldn't read the label though because it was painted to be used in a previous project (so no knowledge of the capacity).

What happens when you connect a motorcycle battery wrong?

To be fair we were under pressure for preparing a test on a lake and we were 3 to be working on the small USV. Lack of attention and the Vcc cable being brownish, not exactly red, the polarity has been swapped and the familiar combination spark + smoke + weird smell. The fact that the battery packed a large amount of power and was not current limited and the fuse was not installed because the order did't arrived yet.

We blew:

1. A compass
2. A power module
3. The pump of the water cooling

The telemetry that worked only in one direction