I fly model aircraft as a hobby. On some model aircraft the battery connectors can be reversed especially the cheap JST ones with a broken or missing polarity locking tab. Or, the batteries can be mis-wired or a soldering mishap can lead to the poles being swapped. The classic solution to a problem like this would be a diode, probably a Schottky one.
But on a system where currents can exceed 100A, a diode is simply not practical; cooling and size constraints come to mind, as well as the wasted power being approximately 0.4 x I. If the power to an ESC is reversed, it may cause the body diode of the MOSFETs to conduct, leading to very high currents, immediately destroying the ESC. That sucks, of course. But it may be worse; if the ESC has a BEC output (a voltage regulator), the reversed polarity could break down the regulator and fry attached devices, such as servos, receivers, cameras and the like. Which would make for a really bad day.
Being an RC aircraft application, this needs to be reliable, crash-resistant (i.e. relays are probably not an option due to their mechanical nature), small in size, and low in cost.
So what solutions for this problem are there?
Best Answer
Any reverse polarity protection you add will add to the complexity, weight, loss and unreliability of the system, so it's probably not worth it.
In short: you can't really add reverse polarity protection in this case without compromising normal operations, so it's better to be careful to never reverse the polarity in the first place.
Make sure you use polarized connectors like Deans Ultra plug in stead of crappy ones that can be reversed with a little man-handling.
Be careful to put the connectors on the batteries correctly.