It's come to my attention that reverse polarity protection is needed for the ZeroPhone battery. I've plugged batteries in reverse a couple of times myself, with varying levels of damage, and esp. with Gamma revision there's a lot of reports about people plugging the battery incorrectly (since the cheap plastic holders actually have wrong polarity marked when compared to the 18650 PCB). I've researched this in the past, and here's a circuit that I've found, that's replicated perfectly with no additional BOM items:
It's come to my attention that reverse polarity protection is needed for the ZeroPhone battery. I've plugged batteries in reverse a couple of times myself, with varying levels of damage, and esp. with Gamma revision there's a lot of reports about people plugging the battery incorrectly (since the cheap plastic holders actually have wrong polarity marked when compared to the 18650 PCB). I've researched this in the past, and here's a circuit that I've found, that's replicated perfectly with no additional BOM items:
Blog post about it here (archive link), with some explanation and useful discussion.
Also, possibly there's a need to add a reverse-biased LED + resistor, to notify the user about the mishap?