So I know this is a pretty dumb question. But I figured you guys would know. I accidentally bought a 3-Pin female DC jack rather than a 2-Pin. Am I still able to use this for charging my battery paired with my BMS? How do I determine what pin is positive and negative?
The outside of the barrel is always the negative and the inside pin is always the positive. Get a multimeter and switch it to continuity mode, touch one probe to the middle pin of the plug and then probe the 3 pin coming out the back of your plug to figure out which is the positive lead. Then repeat the steps to find the negative lead.
The third pin is a sense pin to detect if something is plugged into the jack or not.