I have a project in mind that amounts to little more than rebuilding a broken eGo-T (electronic cigarette). The battery when I took the busted eGo-T apart had quite a kick and I got a minor burn from it. (It's a lithium ion battery, I think). As I have no way of discharging the battery I was thinking that I would just hook it back up and solder some new wires into it. That strikes me as potentially problematic, not only because I do not fancy another burn but also because I am worried about damaging the PCB.
Edit #1: I am getting 3.8v on the Multimeter so it is definitely still at full charge.
Edit #2: The battery has solder tabs on it so according to the answer to Is soldering wires directly on a NiMh battery safe? I should be okay I think? I'm a total newbie so I could still be wrong.
Aside from the very real risk of heat damage to my fingertips are there any other risks I need to be aware of?
Best Answer
Please, practice some engineering safety skills and first use a multimeter and check the voltage level of the battery. If it's a single cell Lithium Ion battery, it will be between 3-4.2V with proper charge, and <3V is getting on the low side. It can still discharge some serious current below 3V though, so perhaps next time use isolated equipment and/or gloves/tools. Remember to use some kind of eye protection in case they do actually explode from heat or expansion. Use leaded solder if possible, and if you have temperature control on your soldering iron get it as close to 260-270 degrees Celsius as possible so that it will melt the solder but hopefully do less damage to the batteries.
You will have no problem as long as the positive terminal does not short with anything. Perhaps (while not grounded yourself) put some electrical tape around the positive terminal/wires and make sure the PCB is safe, the ground wire is soldered and ready, and then you may carefully use tweezers or something on insulated wire to position the exposed wire and solder it to the PCB pad or whatever you are trying to do (you fail to mention what setup you have, how it all connects, and what you were doing when it actually shorted and burnt you other than you took the eGo-T apart).
Maybe use a plastic/insulated vice to hold the item while working on it too.