A few of my buddies at work are still using 3.7 volt 650mah
batteries, and I have taught them all how to wrap 2.2 ohm micro
coils and cotton wicks for their Protanks and mini Protanks. We have made a 510 adapter that connects to our digital multimeters to check them before use though. As Visus said, you always want to check for shorts before attaching it to your battery and firing it up.