First post but lurking for over a year
I bought some cheap heating pads on EBay a long time ago. 4v wouldn't get all 5 in parallel hot enough and 8v was unbearably hot so they went in the pile of crap for awhile.
I pulled them out to see if I could regulate the voltage with a DC voltage regulator that included a 10k potentiometer (which doesn't matter because the regulator circuit allowed it to work for my test). It did pretty well except for the need to be EXTREMELY precise while turning the pot.
The wire for the heating pads seem to be sandwiched between what was sold as carbon fiber cloth. There is a 2 wire"loop" which returns to the other side of the battery. I couldn't tell if they connected inside each pad or only at the termination pad,so I tore one apart. The wire inside was so fine and the "carbon fiber" so tightly glued I never found out about the connection. I did salvage about 1 ft of the wire to test it. The wire is about 1mm thick with some type of thread in it about like a human hair. I connected the wire negative to positive on a 1.2v AA cell, a 3.7v cell and a 7.4v battery pack. All fully charged. No spark. UnNo heated wire. No heated batteries. No ohm reading on the wire itself. No battery discharge at all after 15 minutes. I took the hair sized filament out...same thing.
What did I do wrong?
Okay. To answer some questions. If I connect a wire from positive to negative on an 8 volt 4A battery the power should go somewhere. Heat the wire, drain the battery, short the battery...what else? Energy can't disappear.