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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.

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    \$\begingroup\$ I don't see anything here that indicates zero resistance. \$\endgroup\$ – DKNguyen Jan 5 at 21:51
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    \$\begingroup\$ Most likely you are seeing infinite, not zero, resistance. Possibly because of transparent varnish or lacquer or similar coating on the wire. \$\endgroup\$ – Brian Drummond Jan 5 at 21:53
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    \$\begingroup\$ "No ohm reading on the wire itself." You need to write clear technical information. Does this mean 0 Ω or \$ \infty \$ Ω. \$\endgroup\$ – Transistor Jan 5 at 21:55
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    \$\begingroup\$ @PaulPease No. Infinite resistance implies zero current flow. Zero current flow means no power consumed. No power consumed means no heat. \$\endgroup\$ – Elliot Alderson Jan 5 at 22:13
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    \$\begingroup\$ @PaulPease No, an open circuit on any battery will not cause a fire. An open circuit means that no current flows. I think you have some really fundamental problems with the basic concepts in this area. \$\endgroup\$ – Elliot Alderson Jan 5 at 22:31
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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.

If you can't even read the resistance on a meter, you effectively do not have a complete circuit, so no surprise you can't get it to heat up. The wire may be broken, you may not have good contact, or it may be laminated to prevent contact. Time to troubleshoot and figure out why you don't have a circuit.

If I connect a wire from positive to negative on an 8 volt 4A battery the power should go somewhere.

From what you've said above, you didn't actually connect the wires, so no power goes through the wire.

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