I am designing a pair of heated pants and have run into an issue with having to use batteries (or any other portable power source) to power them.
What I have now is about 50ft of Teflon wire with 5Ω resistance. The wire is 30AWG PTFE W-16878 Stranded wire rated for 600 volts.
For the power source, I have two of these 1.2 V 3.1AH batteries As they were the best option for a high current battery that can also handle higher temperatures.
The issue is with the two batteries in series they only provide 2.73V so when I connect the wire to the batteries it only pulls 0.546 amps which is not even enough to produce a noticeable change in temperature. Ideally the power draw should probably be around 30 - 60 watts but is subject to change based on how much heat the wiring actually ends up producing.
My first thought was to use an op amp and create a current to voltage converter, but there is the issue of if the op amp can handle the current I put in, and if it can continue operating when the circuit gets heated as the pants are heated. To be safe, any circuit made for the pants will use the same teflon wiring so I can avoid any wires burning up.
However, there is likely another easier solution that I am missing which is why I am posting here. I have tried researching battery powered motors to see if they might use circuitry that may help solve this issue, but had no luck finding anything useful.
Also please keep in mind that any solutions need to be reasonably portable as these pants will be used all winter.
Edit: The specifications for the wire is MIL-W-16878/4 Type E Stranded Wire with a temperature rating of: -55°C to +200°C. I can't seem to find a specific current rating.
Also as stated here: "M16878/4 is used in high temperature electronic applications M16878/4 has excellent thermal aging, solder damage, flame, and moisture resistance." Which is why I choose this specific type of wire.