AC or DC Heating of a wire


I am working on a project that the goal is to heat a piece of 20cm wire to 100 degrees C as fast as possible (100ms) and the power source being a 12V lead acid battery. The 20cm wire has a resistance of ~1 ohm. My question is: - What heating method would be more effective? AC or DC? DC would be like shorting the battery with a MOSFET switch. AC would be like using an inverter. (note: the accompanying electronics should be small size) - What do you think of a step up converter and shorting the wire with a higher voltage?

Please share your ideas of what would work best and more effective (fastest)... Thanks

Shouldn't matter if you use 12V DC or 12V RMS AC.

The higher the voltage the more current you can shove through a given resistor. The more current, the more wattage and the faster it will heat.

Even a small 12V VRLA battery will deliver above 125W into a 1R load, at least for a minute or so. I think your wire, in air, would reach 100C faster than 100ms. How are you going to measure its temperature so quickly?

Why 125 and not 144 watts?


A fully charged 12V battery has an open circuit voltage around 12.5V. If you put a load on it, the voltage will drop. You don't say the capacity of your battery, but to a 7AH alarm battery, 12-ish amps is a large load. Its fully charged voltage might drop to the 11V range to deliver that current. If the battery isn't fully charged, then the voltage will sag more.

A pair of fully charged 400AH L16 batteries would not even notice a 12-ish amp load and would deliver 12.5A at 12.5V no problem.