How to make a small battery heater?

Question

I really want to make a small heater using small or tiny battery. The temperature needn't be high, just over normal room temperature. I want to use it to keep some small metal part warmer but not hot.

Answer 1

Batteries are not an efficient source of power for heat. Even a "D" cell battery would likely not last more than a day. The inconvenience of a larger batter or rechargeables makes it best if you just plug it in.

Answer 2

Why? Any resistor in a circuit is a heater of sorts. If I put a 1000 ohm resistor in a 12 volt DC circuit, I dissipate 12mw of heat in the resistor. A typical D cell alkaline battery has about 2.2 Ampere-hours capacity. If I replace the 12v supply with a single 1.5v D cell, then the current drops to 1.5ma, and the resistor dissipates 1.5mw. 2200/1.5=1467 hours. 1.5mw is not a practical heat source, but 15mw MIGHT be, so a resistor of 100 ohms would work, reducing the time by 10 to 147 hours under an ideal case. Something less, in real life, because a battery can not sustain a constant 1.5v over the useful life. The real question is, how much heat do you need? Without knowing the requirements, no one can answer this question with definitive numbers. I can only use examples as I have to illustrate how things work.

Answer 3

Have you thought about using a light bulb, it will generate heat and you can adjust the heat by how close you place it to your part. Also you can use different bulbs to adjust heat 75W or 150W or higher or lower ones. This will give you a wider choice and possible make it safer.