What is the Most Efficient Way to Heat a Small Object Using a Battery?

[mrm0rgan]

i hope I am asking this at the right place i just have a few questions... why does it take so much power (115v) to heat up a small coil(heating element) roughly the size of a spring in a pen. what could get just as hot, maybe a resistor? i have a 18 volt battery from a drill and i need to get something small hot (red hot!) for atleast five minutes. if anybody can help me it would be appreciated. now i know that a battery could do it but it would be extremely expensive. but what else could i use instead of a coil (basic heating element). something that a 18v battery could get hot?

 

[vk6kro]

You can get high power at any voltage. Power is the product of voltage multiplied by current.

So, you could get 10 watts by having 110 volts at 0.0909 amps or by using 12 volts at 0.833 amps.

The 12 volt option would be safer, of course.

The classic resistor in a coil shape would be made of Nichrome wire.
A coil that was going to dissipate 10 watts at 12 volts would have a resistance of 12 volts / 0.8333 amps or 14.4 ohms.

Nichrome wire is available in different thicknesses and the thicker wire has less resistance per foot than the thinner wire. There are wire tables on Internet where all this is available.

http://www.interfacebus.com/properties-of-nichrome-wire.html

For example if you did want to make the coil above and you wanted a coil that had 6 inches of wire in it, then you would want Nichrome wire that had a resistance of 28.8 ohms per foot.

This would be 37 AWG wire according to the table above.

Wire comes in a range of thicknesses, so you would get whatever was closest to this value and whatever you could buy locally.

Finding some of this wire may be a problem as it is expensive to buy a roll of it when you only need a few inches. You could try a local electrical repair store and ask nicely.

This wire does not solder easily so you have to clamp a connection to it or get some silver solder.

 

[mrm0rgan]

thanks for thr reply. i appreciate it. sorry if I am sounding like a lame. if what your saying is correct how come they are still using elements that use 115v like a little space heater ect. if I am understanding you correctly. the thing is there is this product it takes up 115v when you plug it in and i want to make it cordless it has a heating elements in it just two small one bout the size of a spring in a pen. i want to make it cordless but everybody that i talk to says you have to use that many volts to heat up an elemnt. its just there has to be something out there with the tecnology we have today that can get something red hot like a heating element that can get red hot from just a battery small cordless drill like battery.

 

[Jiggy-Ninja]

thanks for thr reply. i appreciate it. sorry if I am sounding like a lame. if what your saying is correct how come they are still using elements that use 115v like a little space heater ect. if I am understanding you correctly. the thing is there is this product it takes up 115v when you plug it in and i want to make it cordless it has a heating elements in it just two small one bout the size of a spring in a pen. i want to make it cordless but everybody that i talk to says you have to use that many volts to heat up an elemnt. its just there has to be something out there with the tecnology we have today that can get something red hot like a heating element that can get red hot from just a battery small cordless drill like battery.

The specific heating element in your space heater is made for 115V. You will not get it to work well at 12V no matter what you do.

It is possible to make a heating element that creates the same amount of heat with 12 volts. But it will be different than the one in your heater. Namely, it will need to have much lower resistance.

Bottom line, you will not be able to make that heating element work well at 12V no matter what you do. So do what vk6kro said, get yourself some Nichrome wire, and just make one. All it is is a resistor, literally the most basic circuit component you can possibly make.

The reason they use an element designed for 115V is because that's what comes out of the wall plug, plain and simple. No need for any circuitry to transform the voltage to the right level.

Finally, volts is not a unit of power. Power is the amount of energy used per second, and is found by multiplying the voltage (energy per electron) and the current (electrons flowing per second).

 

[mrm0rgan]

now I am getting it sorry just takes a while for it to sink in lol anyways thanks for your input it has been really helpful... both of you take care..."Of all the things i miss i miss my mind the most"