Heating Element

[bitem2k]

HI,

I want to make a portable hand warmer for my girlfriend. Any idea how i can heat up a bit of metal using a small-ish battery?

thanks very much.

 

[dch222]

You won't get much heat out of a small battery.

Have you seen those chemical warmers which you boil to recharge and can trigger by pressing a button? Put inside gloves they can keep you going for about an hour.

 

[bitem2k]

Hi, dch222
thanks.
Never seen those, but i will look into it.

What about a 12v Car battery?

 

[Nigel Goodwin]

Hi, dch222
thanks.
Never seen those, but i will look into it.

What about a 12v Car battery?

Bit big to carry around!.

Why not just buy here a pair of nice gloves?

 

[bitem2k]

Yeah i agree with what your saying, however im just experimenting with different ideas, but i have failed to find any info on heating elements.

On my travels around the web i have found many battery powered heating contraptions. I.e , I found something called a portable vaporiser, which is for heating herbs apparently. It claims that it can heat for an hour from a 1500mA hour battery.
[EDIT] https://gotvape.com/store/vapir.oxygen.vaporizer.php

Could you please explain the basic idea behind heating element, or maybe where to get one from, or how to make one.



thanks very much.

 

[Nigel Goodwin]

It's just a resistor, usually a wirewound one, or resistance wire wound in some fashion.

 

[bitem2k]

Would nichrome wire be suitable?

thanks

 

[Nigel Goodwin]

Would nichrome wire be suitable?

Yes it would - be careful about how hot it gets though!.

 

[bitem2k]

Nice one mate, thanks very much.

Would this Cause the actual battery to be heated dangerously hot? Like a short?

thanks

 

[Nigel Goodwin]

Nice one mate, thanks very much.

Would this Cause the actual battery to be heated dangerously hot? Like a short?

Probably so, depending how low the resistance is.

Apply ohms law! - 'V = I x R'

Or rearranged - 'I = V/R' - so the lower R (resistance) is the higher I (current) is.

The actual heat in the resistance is 'W = V x I'.

 

[bitem2k]

If I wrapped the wire around some metal, would the metal be dangerous to touch, electrically speaking? (not temperature)
I.e. if you touched the water inside a kettle after just turning it on, would you be electrocuted?

The actual heat in the resistance is 'W = V x I'.

Does the battery get as hot as the wire?

Thanks

 

[Nigel Goodwin]

If I wrapped the wire around some metal, would the metal be dangerous to touch, electrically speaking? (not temperature)
I.e. if you touched the water inside a kettle after just turning it on, would you be electrocuted?

No, because the kettle element is insulated from the water, and then cased in an earthed sleeve.

In your low voltage case it's too low for a shock.

Does the battery get as hot as the wire?

Same formula applies 'W = V x I' - so exactly the same amount of heat.

 

[bitem2k]

I have seen some vague articles about heating a cup of water with several AA cells.

So if I were to heat the wire to upwards of 100 degrees
would I would have to insulate the wire.

If the battery gets as hot as the wire is this dangerous?

If not AA cells , what about 12V car battery?

Sorry if this is all ridiculous, I’m very confused!

thanks

 

[bitem2k]

Also at what voltage would you be shocked?
Is it dangerous to touch both terminals of a car battery? I have always steared clear of touching both!

 

[Nigel Goodwin]

I have seen some vague articles about heating a cup of water with several AA cells.

Expensive and slow!!.

So if I were to heat the wire to upwards of 100 degrees
would I would have to insulate the wire.

Not electrically, but thermally to prevent burning?.

If the battery gets as hot as the wire is this dangerous?

It's NOT a good way to treat a battery!.

If not AA cells , what about 12V car battery?

There is a LOT!!!! of power in a car battery, easy to cause a LOT of damage. Normal non-rechargeable AA's etc. don't have much energy stored in them, and a fairly high internal resistance - so are reasonably safe. NiCd or NiMh have low internal resistances (particularly NiCd) and can provide enough power to be dangerous (and to self-destruct).

 

[bitem2k]

**broken link removed**

Blow Through Product Function Allows for Quick Heating and Inhalation
Battery is external, uses cord to attach to Oxygen unit

If the battery is external and the unit heats up to 400 degrees F, how can that be safe?

 

[Nigel Goodwin]

If the battery is external and the unit heats up to 400 degrees F, how can that be safe?

The same amount of power dissipated in load and battery doesn't mean they get as hot as each other - to get 400 degrees you have a very small element, and a comparatively massive battery.

 

[bitem2k]

Ok, thanks for clearing that up.

 

[Sceadwian]

BTW a good source for high power handling nichrome wire is... toasters! =) Insulating it is a bit if a problem though.

 

[Nigel Goodwin]

BTW a good source for high power handling nichrome wire is... toasters! =) Insulating it is a bit if a problem though.

Personally I've always used wire from electric fires, either the bar or silicon tube type - we even used to stock (years back) replacement elements (coils of wire) to go inside the silicon tubes.