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### Topic: get heat from battery (question)? (Read 5692 times)previous topic - next topic

#### zhirantaha

##### Nov 16, 2012, 02:15 pm
hi
i want to convert 9v battery or 12 volt battery into heat, i mean to get a heat from the battery to warm something up, it not important if the heat is not too much??
is it possible?

#### johnwasser

#1
##### Nov 16, 2012, 02:41 pm
Energy in a battery can be converted to heat.  Use a resistor.  Current is voltage/resistance. Current times voltage is heat in watts.  If you dump a 12V battery into a 2 Ohm resistor you will get 6A of current and thus 12(V)*6(A) = 72 Watts of heat.
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#### fungus

#2
##### Nov 16, 2012, 02:56 pm

hi
i want to convert 9v battery or 12 volt battery into heat, i mean to get a heat from the battery to warm something up, it not important if the heat is not too much??
is it possible?

Seems like an expensive way to do it. A battery won't last long if you draw enough current to make it hot. Why not use a normal heating element?

No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

#### majenko

#3
##### Nov 16, 2012, 02:58 pm

Energy in a battery can be converted to heat.  Use a resistor.  Current is voltage/resistance. Current times voltage is heat in watts.  If you dump a 12V battery into a 2 Ohm resistor you will get 6A of current and thus 12(V)*6(A) = 72 Watts of heat.

... and a very smokey resistor ...

Make sure your resistor can handle the power, or it will burst into flames.  A little ¼W one wouldn't be suitable

You can make your own heating element using Nickel Chromium (NiChrome) wire.  A good source for this is from an old electric heater, surprisingly enough

#### zhirantaha

#4
##### Nov 16, 2012, 03:23 pm
i couldn't what you all said
please explain it clearly!

#### zhirantaha

#5
##### Nov 16, 2012, 03:27 pm
can i get a enough heat by 9v  battery and normal heating element??

#### fungus

#6
##### Nov 16, 2012, 03:31 pm

can i get a enough heat by 9v  battery and normal heating element??

Enough heat for what? You'll get better answers if you tell people what you're trying to do.

No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

#### zhirantaha

#7
##### Nov 16, 2012, 03:37 pm

can i get a enough heat by 9v  battery and normal heating element??

Enough heat for what? You'll get better answers if you tell people what you're trying to do.

for water!

#### dxw00d

#8
##### Nov 16, 2012, 03:42 pm
How much water? What temperature increase do you need?

#### zhirantaha

#9
##### Nov 16, 2012, 03:44 pm
the amount of water is less than 2 L and change  the temperature up to  25c from 10c

#### majenko

#10
##### Nov 16, 2012, 04:52 pm

the amount of water is less than 2 L and change  the temperature up to  25c from 10c

Over how long a period?  (i.e., how fast do you want it to heat up?)

#### fungus

#11
##### Nov 16, 2012, 04:57 pmLast Edit: Nov 16, 2012, 04:59 pm by fungus Reason: 1

the amount of water is less than 2 L and change  the temperature up to  25c from 10c

How many joules of energy is that? How many are in your battery?

Answer: Over 120Kj of heat needed, only 18Kj in a 9V battery. You'll need about 15 batteries to do it.

No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

#### zhirantaha

#12
##### Nov 16, 2012, 05:06 pm
the time as fast as it can

#### johnwasser

#13
##### Nov 16, 2012, 07:38 pm

Answer: Over 120Kj of heat needed.

120,000 Joules = 33.333 Watt-hours

A 100 Watt heater would heat the water in 1/3 hour (20 minutes). Do you need faster heating?

200 Watts would take 10 minutes.

2,000 Watts would take 1 minute.

20,000 Watts would take 6 seconds.
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#### John_S

#14
##### Nov 16, 2012, 07:54 pm
Quote
20,000 Watts would take 6 seconds.

...annnd a 9V battery would take 10 days.  XD

9V at 150ma = 1.35W
333Wh/1.35W = 246hours

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