:)urgent urgent urgent ; Heating element voltage

[alhumaidi]

Hello
I have 220v 1200watt water heating element and I want to convert it and use 12v battery about 120watts 10 amps . our heating element is different I guess from yours but the idea is connecting the 12v wires dirictely to the copper pipe , it didn't work no heat any ideas?
Another thing I added another copper pipe small one ; and connected the two wires (+)(-) in the top of the copper pipe it gets heated but also the wires get heated and burns ; so I saw some subjects about adding resistors ; what kind of resistors I can use and how can I attach them to the heating element so I can use 12v battery 120 to 150watts and what I can use for automatic switch off when it get heated enough
Waiting for your replies

 

[Les Jones]

You will need a heating element with a resistance of 1.2 ohms to provide 120 watts of heating from a 12 volt power supply.

Les.

 

[alhumaidi]

I already have the heating element
Can I add resistor of 1.2ohms

 

[Les Jones]

The heating element you have will require 69.6 volts to provide 120 watts of heating. To use a 12 volt supply you need an heating element with a resistance of 1.2 ohms. Your existing heating element has a resistance of 40.33 ohms so with a 12 volt supply would provide 12 x 12 /40.33 watts = 3.57 watts. The only way you could use the existing element would be to use a step up converter to convert the 12 volts up to about 70 volts. The converter would only be about 90% efficient so you would be using about 132 watts from the 12 vollt supply to get 120 watts of heating.

Les.

 

[MikeMl]

And you will have to explain to us why this is so URGENT?

 

[alhumaidi]

And you will have to explain to us why this is so URGENT?

BeCause I'm leaving the city in 8 hours no internet connection for 3 weeks

 

[alhumaidi]

The heating element you have will require 69.6 volts to provide 120 watts of heating. To use a 12 volt supply you need an heating element with a resistance of 1.2 ohms. Your existing heating element has a resistance of 40.33 ohms so with a 12 volt supply would provide 12 x 12 /40.33 watts = 3.57 watts. The only way you could use the existing element would be to use a step up converter to convert the 12 volts up to about 70 volts. The converter would only be about 90% efficient so you would be using about 132 watts from the 12 vollt supply to get 120 watts of heating.

Les.

OK ; if I convert the 12v to 70v it will use more amps of the battery I mean if I use 100ah battery how much time until it needs to be recharged
I'm not expert in electricity so I have to ask you the Resistance that you are taking about is it some component On the heating element ? If it's ,,, where in the element cause our heating elements doesn't have much components

 

[Les Jones]

The heating element IS a type of resistor. It will probably be made from a coil of resistance wire inside a stainless steel tube which is packed with an insulating powder (Probably aluminium oxide.) to insulate the element (Electrically. ) from the tube and to provide a good thermal path from the element to the tube. If we ignore the fact that the converter is not 100% efficient then the current drawn from the battery will still be 10 amps. NOTE the current trough the element will be 120/70 = 1.7 amps. The time taken to charge the battery will depend on the charging current. The maximum charging current would have to be found from the specifications of the battery.

Les.

 

[Pommie]

I needed 12V heating elements for an incubator I was building. I used 20W 6.8 ohm resistors paralleled up. Need more heat, add more resistors.

Main problem will be making them water resistant.

Mike.
E.G. **broken link removed**

 

[Les Jones]

I think the heating element from one of these would be the easiest solution.

Les.

 

[Pommie]

I think Les nailed it. Even cheaper than my resistor solution.

Mike.