Hi,

I'm currently working on trying to heat two heat pads. The working spec of them is:

Operating Voltage: 5V DC

Operating Current: ~600mA (~8.3Ω)

They are joined in parallel. I'm working off this example :http://etextile-summercamp.org/2013/wp-content/uploads/2013/06/heatcontrolling_breadboard_example2-1024x682.jpg

I understand that parallel resistors combine according to 1/R = 1/R1 + 1/R2

So in theory, 1/R= 1/8.3 +1/8.3, therefor 1/R= 0.12 + 0.12= .24

Therefore 1/.24= 4.16ohms

I'm using 3 x 9v batteries in parallel, so the voltage of the batteries in parallel is 9v, (the capacity is increased by putting them in parallel)

Then using ohms law to calculate: i=v/r,

I=9v/4.16= 2.16amps, which would give 1.08amps per heat pad.

I'm just wondering how long I would get out of the 3 x 9v batteries in parallel? I don't know what the mah rating of the batteries is. The battery type is a kodak 9v xtralife alkaline battery

Any help would be greatly appreciated

Thanks

Liam