Thanks for the replys, esp redleader for this:
Quote:
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So lets say the supply is putting out 12v, the wire has .01 ohms resistance, and the element has 1 ohm. Total resistance is .01 + 1 = 1.01 ohms. Current is then 12v / 1.01 = 11.88 A. The voltage drop across each part is then V = I*R. So you'd have 11.88*.01 = .1188v across the wire and 11.88*1 = 11.88v across the element.
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You were correct about the charger not being adequate.
Unloaded it outputs 11v when set to 6v, so I assumed it would be fine. However with the graphite the voltage drops to 1.36v, @3A (or higher, the charger ammeter doesnt go very high...).
Also this time I kept it connected a little longer, I did notice the graphite was getting warm. I think with a proper 12v supply, that of a pc, this could work very well.
I will look at high current voltage regulators next, I need some way of controling the current and voltage.
For this I will probably need SMPS/PWM type regulator as the current will be too high for a linear type, which could waste as much power as the heater is using. SMPS should be a lot more effeicnent.
My multimeter isnt the most accurate (it could about £5) but has upto 10A for ammeter function
BillA what do you use for controling your heater element?