OK. I'm just about to finish my electric heater for the spin-on fuel filter, so that it will heat vegetable oil where it hurts more, fuel filter and pre injectors (injector line heaters will be my next week homework ).

I need some help though as where or how can I plug them so that they turn on and off when I turn on and off the ignition key. I thought I might use the stereo wiring, but I'm not sure it will hold the load ( I think it'll be around 10-15 amps).

Any help appreciated .

Cheers, Deni

that is what they are for. handling the loads. have coil V coming from the radio or the CL, and draw a fresh fused circuit from the battery.
simple.
John

Hmmm some language barrier here , what do you mean by "draw a fresh fused circuit from the battery"?. Also whay would I need the relay. I want to run the heaters for as long as the car is runing as it will be the only mean of heating the oil.

A relay would have 2 circuits. One power circuit and one control circuit.
He's saying to use a fresh fused power circuit straight from the battery and use a control circuit from the radio or climate control.

I would just go through the fuse block and take of from a circuit that's on when the key is turned and off when it isn't.

danny

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You're using a relay so that you won't be putting a big load like that onto your fuse block. The relay will easily tack onto almost any fused switched circuit without causing any overloading problems, as the coils generally don't draw more than an amp. Then, you will have a switched circuit that will be able to switch as many amps as the relay is good for straight off the battery, where you will be able to get plenty of current.

This will also help when you add those injector line heaters, they will present more load to whatever you're hooked to, so a big capacity relay (probably around 30A) should be what you need. Make sure the coil is 12V as well.

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Thanks for the ideas guys! The fuel filter heater is around 3.5 ohm, that mean 3.4 amps@ 12v (~41w). The injector line heaters will be around that size as well, so together they will be drawing around 12-14 amps max. I will check out the relay option.

Cheers for the help.