Help a civil with an electrical control problem
Help a civil with an electrical control problem
(OP)
Hi guys and gals,
I'm a Civil so bear with me on this one. I've recently installed an electric fan in my car to replace the mechanical unit it once had and am running into a problem. When installing the fan I could not find a wire thick enough to connect to the fan so I just hard wired it to the battery (fan is on a thermostat controller so it's not on all the time). But the issue i'm having is that when I turn the car off and the fan is on it keeps running I want the fan unit to only have power when the vehicle is running.
I was thinking of using some sort of switch that trips when it gets a 12V current from the ignition (I had this with an amp I used to have). A buddy of mine suggested a IGBT or a MOSFET. Would this work? If so say I want it turned on by a 12V signal, when the fan turns on there is a very high amperage peak of 60-70 amps but the constant draw is about 30-35 Amps with a 15 volt max. What should I use?
I'm a Civil so bear with me on this one. I've recently installed an electric fan in my car to replace the mechanical unit it once had and am running into a problem. When installing the fan I could not find a wire thick enough to connect to the fan so I just hard wired it to the battery (fan is on a thermostat controller so it's not on all the time). But the issue i'm having is that when I turn the car off and the fan is on it keeps running I want the fan unit to only have power when the vehicle is running.
I was thinking of using some sort of switch that trips when it gets a 12V current from the ignition (I had this with an amp I used to have). A buddy of mine suggested a IGBT or a MOSFET. Would this work? If so say I want it turned on by a 12V signal, when the fan turns on there is a very high amperage peak of 60-70 amps but the constant draw is about 30-35 Amps with a 15 volt max. What should I use?





RE: Help a civil with an electrical control problem
RE: Help a civil with an electrical control problem
RE: Help a civil with an electrical control problem
I would not use a semiconductor device for this. No need, less reliable and more costly than a relay. There are many made for this and similar purposes.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Help a civil with an electrical control problem
However on many older cars that wasen't possible. (I only have older cars, because I can't understand all that crap under the hood).
Another option is to use a vacuum relay, so it only runs when the engine is pulling a vacuum.
RE: Help a civil with an electrical control problem
There is probably a spare position in the fusebox for a relay which you could wire out, or just install it in a convenient and *dry* location. Virtually every radio/CD player has a switched live signal which is only live when the engine is running.
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If we learn from our mistakes I'm getting a great education!
RE: Help a civil with an electrical control problem
You may be able to find a suitable feed on your alternator, but this type of alternator is by no means universal. Use caution.
Bill
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"Why not the best?"
Jimmy Carter
RE: Help a civil with an electrical control problem
Just use a relay such as this one;
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Find a 12V accessory power wire. If it's an older car there is probably an "Accessory" spade terminal right in the fuse block. Otherwise, use a fuse tap or something else to get the power from the accessory fuse. This way, the fan will also turn off while you try to crank the car.
Oddly enough, this doesn't sound anything like a problem a civil engineer would have while working....
RE: Help a civil with an electrical control problem
That's just what I needed.