5v Signal For A Relay

hoopty5.0

mechanicus terribilis
15 Year Member
Dec 14, 2010
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SW Houston
I need to wire up some electric fans, but need to do it before I can get a controller in the mail.... Like tonight.

Assuming I was to use a manual switch to temporarily control the relay, where in the engine bay could I tie in to? Or my understanding of relays wrong and in that case, feel free to lash me verbally. Any help is appreciated. The car runs and drives well, but absolutely hated the gridlock this morning. I need to move more air at low to no speed.
 
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I think you are over thinking this...
Use the diagram below. Use a fuse between the battery and the relay that is big enough to handle the full load amperage of the fans. The switched 12v source can come from anywhere. If you want to use a toggle switch for now then just feed 12v to the switch and then to the relay.

In your case I would use one relay for each fan, being a twin setup. I want to say I used a 30 amp fuse for each fan when it was installed in my car, full load amps should be 19 per fan if my memory serves me correctly.
relayblank.jpg
 
I think you are over thinking this...
Use the diagram below. Use a fuse between the battery and the relay that is big enough to handle the full load amperage of the fans. The switched 12v source can come from anywhere. If you want to use a toggle switch for now then just feed 12v to the switch and then to the relay.

In your case I would use one relay for each fan, being a twin setup. I want to say I used a 30 amp fuse for each fan when it was installed in my car, full load amps should be 19 per fan if my memory serves me correctly.
relayblank.jpg
Haha, yeah I do tend to overthink things. Thanks for the diagram, I'll try and get it done this evening.