fan wiring help....

[dnhieu]

alright i need some wiring people to help with this one. for some reason my fans are not getting a full 12v. i have checked all the fuses and relays and im starting to get a little pissted . im giving up on all the stock wiring and will be wiring everything to a switch inside my car...

alright here is a wiring diagram that i will be using. i will be wiring it this way (unless someone has a problem with it) to the dot except for where it says devices. i obviously will be wiring in 2 devices (slimline fans) in parallel. this is so i get a full 12v to the fans.

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my question to you guys what size inline fuse do i run? what gauge wire do i run? and what size relay do i run?

please only serious wiring people. i really dont want to burn my car down.

thanks in advance
david

 

[XtremeGST]

10g wire, as for a inline fuse you have to know how much AMP draw the fans are going, so lets say you have a 15 amp draw fan it can spike between 15-20 different fans demand different loads and as the load increases the more AMP is draw, so you will need to figure out how much AMPs your fans demand at full RMP's then you can decide on what fuse you want to run.

Remember OHM's Law

Ohm's Law for DC Circuits
Current:

I = E/R = P/E
Voltage:

E = I*R = P/I
Resistance:

R = E/I = P/(I*I) = (E*E)/P
Power:

P = (I*I)*R = E*I = (E*E)/R


That should help you figure out what you need to run for amps.

 

[dnhieu]

DAMNIT MAN!!!! i hate ohms law. i did the crap last semister and i already forgot it all. would anyone have a step by step instruction on what they would do to figure out the right size fuse i would need? i guess i would need to start by figuring out how many amps my fans currently draw at 12v but how would i do that if i know anything but the voltage im trying to reach?

thanks again
david

 

[dnhieu]

alright i think i figured it out. i went to the parts store and looked at the instructions. it says at 12v the fans will draw 25 amps. this means if i wire them in parallel that it will draw 50amps. i will use 8 gauge wire (should be enough for 50amps) and wire them directly to a switch with a 60 amp fuse just incase it drops below 12v (which it does at nite time when the headlights are on)...

anybody see any problems with this?

thanks again
david