C3s4me

I upgraded radiator and added duals fans. My aftermarket replacement alternator is stamped as a 63 amp. The fans have over a period of time has ran my battery down. My question is how much bigger amp alternator can I upgrade to without needing to upgrade wiring? Fans draw about 25 amps max. I was thinking of upgrading to a 90 amp alternator..... Would I need to upgraded wiring?

mrvette

NO, leave the stock wiring in place .....the thing you need to do is take the power wire straight off the power output stud on the alt. and up/over the front to a relay mounted on the shroud, that controls the fans, then to the fans directly.....use a 30 amp blade fuse in holder for the power wire at the alternator end.....

I upgraded my alt to a 17SI unit which is factory 108 amp.....

DO NOT take any fan power off the battery wiring, that is a huge no no and most likely the reason for your 'run down battery' syndrome......

C3s4me

Thank you for taking the time to respond... It is hooked up to relay.. Fan only comes on at temperature or when a/c is turned on....r

DUB

with using the 108 amp alternator. A 90 amp alternator will also work but it depends on what other electrical stuff you have added to your car that was NOT facotry equipment.

Sometimes trying to get another wire in the rubber boot that protect the wire on the alternator can be a bit if fun.

This statement is somewhat confusing. Simply because taking it off of the back of the alternator is still in the same circuit as the battery wiring...which is why this above statement needs to be really clarified. I KNOW why you wrote it...just wanting to make is so others know why.

Pulling power off of the positive battery cable terminal area can be done....along with pulling the power off of your starter solenoid.

I will write this and may help...that IF you are pulling power to run components that draw a lot of amps....you DO NOT want to pull THAT power off of a component that is being supplied power....for example...by a 12 gauge wire. By doing it that way...you are trying to power up TWO components that are needing a lot of amperage and they are trying to get that amperage through ONE 12 gauge wire.

This is why I wrote you can use the positive battery cable area (using the correct type of cable bolt)...or the starter solenoid where the positive battery cable goes. AND as mentioned...it can go on the back of the alternator.

In many of my custom wiring scenarios. I have replaced the wire on the alternator with a MUCH MUCH larger gauge and THAT wire is going to a junction block...and from that junction block. I can pull power off of it...and still being aware of how many amps I am pulling off of that junction block...or I make my own junction block that can handle HUGE amounts of amps.

DUB

DUB

DUB