FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: CV355 on January 01, 2022, 06:37:20 PM
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I have heard two opposing opinions on the matter of powering electric fans (independently fused and relayed of course) off the alternator. Some people say it is fine, others say to avoid it. My battery and solenoid are in the trunk, and there are no other available ~30amp connections available without running a dedicated cable up from the distribution block in the trunk. If I have a 1-wire internally regulated alternator running to a megafuse and 10ga cable going all the way back to the battery, is there any harm in running the fans off that? The only downside is that the power isn't "conditioned" through the battery in this case.
I'm upgrading the cooling from a single pusher fan to a dual puller and shroud. Total draw is only 22amps when running but it will spike higher on initial startup as expected.
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The heavy output cable from the alternator goes to the battery positive so whether the tap is on the battery post or the back of the alternator, or a mega fuse terminal, it's still battery buffered. You do have the field current and people use that to power an electrical choke. You can't use field current to run fans.
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The heavy output cable from the alternator goes to the battery positive so whether the tap is on the battery post or the back of the alternator, or a mega fuse terminal, it's still battery buffered. You do have the field current and people use that to power an electrical choke. You can't use field current to run fans.
So I should be fine running off the megafuse terminal almost straight from the alternator then?
I did an AAW Classic update kit, but unfortunately it sends nothing with a 30a fuse out to the front of the car (it does have ignition +12 to power the relay, but it expects you to use the AAW fan relay kit assuming there's a battery 1' from the fans), and almost all of the engine connections are 5a fused or less. We had the single fan running off the alternator just for initial startup and tuning, wasn't sure if this was an acceptable method long-term.
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Yes, you can run the fans right off that alternator terminal.
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Since you're not running a "sense" wire for the regulator, that should do as well as anything. When using a 3 or 5 wire alternator, I'd recommend feeding fans and other heavy current items off a separate fused lead with the sense wire connected to the same terminal in order to tell the regulator what the real system load it as any particular time. I prefer the multi-wire setups even on the race car. Just not a single wire alt fan.