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Discussion Starter #1
Daveoxide and I just installed a nice 1100 CFM electric fan in Lottie.


I have a really nice 60 amp alternator, but I've heard that that isn't enough.

My question is not if 60 amps is enough. My question is how I can tell if 60 amps is not cutting it BEFORE draining the battery to death? I've got a voltmeter inside the car constanting measuring alternator voltage. I've also got access to a nice Midtronics alternator/battery computer checker diagnostic tool.

Will I see my alternator voltage drop to 8 or 9, meaning it can't handle the draw? Or what?

Thanks for any help!
 

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If the alt can't hang, the voltage will drop. How fast will vary on how much a$$ your battery has.
 

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Discussion Starter #3
It's a very expensive NASCAR battery, over 800 CCA and a 120 minute reserve capacity.

SO I should watch the voltage on my gauge pretty religiously? Will it be too late to save my battery once the voltage starts dropping?
 

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It'snot going to hurt the battery, just run it down a little. Crank the car and when the fan is running, see if the voltage goes below 12 - 12.5 V. It should do it within a minute or two. Also, turn your headlights on and a few other accesories to simulate real world conditions.
I think a 60 amp'er might be pushing the low side. The fan alone will probably pull atleast 25-30 amps.
 

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im running a 2000 CFM fan on what I think is a 60 amp alternator. What you gotta remember is that the fan doesnt run all the time. It will only run for a brief time while at stoplights MAYBE. Mine usually doesnt kick on unless I get in REALLY heavy traffic.
 

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The closest i could come up with is a spal 1300cfm fan (for comparison), it draws 8.1 amps. I think you'll be fine with the alt you have.
 

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You could, if you really wanted... get an amp meter and put it in line with the battery. turn everything on (electric fan encluded) and spin your engine up a bit... see how much curent is being drawn from the battery. it should be nothing. actually, it should be negative... since the alternator is supposed to charge the battery.
good luck!

- Jason
 

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Discussion Starter #8
OK, thanks guys!!

I'll keep an eye on my voltmeter :)
 

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It will only run for a brief time while at stoplights MAYBE
Actually, I see two problems with that, Jim. First is that he lives here in the Sacramento Valley where 100 degree days are common, and 110 degree days are not uncommon. His fan is going to run a LOT, especially since he doesn't have an aluminum radiator.

2nd problem is that the fan running at idle is where you run into problems. That's when the alternator is putting out the least amount of current.

60 amps MIGHT cut it, but I'd upgrade to a 100 amp. When I had a 30 amp alternator and electric fan, it only took me 2 times of having a dead battery to realize the need for a higher output alternator. At night, I could always tell when I was having a problem, as my stereo would start cutting in and out.
 

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Discussion Starter #10
I'll look into a replacement really soon, John.

Any recommendations?

I didn't consider needing to buy a better alternator. LUCKILY it's August and the hottest part of the summer IS over. Whew. Hopefully it'll be OK, and I'll be watching my gauge!!
 

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When you go to the local parts store, ask for one for an AC car. The parts books should show the max current output. I always check to see if my alternator can still put out between 12.5 and 13 V DC with full load on it, all accessories on. Let the car run a couple minutes then test. You'll know right away if the Alt can't keep up.
 

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Discussion Starter #14
What year Versailles? 75-79?
 

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We just started to carry Powermaster Alternators, check out our web site for prices...

We only show a few on there now, they make a nifty chrome one too...
 
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