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Alternator can't cut it after Windstar fans

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pismorat

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My 100amp (I think) alternator isn't cutting it after I've put Windstar fans on the truck (489BBC). When driving and the fans are on, the voltage gauge is only reading 9v. Turn the fans off and it goes back to 13v. Also, the alternator is getting very, very hot and starting to make a whining noise only after a few drives. I run v-belts; what alternator options do I have?
 
pismorat said:
My 100amp (I think) alternator isn't cutting it after I've put Windstar fans on the truck (489BBC). When driving and the fans are on, the voltage gauge is only reading 9v. Turn the fans off and it goes back to 13v. Also, the alternator is getting very, very hot and starting to make a whining noise only after a few drives. I run v-belts; what alternator options do I have?
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I don't think your alternator is the problem.
If it only goes to 13v, you still have a big draw.
It should be 14-14.5volts.
Plus from 13 to 9, that's a serious drop, sure the fans are working properly?
No short, no bad bearings...?
I say double check everything before you start throwing parts at it.
 
upgrade the alt to batt pos+ wire . its small from the factory . go big wire .

then if you still have problems how old is the batt ? what cca ?

look for a pontiac transport mini van full optioned out van alt . lots of guys run these as there easy to get and do 140 amps .

i run serp belt and got my 200amp unit from these guys . they offer all kinds of size outputs . been almost 10 years now i think no problems. https://www.ebay.com/itm/90-95-NEW-...Parts_Accessories&vxp=mtr&hash=item1e53e55754
 
Quadruple check your grounds. Remove paint from connections.

And take a multimeter and test the voltage from the alt charge post to the alt case. Should see 14.5 ish while running. Move the ground side to the bracket and the the next thing further away until you see the voltage drop
 
I did find a faulty frame ground last weekend and fixed that. I will do all the voltage tests you mentioned and check all grounds again; thank you. I am running dual batteries, both AGM 700+ CCA. The main battery is a year old; the alternate is the one with the fans and accessories on it and is 7 years old. Probably close to needing to be replaced, but I don't think that would cause the issue? I am running the factory 3-wire setup on the alternator, but I will upgrade that charging wire for sure; good suggestion!
 
Summit has a 140amp v-belt alternator that I've ran on a few different cars/trucks with good results. IIRC it's about $120
 
pismorat said:
I did find a faulty frame ground last weekend and fixed that. I will do all the voltage tests you mentioned and check all grounds again; thank you. I am running dual batteries, both AGM 700+ CCA. The main battery is a year old; the alternate is the one with the fans and accessories on it and is 7 years old. Probably close to needing to be replaced, but I don't think that would cause the issue? I am running the factory 3-wire setup on the alternator, but I will upgrade that charging wire for sure; good suggestion!
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7 year old battery could be a part of the problem.
A battery should have enough juice to keep up with a demand like that for a while before taxing the alternator that bad.
Are the batteries separated?
 
The batteries are joined by a solenoid. I can run both (normally) or either one independently. Most my accessories are powered by a power strip that's fed by the 7 year old auxiliary battery. The main handles the engine and lights.
 
I went CS144 alternator, but be ready to go serpentine, double V belts were still slipping.
 
I run an alt out of a 79 Caprice Classic 100 amp. No issues charging, no issues with my Windstars. Both batteries should be the same age and stuff or one will drain the other as a side note.
 
Yes, both should be the same age, brand, model, etc.
 
Good call! I took the auxillary battery and had it load tested...no dice. It was shot, so I got a new one, same as the main I am running. Hooked it all up and it is better, but now I blew the 30 amp fuse attached to the smaller fan with the larger motor. Got too dark to keep messing with it, so back to it in the morning. Probably need to step the fuse size up on that one?
 
A motor tries to deliver its rated power output. That output can be rated in watts or horsepower, or other methods.
Lets say that motor is rated to put out 360 watts of power.
Watts equals Volts times Amps. Amps equals Watts divided by Volts.
360 Watts, divided by 14.5 Volts equals 24.82 amps.
360 Watts, divided by 12 Volts equals 30 amps.
360 Watts divided by 9 Volts equals 40 amps.

Low voltage will cause an electric motor to draw more current. Sometimes a lot more current if it stalls.
If you have not had any problems with the fuse blowing before, I would just replace it and toss a spare in the glove box. I doubt it will give you any more trouble.
And, of course, remember the fuse's purpose is to protect the wire. If the wire size is rated at 30 amps, a larger fuse without increasing the wire size can cause unwanted types of excitement involving fire extinguishers.
 
I had to up my alternator when I went with Windstars and also upgraded my headlights. There are good aftermarket options out there that drop on. One thing too is are you turning on the fans full blast all the time or staging them? The current draw is quite high when they are full blast, but this is seldom needed.
 
Mastiff said:
One thing too is are you turning on the fans full blast all the time or staging them? The current draw is quite high when they are full blast, but this is seldom needed.
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I was going to mention that too. No idea how much my LS-fans draw, but they don't both come on at the same time, and the 110A alternator has no problems. One comes on as needed, if temps continue to climb the secondary fan comes on.

AC can throw in some variables, but generally if not already done so, running both fans all the time is probably not desirable. Better to stage them, so that the secondary comes on when the primary can't handle things. Every vehicle/drivetrain combo is going to have unique cooling requirements, but testing with one fan hooked up will give you info on when the secondary is needed, then you can tailor the fan setup to those requirements.
 
I ended up with the new battery, now the alternator seems to handle the one fan OK. I try turning on the smaller fan (longer motor) and it keeps popping the 30 amp fuse. I've got it wired with 8ga. wire, so it'll handle a larger fuse, but I'm wondering why it pops now, when before with the old battery it wouldn't. Any thoughts before I up the fuse?
 
I wouldn't install anything more than Ford used, what was it?

FWIW I've also not been pleased with aftermarket fuses. I'd recommend pulling OEM fuses if you haven't. I tested some "5A" aftermarket (read: chinese) fuses, and they didn't blow when running the heater blower on high, which is supposed to draw somewhere around 10-20A constant. I wouldn't be surprised if many aftermarket fuses also don't hold up to their stated rating.
 
They should be on relay's if they are not. Mine ran fine on relays with a 20 amp fuse for each fan, controlling the relay.
 
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