Alternator ????
Thread Starter
Pro
Joined: Jul 2004
Posts: 605
Likes: 0
From: Alta Loma CA
Alternator ????
I have a 100 Amp Powermaster alternator. My car is setup with dual fans from a Ford Focus. One fan is on all the time, the other is set to come on when the A/C is on (I am going to change that to a temperature controled setup). Both fans run thru seperate relays. Today I noticed that when the second fan comes on the Ammeter goes to a 15 amp discharge. Without it on the gauge is normal. No change when the headlights are on. Checked the voltage at the battery. One fan on it was 13.6, when the second fan came on the voltage dropped to 12.5. Which says to me no charge. I also noticed the alternator was whinning with a beraing like noise. Verified it to be the alternator by taking the belt off, no noise with the belt off. Also with the car in vent mode and blower motor running no effect on the Ammeter. What do you guys think?
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,112
From: Crossville TN
Your alternator is not 'keeping up' with the amount of discharge from the fans. I don't know what the current draw is from each fan, but that sounds like a lot being dumped in them. Could one of the fans be faulty? Are you trying to run a big stereo system at the same time? Could the alternator be defective? If the system is working properly (the battery will take a charge and the alternator is properly sized), you should see a movement of the ammeter needle to the 'discharge' side and then it will recover back to "0" pretty quickly. Otherwise, you have a problem in the charging system somewhere or a fan is providing a 'short' from power to ground.
Burning Brakes
Joined: Aug 2005
Posts: 1,164
Likes: 1
From: Europe, France
If you can, check the current draw of the second fan with an ammeter clamp, and compare it with the current of the first one.
If you get the same readings, remove & have your alternator rebuilt, probably rectifier or regulator is bad.
Maybe a 100 amp alternator is a bit weak for your installation. If the aternator died once, it will probably die again for the same reason...
A direct change to a 130A or 160A alternator could save you money, assuming it's the culprit...
Last edited by 73StreetRace; Nov 25, 2009 at 10:36 AM.
Thread Starter
Pro
Joined: Jul 2004
Posts: 605
Likes: 0
From: Alta Loma CA
Pulled the alternator today. Had it checked at both a Kragen and Auto Zone. Both stores machines showed it to be bad. Ordered a new 160 amp Powermaster. Old one turned out to not be Powermaster but a Tuffstuff.
Hopefully that will fix the issue.
Hopefully that will fix the issue.
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Burning Brakes
Joined: Aug 2005
Posts: 1,164
Likes: 1
From: Europe, France
If you've got headers, check that the alternator isn't too close from the exhaust pipes.
It can cook electronic components quite fast. A heat shield ( sometimes made of a simple sheet of polished stainless steel ) can help in this case.
I did it for my ignition coil which is just above the headers and it helped a lot.
It can cook electronic components quite fast. A heat shield ( sometimes made of a simple sheet of polished stainless steel ) can help in this case.
I did it for my ignition coil which is just above the headers and it helped a lot.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,112
From: Crossville TN
Make sure you have dedicated wiring and ground for the radiator fans so that no fan current flows through original wiring [except for the main battery wires]. Fans grounded to the radiator shroud should be run to chassis, instead.
Le Mans Master
Joined: Apr 2001
Posts: 5,000
Likes: 1
From: Minneapolis, Mn USA
I'm surprised I haven't seen this yet, but I'll throw this out there.
If you have electric fans and stereo equipment, IMHO, the best upgrade you can do is go get a CS144 alternator 140Amp. Its obviously capable of higher power, but its real benefit is that its capable of outputting the level of current you need at idle speeds, when the power draw is highest with the fans blowing hard, and is a relative easy mod.
If you have an alternator light , then you dont need to add any resistor to the converter plug, its psuedo plug and play:
1) zip off the serpentine pulley with an impact wrench
2) zip on your old V-belt pulley with same impact wrench
3) get the EC81 wire plug adapter for SI alternator to CS alternator from NAPA
4) Get slightly longer V-belt if needed
5) mounts up to yor existing brackets, but youll need to get a nut-bolt for the top as the CS144 has no threads on it like the SI alternator.
Mines been powering my Mark VIII fan for 2 years now without a hiccup.
B.
If you have electric fans and stereo equipment, IMHO, the best upgrade you can do is go get a CS144 alternator 140Amp. Its obviously capable of higher power, but its real benefit is that its capable of outputting the level of current you need at idle speeds, when the power draw is highest with the fans blowing hard, and is a relative easy mod.
If you have an alternator light , then you dont need to add any resistor to the converter plug, its psuedo plug and play:
1) zip off the serpentine pulley with an impact wrench
2) zip on your old V-belt pulley with same impact wrench
3) get the EC81 wire plug adapter for SI alternator to CS alternator from NAPA
4) Get slightly longer V-belt if needed
5) mounts up to yor existing brackets, but youll need to get a nut-bolt for the top as the CS144 has no threads on it like the SI alternator.
Mines been powering my Mark VIII fan for 2 years now without a hiccup.
B.
