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the fans draw a lot of current and I think the alternator isn't up to the task of recharging the battery. My generator light comes on at low rpms and goes out when I blip the throttle. I w at the goodguys show and I I started up the p car to throw a couple of revs for onlookers. When it was time to leave I didnt have enough juice to start the car. The fans are wired to come on when I turn the ignition key.

You have jumped to a BIG conclusion based on no real evidence.

Because you have a low battery condition, you think it is the fan's fault?

Do you have a voltmeter? You need one to check your charging system.

An at rest battery should have between 12 and oh, say 12.6 volts. Check it at the terminals of the battery.

A running car, with a good alternator and voltage regulator, should be providing between 13.5 and 14.5 volts to the battery, checking it at the battery terminals.

See this link for a tutorial on charging systems:

If you find this to be the case on your car, THEN you can start to blame the fans. Wink

First off, there is absolutely NO reason for you, living in the cool Bay area, to have BOTH fans come on with the ignition. One, Maybe. Both, never.

Next, what is the purpose of the thermo fan switches? From what you wrote, they are doing nothing but plugging two holes. They are supposed to be switches, usually with two DIFFERENT values to turn on first one fan and then the second, but only when coolant reaches the switch temp value. You should probably swap one of the 190 units for a 170. Lowest one on the bottom. You do have a fluidyne, right?

If you have them wired into the relays, but your fans come on at the turn of the ignition, your relays must be wired incorrectly.

Yes, your fans COULD be the culprits.

But first check your charging system.

Then check your relay wiring.

Get back to us and we will figure this out.

Summer is coming. Wink

Last edited by lf-tp2511
...Actually the Volts should be 12.2 Standing and 13.8 Max.(when on 'The Charge'), With the engine running at 3000 RPM! This will lower from 13.8 as the Battery becomes Fully Charged. You should Never see 14. Volts! Over 14. and you have a regulator problem, and Your Battery will Boil Dry. NOW! Lets talk Battery! How old is it? I Bet That is your Problem. Older than 3 Years and You can expect it to start going bad. The Battery must do Three things!
'Take' a Charge.
'Hold/Maintain' a charge.
and then be able to Deliver Full Amperage to the Starter, on Demand.
I had this same problem, although it took One to Two days, of 'Sitting', before the Battery was incapable of turning the Starter; even though I would disconnect it with a Master Switch to keep it from 'Draining' overnight. That Battery was 5 years old. Amazing what a Brand-New Battery will do for You. Do what Larry suggested, and get a Voltmeter and test that thing! If the Volts go UP when the RPMs are increased from idle, there is Nothing wrong with the Charging System!! Also! Check the Voltage While Cranking the Starter! If they drop below 8.5 While Cranking, Buy a New battery and get the Highest Cold Cranking Amps that You can FIT into the Car!...
Last edited by marlinjack
I have had more than one red Optima in my daily driver in the past few years. I know that some guys have had nothing but good luck with them, but my luck has not been so stellar. In the past eight years, I have gone through 3 of the red Optima -- two were absolute turkeys, and the final one that is in the Jeep now is 6 years old; so definitely a mixed bag. I read in Consumer Reports that the best battery made today readily available -- you guessed it correctly; WalMart lead acid batteries. Scary I say......

If you ditch the red Optima and try a lead acid battery, I will totally understand.

Years ago I had a Optima red top in my Pantera and it ran down. I tried charging it with my home charger and I couldn't hold a charge. I went back to a lead acid battery. I didn't know that typical home battery charger could not charge a run down Optima. Go to Optima's web site. There's very specific charging instructions. It's not the same as a lead acid battery and the typical home chargers can't do it. I accidentally ran down my 6 year old red top that's in my hot rod and took it to an Interstate shop. The shop manager was familiar with them and charged the battery at no cost.
Check your voltage regulator too. I had the same symptoms and it turned out to be my voltage regulator went bad/shorted and had a constant 20 milliamp draw (or something like that, I don't recall exactly). Would run a fully charged battery flat in about 8 hours. New $29 voltage regulator solved my problem.
Originally posted by Cyboman:
That is a sweet Rod. '32s are my favorites. I like that style in a Tudor. I almost bought one years ago, and I'll have one some day! Thanks for sharing.


Thanks. I've wanted one since I was a little kid and a neighbor had one. I got it 2 years ago. Wish I hadn't waited so long.
I have also had a number of Optima Red tops go bad on me. They do not hold up well on a non daily driver, unless you put a battery tender on there. Yellow tops can handle not being run, better. Currently I am making the switch to Odyssey.

I also run duel Flex-a-Lites, but mine run on a thermostat and I've never had any problems.

On the alternator, I see this on the Pantera Wiki:
"It is a plain-vanilla Ford Motorcraft alternator for a '72 Ford. You may find a 47-amp, a 63-amp or 75 or100-amp 'Police Specials'- they all use the same cases and are visually identical. To find a high output unit, I had to take a couple of junkyard refugees to an auto-electric shop and let then spin them up on their tester to see which was which. IMHO, the 47- & 63-amp are too low output to support headlights, AC, a stereo, two radiator fans and a CB, at low rpm in traffic. Cheers- J Deryke"
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