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Overcharging Issue: Toasted Voltage Regulator?

khansmithkhansmithMember
Good Morning:
I wanted to get some verfication on a diagnosis I made on my charging system this week. Issue was that I accidently had a wrench fall across my battery terminals (I know...I know....I have a rubber boot on the + terminal but I was taking the battery cables off when it happened) and wasted my new/old optima redtop. I bought a new red top and after running the car for 2 mins the battery started to hiss. I called optima and they said the battery was probably being over-charged but to get it load tested just in case. I had a load test performed and it passed. I then decided to verify if the voltage regulator was the issue

I devised the following test with Mike Dailey:
1.) Measure battery voltage without car running
2.) Start car
3.) Put volt meter across battery while car is running
4.) Observe for a steady output ~14-14.4 Volts with no accessories on. With accessories ~13 volts. AMP's should subside if battery is charged.
5.) Shut off car
6.) Measure battery voltage. Looking for ~12.8 volts.


I conducted the test this morning with the following results:
- Pre-test battery voltage ~12.4 (no engine running)
- Engine Running Voltage 18.6 (Runtime was ~ 60-90 seconds)
- AMP Guage: Pegged to the right!
- Post test battery voltage 13.9 (no engine running)
- Battery making slight hissing noise out of top ports

Questions:
1.) Is my voltage regulator fried?
2.) Is the stock alternator an internal regulator design?
3.) Is the correct replacement alternator for a 1974 Pantera the same as a 1971 Mustang?
4.) Any other observations you would like to share with me?


Thank you in advance for your input and insights.

Khan Smith
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lf-tp2511lf-tp2511Member
Khan,

I just went through something similar with my battery.

After seven years, the battery in 2511, the same little thing that was there when I bought 2511, went south.

I finally found a correct sized replacement and installed, and then ran a voltage charging test like you did.

WOW! I too had something in the 17 volt range.

I made a quick call to Bosswrench Jack and we decided that with a new off-the-shelf battery, those voltages might be just fine, until the battery was fully charged.

Yup, after some driving time, the charging voltage went down to the correct range.

Now, bear in mind, this doesn't mean YOUR voltage regulator isn't broken...

For your questions:

stock alt is NOT internally regulated
yes, '71 'stang unit is fine

Finally, I do not like the mention of your battery hissing. Something may be wrong there. And yup, I'd guess regulator.

Do you have another, known fully charged, battery you could swap into the Pantera and run that test again?

Larry
khansmithkhansmithMember
Thank you very much for your answer.

I have run two different batteries with same output. I asked Optima rep about the hissing and they said that was normal in an overcharge but that the battery is not broken at that point. This is why they have those two round black colored ports on top of the battery. Battery passed a load test with flying colors.

I should add that the battery before my mishap seemed to charge fine in the car.

Follow-up question:
I have only worked on internally voltage regulated alternators. If regulator is external:
a.) Where is it located?
b.) Where can one find a replacement regulator?
c.) Is it easy to replace?
d.) Would it be easier just to buy a new unit (not worried about cost)?
garth66garth66"When speed is the only thing that counts"
Hit your local Kragen/Checker/Schucks for a cheapie $15 voltage regulator.
http://shop.oreillyauto.com/Pr...PartType=204&PTSet=A

Swap it out with yours and see if your charging voltage is where it's supposed to be (14-14.4).

Or better yet, just borrow the regulator off your Cobra for the test. If the voltage regulator is the culprit, then order a better quality $30-60 voltage regulator.

Answers to follow-up questions:
a) On the passenger side firewall in the engine compartment.
b) ANY auto parts store, and some gas stations.
c) Easiest part to replace on the car, besides the air filter. Just back it onto ramps or jack the passenger side up so you can crawl under it more easily.
d) Yes. Get a new one. They're cheap!
bosswrenchbosswrenchMember
FWIW, the last time I heard ANY noise from a battery, it was fluid boiling inside an OEM Ford-Motorcraft part....The next start, a water-fill cap blew out and shattered against the hood. The hissing turned out to be an internally shorted battery- which finally ignited the small amount of hydrogen normally generated during charging. The same thing happened to a friend's autocross racer, with the battery mounted next to the driver for better balance. Except in his car, the entire side of the battery blew off on start-up, showering his wife in sulfuric acid! A VERY quick trip to a nearby motel and a thorough shower prevented any scarring, but all her clothes were a total loss.
Bottom Line: if a battery starts making noises, get it out of the car RIGHT NOW!
garth66garth66"When speed is the only thing that counts"
quote:
the entire side of the battery blew off on start-up, showering his wife in sulfuric acid!

Wow! Glad she was alright. I had the DieHard battery in my 66 Mustang explode without warning when I tried to start the car, which showered my recently restored engine compartment with battery acid. I HATE Sears DieHard products!!! Mad
57545754If you're not kickin' up dust, you're collectin' it!
I had the overcharge problem when I first got my car in '08 (over 17V going to the battery at 2500rmp, and the battery boiled over, but also had the tach acting up and the Ammeter was pegged at 75amps until it burned out), replaced the VR (CarQuest part VR166 made by Standard Motor Products), swapped out the Ammeter to a voltmeter, and replaced the battery which I put on a battery tender over night to make sure it was fully charged before starting the car.

I'd also suggest going and spending $20 to buy one of those black plastic battery boxes (if your car parts store doesn't have it, any RV dealer should), cut notches at the top for your battery hold-down clamp and you'll rest easier knowing that if the battery boils, you won't be replacing your carpeting, you just pull out the battery, take out the box, toss a little baking soda in the box to neutralize the acid and rinse it out with a garden hose. I don't know how it would handle the side of a battery exploding, but I'd hope it would provide some measure of protection. I don't keep a lid on mine, maybe I should consider that after reading some of these stories.

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khansmithkhansmithMember
quote:
Originally posted by #5754:
I had the overcharge problem when I first got my car in '08 (over 17V going to the battery at 2500rmp, and the battery boiled over, but also had the tach acting up and the Ammeter was pegged at 75amps until it burned out), replaced the VR (CarQuest part VR166 made by Standard Motor Products), swapped out the Ammeter to a voltmeter, and replaced the battery which I put on a battery tender over night to make sure it was fully charged before starting the car.

I'd also suggest going and spending $20 to buy one of those black plastic battery boxes (if your car parts store doesn't have it, any RV dealer should), cut notches at the top for your battery hold-down clamp and you'll rest easier knowing that if the battery boils, you won't be replacing your carpeting, you just pull out the battery, take out the box, toss a little baking soda in the box to neutralize the acid and rinse it out with a garden hose.


Great idea! Thanks for sharing
bosswrenchbosswrenchMember
DeTomaso gets some criticism on parts of his designs, but no one said much when Porsche installed the 914's battery on top of the fuel injection brain-box!
Nevertheless, for safety's sake I recommend either dropping the Pantera's battery below the front-trunk floor ala the post-Ford factory Panteras, or dropping the front brake line (that runs behind the battery in its stock position) below the floor. That line connects the two front calipers together and is only protected from battery corrosion by a loose piece of shrink-tubing, usually torn or missing entirely.
garth66garth66"When speed is the only thing that counts"
quote:
I'd also suggest going and spending $20 to buy one of those black plastic battery boxes (if your car parts store doesn't have it, any RV dealer should), cut notches at the top for your battery hold-down clamp and you'll rest easier knowing that if the battery boils, you won't be replacing your carpeting

Good call! The battery boiled over on the last owner of my car, so now my battery sits in one of those boxes. I still need to replace the carpet though. Maybe next summer.
ea3528ea3528Member
Kahn,

I am replacing all electrical wiring this winter ... from the battery to the solenoid/starter - and also from the ammeter/volt meter to the fuse panel, solenoid and alternator.

In speaking with Jon Haas from Pantera Electronics, he convinced me to replace my stock Motorcraft alternator with the GM si12 model. It was a $90 touch and does not require a voltage regulator. I liked the mod because it simplifies the wiring schematic and also throws more current (regulated) at the battery. This was important to me because I am also adding a stereo, GPS nav and a few more gauges.

Anyway, if you are interested in the specs, please send me your email and I will pass along what I have ...

Cheers,
EA
#3528
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