North American Turbocoupe Organization



Charging Questions
Rob H Offline
Junior Member
#1
Hi there, wondering if anyone can give me a bit of advice. I'm not great with cars, but I learn as I go, kind of get the basics and can follow instructions.
My Tbird has been running pretty good for a bit now.
I had some problems a couple years ago. Some mysterious stuff was happening.
At the time I replaced the battery and the alternator with brand new Ford parts at the local dealership. The mechanic also spent some time looking for other problems just in case.
Things were going pretty good, haven't had many problems since.
I left the lights on the other day for a bit while I was doing something. Prior to that I would have to say everything was great. I took out for a good run after boosting it, and had no problems until today.
I started and stopped the car a few times between stops in town, the car didn't run much between stops.
Got in and battery seemed almost dead, couldn't start. Again boosted and drove around for about 10 minutes and went home.
Testing with voltmeter at the battery with the car running showed about 12.65 volts, not steady. Turned car off and tested. Had 11.8 volts at battery. Started up again without boost. Now it shows pretty much that same voltage with the car running or not.
I know the reading with the car running is too low, and then it got even lower on the second reading, but it seemed to have charged the battery alright in the 10 minutes I drove around.
Any ideas? Anywhere else I can test to get an idea besides right at the battery?
Pretty sure the shop is going to say it's the alternator, and it could be though it's practically new. Installed October 2016, but only a couple thousand km on it since then.
I would really appreciate any help you guys can offer.

Edit: More or less the question is this. Does this indicate that the (almost) new alternator has already died and I need a new one, or is there possibly something else causing this?
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Jeff K Offline
Administrator
#2
With those voltages, it is obvious the alternator is not charging the battery.

Was the replacement alternator really a NEW unit, or some cheap "spray can rebuild" from a discount parts store? Take the alternator off and take it to a parts store to have it tested.

Could also be the alternator is not getting the 12 V signal to "turn on".

Do you have a DMM and a test light so you can do some testing?
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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Rob H Offline
Junior Member
#3
The alternator was definitely brand new through Ford.
I do have a digital multimeter and a test light. I only know how to do what I'm told to do with them Smile
What would I need to check?
Thanks
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Jeff K Offline
Administrator
#4
FIrst step is to take the alternator to a parts store and have it tested.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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Rob H Offline
Junior Member
#5
Sorry for the late update.
I took the alternator out and off to the parts store I went. Got thinking that maybe Ford would test it. as they installed it and they were on the way.
Messaged my cousin who works there in the body shop, who told me they don't do that there, they would need to test it in the car. Asked where he would suggest taking it, and I more or less meant, of all the parts shops, which one to go to?
Turns out none of the parts shops here test alternators anymore. As a matter of fact, nobody at all tests them. Possibly Canadian Tire I was told.
Fortunately a guy overheard me talking to someone and pointed me to the only shop around that does just out of town. A big truck shop.
The guy seems to really know his stuff. Said the alternator wasn't putting out anything but that if I left it with him he would figure that out what was wrong, said it might be just the voltage regulator, if so he would rebuild it right away.
So he tested it more and I don't remember what he did different, but he said it is actually putting out about half what it should, not the nothing he originally said.
So I'm taking it back to him tomorrow after it leaves Ford for a much needed detailing.
Also, It turns out it the alternator IS a rebuild or re manufactured(same thing?), it's been a couple years since it went in, I thought it had been a brand new part, going to ask Ford about that tomorrow.
He said they are often rebuilt with crap parts even the good rebuilders he said. He said he will open it up and fix it, and also replace any cheap crappy parts, and if it fails again, at least he will know the alternator was a good one when it went in the car.
So that's where I'm at, so I think for now I'm good, assuming everything is good when t goes back in.
Is there anything I should test once it's back in and working?
Reading through forums and talking to some people, heard mentioned exciter/sense wire several times, that they can go bad, or get loose...

PS I thought it was weird that the voltage regulator was on the alternator. I thought it was inside it soldered, or completely external, mounted on the fender.
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Jeff K Offline
Administrator
#6
Voltage regulators have not been remote mounted since the early 1980s. The regulator also has the brushes for the rotor built into it.

The stock alt is pathetic in the first place, with an output of only 70 Amps, which isnt really enough for a car packed with electronics and electric powered brakes. In the future you may want to consider a 130 Amp 3G alternator upgrade.

Strange no one up there tests alternators...... around here, virtually every parts store tests alternators.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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Rob H Offline
Junior Member
#7
Yes and I also thought it was strange, it's been a long time since I took one to a shop.
I guess it has something to do with people not testing parts. Just replacing them. Maybe not enough demand
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Rob H Offline
Junior Member
#8
Just an update.
I wanted to know that my battery was fine. Didn't mention it earlier but somehow, sometime that I don't know, my brand new Ford battery got swapped for a battery of unknown origin. Too much to explain, nobody knows anything about when or how.
Had it tested and it was perfectly fine, good for peace of mind. While I was there out of curiosity asked if they happened to have an alternator in stock. They did, so I grabbed it, and now everything is good. MM shows almost 15 volts at battery when running.
I really wanted my car for a road trip tomorrow, and when he said the alternator(rebuilt Champion) had a three year warranty, I was sold.
I'm still going to take the other one and get it looked at, keep for a spare.

The mystery to me is how a car with a dead battery, and an alternator that is apparently not charging said dead battery can drive around just fine. Had to boost it again when I picked up from Ford, prior to installing the new alternator.Started up great! Drove it two km home, the same with it this morning. Drove it up there, didn't even have to boost.
This all just reminds me of the same situation I was in two years ago, was behaving quite similarly. Ended up buying a new battery, and a new alternator back then as well. Would start when boosted and drive fine.
Now that I'm up and running, I'm not needing answers, but I just don't get it.
Anyways, thanks Jeff!

I can now say that almost everything on my car now works, and it's running great again!
Hopefully that's the last time that weird scenario plays out.
This thing is almost as good as I've been trying to get it for the last 3 years!
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Jeff K Offline
Administrator
#9
What exactly does "almost 15 V" mean exactly? Typically, charging voltage will start around 14.3 to 14.6 V after a cold start (depending on the temperature of the regulator) and tail off to 13.9 to 14.2 V after the engine has been running for a while and the regulator heats up. Any charging voltage over 14.7 to 14.8 V is too high, and anything over 15 V can start to "cook" the battery and damaging sensitive electronics.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
Reply

Rob H Offline
Junior Member
#10
I suppose it wouldn't have taken any longer if I had actually posted the exact voltage. I installed the alternator in the dark and just did a quick check. If I recall correctly was 14.65.
The car was not warmed up as it hadn't been running for a few hours. I remember thinking the old alternator was warm to the touch as was everything under the hood I guess from sitting in the sun all day.
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