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OT alt. voltage

flembo

flembo

Well-known Member
My wife came home saying the check charging system light came on,on our 2005 ford expedition then went out after about one minute then came on again about 10 minutes later she parked at the church and when she came home the light never came on. I checked battery voltage with a tester and showed about 12.4 volts I did a load test and still 12.4 volts I then started the engine and it showed 14.2 volts for about 10 seconds then dropped to 13.5 volts then back and forth from 13.5 to 14 volts. Is it normal to vary like that 13.5 is right on the line between low and ok it never went into the red while I was checking it aprox. 10 minutes running. To make this tractor related I have a 2n converted to 12v. by the po. that shows 16 volts when running it appears to be wired correctly never burned a coil starts and runs great every time I think I replaced points 2 times in the 6 yrs I have had it. I checked to see if the small wire is connected to the large post on the back of the alt. and it is. I am posting here because I know there are a lot of knowledge here.
 
12.4 means the alternator has failed. You will never charge anything with only 12.4
It appears your alternator is failing,in order to charge 12 v you need anywhere from 13.5 to 14.5 constant. I don't know why it is fluctuating other than failure of the alternator. We had a guy near me that used to repair alternators and it was usually $25,unfortunately he isn't around anymore. CARQUEST wanted over $300 for an alternator,got it repaired and back in business for $25. Good luck but I think your alternator is toast
 
I also think the alternator is failing. 14.2 is correct. dropping to 13.5 is an indicator that a diode might be going bad, or a connection internally is intermittent. 12.4 volts while turned off is also not ideal. 12.6 or a tiny bit more is appropriate for a fully charged battery. Testing it at the "store" might show passing due to the intermittent issue. Jim
 
You have an alternator failing. Word of warning, most rebuilds apperently do not include a new regulator if purchased from a discount chain. I have had several Fords in my shop that have had multiple Autozone alternators on them with the same problem. Motorcraft alternators, while pricey, fix them. BTW, a $25 alternator rebuild for sure did not include a new regulator, diodes, slip ring machining, or any electrical testing on rotor or stator. Local place near here calls them rebuilt when they replace bearings and paint them silver. Replace a lot of those also.
 
Thanks all, for the replies btw Michael the 12.4 volts reading was the battery with engine off. This alt. was just replaced by the ford dealer in august I guess it will be going back.
 
My neighbor had alternator failure on her Ford car. She took it to a battery warehouse and they told her the battery and alternator were ok. They told her to take it to a Ford dealer that she had an electrical problem causing the battery to discharge.

I took her some green beans and beets from our garden and took along my multi-meter. She said the Ford dealer wanted $100.00 just to check the problem. I had her to unlatch the hood and start the engine. She was only reading battery voltage about 12 volts. I told her one of two
things was causing her problem either a broken belt or the alternator was defective. The belt was ok. I even called several repair shops for a price. Around $475.00. Several auto parts store wanted $100.00 for a rebuilt alternator plus the old core. Hal
PS: I'm too old at 82 to work on them. Had it been mine I would've done it.
 
Is it winter / below freezing where you live? If so, I have had alternators temporarily quit working when water splashed into the alternator and froze the brushes so they would not contact.

A little heat to melt the ice and they worked again.
Are you checking voltage on the 2N using a digital meter? Many go bonkers and read higher than actual voltage because of the electrical noise of the tractors ignition system. Always use an analog volt meter to check charging system voltage.
Another thing to check if your using a SI type Delco alternator on the 2N. The regulator plug can corrode and send a false low voltage signal to the alternator, causing it to step up the voltage. Often the simple act of unpluging and plugging that plug back in will clean the contcts enough that the alternator goes back to normal voltage.
 
Jon the answer to your first question yes it is below freezing but the car is garaged and the roads were dry today. About the multy meter no I use a anolog meter but I will check the plug again. Thanks for the reply Don
 
let us know what you find on this. I personally don't think 13.5 volts is too low. Our Delco's on amc,s back in the 80,s were right on the money at 13.9volts. The varying voltage does raise a flag. Please get back to us if you find something. Thanks,Bill
 
A simple poor connection can cause a problem like that. It can arc then sort of weld it self up so the connection is good again for a while and can be hard to find
 
The regulator is failing but the dealer won't help you until it does. What's bad is Ford dealers can't get a new regulator themselves so how are they going to properly rebuild an alternator?
 
If a battery is fully charged it should read around 13 volts right after you shut off the engine.
 
Lifetime on the first replacement, nothing on the second one, unless you have got lucky or know the people working in the store. chris
 
Lifetime on only the first??

Disagree. Lifetime means LIFETIME. If they tried that on me (or many other customers), they would find themselves in court.

I have done a LOT of business with Auto Zone. On occasion, I have had problems with warrantied items that I have purchased from them. Always have been replaced without question. Labor not included. If you look at their computer screen when they are looking up warranty, you will see that the lifetime items come up as "999" under the warranty column. This does NOT change after a warranty adjustment.

Could be that the store manager in your area is trying to make his bottom line look better by denying warranty claims.
 
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