Voltage regulator/alternator issue

azfordman · #1 (**permalink**) 12-19-2010, 06:01 PM

Had in issue on my run today. First pit stop around 80 miles from home the car would not restart. Opened the trunk and found one of the battery covers had blown off. Cleaned everything, put three 32 ounce cups of water in the battery and got a jump start. John was there as well and he was a huge help! Watched my volt meter going home and it never went over 14 volts. It ranged from 12-14 depending on if the fan was on or off. Our thought was the voltage regulator may have been bad or sticking and was overcharging the battery. 1/2 way home the volt meter dropped to zero.... Limped home since the car was running like crap, I figured due to lack of voltage to the ignition system. The covers had popped off the battery again. Cleaned the trunk out with water and baking soda and there wasn't really any reaction from acid. Had an extra voltage regulator so I changed it out. Put about 8 ounces of water in the battery and the car started right up. It ran for a while and there was no problem with the battery. However, using a multimeter I am getting only 12.1-12.4 volts on the battery and off of the alternator, and that is at idle or revving the engine. If I disconnect the battery the car dies instantly. Question is.....if the regulator crapped out over charging the battery could this have also fried the alternator or is something else going on I should look for? No performance items, just stock ford alternator and voltage regulator. Thanks for any input, Mark

CHANMADD · #2 (**permalink**) 12-19-2010, 06:06 PM

If changing the regulator doesn't work then it has to be the alternator..TGood time to switch to an internal regulator.........you know all the manufacturers went that way for the exact reason that you are experiencing.

azfordman · #3 (**permalink**) 12-20-2010, 10:45 AM

Upgrading the alternator to include an internal regulator is a possibility, but it does not answer my question, is there something else going on or could a stuck regulator have fried the alternator?

mickmate · #4 (**permalink**) 12-20-2010, 11:52 AM

I guess you've got issues with each spilling over to the other. I had a battery lead break and it took out a battery and an alternator since it had nowhere to go. Do you have voltage to the field still on the alternator? Remember we had a problem with that and that will stop the alternator putting out.

strictlypersonl · #5 (**permalink**) 12-20-2010, 11:59 AM

It may be that your battery has an internal short between sections. That might not show on the posts, but each group of plates will be overcharging. The zero voltage reading is confusing though...

azfordman · #6 (**permalink**) 12-20-2010, 01:00 PM

May have got it....! Was calling around pricing alternators when Bernie from North End Auto returned my call. After a short conversation he suggested checking the fusible link. That was it! Thanks Bernie, this is the second time you have helped me out! I did a quick bypass and splice and am now getting 14+ volts out of the alternator when revving the engine. Another bullet dodged....guess I will wait and see how the battery holds up....thanks again guys!

strictlypersonl · #7 (**permalink**) 12-20-2010, 01:40 PM

Where was the fusible link? This doesn't make (electrical) sense to me. The only way to boil battery juice like you experienced is a major over-voltage.

azfordman · #8 (**permalink**) 12-20-2010, 01:54 PM

I believe it was a secondary or in conjunction problem.... It looks like it was in line with the field line of the alternator. From what I can recall from auto shop this is the line that supplies power to the alternator. From what I can tell....still guessing to a point, the voltage regulator went bad....sticking "on".....this continued to push power into the battery even though it was fully charged, boiling the water and blowing off the covers. My plan was to jump start the car and drive home with the battery disconnected via the + disconnect switch in the cock pit of the car. After I got on the road I did kill the battery cut off, but the car started to die, so I switched it back on. Apparently somewhere in this process the fusible link burned out, thus not allowing the alternator to send out any voltage, or at least only minimal voltage. The car ran like crap driving home, I assume from a lack of voltage supplied to the ignition system. With the fusible link connected I was not getting more than .5 volts to the field of the alternator. With the fusible link bypassed I was getting 12 volts to the alternator. I even turned off the battery shut off and the car kept on running, so I know the alternator is working. Does this make sense? It kind of does to me......