Battery Help!
Thread Starter
Cruising
Joined: Mar 2010
Posts: 10
Likes: 0
From: Toronto Ontario
Battery Help!
Hey all,
I just got a brand new battery and alternator. Everything runs fine during the day, but at night once the headlights are up, the lights dim unless I rev it. Also at night, after driving with the headlights up, once i park, and try to restart it again, the battery dies, and I need a boost. What should I do?
Thanks in advance,
Leonard
I just got a brand new battery and alternator. Everything runs fine during the day, but at night once the headlights are up, the lights dim unless I rev it. Also at night, after driving with the headlights up, once i park, and try to restart it again, the battery dies, and I need a boost. What should I do?
Thanks in advance,
Leonard
Le Mans Master
Joined: Feb 2001
Posts: 6,304
Likes: 278
From: Ocala FL
Only drive in daylight. 
Sorry, couldn't resist. Obviously, the alternator isn't charging. check the usual like belt snug, right size crank pulley, right size alternator pulley, and all wires connected. If it is a '68 with the external regulator, be sure it is adjusted right.
On '69 and up with an internal regulator, you need to be sure it is charging on all three phases. An alternator is an AC generator with three phases and have three diode packs. One could be out and then it is only partially charging. the regulator usually works or doesn't.
Most alternator testers (simple volt meter) won't see one phase missing. You really need a 'scope on it.
Sorry, couldn't resist. Obviously, the alternator isn't charging. check the usual like belt snug, right size crank pulley, right size alternator pulley, and all wires connected. If it is a '68 with the external regulator, be sure it is adjusted right.
On '69 and up with an internal regulator, you need to be sure it is charging on all three phases. An alternator is an AC generator with three phases and have three diode packs. One could be out and then it is only partially charging. the regulator usually works or doesn't.
Most alternator testers (simple volt meter) won't see one phase missing. You really need a 'scope on it.
Le Mans Master
Joined: Feb 2001
Posts: 6,304
Likes: 278
From: Ocala FL
What happens occasionally is that you jump start someone with your car, and then about 3 or 4 months later, you have battery problems. What can happen is the electrical system will surge with transient spikes when the jumped car starts. This will sometimes hit the internal regulator or one of the diode packs. Then you are running on 2 of the 3 phases instead, so that the charging is not full and there is a discharging in one phase.
If you don't know the history of the car and you just bought it, odds are the alternator has been zapped and you need to just get another. If you go for one of the lifetime warranty parts store alternators, I avoid Auto Zone but have had decent luck with Advanced Auto. Pep Boys are sometimes fine; other times not.
I haven't had much experience with O'Reilly's so I can't comment.
If you don't know the history of the car and you just bought it, odds are the alternator has been zapped and you need to just get another. If you go for one of the lifetime warranty parts store alternators, I avoid Auto Zone but have had decent luck with Advanced Auto. Pep Boys are sometimes fine; other times not.
I haven't had much experience with O'Reilly's so I can't comment.
Instructor
Joined: Jan 2005
Posts: 146
Likes: 1
From: Roanoke Rapids NC
when I first got my '74 I was having similar issues, it took 2 things to fix it. The first was that there is a fusable link in the wire bundle that runs to the alternator, mine was wrapped in electrical tape so it was very inconspicuous at first. Second was the type and condition of battery. I went through 3 Optima Red Top batteries the first 5 years I owned the car because the guy at Advanced said they were "da bomb" I just switched to a conventional AC Delco battery and was utterly amazed at how it improved my car electrically. I can even crank the car with the headlights on! something I've never been able to do.
Good luck!
Brad
Good luck!
Brad
