Wierd charging issue???

[mtnman82]

2001 Expedition with the 4.6l. The boy came home yesterday and said the battery dash light was on and the electrical was cutting in/out. I checked it out and found one of the wires to the positive terminal was loose in it's crimp fitting. That was causing the cutting in/out. But I also found the battery at ~11.3v with the car running. So I took the alternator out and had it checked - it immediately failed the test. I could also feel a little something grinding when I turned the pulley. So got a new one, slapped it on and now the battery light is off on the dash. BUT, the battery still reads 11.3v. I was expecting a nice healthy 14.4 volts.

Should I be looking for something else wrong with the charging system, or am I overlooking something?

 

[FordandPolaris]

How old is the battery? Could be a bad battery not wanting to charge any higher than 11.3 but I agree as long as the vehicle is running it should be at about 14v. Make sure the terminals don't have crud on them that would be interfering with the reading too...

 

[mtnman82]

Thanks for the reply! Battery is only a year old (Duralast Gold). I replaced the old corroded terminal clamps with new ones. I just went out and disconnected the battery from the car and put a charger on it. The battery was actually at ~11.9v and climbed to over 12v during the short time I had it hooked up. I connected the battery to the car again and it read ~11.95v with the car off. When I started the car it read ~11.3v. It stays at 11.3v if I rev it up. When I turn off the car I see the battery voltage slowly climbing(!).

Really at a loss here... I was doing some more searching and found an article that said the battery needs to be 12.2 or greater to 'turn the alternator on'?!? I've never heard/seen this, but am charging the battery presently. It's only a 4 amp charger though... :/

 

[bedrck46]

If you have access to another battery try using that just to check things out Sounds like the battery is week and it doesn't matter that its only a year old Take the battery and have it tested but take it somewhere different than where you bought it
You may also want to check your meter against a good battery If your meter isn't reading correctly you need to find out
With a good battery and running about 1000 rpm's or more you should be seeing more than 13.5 volts

 

[mtnman82]

Thanks for the replies guys. Problem solved - I noticed the battery dash light wasn't coming on in the key on engine off position and it was with the bad alternator. Pulled up the schematics and saw the two fuses in the circuit so decided to check those first. Sure enough, the fuse in the engine compartment (11, 20A) was burnt out. Replaced and now all is good - 13.7v.

 

[vigman]

Well player sir.. and good info!

 

[cjennjr]

I'd better check my fuses, too. My battery light flicked for 5 seconds while driving and now it's solid red. Hope it's the fuses and not the alternator - but, if it is, I'll just replace it. My '98 Expy still has original alternator after 16 years of work...

 

[cjennjr]

Well, I took my alternator off and had it checked at Auto Zone - it was COMPLETELY dead!! So I purchased a new one, installed it, and everything is good!!!!