I have a 2005 Ford Excursion that started an intermittent battery light flicker. I immediately tried to put a multimeter to the batteries, but the light would always go out before I got the hood opened and meter connected. Then I got smarter than the light...I connected the meter to the battery and ran the leads into the truck so I could monitor the battery charge as I drove down the road. When the battery light came on, the meter would be reading 13.8 VDC to 14.2 VDC which tells me the alternator is working correctly. I did this for both batteries and the same voltage values were present. I'm a little perplexed at this point since the batteries are relitively new and the alternator seems fine.....any ideas?

 

Change your alternator. You may get the volts but not the amps. I had the same problem and get good volts reading and battery light flicker.

 

As well, you may be getting a volt reading from the batts when the alternator is not charging. Just curious, what was the meter reading when the light wasn't flickering?

My Taurus did the same thing, and it was the alternator. My bet would be on it.

 

It was reading 13.8 VDC to 14.2 VDC on both batteries.

 

Interesting. I would have the alternator tested, on the truck. While Autozone may not be the best parts store in the world, I have found their testing equipment to be accurate.

 

I'd say change your alternator before you drain your batteries and have to change out both batteries and alternator.

 

my batt light would come on only at high rpms(4,500-5000rpm), then on the way back from a 1,000+ mile road trip 50 miles from home the battery light came on. i instantly turned off everything i could and made it home. luckly i made it home and the battery was still showing 11.9volts. i replaced the alt and she fired right up.

best to atleast get it checked. i'd just replace it depending on miles. my factory one had 120k on her before she gave up the ghost for good. goodluck!

 

This happened to me. It was charging, just slowly. Replaced the alternator and problem went away. Last time I went cheap on the alternator, got 2 years out of it. I did it right this time, so hopefully there won't be any issues.

 

Start the truck, disconnect the batteries and read the voltage at the alternator. If the truck stalls out after disconnecting the batteries then you know the alt. is bad.

 

I am not sure I would do that. You are likely to fry some electronics. The battery is your primary means of regulating voltage and controlling voltage spikes. If you unhook the battery while running the voltage could go way high or way low. Either situation is bad for all the electronics. The brushes could be going bad causing intermittant problems. Brushes are cheap compared to a new alternator. Taking it to Autozone is not a bad idea they have a machine that even their dummys are smart enough to use.

Perry

 

+1
Don't run without the batteries! (Even if they're going bad)
Your alternator will be trying to charge batteries that aren't there and you could get some serious spikes.

 

When I was a kid I used to fry motorcycle bulbs by taking the battery off. It would blow every bulb on the bike and those headlight bulbs were expensive.

Perry

 

OK....I got a new alternator and have the old one off, but the serpentine belt is not cooperating. Where is the idler pulley to adjust and give a little more slack to install the new alternator?

 

There is a spring loaded pully that has a square hole in it for a 1/2" rachet breaker bar whatever. Put a wrench on it to remove the tension.

Perry

 

Where is the spring pully located?