Battery Light On - intermittent

[MPR]

2001 LB7 - Battery light comes on after start up, sometimes for up to 20 minutes. It will go off and may not come on again until another start-up. Or it may do this a number of times in a 30 min. drive.
Batteries both show 12.8 volts at rest. When engine running have 14.2/14.4 volts at battery terminals. Vehicle voltmeter shows 14.2 while running. All appears normal except the idiot light.
Have a 2000 mile tow coming up so don't want any on the road problems.

Any ideas amongst you electrical gurus?

[Mark Rinker]

How old are the batteries?

[MPR]

The batteries are the original OEM. The truck was a late April 2001 build.

[Mark Rinker]

If it were me, with a trip in the planning, I'd replace both due to the length in service. Personally, I have been using AC/Delcos from the dealership. The price and warranty are very competetive. I always replace in matched pairs as well.

If you are skeptical about replacement, have them both load tested by a professional. If both test out okay, then it may be as simple as a bad connection that can be cleaned up at that time.

[MPR]

Thanks, Mark. Will have it checked out.