For the last several weeks my battery indicator light has been going on when I pass through a highway construction zone. It goes off once I leave the zone. It's about 25 miles from my home. I've taken other trips of more than 25 miles outside of that area without incident. Does this sound like electrical interference or a faulty alternator?

I'm planning to take it to Autozone to have the alternator checked as soon as the ice clears from the road (tomorrow?) I have a road trip to Jacksonville planned for next week and would like to get this resolved now instead of on the road.

 

Why don't you go to Walmart or an auto store today and get one of those voltage monitors that plugs into the cigarette lighter socket ?
You could then monitor the voltage as you pass thru the twilight zone .......

 

Maybe your battery has a hard time holding a charge or the alternator is producing enough power. So when you reduce speed for an extended time the power used is more than the power generated or held, resulting in a red light.

It could be poor connections at the battery or the cable to ground or the alternator. How old is the battery?

 

I don't think the speed is a factor in this case. It's a major highway project and although there's a lot going on speeds are 60-70+ mph. It doesn't happen when I drive on the back roads closer to home where speeds are reduced.

The battery is a 850 amp Bosch that's only been in the car for about 6 months. I'll have that tested if the alternator proves to be OK. I'll also check the cable connections in case they're moving due to the rough surface.

Reading through other threads I hadn't seen interference problems discussed. I'm trying to cover as many the bases beforehand knowing that trial and error can take some time.

additional - there was no code on the OBDII reader when this occurred.