When I first start the car in the morning, sometimes the battery light will come on. It will go off after a short time (1/4 mile). Other times it will come on when on the highway. I find that if I shift, thus changing the RPMs, the light will go off. I checked the battery and it's at 12.8v when car is off. Checked with car running and it is right at 14.0v. Belt is newish and seems tight. The positive battery terminal connector has been eaten away some and I'm going to replace that. Any other ideas?

This is has been going on forever by the way. I brought it to the dealer years ago at 30K miles for this isssue. They put in a new battery, still happened. I'm at 98K now.

 

First make sure your Battery Terminals are tight. Next get your alternator checked, if you know your battery is good.

 

Does the tach jump or drop at all during idle?

 

+1
and verify the terminals and clamps are clean.
We tend to have a wave of people with electrical issues that end up being a loose connection at the battery.

 

No, my idle is smooth, I replaced the coils < 20k miles ago.

My positive battery cable is not very tight and cannot be tightened due to the copper being corroded. I have a new connector on order. I'll start there.

Thanks!

 

I had the same thing happening. I was having low voltage issues while running, so I changed my alternator. When I changed it out I found my terminal "B" connection looked like the one in this thread (https://www.rx8club.com/showthread.p...light=terminal). Also, part of the wire leading from the connector had melted through the coating and was starting to get a nice copper petina on it . That's probably what caused the connection to melt in the first place. Changed out the alternator and replaced the bad part of the wire and put on a new connector. Works fine. Just something else to check.

 

Umm, not a great idea to have ANY Loose Battery Terminal Clamps..PERIOD!

More than likely why you are getting the intermittent Battery Light on your Dash, it is signaling that Power from the Alternator to the Battery has been interrupted.

Just think of it when you put a Plug for the Kettle in your wall Socket and it is not home correctly or hanging out...what happens?.

1. This can be creating an 'ArK", or Spark, like a welder.
2. It can in extreme cases ignite any Gases in your engine bay, with a fire as a result.
3. Can also melt wires and start a fire, or blow a Main engine Fuse.
4. You can short out and damage your Alternator and or it's Internal Voltage Regulator, as it will be having trouble 'regulating' supply to your battery.
5. Shorten Batteries Life.
6. Or a Loose Alternator Drive Belt (you said it was OK)

Basically I am saying, you should FIX this issue before you drive your car .