Well I was driving my 04' disco II home after being in the shop for a week, when suddenly disaster struck...my battery light on the dash began to blink and then stop for a bit, and then continue blinking again. My scanguage usually gives me a readout of 14.0volts when the engines running, now that number was changing erratically from 13.1-14.7-15.6-13.8 volts. This struck me as odd, so when I got home I put it into park and let it idle and I was getting around 13 volts. She did start up again after turning off though. So is this most likely an alternator issue? Battery is less than 6 months old, and I have a 2 battery setup. Please let me know what I might be dealing with here

 

Connect one battery and attempt to reproduce then connect the other and see if it happens there as well to narrow down the issue, when was this dual battery setup done? (recently)? Does anything else happen when this happens? (the usual - lights flickering/dimming, etc.)

 

Clean the terminals on the battery.

Check the belt - may be loose. Check the tensioner.

A red light - alternator output could come on if the belt stops for a second.

What can stop the belt?

A failing bearing in:

o air conditioning compressor idler
o one of the many idler pulleys
o power steering pump jamming - r u low on PS fluid?
o water pump bearing going bad - is there any low freq groan at idle?
o Alternator bearings freezing.
o Alternator malfunctioning - bad brushes in alternator from high mileage. Bad rectifier diodes failing.
o grounding issue - check ground strap from driver's side head to the firewall. This is a braided strap.

 

Thanks for the responses, I took it out last night just around the block and I couldn't reproduce the weird voltages or battery light, so that's good I guess. I'll just keep an eye on it