I have the Edge programer in my truck but mainly use it for the display, anyways I can keep a close eye on the battery voltage this way, If I`m not mistaking it usually reads 14.0-14.2 volts whenever it is running, Well I got in it to start it up today and it seems kinda weak turning over, I drove it on to work and it was fluxuating between 13.7 to 14.0 volts. I just put a new battery in 3 weeks ago so I thought the alternator might be going out next, took the alternator off and had it checked they said it was good. My question is when the truck is idling what is the voltage supposed to read? now it is reading 12.0-12.2 volts while idling, when I drive down the road it goes up to 14.0 volts what is is supposed to read????? Thanks for any Help!

 

My truck's not as old as yours, but I doubt the correct readings would be much different. A voltage reading of 13.7-14.1 while driving is what I see, depending on the charge state of the battery and my use of other accessories. It's not below 13.6 at idle either.

If you're seeing 12.0-12.2 at idle, you are discharging the battery. A fully charged, new battery will easily output 12.7 no-load volts, and the alternator voltage has to be higher than that to charge the battery. So, your alternator could be malfunctioning. I'd have it checked again, maybe at a different place.

- Jack

 

that is what I was thinking too, I got in it this morning and it was reading 10.7 volts when I started it up.... something is definately not working right, I think I will have it checked at another place and see what they say. Thank you for the reply Jack!

 

I went back to Advance this afternoon and they checked the alternator on the truck with it running and the little report he printed off the code reader said the battery was fine, the starter was good but the charging system had a ripple in it which means the voltage was up and down when it should have been a straight line across, he said he thought it was the voltage regulator which is on the alternator so I bought a bigger 130amp alternator and it reads 14.5 volts idling and while I`m driving it so now I have a new battery and a new alternator so hopefully I wont have any more problems for awhile!