I know nothing about batteries !!!!

[jgos929]

With the truck off the batteries are under 11.6v and running the batteries are at 13.7v. Does this mean my batteries are going bad or my alternator maybe? I've searched and read that with the truck running it should be in the 14's. I have a buddy thats a route driver for Interstate that can hook me up with a good deal on some batteries but the ones I have are from the middle of 08. I don't wanna spend the cash if I don't have to.

[Goose350]

It could be either one really. The alt should be putting out 14.2v while running

[cpolchow]

Honestly 13.7volts is about right, anything over is the begining of the reg going out on the alternator. The only way to tell for sure if the cells are good in the battery is to get a hydrometer and check the levels if is not a maintenance free battery. The other way to tell is to bring it to that local battery shop and have them do a load test on the batteries. Make sure though it is not one of those push button load testers, those are only 100 amp and are not big enough for our size batteries. They should have a 250 or 300 amp load tester.