Dead batteries

[snwbrdngrx14]

A few months ago my truck wouldn't start, drained batteries i jumped it and didn't really have any problems since then although my batteries did seem weaker. Iv'e had them and my alternator check which is new as of the fall and they said they were fine This morning i tried starting my truck and it wouldn't start. i couldn't get it jumped so i finally switched the batteries and it started up. but now i went to start it (3 hours of it sitting) and the batteries are drained again and barley started. also when i turn my key on, all the lights come on and the radio. after a few seconds the radio turns off then turns right back on. My batteries are from 2008, is it possible that they are pretty much dead but after they are charged they hold there charge for a little ? or could it be anything else ?

[NoRalPh]

Couple of things, First did you recharge your batteries on a battery charger after they went low, or let the alternator do it? Your charging system isn't a good way to recharge dead batteries. It just isn't going to do the job unless you drive for hours at a good rpm. Plus, overtaxing the alt is never worth the risk of damaging it.

Second, you should stop guessing about the condition of your batteries (they are So Important to a diesel w/GPs) and have them LOAD TESTED. Take them out, put them on a charger and be sure they're both Fully Charged, and take them to someone with a good Load Tester (NOT one of those 100A handhelds that some of the Auto Parts Stores try to use) and have then tested at a High Rate (200-300A) to know if they need replacing.

Then you know where you stand with the batteries and can look elsewhere if the problem continues.

[snwbrdngrx14]

i was so frustrated from working on my truck all day yesterday that i went out and bought two new batteries, i just got done installing them and you can tell there is so much more power now. so i'm assuming that it was the batteries. but thanks for the info i'll defiantly keep that in mind for next time.