Saturday started great, lots of fire, as usual.
Sunday, start sounded sluggish.
Monday morning, click, click. Jumped it with wife's car and all was good. Went out during lunch and click, click. Jump worked and went to NAPA for new battery. Started great!
Tuesday morning, click, click. Jump worked. Wednesday the same thing.
Battery reads 13-14 on meter. No warning lights showing.
Any ideas?

 

How old are the batteries?

 

What vehicle are we talking about? When you say new battery as in one new battery that might be the problem. Depending on what vehicle you're talking about, these diesel trucks take two batteries. Always replace both batteries even if one checks out "ok". If your alternator's charging circuit is crapped out then as your truck takes battery power and depletes it the battery will be too low to operate until jumped again. Eventually it will not even run on a jump once the batteries are completely depleted from not getting a charge out of the alternator.

That all being said, it could be much more than that. It could be a PCM in that truck causing the issue.

 

A voltmeter is virtually meaningless in determining battery quality of life. A battery may show full voltage and still have not enough amps to crank. Also, in a dual battery system, you NEED to check the voltage of each battery individually by first removing the grounds and then the positive connections. If you do NOT know how to SAFELY, then have someone who does help you. Using a battery hydrometer (maybe $7 at any supply store) to check the condiotn of each and every battery cell is the simplest and most accurate way to determine battery quality. If you have sealed battery, then the hydrometer will not work, and you should have it tested with a load tester.

All that being said, to diagnose your problem, start with the basics…check and remove each and every battery terminal connection. ALSO, be sure to check the conneciotns at the starter, as well as the ground connections on the body and block. While the batteries are disconnected, check voltage and use a hydrometer to check battery cell condition. Afterwards, clean and tighten each and very connection. If nothing shows up here, you MAY have a faulty/corroding battery crossover cable, which is the large positive cable that runs between the two batteries. Often it can corrode BENEATH the insulation a few inches back from the battery terminals. To inspect it, you will need to disconnect it and use a razor to slice the insulation a few inches along its length and look for oxidation/corrosion amongst the strands…it will be OBVIOSU if it is there. If it is, you will need too replace the xo cable…if not, simply use several layers of electrical tape to wrap close the slice that you made.

Like others have said, id one of your batteries tests "bad" by any of the test methods, then you REALLY should replace BOTH batteries in a dual battery system, as the state of charge of one affects the ability f the alternator to charge BOTH equally.

 

The batteries are 3 years old. This is a two battery system.
2012 Dodge Ram 3500 Diesel. 6.7 liter.

 

I'm sorry. I didn't tell you what vehicle. 2012 Dodge Ram 3500 Diesel. 6.7 liter. Never before had a problem. 68,000 miles. Almost all highway.

 

Well a three yerr old truck is unlikely to have a problem with the xo cable, but everything elsa I said remains true.