Archived Intermittent / Sporadic Will Not Charge

[Joelbeal]

2006 2500 5.9. It sporadically stops charging, leaving me stranded in the worst places. Third time is today. Batteries are 3 months old, alternator is 2 weeks old. Replaced all battery cables - 2 were corroded. It always happens immediately after startup - voltage drops below 12 and just keeps dropping. When the battery is recharged - it always seems to work for a week or two.

What can it possibly be? Crankshaft position sensor? I am running out of ideas.

 

[Bob4x4]

Sounds like you have checked the basics,the pcm controls the field.You should have the batt feed,one field wire is a constant ground the other is powered by the pcm.The pcm has a few inputs to determine how to adjust the field power.

 

[klcammie]

does the 06 have a batt. sensor under the driver side batt. like the 01. when you changed batt. was it contacted?

 

[cerberusiam]

Battery temp sensor reading high could conceivably shut down the charging system. That is all that controls charging of the batteries.

 

[Joelbeal]

I still have no answer, but here is what I determined. I have a mini-fridge that I leave on overnight when I am traveling. Every time, was after the fridge was left on all night - and the batteries failed to charge the next day. It's not happened since I made this post, so I guess the post magically fixed it.

I cleaned out the battery trays and made sure that both batteries were completely full of water - 1 was a little low. Not much, but a little. Theory here - minimize any affect of heat on the battery heat sensor. Completely cleaned every battery cable connection.

Perhaps the combination of the above reduced heat detected by the battery heat sensor which in turn allows the alternator to charge.

 

[MattandLana]

OK I don't know the rating of the batteries in the Rams, but running a fridge off a starting battery could be your problem. You may know this, but starting batteries are designed to provide very high current (100s of amps) for short periods. Contrast 'deep cycle' batteries which are designed to provide smaller current (10-30 amps) for long periods. Critically, both types of batteries will be seriously damaged if they are flattened - that's why we should always have a low voltage cutout circuit in a fridge circuit. It's possible that the fridge flattening the batteries 'killed' them so they could no longer take a proper charge. Sometimes the partially-charged damaged battery can still provide enough power to start the engine, which is why the problem can seem intermittent.