[AnchorJoe]

OK, so I had the batteries load tested and both were below 50% rating. Should be ~800CCA and one measured ~400CCA and the other measured ~450CCA. So, I replaced both batteries last night.

Now, a symptom that I am seeing is when I idle down from higher RPM's (1800-2200), I notice that the alternator charge guage drops off to below 14VDC then goes back up to just below the mark in the middle of 14 and 19VDC. I haven't noticed the charging system doing this while I have been driving, just when it idles down near a stop or in a parking lot after rev'ing the engine up a little. Does this sound normal?

My experience on other vehicles is that regardless of engine RPM, the charge stays relatively stable with no change in load. But these HD trucks seem to be a different beast to me, so I am not sure now.

Thanks for any input.