I brought the van home and parked in the shade of the carport. I put the tester on it and found that the battery was below 80 % charge. Alternator output is over 14.25 volts so that checked good. I put the new AGM battery back on the battery charger and after 4 hours at 12 amps it is reading full for the first time since I bought it.
Was a half dead battery installed in my van. Would that make the alternator falter while trying to run the AC full blast in 122 degrees? Will a full battery make the problem go away? I checked the battery when I went to bed and checked it again when I got up and it didn't go down any so that tells me there is no short or phantom load causing it to drain during the night.
Batteries are only supposed to start the vehicle. The alternator supplies the power to run the various systems. IF a battery is half dead the alternator will try to charge it back up and that leaves very little juice for everything else. I think the battery may have been the cause. The dealership said they will ck what I cked for free but if there is no "Engine light" or idiot light on finding the problem could be hard even for an experienced mechanic and also very expensive for me!
I am going to play with this weekend and take it down to the dealership on Monday and see what they think. 120 degrees is awful hot on any vehicle. The ac has trouble keeping up so being out and about during peak heat 12-5 is foolish if not absolutely necessary. I'm staying home till things cool down to normal temps or I am going to start limiting myself to early mornings and after dark for going places.