Straight to the point: Is a single ~1000 CA battery hard on the starter in a hot summer climate? (Arkansas) Long explanation why I asked, but not really required to read to answer the question: For whatever silly reason, I kind of don't want to move my 1.5 year old matching batteries from my RV back to my truck. I bought them for the truck a couple months before I got the RV, so I swapped em out. I'd rather not run them for 6 months in the truck if I can help it. I figure that if I can avoid 6 months of stress on them, it's a good thing. The RV's starting batteries were mismatched, having a 27 and a group 31. Vans do call for mismatched sizes, both smaller than what trucks call for, and one of the two is only 725CCA. The two sizes called for are group 24 (725 CCA/890CA) and group 27 (840 CCA /1035 CA). I've been trying to recondition the 31 and it's not looking good. It drops like a lead balloon to 8.xV even after heavy charging (8A-15A). I topped off the water in it today (probably just overfilled, since it was overflowing out of the vent when charging) and I'm trying my smart charger's recondition feature a second time. First time before I topped off the water, it gave up trying after 24 hours and the battery was back to 8.xV after it sat overnight. It was charging at 14.4V so I'm guessing 15A? If it fails again, I'll try one last thing: putting it on a 5A dumb charger that's built into my tiny generator. I've read that sometimes it takes a dumb charger to force a charge on a deeply discharged battery. But I don't have high hopes. Failing that, the single group 27 battery seems fully serviceable. I mean, I was able to start the RV on the bad set of batteries (in winter) even with the bad one connected, probably drawing down the good one. I left the 27 attached to the F250 for almost a year by itself (started and moved it that way to the back yard) and it wasn't dead. It was low (12.xx) but the dome light still came on when I got back here in late January. I'm in the south where it's gonna be bloody hot, so there won't be thick oil issues. I have a manual GP button in the truck, so I can cycle it just once a day when I go out, since that's all it ever needed before in summer, even in cooler climates. I'll stick the 31 in on the driver's side with just the positive terminal connected for safety's sake, but negative disconnected so it can't draw down the good battery. I just wanna conserve my matching 65s for the RV and also not spend money on a second battery if I can help it.