Alternatives to APU

[Nostalgic]

My truck came with an electric powered a/c. I took the cheapest route, with 4 starting batteries, and 4 deep cycle. Just plain old flooded lead batteries. I have a blue sea systems automatic charging relay that connects the deep cycles to charge when the truck is running. I'm not sure what I was thinking, but I ran my inverter cable to the starting battery bank, so I get nervous if I'm on a 34 and have made a few cups of coffee and ran the fridge and tv for a day and end up idling for a few hours to make sure they're topped off.

I've thought about switching to AGM's every summer when I test and replace the underperforming ones. This year I replaced 5, but it was still cheaper than buying 2 quality AGM's.