Well I decided to pull the trigger on LifePO4 - will post as the components come in and I install. While I flirted with a coach electrical system redesign, the dollars for what I had in mind started adding up too fast, so I backed off and am treating this strictly as a repair of the failed Magnetek and house battery. Even so, it is pricey. LifePO4 definitely has traction in the yacht world, and is gaining traction in the Class A motorhome world.
My goal is to be able to keep the Vitrifrigo cold, run the lights at night, and charge devices, for at least 3 days without starting the engine or accessing shore power. Design-wise the battery capacity can scale up later without throwing the first build out, but using Solar to recharge anything bigger than what I'm planning isn't practical.
So here's the plan: get a *usable* 144Ah (when new) out of the following:
4x 180Ah 3.2v LifePO4 cells wired in series
Progressive Dynamics PD9180AL 80 Amp, 12 volt, Lithium Ion Converter/Charger
Victron BMV700 Battery Monitor
BlueSea 6006200 Battery Switch
Zamp RoofSide Solar Port (hardwired into charge controller)
Zamp portable solar system (size TBD)
This design will require no metal cutting, and the LifePO4 cells are so small they will fit inside the OEM battery box. I'm buying cells (vs. a pack) to save money. There is much discussion as to whether you need a battery management system and balancing tools when you assemble these cells into packs. I'm buying from a supplier that serves the custom electric vehicle market, and they are confident that for what I'm doing I can just wire them up in series and hook up to a charger. More to come! This is my early-summer project