Thank you all for the helpful advice. For some reason I had not thought of doing two banks :S but that is an obvious solution to the temperature and potentially size difference between the location in the engine bay and in the basement, yes? Just run a temperature sensor to each bank and a switch to select which bank the charge controller is monitoring.
To clarify on the space, I *can* actually fit either the GPL-4 (220 AH) or the GPL-6 (300 AH) pair in the engine compartment. There is even space for the GPL-L16 pair up there with a slight mod of the rack, however IMO the 16's are tall enough that blocking air flow to the radiator is a concern. So I conclude that the 300 AH pair is the max for the OEM location.
The storage bin has the converter and separate inverter in it now. There is adequate additional space for all the batteries mentioned, although if two 16's go in then I'll want a sliding tray to make it easy to roll them out to access the other equipment.
I plan on making the solar inputs as large as reasonably feasible, within practical limits. This is a 30' roof and has a lot of penetrations now with dual air and satellite etc. And it will be flat fixed mounting. I don't want the remaining roof mounted equipment to be unserviceable... When we go FT I suppose a portable setup to supplement could be an option.
I accept that the genset just has to make up any deficit, and I'm in full agreement with Mex, no generator loafing. So the 80 amp converter is not set in stone either.
Based on what I am hearing sounds like the best solution is the two separate banks. Adds complexity, but with proper fusing and selection switches as suggested it will also pay for itself when (not if) a cell fails.
Someone mentioned how long to keep the rig? We expect 10 years or so. Of course if that changes I can always transfer the gear to another rig.
I'm a bit concerned about the floor of the storage bin. Probably need to reinforce and put in a sliding tray to support the 16's if I do that. A pair of those is 238 pounds.
PS- 8D are a bit wider and don't fit either space. I have more height available but am width constrained in both spaces.
