We then spent 6 days at a National Forest Campground which is also rain forest on the Olympic Peninsula. We received only some diffuse sunlight through the thickly grown 120' second growth forest. We still used the microwave, the juicer and watched Mystery Theater (DVD) using the inverter. We had dropped only 45% DOD (-5500 W-hrs) and could thus have remained for another 4 or 5 days before looking for sun (or turn on the gen set 1 kW generator). We drove through rain and mist today and recovered 3000 W-hrs.
To my way of thinking, since a battery can't produce energy out of thin air, most of this story just shows that your solar input is large relative to your actual needs. The part that is slightly relevant to the specific batteries is perhaps being able to continue for another few days, but of course AGM batteries can also be extended to a fairly high DOD - say 70% or even 80% at a pinch - without seriously reducing the life-cycle figure.
Common mistake is to look at the manufacturers figures and see that, say, 80%DOD will give you 200 cycles and then say if you ONCE drop to 80%, you will only get 200 cycles. Not true!
Things might have changed with development, but a common refrain about Li batteries was that if you ever did flatten them, they were completely ruined. Same was said if you managed to overcharge them. Then came battery management systems to stop that happening, but of course they are probably even more prone to failure than a quality charger, but at least it is one extra layer of safety for those willing to pay for it.
Li batteries have the potential to save weight and that can be important in some applications. RVs are usually not an application where that might be important. Lifetime costs per total energy used would matter to some, but unless that saving is very large, most users won't be all that fussed about paying for it 20 years in advance.
And of course we still get back to the simple fact that batteries don't make energy in the accepted sense so you still need adequate solar, or generator, or as makes a lot of sense, a good system for charging the house batteries from the engine alternator. With the first and last methods working properly, you can scrap the generator and save a lot of cost and weight. Yes, running one type of battery 15% lower than another does seem to be an advantage, but you can only do that once before needing some way of charging the batteries up again. Without that, a flat lithium battery is just as useless as a flat lead battery.
