The focus seems to be on handheld devices (phones, tablets, etc). But what if they went big to start, looking at traditional deep-cycle applications. Wet-cell batteries (like on golf carts) need regular topping-up with distilled water. AGM batteries remove that requirement and can be discharged deeper without damage, but still have liquid electrolyte in them. RV owners are now experimenting with LiFePo chemistry batteries, but the price is objectionable. I think there's a potential sweet-spot in there.
Yes, boat and RV owners would love deep discharge battery packs that have longer lives. Wet-cell is about a 48 month life, the AGM's a little better. A full set replacement for a large RV is about $2K, so getting another year or two is a big deal.
