How to extend Battery Bank time of failure?

Sakamochi said:

Thanks for all of the excellent inputs and perspectives, especially BB - you've helped me in the past and I appreciate it. 
Some responses I see as probables, some not. At 5500 ft elevation in Northern AZ sun is not an issue. My house is 2,000 sq ft. Refrigerator, freezer, little vampires here and there average 2.5kw per day bny themselves (no people). Running the heater (always 54 degrees or better inside) and putting people in drive that to 5-7 kw per day occupied. Its kind of a balance: winter- heater/summer refer and freezer run much more so its almost the same average power.  My power system is old (16 years), with low PV power (the panels cost $600 each - 140 watts then!!) They are on a tracker array, so they get as much sun as possible all day. That was the way to make up for expensive panels back then. The DEKA's L16's are 5 years 2 months old (not 9 years old). The batteries see about 30 degrees at the low and 113 at the high in the box. No fixing that more than what I have already done. As far as "bubbling and stirring things up" the batteries do too good of a job of that in the summer. 100% more water than when new in the heat. As far as "my bank is too big" - I beg to differ. We would never make it thru two days without sun. We would have to run the generator. Generator=you did not plan your system right IMHO. My neighbor has the 24v version of what I have, same-same everything except he has to run his diesel genny nearly daily to keep up. His batteries (also DEKA 2V) do last longer that mine (by a year or two), so maybe beating the crap out of them is actually a good thing, I never thought of that idea before. Typical SOC varies: season winter is right around 48 volts, sometimes a little lower, could get down to 47.5v. The generator is automatically step programmed to not allow discharging below 50%, and as I wrote, that has happened twice in ever. I agree that the absorb takes forever on the generator (which can put 35 amps into the bank thru the inverter/charger). I usually quit that when charging in bulk at top end when I know Mr Sun is forecast to roaring back on the next day. Again, that is probably 2-3 times a year, so of no consequence. We go into "conserve power" mode when these winter storms hit and cut sun power for days - no microwave, coffeemaker, hair dryers, etc. The wind generator does really pull its weight, again in the days of high cost PV that was the way to go. Not so anymore. When the wind gen dies, it will not be replaced. No one has parts for them anymore.. We have a BIG solar farm (thirty systems, 300 ft tall, 100 ft blades) just to the west - so we are in the "wind belt". Sustained 900w charging happens quite often, especially when there is those storms without sun. Undercharging? Almost never (storms and/or guests beating up on power overnight could lead to generator needed as previously described)  A usual day starting at 48 volts to completed absorb usually takes 6 hours or less from "wake up".  If we really slam power (lets say 7.5kw for the day) it might take all day to get there on a not too hot all sunny day (10 hours). The PV can hit 16kw in one day if everything is just right. 

I think it might be right to change the whole system out when the DEKA's go. The LifeP04 with all its accompanying parts would likely be the way to go - I'll need some trustworthy tech help to come up with a spec as to what that is for sure. I think this could be had for $20,000. Or maybe, in my 8th decade of life it might make more sense to spend less on yet another set of FLA which may outlast me!