Maybe a bit late for input on this thread.
In 2014 I installed a Crown forktruck battery, 12LM85-15, rated at about 790 AH ( 20 hr rate).
After some discussion with Crown, it was specified as their "H2GO" design, which has large water capacity above the plates, recombiner vent caps, and a level alarm.
The target specific gravity is 1.285, as someone mentioned in an earlier post this is typical for industrial batteries.
Under our normal use, which depletes the battery 15-20% overnight, it has performed great.
After some discussion with Crown's tech department, the absorb and equalize voltages were tweaked, and as a result the SG stays in pretty good shape.
The absorb voltage is higher than what is perhaps usual, at 30 volts, but that gets the absorb SG to about 1.265-1.27 daily, and I EQ every 10 days for 3 hours at 31V.
As mentioned above, these settings were determined after a few months of monitoring the system and chatting with Crown.
I water every month or so, adding about 3/4 liter per cell.
The absorb terminates at 11 amps, typically taking 5-6 hours.
As far as I can tell, the battery capacity has dropped somewhat in the 7 years of operation, but I haven'[t bother with a load test to quantify the drop because the battery still does what we need.
In the discussions with Crown, they encouraged me to not treat it as a precious object, but instead discharge it quite a bit once in a while and then charge it as fast as I can ( about 90 amps). Their main concern with life is making sure that it is fully charged - hence the somewhat aggressive absorb and EQ voltages.
A couple of nice things about a battery like this:
-the cell to cell connections are welded lead, so there is no cable corrosion or maintenance
-The wiring connections are a type that will handle forklift currents - so typical inverter currents are well under the limits.
On the other hand, it is a brute - 1200 pounds.
Prior to this battery, I bought a reconditioned forktruck battery of a similar size, for about 1/3 the cost of the Crown. It lasted 3 years. From the beginning it was evident that it was not in real good shape, taking a very long time to finish absorb, making the system pretty inefficient. Once I understood better what good looks like, I abandoned it and bought the new Crown. Got $300 scrap value from the old battery.
The system is unused 4 months or so during the winter. I leave the charge controller on, with a 1000 watt bank of panels adjusted vertically to shed snow. The inverter is on a low power standby, drawing 5 watts or so, with a timer to turn on the modem, local computer, and network so that once every few days I can take a look at how things are doing. Mainly this is just to make sure the battery voltage is high enough that the freezing point is well below the ambient temperature.
The charge controller is set for a short absorb and no equalization, to limit water consumption, to ensure that low water is not an issue during the winter sleep.
In the spring, it takes a few sunny days to get the specific gravity back up to 1.28 or so, but so far that has been OK each spring.
Unrelated to the forktruck battery subject, for years I used a AC generator as backup, powering the AC system and using the inverter as a charger. It was always a balancing act between the charge rate and having enough AC to run pumps, etc. A bigger generator would help, but there is a limited selection of high amperage 120 volt generators. Currently I have a 70 amp, 24 volt generator connected to the battery, and run it whenever the battery needs it. The generator runs flat out for either a set time or until the battery reaches about 80% SOC, monitored by the WB Jr and the Magnum inverter. Works great.
