Re: ups batteries
UPS batteries "don't last long" in UPS service because they are usually stressed by high currents. In the case of the one label in the photos, it is also from using a string of undersized batteries, choosing portability over run time.
I use selected large UPS pulls at low current for a long time. I can power a camper carefully on one 12-volt pull for a couple of days of boondocking without recharging. If you had the ability to test the individual batteries and find good and matched ones off of the pallet, it might be good to pick through the lot, and then sell the rest to a recycler for the materials.
HOWEVER, the photos of this lot show at least some of the batteries with four vents per case. That would mean this particular bunch of batteries that are visible would likely be 8 volts each (2 volts per cell). Great for making 24-volt strings, for 12 volts not so much. The UPS spec shown is 120 volts DC, 7.2 AH. The 120 volts would be fifteen 8-volt batteries in series. 7.2 AH is a pathetically small number. That means that each battery is probably 8 volts, 7.2 AH. You could parallel battery strings to get more AH of storage. But there seem to be several UPS units and a mix of battery sizes on the pallet, so the photos and specs may be a mish-mash.
The pulls I have are 12 volts 140 AH each, removed from a 288-volt system, but 100 AH or 120 AH is more common. You may also find UPS strings made up of 6-volt batteries (3-cell) or 2-volt single cells instead. These can be wired in series to get the desired DC voltages. The capacities of deep-cycle designs are usually specified at the 20C rate (100 AH = 5 amps for 20 hours), but I have seen a few batteries rated at 10C (100AH = 10 amps for 10 hours). If you draw more than standard current, you will get less than rated amp-hours out. If you draw less than standard current, you will get more than the rated AH to full discharge.
Also, sealed batteries cannot take the higher charging voltages that wet cells can. A bus alternator could kill these without some kind of voltage control. The limit is usually 13.5 charging volts on a 6-cell, 12 volt battery string. If you overcharge them to the point that they vent gas, the capacity is permanently lost. You can't just add distilled water to fill it back up like a wet cell.
Done right, UPS pulls can be an inexpensive option for assembling large-capacity battery plants. But using them is not just as simple as hooking up car batteries. And you should have some means of testing the remaining capacity of each battery to weed out failing cells.
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.