Hi Francis,Aloha this is not a discussion to promote agms vs lithium, but I have noticed that small AGM's (such as 9hr ones) that you would find in UPS's have about 40-50% more ah versus weight compared to an Optima for instance.
Optima=520 cubic size 41 # and 50AH
UPS Bat=60 cubic 5# and 9 ah
So you can put 8.2 of these UPS batteries @ 41# in the optima space and get 74ah and even have a smaller footprint.
I recently got 100 of the UPS batteries for free from company that changes them out every 18 months, so wondering if it is worth a try to say parallel 10 and series 16 to make (total 160) 192V @90ah.
Other than "Forget it and buy Lithium" does this seem workable?
Those will not be deep cycle batteries meaning a cycle life in the dozens instead of 100s. And they likely will not have the power capability of the larger Optima, even when paralleled.
And why do you think your source is changing them out and giving them away? UPSs typically have a crappy float charger which cooks the electrolyte out of AGMs in a couple of years. Even if they are still functional when you get them, chances are they won't be for long
If they're free and you got the time to play with them, why not? But don't get your hopes up.