[john61ct]

Nice score!

As big an Ah charger you're willing to buy with adjustable voltage outputs. Start at 60-80A, $400 and up.

Could get away with an adjustable PSU and regulate manually, but not worth the hassle for what you'd save.

Note UPS batts aren't really designed for regular deep discharge, but they may still serve nicely for a few years.

What is each unit's capacity in AH, at the 20-hour discharge rate?

Ideally you'd load test to benchmark that now, so as they wear out you can track their SoH.

 

[john61ct]

Totally disagree with that last.

If you can get say $3/Ah @12V, would be worth swapping for a known-good no-engineering-needed true deep cycling bank of a long-lasting mainstream chemistry.

But very unlikely to get even $1/Ah

_______
20-hour load testing is really the only accurate measure, not rocket science, without some specialist tools just pretty tedious.

Get through to tech support at the maker if you can't find manuals or spec sheets online.

 

[john61ct]

Enersys - fantastic outfit BTW their Odyssey line is among best AGM in the world, they invented TPPL, ex-employees started Lifeline and Northstar

and also spiral-wound (spun off as Optima, now not so great under JCI)

Here's one of the founders

Bruce Essig [email protected] / (660) 429-7506 / Fax: (660) 429-1758

 

[john61ct]

One of the things I've been thinking of doing is setting up some old car batteries as fast-charge station for an EV. Trickle-charge them all day long at whatever rate, but if I pull in and want to juice up quick, well, they're lead acid starter batteries, I could yank power out of them fast.

as long as the starter-batt bank was say 10x the wH capacity of the source bank, and configured to a higher voltage, and

some sort of DC-DC charger in between to regulate the voltage and limit current

or maybe something like a big Victron PowerAssist.