Where can I take old UPS batteries for recycling?

Good news, scrap yards almost always take these and they pay by the pound. The sealed ones from UPS units are the same lead and same grids as a car battery, just with an absorbed electrolyte instead of free liquid, so to a scrap yard they're just battery weight. I've hauled pallets of dead UPS batteries to my local yard and walked out with cash every time. Call around and ask if they take 'sealed lead acid batteries' or 'SLA batteries' specifically. The word 'sealed' seems to be what trips up the counter people, because a lot of places have a mental list that only says car batteries. Once you say SLA or point out it's still lead acid, most yards will take it.

Yard route is the way, but if you strike out on the phone, try any place that sells batteries. Back when I was doing telecom installs in the 90s we'd just hand the dead UPS bricks to the supplier and they got hauled off with the rest. A lot of auto parts stores and battery shops will still take them even if they don't sell that type, they just toss them in the same core bin. The big ones you mentioned might actually get you a few bucks each since they're heavy. Whatever you do, don't let them ride around in the trunk much longer, a cracked case makes a mess you'll be smelling for months.

I have to push back on the 'every yard takes them' claim, becasue that was not my expirience at all. My local yard turned away a whole batch of UPS batteries last year. Guy at the scale said anything without a car battery style case goes in thier electronics stream, and they actually charge to take that. Had to drive to the county facility and pay a fee there. So yeah, call first, but also call the county hazmat place even if their website looks useless, sometimes the phone answer is way better than the site.

Did a data closet cleanup a couple years back where we pulled 18 of those blocks out of one rack, and the IT decommissioning company we used took the whole lot for free since they alredy had a relationship with a recycler. If your work has any vendor that handles old servers or electronics, ask whoever manages that contract, they likely have a channel for batteries already. Also put cardboard between the terminals if they're rattling around loose in the trunk, a shorted battery is no joke.

Another angle that worked for me when I had a stack of these from a server rack swap: I put the whole dead UPS units on marketplace for free and a guy came and took all of them in one trip. He resold the working ones and scrapped the rest, batteries included. Saved me a single phone call. If the big ones are still in their enclosures that might be the fastest way out of your trunk.

Update: took the first suggestion and called a scrap yard out my way, and yeah, they took the whole lot. The guy at the scale just weighed them and paid a few bucks per battery, sealed ones included. Never even asked what kind they were. Two of the places I called earlier must have just had wierd rules. Trunk is finally empty.