Solar battery maintainer

It's always hard to keep the batteries up on equipment that sits for long periods. I found a solar battery maintainer/desulfinator that's working well for me.

Solargizer from Pulse Tech like these:
(I don't sell these, just examples I've found online)
https://www.ebay.com/itm/274330466964

https://www.easternsurplus.net/PartDetails/7209/ALL-5225-24V-Solar-B...

These two are 24v...

Solar battery maintainer