I have a pair of hardy transformer chargers that I use for charging. But dumb chargers are no good at low float, that takes electronics. I ignored the cries of my real chargers and bought a battery tender a few years ago. Apparently, my batteries all tell me that I don't drive enough, and the cost of car batteries is up in price from before COVID. I know because the $60 battery and the $99 AGM batteries that I bought before became $200 and $300 to replace... So now anything that sits gets plugged in to a tender. If prices keep going up, I'm going to make my own batteries, it's not exactly rocket surgery. I can get 600 CCA out of a battery made from a rubbermaid tub and wheel weights, right? Deep cycle is even easier, just iron and nickel electrodes and KOH or H3PO4 as an electrolyte, in 8 cells. Maybe add sodium slilicate to keep it from sloshing in the back seat...