I have a schumacher 'smart' charger I bought at a box auto parts store. The directions are so sparse I had no clue what it did so I monitored it with a voltmeter.
It looks like an older version of this and with similar specs:
https://www.schumacherelectric.com/products/6v-12v-125a-proseries-battery-charger-engine-starter/
It is actually pretty terrific. When charging it maintains a voltage about 1-1.5volts above the batteries current float, so rides the voltage up nice and smooth. A full charge of a fully discharged truck battery takes about 24 hours. I know its a horrible thing for a battery but this charger does a terrific job of restoring batteries.
I've also had batteries so low that they wouldn't charge. I put charger in the 'boost' mode and it zaps battery with 14v and lots of amps. After about 15 minutes the battery 'woke up' and started charging normally. I don't know what it means chemically, battery was behaving like it was shorted at low amps, but at high amps it unshorted itself?
Charger also acts as a maintainer with very infrequent bursts of +0.3v.
However: user interface is 3 lights and a button. it gives you no clue and almost no control of what its doing. I now always use it with a multimeter so I can see that its behaving sanely, because otherwise you just don't know.
I imagine there are fully instrumented chargers out there and I'd love to have one. Something that shares data over wifi or something, gives me a voltage graph so I know it hasn't gone crazy.