I usually just buy tools that I don't use a lot at Harbor Freight. But I bought this awhile back https://www.harborfreight.com/4amp-...ntrolled-battery-chargermaintainer-63350.html and holy crap it is awesome. It has exceeded all expectations, which honestly wasn't that high.
I have those on boat, mower, rv and 2 back ups. Have performed as well as a charger I bought years ago, that cost more than those 5 combined.
Highly recommend for every shop.