I'll put in the
worth of experiance I have. I grew up where my father had only one charger, and still does. The thing has to be 30+ years old. Anywho, it had a couple settings: 6v or 12v and then different amperages with each respective setting (it was also automatic; shut off when the battery was charged). If you wanted to charge a battery, you hook it up and set it to a low amperage and walk away. If you needed to start a car, truck, or tractor with a dead battery, you cranked the charger up, waited 1 minute, then turned the key. 98% of the time, it worked like a charm. The other 2% either the battery was completely gone, or you'd have to wait 2 minutes then turn the key
Now that I'm a big boy and out on my own, I picked up an automatic trickle charger I found on sale, it was less than $15 at Farm & Fleet. It's what I used throughout all last winter. If I knew a snow storm was coming, I'd hook it up the night before and have a full battery the next morning. However, if I ever didn't do it or woke up to a dead battery on a different machine, I'd have to start a tractor to jump the dead battery.
All that being said leads up to this; get a cheap trickle charger for winter/overnight chargers/battery maintaining, and get a decent larger charger for those quick start tasks (or I suppose a jump box). The only application I see for the chargers so big they are on a cart is for farms on machines with multiple batteries or just a single humungo battery (technical term, I hope y'all understand). Anywho, that's just my