Battery Chargers

I have a roll-around Schumacher thats 40 years old, works like a champ, but no auto features. It will boil a battery into a hard boiled egg if youre not careful. My dad bought it to charge six and eight volt batteries. Does 12v too of course.
My new (old) car has abysmal battery access, so it has a red top. Needed a special charger. Got a $25 one from HF. Works fine, no complaints. I think its probably $40 now.