Best battery charger I had was one I removed from a warehouse cart that was similar to one an electric forklift would have--only bummer it was 24V only,so I had to keep a second 12V battery around to hook up in paralell to use it on 12V batteries..(or I could charge 2 at once!)...that thing weighed 50 lbs I bet,and had a screw in glass fuse,it seemed to revive dead batteries better than any others I've had since,like it de-sulphated the plates or something..
Sadly,it was left behind at the junkyard ,where I had used it a lot more than at home..most likely it was scrapped when the place went out of bussiness,or it might still be in the building...I'm not about to go look for it!..
I've had a Sears 10/2 amp charger with the trickle charge feature to charge motorcycle batteries since I got out of high school in 1977,it still works OK--so does a Schumaker I got for 3 bucks at the flea market a few years ago,that looks as old as the Sears...I also have a 1 amp one in that brand for motorcycles too..
I had bought 2 brand new chargers about 6 years ago that failed the first time I used the 55 amp "starter boost" setting,I think they were Schumaker too,but they were in plastic cases and were lightweight..I ended up getting my money back after the second one died the same day I got it..
I'd like to get a big charger thats on wheels,but haven't felt I really need one bad enough to justify the cost...I can buy a new battery for that much!..