I don't consider them a real charger, but I know a bunch of guys here swear by them
for me 10 amps is a charger
if the battery was down 100 amps it would take 10 hours to get it up 100%
......a 5 amp charger would take 20 hour
that 3.3 would at 30 hours to get it up
if I get home at 5pm from fishingand am leaving to go fishing at 5am that only give me 12 hours to get the job done