Yes, 0.83 amps is just a maintainer once the tractor, motorcycle, third car, jetski, ATV/UTV, etc is placed into storage with a full charge already. Plus you are not charging overnight. That wouldn't be enough current to erase the affects of sulfation when deeply discharging. Each 100 amp/hour deep cycle battery deserves 10 amps minimum & 13 amps maximum of AC shore power charging if you want the maximum performance and maximum longevity from your batteries. Don't screw around with an emergency garage charger. You don't want to turn your back on these for very long. Get a 3-stage dual-bank true marine 'smart' charger.