The Noco Company Genius 3500
The Buzz: Our most powerful unit of the three, the Genius 3500 has a charging capacity of 3.5 amps. It has dimensions of 711/16 inches long by 211/16 inches wide by 17/8 inches high. It is a fully automatic switch-mode charger. The DC cables have clamps and eyelets, and there are built-in status indicators that show charge level, standby mode and battery type. Its housing is rated as waterproof, and the unit comes with a five-year warranty, the longest of the three reviewed here. It can also fit in your pocket or slide into a backpack.