You want to know your battery’s state of charge, state of health, current flow and history? Of course you do—and the Balmar SG200 provides this data with a glance at the standard-size 2-inch gauge. Or for that matter, with a glance at your phone. Thanks to Bluetooth, an optional smartphone gateway, and a free app, you can see all the info right on your smartphone screen. This is a “smart” monitor that learns, autocalibrates and typically provides 97 percent accuracy for multiple battery types in 12- to 48-volt banks.