The instrument is a Amp Hour Meter used to monitor the life remaining in a battery. They are used in large boats, RV's and electric vehicles. They are somewhat expensive at first glance, however it's a multi-instrument run by a microprocessor. It measures amps, volts, amp-hours in a battery[ pretty cool]. It has the potential of saving your bacon in a plane ( I've lost all power on one of my cross country flights).
It's called a "E" meter it's made by Crusing Systems, 1900 N.W. Dock Place, Seatle, Washington 98107. phone 206-748-8100, fax 206-782-4336. cost: $224.95 and $324.95 w/RS-232 interface version. I first saw it in a Nuts & Volts publication. You will see it in my plane some day. KRRon
