Unfortunately, most drivers find out that their charging system has failed when they end up broken down on the side of the road. A little advanced warning can keep you from being stranded in the middle of nowhere. Now you’ll know at a glance whether or not your charging system is working properly. Our L.E.D. Battery Gauge is an array of L.E.D.s indicating the operating voltage of the vehicles electrical system. Green L.E.D.s represent the normal operating range of your charging system, 12.5v to 14.5v. Amber L.E.D.s warn the driver that the vehicle is not charging. If the reading drops below 10v or exceeds 15v, a flashing red L.E.D. will alert the driver of an impending stall or the possibility of damage to the battery and/or sensitive electronic components on the vehicle. Simple two-wire connection and a compact size (about 2" x 3/4" x 3/16") make installation a breeze. A daylight sensor automatically adjusts the brightness of the L.E.D.s. They are bright during the day for visibility and dim at night so as not to blind the driver.