CTEK Power Inc. offers its battery Comfort Indicator, which lets a user know a battery’s true state of charge. CTEK said three LED lights show the percentage of the battery’s charge. A green light means the battery doesn’t require charging, a yellow light indicates the user should charge the battery soon, and a red light means the battery needs to be recharged. The Comfort Indicator features long lead wires so a user can position the light module where he or she can see it from outside the vehicle without having to lift the vehicle’s hood.