Lithium Battery Monitoring Lead O-127Permanent power sport battery lead with integrated battery status / charge system monitor for 12.8 / 13.2 V lithiumMonitor charge of your stored power sport vehicle lithium starter battery or confirm if the vehicle charging system is working correctly2 automatic Modes – Battery charge level monitor (single LED blink mode) and Charging system test (arrow mode)3 LEDs display ‘full to empty’ voltage range for 12.8 V/13.2 V Lithium batteries (LFP/LiFePO4/Lithium nano Phosphate); 4th LED warns when vehicle system or connected battery charger is overchargingBattery charge level : LED matching charge level blinks every 10 seconds (long term draw less than 0.2mA)Vehicle Charge system : LED arrow mode activates when charge voltage reaches effective lithium charge range of 14.2 V – 14.5 V (v green LED)OVERCHARGE warning activates at 14.6 V+SAE charge port with weatherproof sealing cap