Monitor your car battery automatically with this monitor that provides phone notifications via Bluetooth. It monitors alternator function and checks the cranking system of your vehicle during engine start-up. It's compatible with all 12V batteries and stores data for up to 35 days when out of Bluetooth range. Historical data is displayed as a graph for easy review, and phone alerts are sent if data appears abnormal. This monitor has short-circuit and reverse connection protection and has a voltage accuracy of 0.03V. Data is sent to your phone via a free app for IOS and Android.