All car owners should know that electric appliances, such as power switch, spark plugs, and other internal electronics can be gradually damaged if the voltage is too high (exceeding normal tolerances by 15 percent). Similarly, cars will not work properly if subject to under-voltage conditions (specifically lower than 10 percent of threshold).
Nobody wants to suffer a breakdown on the road, however most drivers are indifferent to or unaware of the condition of their car. If you want one of the easiest and most cost effective ways to ensure your car's health, then you need a battery voltage monitor.

Features:
Function 1: Battery voltage monitoring, for 12V cars, SUV, 24V trucks, buses, etc.

Car Battery Voltage Monitor:
Normal value: 12.2-12.8V
Lower than 11.6V: Need to close/reduce the loads, and launch engine charging as soon as possible
Lower than 10V: The generator may not be able to start
Car Generator Voltage Monitor:
Normal value: DC 13.4-14.8V
Lower than 13.4V: Will not be able to charge the battery, please check the generator belt and the car loads
Higher than 14.8V: Power generation excessive, easy to damage the battery and the loads, please check the generator regulator

Function 2: USB charger, for the charger of 0-2.1A cell phones, digital cameras, tablet computers etc.

5V / 3.1A double USB output car charger
3-digit red LED tube display
High efficiency with low heat, PTTC over-current protection