A simple and easy to build circuit that monitors the charge level of your cars battery and that warns you against unpleasant 'surprises'. The circuit uses a LM358 Operational amplifier as a voltage comparator. The red LED glows when the battery's voltage drops to under 11 Volt and the yellow LED glows when the battery's voltage is more than 14.5 Volt. When the green LED glows the battery is within its working specification. The circuit draws its power from the battery that it tests.
Voltage is the most frequently measured electrical quantity.
Can also measure current and resistance. Double sided board. Full details are given in the documentation. The LCD section of the PCB may be cut off and mounted separately. Decimal Point selectable.