This device is designed for early detection of faults in the alternator - battery - starter circuit in vehicles with a 12 V electrical system. It monitors the system voltage and indicates the operating condition using LEDs.
The operating modes are as follows:
- at low voltage (below 13.8 V), the red LED lights up;
- at normal voltage (13.8 - 14.4 V), the green LED lights up;
- at high voltage (above 14.4 V), the yellow LED lights up.
During normal operation, when the ignition is switched on, the red LED lights up. After some time with the engine running, the red LED turns off and the green LED lights up. If later the green LED turns off and the red or yellow LED lights up again, this indicates a fault that must be located and repaired.
The printed circuit board dimensions are 35 x 26 mm.

Technical Specifications:
Application: car battery monitoring.
Electrical system: 12 V automotive system.
Indication: LED (red, green, yellow).
Low voltage indication: below 13.8 V.
Normal voltage indication: 13.8 - 14.4 V.
High voltage indication: above 14.4 V.
PCB dimensions: 35 x 26 mm.

This product is a DIY assembly kit.