TecMate TS120N Battery Tester 12 V

OptiMate Test will display the battery rest Voltage, the charge system Voltage with the engine running and the cranking Voltage - effectively a load test using the vehicle's starter motor.
OptiMate Test is an ideal tool to have in the toolchest for workshop use. Know 100% that your battery and charging system are both in good reliable condition. Totally weatherproof; Fast and easy to use

Check battery charge level. A low battery cranks (starts engine) poorly
Start engine. OptiMate TEST records and indicates (for 20 sec) the lowest start volts
With engine running, verify charging voltage from alternator and voltage regulator

OptiMate Test - A simple, affordable tester designed to be used with the standard OptiMate / AccuMate connection lead, as fitted to a large percentage of cars & bikes on the road, or with the supplied clamp lead