The ultimate pocket tester for on-vehicle battery performance & alternator voltage testing that every service technician or gear head should have! Easy to use! Connect clips to the battery or connect to an installed SAE battery lead, then: 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. TIP: Low charge voltage causes poor battery performance. Too high charge voltage causes excessive gassing and will eventually damage a lead-acid battery. Too high charge voltage is FATAL for a LiFePO4 starter battery! Microprocessor accuracy. Easy to follow instructions on rear panel of the tester. Industry standard SAE 2-pin connector. 40″ / 100cm battery clip set. Fully sealed. A premium tester designed by TecMate. 3-year limited replacement warranty.