The Battery Analyzer.
THE easy- to-understand battery & charging system analyzer for all 12V starter batteries.
The TestMate mini is more than just a voltmeter, it’s a super fast recorder of instant volt drop during ‘engine’ cranking – the best indication of a starter battery’s ability to deliver power when the engine needs it most. Once the engine runs it checks if the charging system is able to bring the battery back to full charge.   
This unique, handheld on vehicle  battery & charging system tester :
1 – Checks Battery Voltage – Your battery’s ‘rest’ voltage is an indication of battery health.
2 – Checks Battery Starting Power –  A reading in the red zone indicates a problem !
3 – Checks Vehicle Charging System –  Is the charging system causing the problem?

• FOR ANY VEHICLE WITH A 12V BATTERY SYSTEM – Any battery size, any charging system.
• 18 LEDS INDICATE FULL CRANKING & CHARGING RANGE – from 7V thru 15V.
• LIGHT & WATER RESISTANT – ideal for outside testing or carrying around in your toolbox.
• INCLUDES MOUNTS FOR ON ROAD TESTING – The rear panel can be demounted to fit temporary & permanent fixing mounts. Cable straps & Velcro strips are included.