Snap-on's battery and electrical system tester, No. EECS500, helps diagnose battery, starting and charging system problems before a customer's car even fail to start. The EECS500 has the ability to test 6V and 12V batteries, and can compensate for temperatures above or below 32 degrees F. An internal magnet holds the unit in place during use and storage. The tester offers a built-in printer and customized printouts with shop information, including test results, date, time and a location for the tech's signature.