CTEK (56-925) 12 Volt Battery Analyzer Easy to use simply attach to battery, no need to disconnect, and follow the on screen instructions It tests the battery in seconds providing an instant on screen result which advises what action should be taken The patented technology used is safe for the user and vehicle electronics It is reverse polarity protected, creates no battery loads, heat or sparks Works equally well with all lead-acid battery types and requires no adjustment to perform an accurate test