Battery & Charging tester 12V 12V - 500 AMP, variable resistance 250 x 320 x 150 mm. Battery testers with variable resistance up to 500 Amperes. Tests batteries up to 1000 CCA WARNING: The knob is set to maximum load during transport to protect the carbon brushes in the load resistor. Before testing, the knob must be turned all the way to the left!