Sealey digital battery alternator tester 12v sealey bt102 compact design digital tester suitable for professional use utilises low current draw technology to evaluate condition of sli vrla agm and gel batteries and charging systems bt102 only just key in the battery rating from the top of the battery simple fast and accurate evaluation of battery condition results displayed on led control panel no internal battery and will test batteries with a residual charge of just 7 volts bt1