TECHTEST Digital Battery Tester for AAA AA C D 9V 1.5V, Household Battery Checker Tester for Small Batteries Button Cell Things seem to be running a bit slow? Still running slow after you replace the batteries? Why waste time inserting and removing battery after battery when you can just test it? Never again get caught with a dead household battery. This handy digital battery tester makes it easy for you to get the most out of your batteries and lets you know when it is time to get a new one. Get accurate readings on AA, AAA, C, D and 1.5V 9V batteries √ Easy-to-read , digit indicates power level √ Check power level of 9V and 1.5V battery √ Quickly test the capacity of your battery √ Test multiple sizes of batteries in one unit √ Lightweight and compact design, measures 11× 6× 2.5 cm √ No batteries required to operate The Battery Tester may be used to test the following sizes: √ 1.5V-----AAA,HP6,MN2400,RO3,AA,HP7,MN1500,UM3C,HP11,MN1400, UM2,D,HP2,MN1300,UM1 and Cell Button batteries. √ 9V------ PP3,MN1604,6F22,006P You can simply test battery voltage to determine whether the capacity of the battery is low or high. It won't directly detect the battery capacity precisely Don't forget : The aa aaa Battery Tester is activated by the battery being checked .Kepp test times as short as poosible,to avoid unnecessary battery drain. If the digits did not show the check that battery is touching both contacts, otherwise the battery is completely dead.