Battery Capacity Tester The Extech BT100 Battery Capacity Tester can be used to test the condition of batteries quickly and easily. As an AC milliohmmeter, the tester measures DC voltage and AC resistance while the battery is in use, helping to save time on repetitive testing trials or large quantities of batteries. Other Features The BT100 can store up to 999 test readings and the device can be connected to a PC using the included Windows-compatible software and data cable to analyze and document test results. Measuring 9.75 x 4 x 1.75 inches (HxWxD), the BT100 also comes with Kelvin alligator clips, Kelvin test leads, six AAA batteries, user manual, and manufacturer’s one-year limited warranty.