A battery tester can be used to check the capacity and operating voltage of button cells, lithium batteries, and rechargeable Ni/Cd-Ni/MH batteries in a matter of seconds. This is done by running current through the battery. If it is flat, the circuit cannot be completed. Vehicle batteries and other lead batteries are tested in the same way using a high-performance tester. You can count on the measurement accuracy of our tested brand-name products. They can be used to reliably determine whether a battery is actually completely flat and needs to be disposed of.