You can simply test battery voltage to determine whether the capacity of the battery is low or high, measure whether the battery is fully charged.
Household battery tester works with all 1.5V batteries, AA, AAA, C, D, N, 1.55V button cells, and 9V 6F22 batteries.
The battery check tester with LCD bar graph displays the capacity of the battery, can indicate whether the battery is in a bad, weak or good voltage condition.
No built-in battery is required, and the battery status can be identified by the LCD bar graph when the battery is placed.
Product Size 2½" x 3½" x ½"(6.5cm x 9cm x 1.5cm)