Sinometer BT558 Self-powered Battery Tester
The Sinometer BT558 is a great gadget, and it really works. A little arm moves up and down to accommodate the battery, you place it between the two points, and the easy-to-read display tells you instantly whether you have a dud, or if you can eke out another few minutes of battery life. Best of all, it fits easily in your pocket, so you can take it anywhere you have battery operated equipment.One side of it handles AA, AAA, C and D batteries, and on the other side, there are two terminals for testing 9 volt batteries, so you'll have no more tingling tongue from the old fashioned "tongue between the terminals" checking method.