It is very frustrating for me when I am busy playing on Xbox 360 and the wireless controller’s battery goes dead. And for frustrating minds like me, the good guys at ThinkGeek are selling a nifty Credit Card shaped battery checker. The task of the card is to check the juice remaining in the battery. Just keep your battery between the card (supports AA, AAA, C, D, N, 9-Volt batteries) and the LEDs show the status differentiated in Good, Weak or Poor. You can get this for just $9 instead of using your guesstimating power.

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