9V batteries are often found in devices that aren’t used very often. If you use a NiCd rechargeable battery you may find it completely discharged by the time you need it. Capacitors on the other ...

Holding the 9V battery, lightly brush the terminals against ... there’s a much bigger surface area of steel in contact with the air. That means more iron is available to combine with the oxygen ...

a few of your instant messaged me the latest in powering your ipod with an external battery pack. this example, which is now making the rounds around the web is made out of an altoids case, 2 9v ...