Image Number 4 for United States Patent #6074778.
A method of extending the useful life of one or more conventional DC batteries in a battery-powered device. The method involves use of at least one dry cell DC battery, at least one metal blank, and a battery-powered apparatus having a battery compartment and an extension housing. At least one dry cell DC battery is placed inside the battery compartment of the battery-powered apparatus. At least one metal blank is then placed in the extension housing for completing an electrical circuit between first and second contacts of the battery-powered device. Using a voltmeter, the voltage of one of the dry cell DC batteries is tested. If the voltage of the dry cell DC battery is below a threshold voltage level required for the battery-powered apparatus, at least one metal blank is then replaced with a partially-charged battery.