Musician/inventor Keith McMillen says he got tired trying to guess whether batteries in various pieces of equipment would last through a show. Battery testers currently on the market never satisfied him so he invented his own.
The handheld battery-operated (9V) Batt-O-Meter uses a gold-plated standard right-angle 1/4-inch power plug to suss out the life expectancy of installed 1.5 V (AA, AAA) or 9 V batteries. It can also test single batteries, incl. 3 V batteries.
Separate settings account for differences between alkaline, carbon-zinc and rechargeable batteries. Onboard auto-sensing algorithms and a microprocessor determine time remaining for the battery and display on an LCD screen.