The Batt-O-Meter is the first and only product that can measure the battery life on your active guitars and basses, as well as your pedals and any other battery powered device that has a 1/4″ output jack. You simply set the Batt-O-Meter for the type of battery, plug it in and take a reading. It gives you great peace of mind before gigs and makes battery checking as easy as plugging in your cable. I was excited when I discovered the Batt-O-Meter because I had this idea myself about 10 years ago. I worked with 2 electronic designers over a 12 month period, but we could not solve the riddle of how to compensate for differences in circuit “load” that the meter would read at the jack. The Batt-O-Meter has a microproccessor which analyzes the load of the circuit to produce the correct battery reading. I have tested the accuracy of the Batt-O-Meter and find it to be excellent. I highly recommend this great product. Requires a 9V battery, not included. Please click below for a video demonstration.