It was designed to be small, light, and portable, and work in conjunction with a 12 Volt battery for field day or portable operation. A second switch will allow us to bypass the battery booster so that we don't have to physically remove it from the battery circuit. My sloppy results are shown in the picture below. Notice also the fuse, which is intended to protect against short-circuiting the main battery. The picture below shows the inside layout and wiring, which is completely non-critical.
Operation is very simple.
3-times the capacity of standard cells, and have current sourcing capability similar to the main battery we'll be using. Connect your QRP rig to the output jack. This is a really neat way to maximize your battery-operating capabilities.