I'm a big biking and outdoors fan, and a challenge I came across was trying to combine both. I own an inflatable standup paddle board, which uses a 12V cigarette lighter jack to inflate. However, I've encountered multiple scenarios where I'd prefer to bike to the lake, or a drop-in point is half a mile from the parking structure. To solve this, I built a portable power supply that uses an 18V Makita battery, along with a DC converter and lighter port to emulate being plugged into a car. This is small enough I can just throw it in the paddle board bag and pop it out to inflate. It also doubles as a great camping tool, where you can plug in other things designed to be mounted in a car, such as USB ports for phone charging, fans, and even a laptop charger (shame on you, you're camping!)