Ham operator [Ken - wa4mnt] wrote us to share a small project that he uses nearly every time he goes out in the field. His portable sealed lead acid battery pack (PDF) always ensures that he has a 12v power source at his fingertips, both for fun as well as in emergency situations.
The battery pack is pretty simple, and includes a 12v, 17ah battery strapped into a light aluminum chassis which he fabricated. The battery is secured with zip ties, so it can easily be swapped out or replaced without much fuss. The frame also sports a tiltable 4w, 17.5v solar panel that keeps the battery topped off and ready to go at all times. He stuck a voltmeter to the top of the battery to keep an eye on things, and he employs a 10A fuse to make sure he doesn’t fry any sensitive radio components should something go wrong.
The battery pack is pretty compact when you think about it, and we imagine it would be great to have on hand for a wide array of outdoor activities. Even if you’re not into Ham field operations, it’s hard to argue with its usefulness during power outages.
[Ken] doesn’t appear to have any published plans for the chassis or the electronic portion of the pack, but we’re pretty sure he would share if asked.