CLA 12V socket with 50cm lead and 250 faston clips. Just clip it on to any suiteble 12V SLA battery
Additional picture shows it connected a  Panasonic 7.2Ah battery

It can be used with a small solar panel to make a general purpose solar charger. Use it to power or recharge your personal mobile devices that can be powered from a car CLA (cigarette lighter socket ).
By also using a CLA USB Adapter  you will be able to power devices that have a USB power cable as well.