A solved problem:<p><a href="https://www.parts-express.com/Marine-Grade-Locking-Cigarette-Lighter-Plug-12-VDC-265-272?quantity=1" rel="nofollow">https://www.parts-express.com/Marine-Grade-Locking-Cigarette...</a>
drive a woodscrew in beside the power plug thing and the "lighter socket" in a car to ensure the thing stays in. (same axis as the plug)<p>Works for shovel and other tool handles too.