It was overcast, my laptop battery was almost dead, and my house batteries were kind of low. But I was about to make a 90-minute drive. "Hey, I could use that other charger thing I have."
A 12-Volt plug and some circuitry on one end and a MacBook magnetic connector on the other. Why go DC to AC to DC via my inverter when I could go straight from DC to DC via the van "power port" (cigaret lighter) as I drove?
I found the charger on eBay. There are a variety of them for different laptops. You need to read the tiny type on your charger to make sure you order the correct voltage and amperage, as well as the right plug for your computer.
When I reached my destination my computer battery was charged and happy. And so was I.