On Thursday, April 9, 2015 at 3:38:43 AM UTC-5, robobass wrote:
When the family makes a road trip I bring along a 12v 4 amp cooler. The ciggie plug melted long ago and I wired up one of those 3/16" cannon shaped connectors used for low voltage home stuff like laptops, external HDs etc. It also gets very hot and is starting to melt. What's a good off-the-shelf solution which doesn't take up much room? The whole ciggie plug thing is the dumbest convention ever, I must say. I can't believe it's still extant.

I would use appliance cord like an extension cord.
Along with an inline fuse.