heating engineers... get one!
Got mine from ebay for £20
Not had any problems with the charge on mine. Used it a couple of moths ago to top the tyres up and left it without charging and used it again a week ago without any issues. Not sure how long it can be left or how quickly the charge goes but been fine for what I wanted so far. I would recommend charging after each use (with mains charger) to be on the safe side though. Pretty happy with it and far easier than the foot pump I had. I do only 'top' my tyres up with it, don't think inflating from flat would be much fun....
I’ve had one of these for nearly two years now, it’ll only work properly when it’s fully charged, you use it once after a full charge and come back to use again in couple of weeks and it won’t work until you fully charge again! Overall a good kit to have as there aren’t many compact compressors around. I bought it to use while riding my motorbike as I’ve got a puncture in a remote area and now won’t go anywhere without a puncture kit with me.
Glad you're amusing yourself.