Just in case you are unaware of what this object (below) is, it is a portable jump-start 'booster' for when your, or your friend's, car battery is dead. Rather than relying on a second vehicle and a pair of long jump leads, this, when fully charged, will not only fit in your pocket, but will remain fully useable for months.
When I recently returned to France, I couldn't find the cable that charges the booster. It was a simple affair that plugged into the wall, and into the booster via a tiny USB plug not unlike that which charges my iPhone. I know where I left it, but it ain't there now!
In frustration I visited a specialist electrical shop to find a replacement, only to be told that I'd have to contact the manufacturer, as such things were not available over the counter.
I searched again, and still found nothing. I looked online and still nothing.
Then I thought.... find an alternative. That alternative was right in front of me in the form of an external speaker for my laptop. It has the exact same small USB port as on the booster. I plugged it in, and BINGO; it works.
I also discovered that the booster had remained fully charged for the past 9 months. Amazing. If you look at my photo, under the BO of BOOST you will see a symbol for a lightbulb. Yes it even has a light for working in the dark.
Luckily I have no need for it at the moment, but it's a great little device to have in the car.