After some recent battery frustration, particularly with the battery power on the Spark, I did some research and discovered the below item from Billy Kyle’s YouTube page.
Not only will this charge up flat devices via USB and USB-C ports, this also has a mains output enabling you to, say, plug in the Spark 3 battery charger using the supplied mains lead, or the Mavic four battery hub via a mains lead.
It arrived yesterday from Amazon, via Prime, and charged up the internal 27000mAh battery in quick time. Relatively expensive I know but having mains power and USB power on tap can be a real blessing. Go to Amazon Uk and search for USB C Portable Charger, RAVPower 27000mAh Built in 220V AC Outlet Universal Power Bank Travel Charger.