Just made a clip up for the Spark to add a extra battery to get me some more flight time.
Not so sure I will use this as because of the way you have to mount it, in a hard landing it could slip and end up shorting ..
I originally ran a couple of wires inside with a connector on the end, which I wish I had left there now.
Only looking at ways to improve flight time, as this is prob what I will take to a trip to Cambodia with me next time and wanted something foldable, but this is small so should be okay.
I know uavmods do something called a Spark Magic battery mod adaptor £36.99 that lets you use a Mavic Air battery on the Spark. That looks quite intresting as it still get telementry from battery to app and also the weight of it is pretty good and supposed to be around 20-25 mins flight time. Only issue is cost of Mavic air mod adapter plus buying a Air battery = around £100 uk pounds and then having to velcro the battery in place. But good way to get a long flight time without too much hassle.