Hi guys. New here so apologies if this has been duplicated somewhere. I got a Spark from Amazon.ca and live in Australia (only mentioning this in case it's a voltage issue). The issue I have is that the Spark's batteries don't seem to charge consistently via the mini USB. If I use a portable power bank, the charging lights don't come on at all, and if I plug via usb to a wall plug adapter, the lights may come on (50:50 chance), and if they do, charging either won't go past 2 bars or just takes ages. If I use the actual DJI battery charger, everything is fine. Thoughts?