@ViktorK I see what you mean now. You want a permanent battery source that can be charged on the fly. I'm not sure this would be appropriate for that, however I haven't tested it to see. I'll have a go and let you know.
The same official micro-USB adapter that works in the jack, just out through an extender so that it can be powered in a custom case. The placement of the jack isn't ideal, I'm just moving it out.
