Today I made a quick and easy adapter to run my Powered Up hub from a lithium battery.
Information for this project came from Philo and Lygte.
The battery:
The Znter 9v LiIon battery is rated at 5.4wH. I choose this over the ZIPPY Lipo that Philo used because:
It can be recharged via Micro USB
It has a constant 9.5v output which means train motors should run at a constant speed regardless of charge level
It is available on AliExpress, I can post