When cycling in unfamiliar territory, it is good to be able to have Google maps available, the trouble is, a) mounting the phone, and b) charging it. I found out that these problems were fairly easy to solve.
The charger I bought was described on ebay as a “Motorcycle Bike Phone Holder Charger Qi Fast Wireless USB Charging Mount Stand”, e.g.: https://www.ebay.com.au/itm/174523726449
This unit runs off 12-24V. The Libelle has a 36V battery, so I also obtained a 36V to 24V DC to DC converter, described as a “Waterproof Buck Converter Step Down Module Power Supply 36/48V to 24V 1A 24W”, e.g.: https://www.ebay.com.au/itm/141943325666
The charger had a sufficiently long lead for me to run the wire down the bike frame, using small cable ties to hold it in place, and making sure I followed the generous loops in the wiring where the bike folds, and into the electrical control box on the bottom of the bike. The DC Converter easily fitted into the box, so after making the connections to the charger (make sure you have the polarity right) and to the wires coming from the battery, it was easily done.
If you would like further details, or more photos, let me know.