The charging boxes are located in a locked parking facility.

You can also "fill up" your e-bike free of charge and theft-proof at the e-bike rental station.
However, only while stocks last: there are 5 lockable charging boxes there.
In order to access the locked storage and collection facility, you will need some coins.

The machine at the entrance to the parking facility requires a €3 deposit before the door opens for you.

You can find detailed information about the parking facility here:
https://www.stadtverkehr-detmold.de/mobilitaet/fahrradabstellanlage
And you can find out how to hire an e-bike here:
https://www.stadtverkehr-detmold.de/mobilitaet/e-bike-verleih