I've bought another USB-Charger for my project, because this Wall socket battery charger is unreliable. Twice my project stopped working using 2 of these and one of these chargers even got damaged.

I've bought this USB Charger instead from a local electronics shop named Conrad. This one seems to be more reliable, because my project is running for at least 3 weeks now without a hitch! I've also updated the components list.