Leaving a charger permanently connected to the USB charging port

In my situation with my Ring Doorbell 1st Gen I can leave the charger plugged in permanently as I am not using the wall mount. In the app it says hardwired. I was thinking this is the same situation as the Ring available solar charger?
What I would like to know is it safe to have a charger permanently connected. (I am using a 850mw phone charger)

Hi @Buddynz. The doorbell is not intended to be used this way. It’s best to charge your doorbell using the micro USB cable, then disconnect the cable and mount your doorbell.