Criticism of the USB connector of Kruse Plumbing can confirm. The S4 is only possible with pressure on the plug on the charger and I have the impression that the USB socket is damaged on this S4. Therefore, I use the charger only as a charger for the spare battery.
I can in my view not fully recommend the unit.
Addendum:
In my review, I got you a new device.
Unfortunately, it has the same problem, the USB connector is only possible with a little violence in the S4.
Therefore, continued: No recommendation for this part.