Addendum: After a successful jump start I charged the unit again. The charging was complete after 10 minutes.
Nachtrag2: After my battery had completely given up the ghost (not even work the remote control more), I had to wait about two minutes after the connection of the power pack, the motor started without complaint and I was able to go to the workshop to be installing a new battery , Charging of the power pack after that was completed after 45 minutes.