Question about GreenCell AGM06

Hello Slimi
Yes, I/we have installed/replaced it as described by highfish. Works like a charm :)

Yes it fits 👍

If I remember correctly, I have exactly these in a Rockster Air. There are instructions for changing the batteries. You need electricity to do this. So you can't change from one battery to another at a festival without having a power connection. Here is the answer from Teufel support:
Remove the battery from the Rockster and leave it without power for a total of 45-60 min.
Now (with the battery still removed) take the mains cable and connect it to the Rockster.
Switch on the Rockster and wait until the BT LEDs start flashing.
Switch off the Rockster and then reconnect the battery.
Now hook the Rockster up to the power again and switch it on.