How to prepare the HTC Vive Controllers for long time storage

I just got a new VR system and would like to store my still working HTC Vive with the HTC Vive Controllers for a long time. Sort of just to keep it. I know with the average electronic device one needs to remove the battery when the device is not used for a long time. What’s the best way for the HTC Vive controllers as the batteries are build in?