Does a firmware update interrupt ongoing charging sessions at my charging station?

No. During the firmware update, operation continues normally. Nothing happens during the entire update. Only at the very end does the device restart briefly once. This restart takes about 5 to 10 seconds. The connected charging stations do not stop charging during this time. In most cases you will not notice anything.

An update usually takes 2 to 5 minutes. With a very slow internet connection and a large version jump, it can take considerably longer, in extreme cases several hours.