According to my understanding, when the Xiaomi 9 PLUS electric scooter is charging, if it has been activated and is in normal working state, it will show a red light when charging. When the battery is fully charged, the indicator will turn green.
< br >
Please note that there may be slight differences between different battery or firmware versions, so it may vary. It is recommended that you check the user manual of the Mi 9 PLUS or contact the manufacturer for more accurate information.