I bought an Acer Scooter 3 Black electric scooter with a declared range of 25-30 km. but drives only

You must be going too fast and full throttle, the range of 25-30km is at a certain throttle level and not full throttle or full speed. Try to ride it at half the speed/throttle to preserve battery. Otherwise there is something wrong with your battery and charging, so take to Acer in your country.

If this answers your question and solved your query please "Click on Yes" or "Click on Like" if you find my answer useful👍