Why does the Xiaomi Massage Gun 2 charge slowly?

Several factors will affect the charging speed of the Xiaomi Massage Gun 2, such as power adapter standard, charging temperature and charging cable damage.
If the Xiaomi Massage Gun 2 charges slowly, please refer to the following details:
1. The power adapter’s voltage or current output is too low, which makes the charging slow. Please select the 10W adapter to charge;
2. If the battery temperature is too high or too low, the charging will be slow. Please wait until the battery temperature returns to normal, then resume use;
3. A damaged charging cable will not transfer power efficiently. Please check the cable for visible damage.