How fast can a 400W motor run?
2 Answers
Generally speaking, under the new national speed limit standards, a 400W motor paired with a 48V 350W controller has a maximum speed of only 25 km/h. If paired with a 60V battery and a (600W) 9-tube controller, the maximum speed can reach 32 km/h. If replaced with an 800W controller, the top speed can reach 35-38 km/h. 2. Electric vehicles leave the factory strictly in accordance with national standards. The controller is what controls the speed of the vehicle. 3. W is the speed limit fine-tuning potentiometer; adjusting it can change the speed of the electric vehicle within a certain range (faster or slower). It is preset by the manufacturer at the factory, and for safety reasons, it is best not to alter the setting arbitrarily, as doing so may shorten the lifespan of the motor and battery. A is the current limiting resistor, which protects the motor and battery from damage caused by overheating or overcurrent when the vehicle is overloaded. Taking a 400W electric vehicle as an example, generally speaking, to reach a top speed of 25 km/h, it requires continuous discharge for 4 hours to cover 100 kilometers. We only need to calculate the power consumption per hour to determine the battery capacity. According to the power calculation formula W (power) = P (power) * T (time), we get 400W * 4h = 1600Wh.
Personally, I think a 400W motor has a speed limit of around 25 to 30 kilometers per hour, which mainly depends on where you use it. For example, electric bicycles are legally restricted to this range. I've driven this type of vehicle and find it quite convenient for urban commuting—energy-efficient and labor-saving. However, the load weight has a significant impact: if you carry a bag or a person, the speed might drop by a few kilometers; with additional accessories or uphill driving, it slows down even more. Battery condition is also crucial—it's faster when new and fully charged, but performance degrades as it ages. I recommend regularly checking the motor cooling and chain to avoid overheating or wear, which helps maintain stable performance. In practice, safety is the top priority—avoid speeding or stunts, especially in crowded areas.
