Sanyo's New Power-assisted Bike Can Travel 1.5x Longer Distance

Mar 4, 2010 18:54 Hideyoshi Kume, Nikkei Electronics

Sanyo Electric Co Ltd announced a power-assisted bicycle that can generate electricity with a motor and store it in a lithium-ion battery even when running on a level ground.

The function is called "eco charging mode," and it can increase the distance that can be traveled by 53% compared with the "power mode," which provides a stronger power assist. Sanyo will release the 26-inch "CY-SPL226" and the 24-inch "CY-SPL224" at a price of ¥157,290 (approx US$1,778) April 21, 2010.

Sanyo's previous models regenerate electricity when the brake is applied and when they are running down a hill. But they do not when being pedaled on a level ground.

Normally, when electricity is generated on a level ground, it becomes hard to pedal, imposing a burden on the rider. But the new bicycle monitors the running condition and determines the timing of regeneration in milliseconds to minimize the burden on the rider, Sanyo said.

To prevent the bicycle from staggering, the regeneration starts at lease five seconds after the bicycle starts moving and only when its speed is 7km/h or faster. Even in the eco charging mode, the bicycle is automatically assisted by the motor when it is taking off from a stop, running up a hill or accelerating.

The regeneration and motor-assisted running are switched to each other based on (1) the pressure that is applied on the pedal and measured by a torque sensor embedded in a crank, (2) the velocity calculated from the motor's rotating speed and (3) the acceleration calculated from the velocity. For example, regeneration does not occur when the bicycle is being rapidly accelerated.

"when in rapid acceleration, the accelerated velocity becomes high," Sanyo said. "And there is an upper limit of accelerated velocity so that the bicycle does not regenerate electricity at a high accelerated velocity."

Another new function added to the bicycle is the "Power Reserve," which notifies the rider that the remaining battery level is low. When the remaining battery life becomes about 1Ah, the motor-assisted running temporarily stops. Then, if the power button is kept down for some time, it becomes possible to use the 1Ah (equivalent to 6km in the eco charging mode).

The rated capacity of the lithium-ion battery is 7.6Ah.

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