Panasonic to Release Regenerative Electric Bicycle with Li-ion Battery

Jul 7, 2008
Naoshige Shimizu, Nikkei Electronics
Panasonic's new electric bicycle can recharge the Li-ion secondary battery with energy generated by the regenerative braking system.
Panasonic's new electric bicycle can recharge the Li-ion secondary battery with energy generated by the regenerative braking system.
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The motor mounted on the front wheel
The motor mounted on the front wheel
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Two-level regenerative power selectable using brake levers on the right and left sides
Two-level regenerative power selectable using brake levers on the right and left sides
[ If it clicks, the expanded picture will open ]

Matsushita Electric Industrial Co Ltd will release the Lithium Vivi RX-10S, an electric bicycle capable of recharging a Li-ion secondary battery using a regenerative braking system, Aug 20, 2008.

By utilizing a regenerative braking system on downward slopes, etc, the assisted travel range is significantly extended compared with systems that don't use regenerated energy. When riding on the course under conditions set by the company, which includes upslopes and downward slopes, the assisted travel range was reportedly extended to approximately 125km with the use of the regenerative braking system, whereas the assisted travel range is only about 90km without using the system.

Following Sanyo Electric Co Ltd's electric bicycle "Enacle," the Lithium Vivi RX-10S will be the second electric bicycle in Japan capable of recharging a Li-ion secondary battery with regenerated energy.

To utilize a regenerative braking function on a bicycle, the motor, which is on the pedal shaft in the existing model, is mounted on the front wheel in the new model. The bicycles are equipped with a one-way clutch on the pedal shaft.

When riding on downward slopes, etc, only the wheels rotate, whereas the pedals remain stationary. Therefore, the regenerative braking function can not be utilized when the motor is mounted on the pedal shaft.

Moreover, the new electric bicycle has a function to change over the regenerative braking force in two levels using brake levers on the right and left sides. When slightly applying the brake on one side, the motor generates half the amount of the maximum regenerative power. By squeezing both brake levers at the same time, the maximum power can be generated. When squeezing the lever firmly, it works as a mechanical brake.

The new bicycle also features "Automatic Mode," which can automatically selects the assistance force in four levels, ie, "high," "medium," "low," and "off" in accordance with the riding condition. The riding condition is estimated based on the value obtained by a torque sensor that measures the pedaling force accordingly.

When the sensor determines that the bicycle is "starting," "riding uphill," etc, the system increases the assistance force, whereas no force is generated when the sensor determines that the bicycle is on a downward slope.

The Li-ion secondary battery uses a Manganese -based positive electrode. The battery weighs about 2.5 kg and has a rated voltage of 26 V, a current capacity of 10Ah and a volumetric energy density of up to 400Wh/L. The expected retail price of the bicycle is ¥150,000 (US$1,395, price may vary depending on country). The annual sales target is 3,000 units.