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BMW Motorrad’s electric C evolution
1 May 2014
|The C evolution. Click to enlarge.|
BMW Motorrad is launching its battery-electric C evolution maxi scooter. (Earlier post.) Its two conventionally powered maxi scooter model—C 600 Sport and C 650 GT—combine the ride qualities of a motorcycle with the specific agility and comfort of a scooter; the C evolution adds the dynamism and emissions-free operation of an electric vehicle.
The C evolution is powered by a drivetrain swing arm with liquid-cooled permanent magnet synchronous motor via a toothed belt and ring gearing. The rated power output is 11 kW (15 hp), with a peak output of 35 kW (47 hp); maximum torque is 72 N·m (53 lb-ft). This enables the C evolution to achieve a top speed of 120 km/h (75 mph, electronically limited) and gives it better acceleration than some maxi scooters powered by engines with displacements of 600 cc or more.
|Cutaway of the C evolution showing the batteries and electric drive. Click to enlarge.|
The 8 kWh capacity of the air-cooled lithium-ion high-voltage battery allows the two-wheeler to cover a range of up to 100 kilometres (62 miles) before it needs to be charged from any domestic mains supply. When plugged in to a standard 220V domestic socket with a 12A charge current, recharging fully from empty takes around 4 hours (with 220V / 16A = 3 h).
BMW Motorrad has opted for a form of energy regeneration for the C evolution that had not yet been applied to a single-track vehicle. Recuperation takes place automatically both when coasting with the throttle closed and when braking.
Riders of the C evolution can set their preferred mix of dynamic performance and efficiency by selecting from the four ride modes.
Road mode provides maximum acceleration, approximately 50% energy regeneration when coasting and full regeneration when braking.
Eco Pro mode restricts acceleration and therefore energy consumption, while the maximum possible amount of energy is recuperated.
Sail mode suppresses recuperation while coasting, allowing the C evolution to glide along virtually free of any braking effect when the throttle is released.
Dynamic mode combines full accelerating power with a high degree of recuperation.
As part of the BMW Group, BMW Motorrad was able to harness synergies with BMW Automobile during development of the C evolution. Besides adopting the same energy storage modules and electronic componentry used in the BMW i3, this was particularly beneficial for electrical safety, which is to passenger car standard.
BMW Motorrad says that the C evolution is the first electrically powered two-wheeler to meet the ISO 26262 standard for functional safety and the ECE R100 standard governing high-voltage safety, both of which have been ratified by the leading carmakers.
|The battery pack is the central component. Click to enlarge.|
As far as the chassis is concerned, the C evolution no longer has a main frame in the conventional sense. The central component here is the battery casing made from diecast aluminium, which has a steering head support made from steel tubing attached to it at the front and, at the rear, the single-sided swing arm as well as a rear frame, also made from steel tubing.
The task of wheel suspension and damping is performed by an upside-down telehydraulic fork at the front and a spring strut mounted on the left at the rear. As on all vehicles from BMW Motorrad, the C evolution comes equipped with safety-boosting ABS together with powerful disc brakes as standard.
The new C evolution is available with Torque Control Assist (TCA), which works in a similar way to the Automatic Stability Control feature on BMW motorcycles with combustion engines. TCA limits the motor’s torque depending on the slip at the rear wheel.
To ensure optimum controllability of the drive torque for the rider, the electric motor’s control electronics monitor the rear wheel speed and reduce the drive torque if a certain plausibility threshold is exceeded. TCA is a particularly useful aid for the rider when starting off and prevents uncontrolled spinning of the rear wheel on road surfaces with reduced grip (e.g. wet cobblestones).
The Torque Control Assist additionally serves to stop the rear wheel from skidding when a sharp rate of recuperation produces a correspondingly high level of drag torque, especially on slippery road surfaces.
Other features further underline the innovative character of the C evolution. It is equipped with a reversing aid, for example, that enables easy maneuvering at walking pace. There is also a first in the form of an LED daytime running light, which additionally dims to double as the sidelight. And for added comfort on cold days, there are heated handlebar grips.
A large TFT color display in the instrument cluster provides current speed as well as data such as the average consumption in kWh/100 km, total power consumption, battery charge status in kWh, average speed, voltage of the on-board electrical system and the high-voltage system, as well as the remaining range in kilometres taking into account the selected ride mode. A bar graph furthermore indicates the current level of energy draw or regeneration.
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