Hard Parts
Inside An Electric Superbike
Motor
A single AC motor located directly in front of the rear wheel powers the Enertia TTR. Manufactured by Perm Motor in Germany, the compact motor is a brushless, permanent-magnet design that is more efficient and durable than the simpler, less-expensive, brush-type motors most other TTXGP entries used. The peak efficiency rating is 94 percent (compared to approximately 25 percent efficiency for the very best internal-combustion engines), and the motor is liquid-cooled to minimize heat-related losses, with a tiny radiator mounted below the headstock. The motor's continuous-power rating is 20 kW, with a peak power rating of 30 kW. In TTXGP tune, this translates to 30 horsepower and 53 lb.-ft. of torque at the rear wheel. Custom sideplates allow the motor to be mounted as a stressed member, and there is no gearbox or primary drive; the drive sprocket mounts directly to the motor output shaft. A cush drive on the rear hub minimizes driveline lash.
Electronic Controls
The TTR's digital controller (the large, finned-aluminum box hung beneath the battery pack) monitors both throttle input and rear-wheel speed, then uses that information to transmit power from the batteries to the motor. Made by DMC (Digital Motor Control) in Germany, this is a beefed-up version of the same highly tunable control unit used on the production Enertia. Manipulating the controller's voltage and current settings, along with other more discreet parameters, creates the "throttle map" that determines the rate at which available torque is metered to the rear tire. The controller is currently air-cooled, but Brammo says it will be liquid-cooled in the next version, since the unit is essentially operating at its thermal limit. A stand-alone, 12-volt electrical system, located under the tailsection, powers the instrument cluster and other conventional electronic components.
Batteries
The production Enertia carries six lithium-iron-phosphate batteries. The Enertia TTR racer carries eight custom racing batteries that use lithium-cobalt chemistry, similar to the Tesla electric supercar. Lithium-cobalt chemistry delivers superior energy density at the cost of long-term stability, making it appropriate for racing but less desirable for street applications. On streetbikes, countless repeated charging cycles make chemical stability more valuable than outright performance. The TTR's 100-volt/90-amp battery stack can deliver as much as 46 kWh to the motor-more than either the present motor or controller can process without overheating, TTXGP experience shows. An integrated battery-management system located under the fairing upper functions similarly to an ECU, only instead of monitoring fueling and ignition timing, it manages the amount of current delivered by the batteries and the charge levels of each individual battery cell.
Chassis
The TTR frame uses the same extruded-aluminum main rails as the production Enertia, mated to a much stronger and stiffer steering head. Custom-machined outer motor plates are welded directly to the bottom of the main spars, so the solid-mounted motor functions as a stressed member for added rigidity. A custom chromoly swingarm pivots directly off the motor plates. A one-off subframe, consisting of a bonded and riveted extension bolted to a machined base, supports the rider. The frame width is identical between the production and the racing machines: Enertia batteries fit in the TTR, and vice-versa.
Suspension/Brakes
Running gear is a mix of bits borrowed from a donor Triumph Daytona 675 and the best parts available from the existing Enertia supply chain. Elka, which supplies the damper for the production Enertia, contributed the fully adjustable, piggyback-reservoir shock. Relatively low power and slower speeds from the electric bike mean less complicated loads on the rear suspension, so Brammo chose to mount the shock directly without a linkage. Triumph forks have been upgraded with Traxxion Dynamics' $2500 AK-Gas pressurized cartridges for remarkably predictable and stable front-end control. Another Enertia partner, Brembo, provided a pair of its massive Monobloc calipers that are frankly overkill for a machine of this size and speed. One caliper would be plenty. Forged-magnesium Marchesini 17-inch wheels slash rotating mass, while an hlins hydraulic steering damper stabilizes the front end.
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