Electric vehicles are the future of transportation, or at least one future. Whether a couple decades from now or a century, there will be a major shift in our fossil-fuel transportation age. Yet with all the hype around electric, the major OEMs have produced nothing more than concept models. Instead small startups have formed the electric motorcycle production vanguard, chief among them Brammo Inc. and Zero Motorcycles. Both companies have created actual electric rides, street legal and ready to roll on American motorways. Motorcycle USA sourced two of them, the Brammo Enertia and Zero DS, for our first ever electric motorcycle comparison.
The 2010 Enertia represents the first production motorcycle from Brammo. Founded by successful dot.com entrepreneur Craig Bramscher, the Ashland, Oregon-based company first targeted the four-wheeled internal combustion engine (ICE) market by producing the high-performance Ariel Atom (check out the much-viewed Top Gear Youtube Video to get an idea on the Atom’s capabilities). Wishing to produce an electric supercar, Bramscher realized the current EV technology was more amenable to two-wheeled design, ergo the birth of Brammo as an electric motorcycle manufacturer.
Head down the Pacific Coast to Santa Cruz, California and Zero Motorcycles produce an entire line of electric rides. Former NASA engineer Neal Saiki founded Zero in 2006, with his space-age credentials bolstered further by his work developing the Da Vinci III, a self-propelled helicopter aimed at claiming the $250,000 Sikorsky Prize. Saiki also sports numerous successful mountain bike frame designs, with his dirt bike leanings making their way onto his first production motorcycle, the Zero X dirt bike. In 2009 Zero expanded its offerings with a pair of street bikes: the Zero S supermotard and the Zero DS dual-sport.
This isn’t our first brush with these two EV innovators. We first sampled a prototype version of the Enertia in 2008 and our editors have tested Zero’s models at various parking lot demo rides since their debut. But our recent comparison test gave us a couple days to really kick the tires of these electric scoots. What we discovered were two different takes on this nascent motorcycling segment.
Where the engine is the most critical aspect of a conventional motorcycle, batteries serve that role in an EV ride. They represent the heaviest component in the design, as well as the most expensive. Battery capacities are also what limit current performance and drive future EV development. The key is energy density, the denser the better, as more capacity means more range and the ability to power higher-performance motors.
Both the Brammo and Zero source lithium-ion batteries, with onboard chargers topping off the proverbial tank via standard 110V wall plug. Controlling the balanced discharge and recharge of the numerous cells is a Battery Management System (BMS), a vital component to maintain the stability and longevity of the batteries. The batteries themselves are rated for hundreds of charging cycles, guaranteed to recharge at least 80% of original capacity by the cycle limit (2000 for Brammo, 1800 for Zero). Afterward they will continue to degrade over time but still be functional at a reduced capacity well beyond their cycle ratings.
The Brammo Enertia makes use of lithium-iron-phosphate batteries developed by Texas-based Valence Technology. A total of six such batteries sit staggered above and below the main spines of the Brammo’s black aluminum frame. Each of the six contain 120 individual cells and cost roughly $500 apiece. Energy capacity for the 78-Volt system accumulates to 3.1 kilowatt hours (kWh), with a recharge taking around three to four hours.
Saiki designed the Zero’s Z-Force battery pack in-house. A single large square pack, the 58-Volt lithium-ion system houses 336 cells. The actual formulation of the battery is lithium-manganese (nickel-manganese-cobalt-oxide positive electrode and graphitic carbon negative electrode). Total capacity for the Zero exceeds the Brammo at 4 kWh. With the extra energy on tap it takes a little longer recharge from empty at four hours.
The Brammo Enertia sources an AC motor from the German manufacturer Perm, while the Zero DS gets its forward momentum via DC motor built by Agni.
Motors generating the rotary power on electric rides are notable for delivering immediate peak torque. Horsepower increases along with the revs until it peaks and diminishes in a linear manner. Some electric scooter concepts and four-wheeled EVs source motors mounted directly to wheel hubs, the motor applying direct force to the wheel. In the Brammo and Zero, the motor is placed at the bottom of the frame by the swingarm pivot. Gone are gearbox and clutch, with transmission to the rear wheel more basic: a single gear and final chain drive. In terms of the actual motors themselves, the Brammo and Zero take different routes.
The Enertia makes use of a brushless AC motor from the German company Perm (specific model designation PMS 120). Direct current is routed from the batteries through a controller, which converts it to a three-phase alternating current. Brammo claims efficiency as the main decision for utilizing the AC motor. The company’s power claims are 29.5 lb-ft peak torque delivered from 0-1450 rpm. The Brammo motor is air-cooled, with a cooling fan resting atop the motor housing.
The Zero DS sources a brushed permanent magnet DC motor from Agni. Zero engineers claim 40 lb-ft torque and 20 horsepower at the shaft, with the Agni powerplant spinning up to a 3400 rpm limit. The 2010 motor configuration for the DS and S models has been notably upgraded with the Z-Force air induction system, which directs air via underseat fan through a filter and hose down into the motor core, where it exits out vented openings.
The Brammo and Zero are stone quiet until the motor is engaged. A mistaken live throttle can cause exceeding woe, so both feature fail safes like an on/off thumb switch at the right-hand control (both require the kickstand to be up as well). Turn the key, flip the side stand, thumb the throttle switch and the Zero is ready to roll. Getting the Brammo booted up is a procedure: Turn ignition key, press and hold start button on tank which triggers an auditory signal, lift kickstand up, move throttle button from off to on (if it’s left in the on position, the LCD display will prompt you to cycle that from off then on), wait a couple seconds for everything to hook up and finally a flashing green warning on the display means the drive is enabled. All told the 15-20 second starting process is convoluted and the next version we’re told will forego at least the tank button, which adds nothing more than an extra step.