Chip Yates' Electric Superbike

Chip Yates and his 240-horsepower electric bike are out to prove a point

Chip Yates is a mechanical engineer with experience at Boeing and McLaren, and a former AMA and World Supersport racer.
At Auto Club Speedway earlier this year, Yates raced against gas-powered bikes in a WERA event, scoring two podiums and turning lap times that would almost have qualified for the AMA Daytona SportBike race held there in 2010.
At Auto Club Speedway, Yates removed the front-wheel KERS and ran a conventional two-disc front brake setup. Only a single disc is required when the KERS is in place. The red hoses cool the battery packs and jackshaft chain, which gets quite hot as the motor runs at 8000 rpm. The small radiator on the front is from a Honda CRF450 and used to cool the motor and controller.
This MoTeC screenshot from a lap of Auto Club Speedway shows some interesting data. The motor draws about 400 amps (yellow trace) under full load, while the KERS, acting only on the rear wheel for this session, puts back about 100 amps. Yates uses full throttle (green) for just a couple of seconds each lap, while he activates the KERS to about 25 percent of its full potential in each braking zone (purple). Top speed (blue) is 162 mph.
The motor and controller are a package made by UQM Technologies and sold for use in electric, hybrid and fuel-cell vehicles. Peak power is listed as 194 horsepower, although Yates has increased this to 240.
The Christini AWD front end uses gears, chains and a small driveshaft to transmit front-wheel power up the fork tubes, through the bottom triple clamp and steering stem and back to the motor.
Power from the front wheel is transferred through one-way bearings in the wheel hub and along these shafts parallel with the fork tubes. The Christini/Honda CRF450 fork has been modified by Ohlins for roadracing, while Yates designed and built the custom hubs and other parts necessary to fit the system.
The Christini AWD front end uses gears, chains and a small driveshaft to transmit front-wheel power up the fork tubes, through the bottom triple clamp and steering stem and back to the motor.
This driveshaft takes power from gears inside the steering head and transmits it to the motor’s jackshaft through a chain. Yates removed the KERS for the short races at Auto Club Speedway, as the batteries have enough juice to last the six-lap events without compromising power.
A single lithium-ion pouch cell is about the size of a small notepad and weighs just under two pounds. It generates a moderate 4.3 volts, but is capable of delivering 1200 amps for short bursts. There are 102 of these on board the electric superbike.
A pack of 34 battery cells sit where the fuel tank would normally reside. While the pouch cells allow for dense packaging compared to cylindrical cells, the overall shape is limited to a cube. Cylindrical shells, on the other hand, can be assembled in different ways to better fit a convoluted shape.
The UQM controller is mounted under the seat, while the rear battery package (not shown here) sits behind. A redesign will have the battery in front of the controller, for better mass centralization. The red cube just in front is the high-voltage connection from the batteries to the motor.
The front fairing is filled with electronics. Seen here are the MoTeC Advanced Central Logger, GPS antenna and sensor box for data acquisition, and an Ethernet connection for downloading data. Tucked underneath is a MicroStrain Orientation Sensor, which uses three gyroscopes and three accelerometers to determine roll, pitch and yaw — data that is used for the wheelie and traction control systems. And yes, that’s a horn, as required by TTXGP rules.
This cart is required to charge the batteries and contains 102 individual Manzanita Micro charging modules, one for each cell. This ensures that each cell is charged to maximum capacity without being overcharged.
A small lever on the left handlebar activates the KERS, while the rotary switch above can be programmed for any utility, such as traction control or maximum KERS effect.
In an electric or hybrid automobile, all the components are present for a Kinetic Energy Recovery System. When the vehicle decelerates, braking energy is converted to battery power by using the electric motor as a generator momentarily.

Tucked away in a nondescript industrial complex south of Los Angeles, in a cramped, unsigned, single-bay unit with CAD printouts covering the windows to shield the interior from prying eyes, is the fastest, most powerful and most advanced electric bike in the country—perhaps even the world. There is no army of engineers, highly paid executives, banks of computers or rows of CNC equipment. Rather, the bike was designed and built by a small group of dedicated people, all working outside of their regular jobs and fueled by a passion of pushing the technological envelope. At the head of that small group is racer, designer and fabricator Chip Yates.

The electric superbike, as Yates calls his creation, makes 240 horsepower from a 145 kW electric motor and weighs 585 pounds—almost 200 pounds of which is the battery capacity necessary to run such a powerful motor for any length of time. But what sets the electric superbike apart from any other bike seen thus far in the TTXGP or E-Power series is front-wheel KERS (Kinetic Energy Recovery System, see sidebar), which pumps energy back into the battery when the front brake is used and allows the bike to go further and faster for a longer period of time than it would otherwise. Furthermore, Yates has forgone competing against electric bikes in either sanctioned series and has chosen to race against gas-powered bikes where possible, and has done so in a WERA event at Auto Club Speedway.

Yates is a mechanical engineer and former AMA Supersport racer, and progressed quickly from his first pavement experience at a track day in 2007, through WERA and AFM club racing in 2008 to several AMA rounds and even the World Supersport event at Miller Motorsports Park in 2009. But a broken pelvis and long recuperation later that year started him thinking about electric bikes. It was being out for a while, missing tinkering, and I saw a series that you could do basically anything you want. In the AMA I was having a lot of fun, but I never felt like I could win a race. But I’d learned enough from being on track with the AMA guys and World Supersport that I was getting pretty quick. And with an engineering mind I’m a pretty good test rider, so by using my engineering ability and brain on a team, we could build a bike that could win not only a race but a world championship.

The bike started taking shape with a Suzuki GSX-R750 chassis and the electric motor and controller purchased as a $25,000 kit from UQM Technologies. UQM builds electric propulsion systems for hybrid and all-electric vehicles, supplying the U.S. Army and various automobile manufacturers. In fact, the same setup used in the electric superbike—the Power-Phase 145, capable of 194 horsepower, 8000 rpm and 295 ft-lb of torque—is found in Saab, Audi and Rolls Royce electric vehicles. The liquid-cooled motor weighs 110 pounds, measures 11 inches in diameter and 11 inches long, and is situated in roughly the same position as the GSX-R’s crankshaft. Yates manufactured the mounting system that utilizes the stock GSX-R mounts, and power runs through a jackshaft mounted in the stock bike’s countershaft position so that rear suspension squat properties are unaffected. The liquid-cooled controller, mounted behind the seat, measures 15 inches square and five inches thick and weighs 35 pounds. While the motor and controller began as off-the-shelf items, Yates has recently been working with UQM on development: With their assistance we’re doing a behind-the-scenes development program to showcase the maximum performance available. They had our motor and controller, and made some changes to go from 194 to 240 horsepower.

Powering that motor are two battery packs, one in the GSX-R’s fuel tank position and another where a passenger would normally sit. Each pack consists of a number of lithium-ion-polymer pouch cells, which individually are fairly small at six inches by eight inches and a few millimeters thick. Each seemingly innocuous cell generates a mild 4.3 volts, but with 34 connected in series in the faux fuel tank and another 68 behind the rider, they combine for 430 volts. Capable of providing up to 1200 amps for a few seconds at a time, that adds up to a serious electrical wallop. They’re used in government missile applications and satellite applications, says Yates. Cost? Approximately $40,000 for the 102 cells. The cells are arranged in the packs with their positive and negative tabs connected with a proprietary aluminum extrusion that helps extract heat from the cell. Those cells, at 1.75 pounds each, add 180 pounds to the bike, not including the wiring or packaging.

Even with all that battery power on-board, it’s still not enough to run the powerful UQM motor for more than a few laps in a race. We originally designed the bike for the electric series, which were 12-lap races. To make our level of horsepower for 12 laps, we had to invent a way to capture more energy than we could otherwise capture from just the rear wheel. And so we captured energy off the front wheel. To do that, however, required what is effectively a complete front-wheel-drive system run in reverse so that the front wheel can load the motor under braking. Many of the parts were culled from a Christini all-wheel-drive off-road bike. On the Christini machines, a chain drive runs vertically from the countershaft sprocket up to a jackshaft; from there, power is transmitted via a drive shaft to the steering head, where various gears, chains and shafts in the steering head and bottom triple clamp turn two more shafts, which run beside each fork tube down to the front wheel. In the front wheel, one-way bearings transmit that power to the front wheel, but do not load the engine if the wheel is turning faster.

On the electric superbike, many of those parts are combined with one-off bits manufactured by Yates, including a special hub for the front Marvic wheel with Sprag one-way bearings so that the front wheel can load the motor—opposite to the Christini drive. The GSX-R frame has been modified to fit the drive through the steering head, and the Christini fork modified by Ohlins to suit the roadracing application. The KERS setup adds enough braking force that only one standard disc and caliper are needed, and converts that energy into charge for the batteries. The limiting factor in the system is how much of that energy can be forced into the batteries in every braking zone, and required that a dedicated test setup be built. We would take the data from a lap of Laguna Seca on my GSX-R600, with all of its acceleration and braking, translate that into amps coming out and amps getting stuffed back in, and then program that into a battery tester. So it sucks 500 amps out, it slams 100 amps in; sucks 200 out for the next straightaway, slams 50 in. And so it will cycle that for the whole race, and at the end you can tell, OK, the battery got this hot, these were the tab temperatures. Was there any impedance buildup in the battery; have you damaged it at all? Did it blow up in your face?

The addition of the KERS and the related testing showed a staggering fact: At Laguna Seca, if you have the KERS you would be able to make 194 horsepower for 12 laps. If you didn’t have the KERS, and you had the same motorcycle with the same weight and the same battery and motor power and everything, our race-finishing software would automatically limit us to about 70 horsepower for all 12 laps. Currently, the system is setup with a lever on the left handlebar to work the KERS separate from the disc brake, but eventually the two will be combined with the amount of motor braking determined by a pressure sensor in the disc brake side.

While the UQM controller looks after the basic interface between the batteries and motor, Yates has added on top of that a MoTeC ECU to control the KERS and add rider aids like traction control and wheelie control. Additionally, a race-finishing algorithm ensures that the batteries last the race given how the motor is used. Everything with any level of intelligence is happening in the MoTeC and being sent to the UQM controller over a CAN bus. There are 150 channels going back and forth. The UQM is talking to the MoTeC also, it’s reporting back. At, say full throttle, the MoTeC will look in its tables, and based on where I am in the race and how much battery power I need to finish, it will come up with a torque command that it sends to the UQM.

While Yates himself does most of the fabrication work on the electric superbike, all these electronics require some skilled engineers to manage. Ben Ingram, our chief engineer, is an MIT graduate who has experience writing control algorithms for Boeing’s unmanned helicopter. He’s the one principally responsible for our rider software, race-finishing software, KERS control software, traction control, wheelie control—all that has been written from scratch by him. Robert Ussery, he’s an electrical engineer from Georgia Tech. He’s currently still working on the Boeing A160 unmanned helicopter. He’s done all the wiring, all the electrical schematics, a lot of the battery pack. He does the entire wiring for the charging system, and he personally charges the batteries. Neither are motorcyclists, but Yates met them through connections at Boeing, where he worked for three years as a licensing executive. The third person heavily involved is Jimmy Summers, Yates’ crew chief that looks after the chassis and suspension. Additional technical support comes from Ohlins, Motec, UQM and the battery supplier, who are all getting more involved in the project as Yates makes progress, provides feedback and can help develop the systems.

While the original intent was to race in either the TTXGP or E-Power series, the rules in both series were changed for 2011 with the maximum weight lowered from 660 pounds to 550ostensibly to ban Yates and his electric superbike. I think the way things have unfolded, we were pushed toward competing with gas bikes, which in retrospect is great. I'm grateful things have worked out the way they have. We have no interest in racing against electric bikes anymore. I don't say that as an insult, I say it as we've moved on and I'm extremely excited about continuing to push the limits of the technology and the batteries. Basically, where this bike is now, it's capable of qualifying for an AMA Daytona SportBike race and finishing about half of it. It wasn't our original goal to prove that electric vehicles can beat gas, but it's evolved into our goal now. I think there's a lot of work to be done but I think eventually people won't be able to ignore it. SR

KERS: Kinetic Energy Recovery System
In a typical vehicle with disc brakes, the energy expended is converted to heat and dissipated through the discs, pads and calipers as waste. A Kinetic Energy Recovery System uses some method to capture that energy, store it for a few seconds, and use it to help the vehicle accelerate as needed. This can be accomplished mechanically or electrically, but the method applied most often uses an electric motor and battery or capacitor. One of the useful characteristics of an electric motor is that it can be utilized as an electrical generator when the load is reversed. When the vehicle decelerates, the motor—acting as a generator and supplying braking force—stores the resultant energy as electrical charge in a battery or capacitor. The motor then uses that charge under acceleration, reducing the power required from the vehicle's engine or motor.

KTM used a system on its 125 Grand Prix machine in late 2008, giving approximately a 2.5-horsepower advantage on each straight. Adding KERS to a car or motorcycle with an internal combustion engine requires all those parts—electric motor/generator, battery or capacitor and some control system to run it—to be added. But with an electric vehicle, the infrastructure is already there. Many electric and hybrid cars use some form of KERS to help reduce fuel consumption, as it is mostly free energy. With all the components in place, it’s a matter of putting them to use. When it comes to electric motorcycles, however, there is a slight problem as only the rear wheel can be used to capture energy. Because most of a motorcycle’s braking is accomplished through the front wheel, very little energy can be absorbed through simple means. To add KERS with a substantial amount of capability, the front wheel must be involved, and this requires that it be connected to, and drive, the electric motor.