I need a long-distance, potentially highway-capable vehicle that can accommodate a car-free lifestyle. Due to various reasons, I am unable to obtain an ID or drivers' license in the state with which I reside. I need to be able to travel long distances in a personal vehicle for various needs, as the mass transit available is quite impractical. I have experience building my own electric car conversion, but for a variety of reasons, I am unable to use it(I can provide pictures if you want. It runs and drives, but it has yet to see more than 30 mph nor is it road legal. It's a Triumph GT6 with a 128V/100AH pack of CALB CA100FI batteries, a modified Prestolite MTC4001 series DC motor, and Soliton 1 controller, and another 20 batteries to add when I get the opportunity for a total of 192V/100AH. It smokes its tires in top gear from a stop, and is currently set for 128Vmax, 680Amot, 400Abatt.).
The research I have done indicates ebike performance well exceeding my needs is theoretically possible, but I have no illusions of this being an easy build even at the minimum design parameters, especially considering that I have never built an ebike before. I am going to give you a brief description of my minimum design parameters(needs), and below that, a brief description of possible and desired design parameters that could accompany the minimum(wants), before explaining a vehicle concept I have thought of. I need to know if my concept is possible to construct within the parameters described, and hearing it from some of the most re-known e-bike builders on the planet would be a good place to start:
Minimum Design Parameters(needs)
-Legality: must be street legal as an "electric bicycle" within the state of Texas and able to be legally pedalled without license or registration
-Minimum Range: must cover 300 miles a day, leaving time for the rider to eat, sleep, and rest
-Minimum Efficiency: able to be pedaled at 15+ mph on flat ground with only 150W of pedal effort and no electric assist.
-Minimum Performance: top speed of at least 35 mph, and the capability to continuously and safely maintain 30 mph on smooth pavement all day long with 150W of pedal effort plus the required electric assist.
-Minimum Protection: the rider's body needs to be isolated from the elements
-Minimum Utility: trail-able on an off-road bike trail at 15 mph safely while able to store small tent/sleeping bag/tools(5 cu ft of storage space in one compartment)
-Maximum Build Cost: cannot exceed $4,000 parts/materials cost
-Minimum Safety Features: gauges, front and rear lights, working turn and brake signals, front and rear suspension, front and rear disc brakes
Theoretically Possible Design Parameters(wants)
-Range: ability to be pedaled and maintain 50 mph for 1 hour with 0.8 to 1.2 kW of electric assist
-Speed: top speed of 70 mph is theoretically reachable
-Stability: I want it to be stable at 50 mph on smooth pavement
-Acceleration: possible tire-smoking acceleration with 0-20 mph in 4 seconds or less
-Power: peak electric-assist of no less than 7 kW, continuous electric assist of no less than 2 kW
-Extended autonomy: solar recharging while vehicle is in use of no less than 150W (this plus light 150W pedal input could potentially allow 30 mph continuous as long as sun is shining, without draining battery at all)
-Entertainment center: nothing fancy, maybe a portable mp3 player or portable radio with some small < 15W speaker system, with a way to keep it charged and operational from the traction pack
So now onto the vehicle concept. I am considering a tadpole pedal trike with electric assist and an aerodynamic fairing, much like a velomobile.
The following vehicle put together is something I wish to emulate, but with the addition of all of the bells and whistles of a velomobile:
https://www.electricbike.com/50mph-mons ... ric-trike/
The vehicle weight must be a total of 100 lbs or less fully assembled, and it must not be capable of exceeding 20 mph on electric-only. Why? It has to be legal as a bicycle in the state of
Texas. The above-linked trike weighs in at 90 lbs and is unfaired. I'm sure a way can be found to safely shave some weight off to get the unfaired but otherwise completed vehicle into the 80 lb range, giving me wiggle room for a fully enclosed faring and some thin-film solar panels.
The legal code describing "electric bicycles" within the state of Texas is as follows:
The lack of any peak kW rating or pedal-assisted top speed limitations on "electric bicycles" opens up lots of design possibilities, while still being legally a bicycle.
Sec. 541.201. Vehicles.
In this subtitle:
... (2) "Bicycle" means a device that a person may ride and that is propelled by human power and has two tandem wheels at least one of which is more than 14 inches in diameter.
The following definition of electric bicycle was passed by the Texas legislature in 2001:
(10) "Motor-driven cycle" means a motorcycle equipped with a motor that has an engine piston displacement of 250 cubic centimeters or less. The term does not include an electric bicycle.
(11) "Motor vehicle" means a self-propelled vehicle or a vehicle that is propelled by electric power from overhead trolley wires. The term does not include an electric bicycle.
(24) "Electric bicycle" means a bicycle that:
(A) is designed to be propelled by an electric motor, exclusively or in combination with the application of human power;
(B) cannot attain a speed of more than 20 miles per hour without the application of human power; and
(C) does not exceed a weight of 100 pounds.
If I want to legally have a vehicle that can exceed 20 mph that relies on electric assist as well as pedalling, this means I will need an electric drive system that accepts input from a torque sensor either in the pedal crank itself or in the gear cluster. I'm not well-versed in the realm of e-bike controllers, but I am assuming that some top-of-the-line controllers available today allow this feature.
Given my requirement of being able to operate on pedal-only, it will need at least a 7-speed gear set with a derailler system.
I have read of velomobiles that weigh well under 50 lbs, let alone 100 lbs. There are also e-bikes that have been built to exceed highway speeds, wherein they would be legally "electric bicycles" under Texas law. My intent is to combine these two archetypes into a unique vehicle that will basically have close to the functionality of a car(with regard to a single occupant's long-distance needs), but the legal classification of a bicycle.
For the electric drive, here is a list of parts I have considered:
-Batteries: x6 Multistar High Capacity 6S 10000mAh Multi-Rotor Lipo Pack, for a total of 36S1P, 133.2V 10AH, 1332 Wh, rated to 10C continuous 20C peak, 15.8 lbs pack weight, total pack cost $588.66 http://www.hobbyking.com/hobbyking/stor ... ouse_.html
-Controller: Infineon (EC244115-LYEN EDITION). I want to set it to 120A max phase current, 60A max battery current, 125Vmax to motor, for 7.5 kW peak power electrically applied to the motor. Weight is 3.5 lbs and cost is $349. If possible, I would like more power though, as that battery pack is easily capable of 12 kW continuous. http://endless-sphere.com/forums/viewto ... 31&t=19719
-Motor: CroMotor v2. With 9.4 rpm per V, with a 133.2Vnom pack(assume it sags to 125V @ 60A), I should be able to reach 1175 rpm. How much torque will this make at what current and to what rpm? I'm guessing around 35 lb-ft at 1175 rpm for 7.8 horsepower peak, and a peak torque of 70 lb-ft from 0 rpm to ~580 rpm with a 120A max phase current. Weight is 24 lbs and cost is ~$600. http://www.greyborgusa.com
-Battery Charger: Need help with this one. Guessing 2 lbs and $150.
-Torque Sensor: Need help with this as well. Guessing less than 1 lb and $250.
Add $200 misc cost and 5 lbs misc weight to electric drive system including mounting, wiring, containment, fuses, switches, ect.
This gives a total of 50 lbs weight and $2,138 cost for the entire electric powertrain system. I will be using a Cycle Analyis CA-LSA at $170 for instrumentation. This leaves only 50 lbs and around $1,800 for the rest of the bike. I will be using about $500 of that for the solar panels and charge controller system, leaving $1,300 available for the construction of the fared bike by itself.
I realize that I will need some very stout components for this build and that they will not be light at all. This means parts from downhill racing bikes, or even mopeds and motorcycles, become necessary. This will make staying within 50 lbs for the bicycle by itself(no ev components) very difficult. The enclosed faring can easily be made to weigh under 15 lbs, leaving 35 lbs for the rest of the bike. If just one rear tire is a moped or motorcycle wheel and tire, this can easily eat 10 lbs or more of the weight.
Matt Schumaker's 50 mph electric trike linked above came in at 90 lbs, but it uses a solid tubular frame and heavy duty motorcycle parts, but also a very light motor that requires a custom belt drive. I am thinking instead of a solid frame which is going to be heavy, using folding honeycomb/fiberglass sandwhich material to build my chassis, as was done with the following custom electric car:
I will have to drill holes to bolt up the mounts for the electric drive, suspension bits, body, and other components. If the material can hold a car together, it should be good enough to hold a high power electric bike together. Enough material to build this bike's chassis is going to run at about $500, leaving $800 left for suspension, disc brakes, wheels, tires, faring materials, and misc components. Is that reasonable?
If this is doable by going the DIY route, then the following performance becomes theoretically possible under the given parameters:
-Drag coefficient: 0.25 (high end velomobiles come in at 0.12, so I think more that double that is possible without too much headache for a DIY build, although I will obtain lower Cd if I am capable)
-Frontal area: 0.5 m^2 (5.4 sq ft; about 20% more area than a typical touring velomobile, to accomodate a flat planar surface to hold solar panels of at least 10 sq ft)
-Fully laden weight: 136 kg (300 lbs; includes bike, myself, and tools/camping gear)
-Rear wheel diameter(including tire): 0.508m (20")
-Coefficient rolling resistance: 0.006 (road bike tires are like 0.0045, car tires around 0.009, so I picked a figure somewhere in between)
-Assumed max torque curve: 70 lb-ft from 0 to 580 rpm, 7.8 peak horsepower and 35 lb-ft @ 1175 rpm
*simulated from a custom spread sheet and http://www.nightrider.com/biketech/accel_sim.htm
0-20 mph: 3.9 seconds
0-30 mph: 6.0 seconds
0-60 mph: 14.3 seconds
Top speed: 70 mph @ 1175 rpm
Total power(pedal + electric) needed for 30 mph: 311W
Total power needed for 40 mph: 621W
Total power needed for 50 mph: 1106W
Total power needed for 60 mph: 1813W
Total power needed for 70 mph: 2783W
Continuous speed with 150W pedal and 150W solar: 29 mph
Continuous speed with 150W pedal only: 21 mph
Range @ 30 mph with 150W pedal input and no solar(80% assumed motor/cont combined eff and 80% depth of discharge): 171 miles
Range @ 50 mph with 250W pedal input: 49 miles
Range @ 70 mph with 500W pedal input: 41 miles
With larger diameter 30" rear tire, 100 mph becomes theoretically possible on only 7 kW to maintain it, at the expense of acceleration and efficiency. That would be nice though, and if it can be worked in without losing acceleration in the case that I am too conservative on expected motor torque values and could fit in a larger wheel, I would gladly take it. Safety at that speed would probably be an issue.
Technology for solar power has gotten a lot better and cheaper, and making an e-bike with the personal transportation capabilities mimicking that of a car, but doesn't require a license to operate, is enticing. 1 kW of solar panels, instead of the planned 150W, would be a true freeway-capable long distance vehicle that is legally a bicycle.
I have some drawings to scan and share, when I get the opportunity.
The build order will be in the following order:
1) Working pedal trike
2) Working electric drive system
3) Aerodynamic body cover
4) Solar charging system
What questions, comments, and concerns do any of you here have with this build? Does this project sound doable and able to be made reasonably safe to operate on the budget imposed? If not, then what is within the realm of possibility that is as close a match to what has been described as possible, based on the personal experiences of the builders here?