Green Sun Electric Vehicles
Design Philosophy Projects Vaporware
Library Gallery Links
Design Philosophy
- Lightweight & Fun
This area of vehicle design is intriguing, has so much potential and is ripe for exploration. Our design philosophy is not to replicate a typical IC passenger vehicle in electric. There are innumerable entities trying to do just that and fighting design constraints all the way. The current reality is that unless you can spring for a very advanced, and therefore very expensive lithium ion or nickel metal hydride battery packs and their respective controller configurations, you are not going to achieve very good performance in an all electric full size passenger vehicle.
The key to getting reasonable performance with a
lower spec, relatively inexpensive battery pack is to maximize the
percentage of total vehicle weight allotted to the battery pack. This is
exceedingly difficult to do using a conventional automobile platform as a
chassis to carry the electric drive system. I think the fundamental
mistake is trying to replicate the standard IC vehicle in an electric
drive form. They are not remotely comparable in price/performance. Not in
price for the advanced battery/drive systems and not in performance for
the low tech battery/drive systems.
Our solution is not to fight this reality but to
explore a niche that we believe presents the possibility of an acceptable
price performance ratio, lots of fun, takes real advantage of the electric
drives desirable characteristics and minimizes some of the drawbacks that
they truly do have. We believe the best path is to concentrate on boosting
the battery packs contribution as percentage of total vehicle weight. We
have no intention of replacing your daily vehicle, although for some
adventurous and hardy souls this is entirely feasible. Essentially, you
just give up the idea of a weather tight climate controlled box in which
to sit while you drive. Motorcycle riders may be particularly comfortable
with this concept as they are very familiar with dressing to deal with the
weather as it is. We are proposing designs that dispense with the weight
and complexity of exterior and interior sheetmetal body work, double wall
doors full of lock and window mechanisms, glassed in interior boxes with
upholstered interiors, HVAC systems, etc. We are proposing essentially an
open air tube framed vehicle. Frame, wheels, brakes controls and electric
driveline, only the essentials necessary to propel and control the
vehicle. The driver dresses with full exposure to the weather in mind. The
goal is to end up with 30 – 50% or more of total vehicle weight devoted
to the battery pack. Reasonable, perhaps even spirited, performance with
lead acid chemistry, the least expensive and most widely available battery
packs, may be achievable. When the time arrives that you can plug in a
reasonably priced advanced battery pack and controller, you may end up
with quite the hot rod.
Think of motorcycles, sidecars and desert racing buggys as the vehicle platforms and you get an idea of a what tube framed designs would look like.
From a practical standpoint, the reality is that inexpensive EV's are short range vehicles under the best of circumstances. Mixing in extreme changes in terrain ( read uphills ) can seriously compromise that limited range if the vehicle is not designed correctly to accommodate them. As excited as we are about EV's and their potential, the current price of the ones with advanced battery/controller packages makes us cringe a wee bit. Considering that the vast majority of most people's trips are short hop interurban journeys, range limitations aren't necessarily a serious problem. But of course we want it all and within a reasonable budget. We believe there is a way to use a relatively inexpensive EV as in around town ride but also allow the capability of longer journeys as well. We would accomplish this with an addition called a range extender. This is typically an internal combustion engine ( ICE ) that runs a generator for recharging the vehicle’s onboard battery pack. We have full faith that eventually the price performance of battery powered EV's will surpass that of ICE vehicles. Until then, as much as we would like to steer clear of ICEVs ( kind of feels like mixing oil and water, or perhaps oil and electricity ), we think this is an effective solution for achieving range in your EV. In our preferred design, the ICE/generator package is self-contained and quick detach so it can be installed and removed quickly. Therefore, you aren't dragging it around town when it's not needed.
***********************************************************************************
Green Sun Electric Vehicles – Projects
For now all of our electric vehicles are still in the
conceptual stages so no metal has been bent yet, but here are the basic
platforms we have in mind. Since our design philosophy expresses very
strong feelings about the difficulty in achieving an acceptable balance of
price and performance when trying to duplicate all of the attributes of a
conventional passenger vehicle, all of the projects we propose are
centered on the concept of vehicles in which the battery pack is a high
percentage of total vehicle weight. Consequently, for most of the projects
we are pursuing, either vaporware or in the flesh, our primary design
focus is to reduce the list of components to the essentials necessary for
a rolling chassis. One useful distinction
we use in designing vehicles is to think of them in terms of the number of
wheels they have, or don't have, such as watercraft or flying things. So,
here are our general ideas about wheeled EVs designed as lightweights from
the start. Whether scratch built or converted from an existing vehicle,
this will be the central guideline we follow.
Two wheeled or monotrack platforms. Much as we
salivate at the idea of an electric motorcycle, the reality of a lead acid
powered two wheeler of even moderate range at highway speed is still a
very heavy, ungainly hunk of iron. The starkly inferior performance in
range and handling of a bike rebuilt with electric compared to its IC
powered version is so because the non powerplant weight of the bike is
already near as low as possible. Substitution of batteries as fuel supply
significantly raises the weight of the vehicle and severely alters the
weight balance. Advanced battery packs and drive systems put a very
usable, albeit very expensive electric motorcycle on the near horizon. For
now, a relatively low speed electric bicycle is the only well balanced
monotrack platform. Lots of possibilities here. The moderate
speeds and short distances of in town use make it fairly simple to
find an acceptable compromise of weight, handling and performance. The
exceptionally low weight of a typical bicycle chassis is extremely
advantageous as a core for an EV project.
Three wheeled platforms. Three wheeled vehicles come in two fundamentally different formats, fixed wheel and leaners. Within each format there are a number of variations. In a fixed wheel format all of the wheels remain perpendicular to the ground under normal circumstances. In a leaner format, they do not. Some leaner designs are very intriguing but there is a level of complexity there that we have never seriously investigated. There are essentially three formats for the three wheel fixed platforms; tricycle, tadpole and sidecar. Tricycle configuration has one wheel in front and two in back on a common axle. The tadpole configuration has one drive wheel centered in back and two steering in front on a common axle centerline. Sidecar configuration locates the front steering wheel and rear drive wheel on a common plane and the third wheel in its own space of to the side of and forward of the drive wheel. In our opinion the handling dynamics of tricycle design are unsuitable for high speed road work so we will disregard that option here.
The tadpole could work very well as a pavement ride but the only existing tadpole chassis are bicycle grade components, there are few if any readily available chassis for a project core, so custom built would be the only practical option. Another strike is the typically low rider position with the tadpole configuration makes it very difficult to see and be seen in congested urban traffic. The third strike is the center rear wheel position makes the vehicle a three track configuration, which can be exceedingly difficult to use on an unpaved surface with typical two track wheel tracks worn in.
The sidecar is the least
complex example of a tube framed vehicle that is eminently suitable for
electric drive in a high speed chassis. Precisely speaking the sidecar is,
in fact, just the framework, passenger compartment and third wheel, which
is then attached to a motorcycle chassis. This combination, although
frequently referred to as a sidecar as well, should really have a name
that differentiates it from the sidecar itself. The terms outfit and hack
are commonly used but I don't care for either so I guess I'll just
continue using sidecar to refer to both the car itself and the whole rig.
Hopefully the context will make it clear which I'm referring to. Sidecar
handling dynamics are well documented and suitable chassis are commonly
available. In fact, it is a relatively simple matter to add a sidecar to
most any motorcycle chassis. As with the motorcycle, the basic chassis is
already close to optimal in terms of powerplant/fuel to chassis weight so
there is not much excess componentry you can remove when you replace the
IC engine with an electric drive system. However, you can add significant
additional weight via the batteries without severely compromising the
sidecars handling. The key here is in paying close attention to weight
distribution. One compromise you must consider is that you may have to
give up the sidecar’s utility for carrying a passenger, rendering it a
solo machine. The reality of this may depend on the variety of battery
layouts deemed possible for optional designs. A peculiarity of sidecar
handling dynamics is that they need ballast in the sidecar to stabilize
the handling. This ballast often takes the form of a passenger or cargo.
Without ballast the driver of the rig must exercise a great deal of
caution depending on the nature of the road. With the ballast provided by
a battery pack, the sidecar could be tuned to be stabile with spirited
solo riding. By the way, sidecars are a real hoot in the snow. It may be
possible to configure the battery pack in away that accommodates a
passenger while maintaining both acceptable solo and passengered handling
characteristics. ( see the discussion regarding
range extenders in the four wheeled platform section, it should generally
apply to sidecars as well )
Four wheeled platforms. This is the platform
where tube frame really promises significant advantages. A conventional
vehicle is encumbered with much superfluous material. The possibility for
significant weight reduction, or perhaps better thought of as a trade for
battery weight is compelling. Although there are a variety of design
possibilities, the configuration that appeals to us most is a two seat
tandem arrangement, driver forward passenger aft, with seats positioned
along the spine of the chassis. This narrow passenger compartment permits
outboard pods to contain the battery packs, one on either side of the
passenger compartment, which keeps total weight as close to the centerline
as possible. The stripper version would entail neither glass, body panels,
nor interior -- other than the seats, necessary controls and
instrumentation. The next step up in complexity might include a windshield
and a body panel for the nose area to improve aerodynamics. Both driver
and passenger would wear helmet and clothing suitable for the ambient
weather conditions, Electrically heated suits, gloves, etc. would be an
option, significantly extending the tolerable range of weather conditions.
Electrically heated 12V clothing is relatively low draw power and should
not significantly affect the reserves available for operating the vehicle.
The ideal platform would include four-wheel-drive, a low range transfer case and selectable lockers in both axles. However, All of these components add weight to the system and may not be essential depending on the power and traction characteristics of the electric motor and drive train. Although a custom tube type chassis gives the freedom to accommodate a variety of drive line layouts, it would be the most design and money intensive choice. The simplest, least expensive layout would probably use a air cooled Volkswagen type I components as a foundation. For the first project it may be expedient to start with a early Beetle pan, complete with front suspension, rear suspension and transaxle. We would fabricate an upper structure of tubing, then locate the seats and a complete steering mechanism on the centerline over the tunnel. Additional changes would concern modifying the remaining pan into a battery pack support or perhaps replacing the sheet metal entirely with battery pack cages fabricated from tubing. Conversion kits to lash electric motors to Type 1 transaxles are commonly available. If the VW transaxle is deemed an essential starting point, the only clean route to achieving four-wheel-drive is probably to acquire the transaxle, front drive line, and front differential from a VW Synchro Vanagon. I believe the single transaxle is also equipped with a granny first gear, a very useful feature. However, the Synchro driveline is likely to be an expensive proposition.
A potentially interesting alternative for a four-wheel-drive EV would incorporate the transmission/transaxle from a Honda or VW front wheel drive, but turned 90° from its OEM orientation so that the axle outputs go front and back, lashing up to differentials in a conventional location, yielding a four-wheel-drive line. The transaxle from a Civic 4WD wagon of the mid-80s is also blessed with a granny first gear. Conversion kits that make electric motors to Honda or VW front wheel drive transaxles are also fairly common. However, a design incorporating either transaxle would demand a completely custom tube chassis.
************************************************************************************
The
The VW based platform, in particular, does open up
another, very interesting possibility. The combination of electric motor
and VW transaxle sets very low in the chassis. The open space above may
present an excellent opportunity to install a self-contained range
extender package. The package would be IC-based, ( fuel type to be
determined ), powerplant/generator combo, fuel container, exhaust, and
electrical system interface -- all be mounted on a base plate. The entire
assembly is, in turn, is mounted, via quick detach, to brackets on the
frame tubes. With all connections to the chassis Q.D., the complete
extender package could be lifted in and out of the chassis. With the range
extender package designed thusly, the vehicle could be used as an urban
runabout in electric only mode and as cross country cruiser with the range
extender package in place. Calculations regarding the watts hours required
to maintain a constant cruising speed are well documented, primarily based
on vehicle weight. I am sure that knowing the coefficient of drag would
permit calculating those requirements more precisely, but it may be
difficult to calculate cD for an open frame vehicle. The sweetest
conventional IC configuration would probably be a powerplant utilizing
B100, or 100% biodiesel. Fuel would, of course, have to be blended during
winter season and since B100 is not commonly available, the capability of
running conventional petro diesel would be essential for travel in areas
where the fuel supply is unknown. It may be possible to incorporate an
in-tank electric heating element that permits year-round use of the B100.
That would be sweet.
We believe there are some exceptionally interesting
possibilities with regards to ultra lightweight four wheel platforms based
on bicycle components. The design issues are not difficult at licensing,
registration and insurance issues potentially are. Unlike with their two
wheeled and three wheeled counterparts I don't believe the State of
Colorado statutes acknowledge a distinction between lightweight and
conventional four wheeled vehicles. I should modify that statement. There
is a category called neighborhood electric vehicles, NEV, but they are
limited to roadway speeds of 35 mph or less. I do not know what the
licensing, registration and insurance rules are for this class of vehicle.
Does it requires a manufacturer statement of origin simply serial number
or some other documentation.
This raises an issue which may be applicable to any
home built vehicle on a Four-wheel platform. Presumably a pedal your ass
four-wheel vehicle does not require any special documentation from the
State of Colorado. Beneath a certain road speed a two wheel vehicle, even
if powered, is exempt from registration. Three wheeled vehicles are
subject to the same category divisions as two wheel vehicles. There is an
additional distinction made for two and three wheeled vehicles which are
limited to 40 mph and, I believe, 4 kW motor or its equivalent internal
combustion engine. This class of vehicle must be registered and insured.
Presumably, any two or three wheeled vehicle with a higher output power
plant or operated on roads at a speed higher than 40 mph fall into the
classification of motorcycle. Do state statutes even address multiple
classes with regards to four-wheel vehicles?
What is the state's procedure for licensing and
registering a home built vehicle, either two, three or four wheeled ? A
related issue is the question of insurance. Typically the state will not
issue a registration and license plate unless proof of insurance is
provided. I don't know if an insurance company can deal with the vehicle
that does not have conventional federal VIN information. Should contact
Steve Rumer and see if he can offer any advice regarding home built
four-wheel vehicles licensed for road travel.