By Gordon Dower and Shelley Damewood
A century after being the most popular type of car and then waning into oblivion, the electric car is
undergoing a rebirth with predictions that it will supplant its CO2 - emitting
rival within the next decade or so. As the energy-storage capacity of the battery approaches that of the gasoline tank,
the rugged mechanical simplicity of the battery electric car becomes an increasingly appealing successor to the fuel-burning
automobile we have welcomed as part of the family. But if we treat the battery electric car as merely a car with different
works we shall deny ourselves some of its greatest advantages that spring from a different philosophy underlying our attitude
toward it. It’s all common sense but not obvious and therefore not so common after all.
In a curious yet rather quaint way, looking to the future involves looking to the past, to the time before there
were automobiles, only “horse-mobiles” where the motive module was distinct from the containing module but these
were not thought of as modular vehicles. There are many different names for the modules (coach, dray, jitney,
surrey…and bay, gelding, percheron, hack…) but there is no word for the composite conveyance, although it may
be contextually implied as in “Your carriage awaits.” Obviously there must be horsepower! A non-modular horse-mobile
would be absurd because of the totally different requirements of its two parts.
Automobiles were often built as separate body and chassis modules that were permanently assembled before use but the
concept of modularity as a useful feature was not envisaged. Indeed, it is entirely lost in today’s unibody construction.
There was no philosophy for it until what was subsequently called a “ridek” was patented. Even then, the philosophy came
later. The title of the patent was “Modular Vehicle Construction and Transportation System.” The idea came from changing
the battery pack in an electric car without disturbing the batteries or their contacts, just as stagecoach horses were
changed in a journey that exceeded their range. This is easy to do if the pack lies in a “modek” or motorized deck, and
the modek is exchanged for another one containing a fully charged pack. Riding on the modek is the “ridon” that carries
the driver and passengers who may remain seated during an exchange that takes just a minute or so, to continue their
journey in the reconstituted ridon/modek, or ridek.
Batteries have greatly improved since 2000, when the patent was granted, and 300-mile ranges with 10-minute recharging
times now lie within the compass of today’s technology (a decade later) so that the original impetus for ridek
quick-change modularity has disappeared, especially with the advent of the hybrid gasoline-electric car. However,
three road-licensed ridek prototypes and numerous papers have not only established the practicability of ridek modularity
but have also given rise to a hitherto neglected philosophy underlying the electric vehicle, a philosophy that applies
to the economic underpinning of cars of the future.
A philosophy begins by asking questions such as: what are the possible advantages of modularization? Where has it been
demonstrated? How can it reduce the cost of car ownership? What inconveniences does it mitigate? Can it reduce waste and
improve safety?
A prime example of modularity is the railway train, by far the most efficient form of land transportation. Another is the
modularization of containers that can move between ship and rail—and also road, leading to semi-articulated trucks.
These were jointed or articulated to negotiate corners. Modularity of their traction and containing elements came later
and they are still called “semis” rather than modular trucks although their widespread use provides all the evidence we
need of the value of modularity in the trucking industry. These developments occurred gradually as business practice showed
the advantages of inter-convertibility and exchange. Similarly, we should expect to see advantages of modularizing the battery
electric car coming to the fore as it comes into use. This philosophical approach will attempt to foresee some of those advantages.
The greatest single expense of car ownership is depreciation and the greatest depreciation takes place over the warranty period
because people tend to change the car when the warranty expires even though it may be running well. This creates a collaboration
of interests between the dealer and manufacturer where the dealer holds the inventory of new cars and the manufacturer facilitates
a servicing and warranty repair system that gives the dealer sufficient income to sell his cars more competitively. Competition
protects the consumer but the system is intrinsically inefficient and unnecessarily expensive because of lack of standardization.
Of course, the customer deserves a choice and free enterprise ensures he has it but the economic dictates of mass production deny
him the customization that the early coachbuilders could provide—and could be provided by the ridon builder.
It takes a great deal of money to bring out a new car model and an assurance of a production of perhaps 50,000 copies. Producing
modeks would cost much less, especially those with electric drives, because they would be standardized to fit existing ridons.
Improvements would continually occur but they would be within the overall modek design and many of them could be implemented as
updates of modeks already in service. In contrast to the 12-year lifetime of the average car, the modek’s life expectancy, given
its robust electric drive and easy maintainability, would be more like 30 years. Almost no original buyers would keep a car so long
but in any business plan such a long service life should be taken into account. This leads inevitably to a new philosophy about the
private automobile, a vehicle that is often so personal and even loved by its owner that it declares the self-image he would show
to the world. That it must perform well and reliably goes without saying. Happily, reliability and impressive performance happen
to be the hallmarks of an electric drive.
Whereas modek design is a matter for conventional engineering, ridon design extends engineering to an art as in architecture,
and must interface with people, and the prospective owner. Modularity allows this to happen. The ridon may be as ruggedly
utilitarian as a military vehicle or as romantically elegant as…well, use your imagination!
So much for philosophy, how about administration?
From the foregoing it is clear that ridek quick-change modularity calls for the divided ownership that only it can allow.
Whereas the ridon might be privately owned, the modek would be provided as needed from a pool of modeks through a system
of modek exchange stations. That is the plan, now for the devilish details:
The above advantages are summarized in the Ridek Modularity Concept Map and accompanying key. Other advantages will emerge.
For example, a plumber who cannot work without his vehicle containing the tools of his trade, would be unemployed if he drove
a non-modular vehicle and had to leave it in the shop for servicing. A courtesy car would not help but a ridek would allow him
to keep his ridon and his tools. It is easy to predict that the convenience and economy of ridek modularity will trump the
non-modular vehicle.
Reduction to practice
The following is a description of a design for an urban ridek based on experience over a decade developing three rideks.
Figure 1 shows a chassis model for a modek 11 feet long. It consists of two longitudinal chassis elements providing attachment
for the front and rear motorized axles (details of the suspensions are not depicted). The mid-section is comprised of a rectangular
box made of laminated carbon fiber. The floor of the ridon forms the lid of this box and gives great rigidity. The available volume
of the box is 508 liters. If only three quarters of this space is used for batteries, the storage capacity could be 100 kWh, to give
a range of about 400 miles. Motors are shown between the front and rear wheels but two are hardly necessary. Motor controllers and
cooling system are not depicted but there is sufficient room for them
In the three road-licensed ridek prototypes mechanical links carry steering and braking controls across the ridon/modek interface.
Ridek III implements automatic alignment and latching of the ridon and modek modules and demonstrates the practicability of the
ridek quick-change modularity concept. It is easy to predict that the convenience and economy of ridek modularity will trump the
non-modular vehicle.
Fig. 1. Modek chassis design. Ridek III prototype