I plan to build an electric car (mainly as a hobby project). However,
before I do any detailed planning, I need to know some general
performance facts for electric vehicles, energy storage and such.
While there appears to be plenty of information about these issues on
the internet, I find it hard to sift through all the available
information in search of answers to my questions. Also the "answers"
are often provided in a way that I do not readily understand (or I
will have to do a lot of calculating to get the result I need). So I
thought I'd give G.A. a go :)
NOTE: I've decided to set a (somewhat) low price initially. I am,
however, prepared to spend more money if needed. Please let me know if
a better price would provide a better answer (and what that price
should reasonably be), I will then post a new question with the
suggested price (assuming I agree that the additional information is
worth the additional $ of course :)
Let me first describe the intended concept:
I want to make a car with the same performance and comfort as that of
your average small sporty combustion-engined car, with the possible
exception of top-speed (130-150 km/h. will be enough) and range
(75-150 km. will suffice).
The idea is to show all those "combustion-freaks" out there that an
electric car can be (at least) as good as their environment-unfriendly
petrol drinkers, while at the same time providing me with a
no-emission car for daily use (I seldom drive more than 50 km. a day,
and mostly in the city where the speed limit is 50 km/h. Occasionally,
though, I will need to use the highways, thus the requirement of a
top-speed of at least 130 km/h.)
I've not yet decided if I'm going to use fuel-cells or stay with the
good old batteries for the main energy storage. This decision will
probably depend on the availability and price of mobile fuel-cell
systems at the time I start building.
I plan to use a bank of ultra-capacitors for short-term energy
storage. This mainly to provide increased efficiency when using
regenerative breaking and for handling short-term peak energy
requirements.
As mentioned, the goal is to provide the same cabin comfort as normal
cars, although I might decide to skip the rear seats in favor of some
weight saving, but I will need some luggage space (mainly for
groceries etc.)
The goal is to achieve a semi-lightweight car (500-750 kg.) with a
reasonable cw. in order to reduce the overall energy requirements.
I'm also looking into the feasibility of making some kind of electric
(and thus active and regenerative) suspension and/or shock-absorbtion.
= = =
Now for my questions:
- What is the power consumption of a car traveling at a constant speed
(say 50 or 100 km/h.) assuming a weight and drag as mentioned above
(ie. that of a normal car)?
- How much energy (in percent) should I expect to loose to heat (ie
elctrical resistance) and friction, assuming that I use good,
low-loss, components? (Keep in mind though, I'm not on a NASA budget
here!)
- How much energy (in percent) can I expect to regenerate when
braking, assuming I choose an elctric engine with a good generator
performance?
- Is it at all possible to get an engine that is both very efficient
as an engine and as a generator, or will I have to do some kind of
trade-off?
- Aside from the mentioned batteries, fuel-cells and ultra-capacitors,
are there any other energy storage solutions that might provide a
better weight/power/price ratio?
- Some questions relating to the abovementioned "regenerative
suspension system" that I'm considering for the car:
-- How much energy would a regenerative suspension (shock absorber) produce?
-- Would the energy thus generated be overly difficult to "convert" to
something useful?
(I've looked at some linear electric "pistons" that could do the job
of shock absorbtion, producing electricity in the process, only I
wouldn't know how much, nor if this energy can be readily stored in
the capacitors?)
-- While such a suspension system should perform better, suspension
wise, than a normal passive spring/damper system, I'm unsure if the
energy produced in the dampers will be large enough to make any
difference, that is: Will it be significant in relation to the energy
used and regenerated by the main engine(s)?
= = =
Finally any kind of useful formulaes for calculating these things
would be appreciated as would some links to sites and/or litterature
references with further related information and/or products.
inventus-ga. |
