Capacitor powered car to give 500 miles on 5 min charge

[MrAl]

<deleted>

[haklesup]

I agree that a properly designed capacitor bank could be safe enough for driving. All you really need is a fuse for each cell and a metal box to absorb any discharge safely and provide protection from impact. No doubt the first few generations of such a vehicle would have some safety bugs to work out. It took years for car makers to admit they were unsafe enough to warrent seatbelts.

I expect that 3500V is needed because the discharge curve of a capacitor is steep (not like a battery at all). 3500V would only be present at full charge, it would drop off rapidly, the motor controller would need to maintain an output of what 12V, 24V, 96V maybe but not much more. So the cap could discharge to almost that voltagebefore needing to be recharged. This is quite different than a battery that maintains a reletively constant voltage as it discharges.

Bob, I think the 3X HP difference between Gas and Electric comes only at the input. HP or torque at the crankshaft (output) is what it is no matter what engine drives it. Consider how hot a gasoline engine gets compared to an electric motor, I can believe 3X more energy is wasted as heat in a gas engine compared to electric.

[MrAl]

Hello again,

(haklesup i wanted you to see this post too, i think we were writing
at the same time)

In a previous post i tried to point out that in order to charge
a 31F cap in five minutes from 1750v to 3500v you need a power
supply that can put out 181 amps at 3500v. That kind of power
supply is impossible using a standard household line of 240v
because the amp requirement at that lower voltage (2640 amps)
is just too darn high!

If the time requirement wasnt as tough, like say 500 minutes
(about 8 and a half hours) then the current requirement from
the 3500v supply would be 1.81 amps which would mean the
power supply only has to be rated at 6335 watts which only draws
about 26 amps from a 240v supply. This could work, but
the user would have to be able to put up with an 8 or 9 hour
charge. Alternately, some way of having one bank charge while
the other is in use and some easy way to swap banks. When the user
gets home, he/she could swap banks and be charged in the time it
takes to swap capacitor banks.

Also, it looks like a 40hp motor 95% efficient will require an average
current of about 14 amps from a supply whos average voltage is
2625 volts, including converter losses. This leads to a half-power
time of 26 hours to discharge the caps (the motor running at 20hp).
This would mean you can get 26 hour run time from a 9 hour recharge.
Running at full throttle the whole time will bring this down to 13 hours
run time...which isnt that bad i guess.
A recharge would cost roughly 10 dollars in the USA.
Assuming you could go 55mph, driving at that speed for the 19
hours (averaged 26 and 13 hours) you could drive 1045 miles.
Running a car that gets 25 mpg you would use 42 gallons of gas,
and at 2 dollars per gallon this would cost 84 dollars.

Thus, the electrical car would cost about 10 dollars compared
to 84 dollars for the gas car.

[Robert Reed]

MrAl
I like your figures, but what would please me even more than that, is it would be $84 less in some MidEast terrorist's pocket. Also , by configuring a constant current souce to drive the motor, we could probably take the 'bank' down to quite a low voltage. Maybe an accelerator pedal that wouuld actually change the rating of the CC source.

[Geoff]

What happens when all of the energy we've been getting from gasoline has to come from the power grid instead? In the summer, places like California are already at 90%+ capacity. Remember the rolling blackouts of a few years ago?
The power grid in the United States would need massive upgrades, and we're not going to get power for 7 or 8 cents per kilowatt if that happens.
What fuel do we use to make this electricity? Alternative power sources aren't able to handle our current needs, so unless someone makes a breakthrough, much of this power will come from oil, gas, coal, or nuclear. Same problems, all we've done is move it from under our hoods to a central location (the power plant). This centralization of power creation may not be all bad, as it would be easier to clean up the waste products.
Maybe someone could figure out the extra electrical capacity needed to power a nation full of "capacitor cars" and the cost of charging them.

[haklesup]

Rather than swapping capacitor banks, one could slowly charge one at home all day then rapidly transfer much of that charge into the cap in the car. I doubt that a 3500V charge voltage will ever be used though. Just the required spacing of the contacts and the contact area for high current would be impractical not to mention the obvious safety issue. A smaller intermediate voltage would be needed. I like inductive charging systems because there are no contacts to touch

Estimating the cost of charging is complicated in CA where electric rates depend on how much you use. My rate varies from .11 to over .33 per Kwh. Its just as well they don't put charging plugs on hybrid cars yet. It would be difficult to know if gas or electric were cheaper on any given day.

I think the ultimate hybrid would have caps, batteries and an engine. Caps are better at some things like soaking up the energy from regenerative braking while the constant voltage of batteries would likely make the controller simpler and less expensive. What's significant about this car is that it shows caps to be on a par with batteries. No I ask which will pull ahead.

First there was the enlightenment, then the industrial revolution followed by the information age. Next Energy and Health will get a turn before we can be enlightened again.

[MrAl]

Hi again,

Robert:
Oh yeah, that's nice too. From 'some' money for them to
'zero' money for them.

Geoff:
That poses a problem which would have to be studied. I
have a feeling it wouldnt work overall.

haklesup:
You missed our discussion on one cap charging another?
We found out that with both caps of equal value and
one cap charged and the other cap not charged, even
with a very very small resistance between the two
after they are connected together here's what happens:
1. 25 percent of the energy transfers to the second cap
2. 25 percent of the energy remains in the first cap
3. 50 percent of the energy gets dissipated in the resistance
(note the system starts out with 100 percent of the
energy in the first cap)

What this means is the transfer becomes only 25 percent efficient,
which would be terrible for this kind of application.
That's part of the reason i suggested swapping caps completely.
The other thing to consider is the peak amps, which would be
way too high if you wanted a real quick changeover. They wouldnt
be able to produce a 3500v cap that could withstand hundreds of
thousands of peak current amps.

[Chris Smith]

The electrical grid has many a myth built in to it.

Solar can reduce the grid simply because the sun is up producing power when WE use it most, the day time.

At night the grid is almost wasted, as industry, people, and machines are asleep.

The dam however is still spilling its water as a waste by product, so any time you utilize the grid 100%, 100% of the time, with any use that makes the grid work fully is better than we use it today.

Electricity isn’t stored at night and then used during the day which make a capacitor driven automobile a wining proposition.

Charge it at night, drive it in the day, thus there is plenty of room for this new technology, .....for now. [population]

Then in the near future renew the energy with solar, wind, and tidal machines and the Arabs can go back to living in the desert in their tents which is where a great deal of them already dream to do.

And thus no wars for ideology, religion, or politics.

[Robert Reed]

There is one unique situation that I know of. At Kinzua Dam in western PA, they pump water to a large pond (1 mi. diam.) all night. Since the dam is still flowing at night they elect to do this rather than bypassing the penstocks. This pond is at a much higher elevation than the dam and has a lot more head pressure. During day time hours and peak usage, this water is released into the penstocks along with river water. In effect they are actually storing energy, albeit at an expense more than the normal flow of the river water. However it does give the power plant the ability to withstand heavy loads during peak periods that it otherwise couldn't do.

[rshayes]

One fact to note is that delivering 50 KWH in 6 minutes requires handling 1/2 Megawatt of power. This is a substantial fraction of the output of many power plants. A busy filling station might need 4 Megawatts of power on a nearly continuous basis.

Loading the capacitor could be done with a 500 KW switching power supply This is somewhere around 1 to 2 thousand times larger than the supplies used for computer systems.

The entire premise, at least according to the patent, is that the dielectric layer in the capacitor will be 1/2 mil thick and withstand 3500 volts of stress. Making a 20 Farad capacitor will require practically flawless construction of a vrey large plate area.

[shillyard]

I think bio fuel is a much better way to go than the power grid.