How can I get speed from electric car

lucky99 · Coal Joined: Jun 16, 2008 Posts: 1

I would like to know how to get the bottom end pep and top end speed from an electric car, I see there are many very fast electric race cars and race motorcycles so many people tell me it not possible with out putting it many more battery's than usual but I would think it would have more to do with transmission and the torque values and rpm values on the AC or DC motors but so far the only specs online are for EVA that have a top end of 40 to 55 MPH and should you need to go in the interstate you would have the motor on a full load where as if the EV could go 90 MPH you could go along at 60 with no problem, so if you have information or conformation that may help me please post.
Lucky99

kpeavey · Expert Joined: Oct 04, 2004 Posts: 1313

I just woke from a short nap after a long day, this is the first post I loaded. I may come across as hostile, but I will try to tone it down.

It strikes me that you do not grasp the complete concept of Powerdown. I thought about the idea of transportation in a pose peak world. Golf carts struck me as being a means by which a consumer mentality could try to hold on to the untenable.

What if cars could be replaced with something lightweight, electric, rechargable, able to haul several bags of groceries or transport a couple of people, and be cheap enough to be affordable for the masses. Golf carts fit the bill. They can be converted to solar operation. They offer an inexpensive, readily available replacement for the automobile. All that is needed is legislation allowing them to be used on public roads. For in town driving and local commuting that does not need to be fed or pedaled, they are a simple solution.

Then I got to thinking, what if my brother had a golf cart, and his neighbor had a golf cart. My brother would have to have a better, newer, bigger or faster golf cart than his neighbor. He would need a nicer paint job. He would need a stereo with big subwoofers. His would have to have heat, headlights, AC and big fuzzy dice. Then I got to thinking there would be entire industries develop just to serve the golf cart accessory market. Golf carts with bubble tops for cold climates. This invariably would lead to the hatchback, followed by the Sports Utility Golf Cart (SUGC).

Peak Oil has many ramifications. It is a problem that is pervasive and without a technical solution. To give you some understanding, I recommend doing some background reading.

What is Peak Oil?

The Peak of World Oil Production and the Road to the Olduvai Gorge

Every paper at dieoff.org

Peak Oil Perfect Storm

Matt Savinar's Life After The Oil Crash

Google: Limits to Growth, Meadows et al, Club of Rome

BP Statistical Review of World Energy 2008

Peak TV

Assessments and Plans

5 Rules for PO Prep

Statistical Thermodynamics, paying special attention to the 2nd law.

Tragedy of the Commons by Garret Hardin

Thomas Malthus, An Essay on the Principle of Population

Professor Albert Bartlett's lecture: Arithmetic, Population, and Energy
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If you want a picture of the future, imagine a boot stamping on a human face--for ever."
-George Orwell, 1984

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Accept the Facts.

mos6507

To actually answer your question, you need more amps to the motor. This is usually done by upping the voltage of the battery pack. The problem is there are only so many batteries you can fit in a car, so you wind up with a tradeoff between speed and range. Really the only way to get both is to go with lithium batteries, which are expensive, hard to get, and unknown reliability.
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As long as I am around, there are no worries we have reached "Peak Words"

--ReverseEngineer

Vegas

amps=torque
volts=speed
amps*volts=energy
amps*volts/time=power

voltage solves alot of problems, but it makes a few too. 300v+ DC is a scary batt, it is capable of arcing accross an air gap. Balls of fire.

It is easy to build a 80mph+ EV, having any usefull range, at those kind of speeds, is not easy.

Powerfull EV's don't use transmissions, they use voltage. To compare it with an ICE vehicle, the motor IS the transmission, the battery is the engine/gas tank, you can use a motor that is too small for the job with an additional tranny, but it is dumb. Want more speed? Increase voltage. Want more torque? Increase amps. More power? Increase amps+volts.

Running a motor at max revs isn't like running an engine at max revs. You can WFO a motor on the bench or in a vehicle for as long as you like, it cannot suck a valve, hasn't got any. An EV going WFO, at top speed, is lightly loaded. It is grades and getting up to speed that load the system heavily.

Call me burnt out EV'er, but I will soapbox about basic physics.
We done had it easy for too long, nobody understands just how much energy it takes to move a vehicle. I don't know how many times I have explaned that adding another gear won't make it go faster(it won't, realy it won't, it will go the same speed and make more heat).
Let alone that an alternator will not charge up the battery as you go...

small_steps

flux (or field) weakening

-good luck-
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"Sometimes one pays most for the things one gets for nothing."
Albert Einstein

cube · Fusion Joined: Mar 12, 2005 Posts: 3775

WisJim

There are a number of good electric vehicle forums--I'd give you a link but I don't have them bookmarked on this computer. V is for Voltage is one, there is an EV listserve but I don't recall details, and there are some Yahoo groups with lots of info in the archives. Cube mentioned 2 good sites above, too. To go faster, you generally need a higher voltage, as just increasing the amps gets difficult after a certain point as it requires heavier wires, more expensive relays and controllers, etc. Generally, you go to a higher voltage, higher RPM motor and more batteries to run the motor. Field weakening can work, too, sort of like an overdrive. We're thinking of replacing the stock 36/48 volt motor in one of our electric cars with a 72 volt motor, since that car needs lots of work. It could increase the maximum speed about 20%.

yesplease · Fission Joined: Oct 03, 2006 Posts: 2482

Best bet is a higher voltage pack and minimization of forces on the vehicle. That means a donor vehicle with the smallest reference area and drag coefficient possible, even if you have to mod it. LRR tires and adjust the alignment to be as straight as possible w/ your weight in the driver's seat. On one hand, a frame off of a pickup w/ some weight reduction and a modded unibody of a small car could probably weigh in at around 3500lbs curb w/ a range of ~200miles@60mph/110mph top speed/180V pack assuming serious attention is paid to what I mentioned above. Otoh, a Metro w/ little attention paid to what I mentioned above would be lucky to see 50+mph and 25 miles at that speed with half the voltage.
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