DIY: making an electric car

Transport and new transport: energy, pollution, engine innovations, concept car, hybrid vehicles, prototypes, pollution control, emission standards, tax. not individual transport modes: transport, organization, carsharing or carpooling. Transport without or with less oil.
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Remundo
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by Remundo » 21/07/12, 10:59

you must learn about the Crr
(rolling resistance coefficient)
Coefficient of Rolling Resistance
[Url = Rollwiderstandskoeffizient] http://de.wikipedia.org/wiki/Rollwiderstand [/ url]

(sorry, no interesting French Wiki pages)

The force which opposes advancement is worth Crr x N where N is the vertical load in Newton

The braking power is Crr x P x V where V is the speed in m / s

The energy to overcome for advance is Crr x P x D where D is the distance traveled in m.

Crr = 0.01 approximately for "ecological" tires (see the larger German page)

The performance of a tire is indeed a rather vague concept. But we usually consider that a tire works at 80% efficiency, i.e. it dissipates 20% of the mechanical power transmitted to the wheel and transmits 80% of this power to the car ...

Additional experience and data.

@+
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Grelinette
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by Grelinette » 21/07/12, 16:44

Very interesting the exchanges and comments on the Coefficient of Rolling Resistance (or coefficient of friction), and a big thank you for the links to the pdf which explain the principle.

This is a problem that concerns us now (in the field of animal traction, of course! : Cheesy: ).

Horse-drawn vehicles can be fitted with the following types of wheels:

- rubber tires
- wheels with metal tires
- wheels with resin tires
- wheels with inflatable tires (motorcycle or car wheels)
- etc

and the widths of the wheels (the tread) can be of different widths: roughly from 2 cm to 20 cm.

For the ground on which the vehicle is driven, there may be:
- bitumen
- concrete
- of the earth
- packed sand or not (e.g. seaside beach)
- a special coating of the type of certain cycle path
- etc

In special situations, we have as a vehicle and as soil: ski type skates on snow (very low coefficient of friction: around 5% of the mass), or an agricultural implement (harrow, plow, ...) on earth or sand, so a very high resistance coefficient!

In short, the question is whether we can find a simple calculation formula which takes into account the type of wheel and the ground, and which gives the minimum energy necessary to compensate for the coefficient of resistance.
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by Obamot » 21/07/12, 19:04

And the coef of rubbing the hooves on the ground, what do you do with it, huh? What do you do with it? : Mrgreen: : Cheesy:

Hello Grelinette! ^^

(well ok I -> [] will neigh elsewhere ...) : Mrgreen:
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by Grelinette » 22/07/12, 08:58

Obamot wrote:And the coef of rubbing the hooves on the ground, what do you do with it, huh? What do you do with it? : Mrgreen: : Cheesy:

Hello Grelinette! ^^

(well ok I -> [] will neigh elsewhere ...) : Mrgreen:

For the horse it is settled: under the hooves I put irons on air cushions! : Mrgreen:
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by Remundo » 23/07/12, 09:36

large diameter iron wheels on smooth and very hard tar: little resistance.

On the other hand, on soft soils, it would be better to have a large and moderately inflated tire (to limit the energy-intensive crushing of the sand).

At first glance, maybe car tires inflated with blocks would be a good compromise between all soils ...

But it would be better to avoid all soft soil, Grelinette ...

PS: the right link for the German Wiki
Rolling resistance coefficient
Autoreifen: automobile tire
Eisenbahnreifen: railway wheel
Quick translation in French
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by YoBahri » 10/10/12, 00:35

I ask myself a simple question.
We can say that the conversion of my thermal car into an electric car is finished. Certainly there will always be improvements to be made.

My question is: Do I have to homologate my car with its new electric motor to drive?

Knowing that this car is already registered. That I did not make any changes in the safety elements or even the bodywork.
The only thing that has changed is the way the car is powered. Basically if I had put a diesel engine instead of a gasoline engine I would have been talking about homologation.

Do you have an answer

For those who want to see what my electric car looks like: www.Code-prototype.com
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by Obamot » 10/10/12, 05:00

Congratulations !!! :D

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And another little "hello":

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For the answer to the question, I think so (but I wouldn't : Mrgreen: ) finally if, anyway (if only for insurance reasons ...). It may be necessary to specify that originally, your vehicle was a car with a speed limited to 45 km / h, right?

In any case, I think that asking some information anonymously to the competent services is essential (ask Remundo by MP if he is not there, he must know ... since he must already have been confronted with this problem, or at least surely already asked the question ...)
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by Macro » 10/10/12, 09:13

YoBahri wrote:
My question is: Do I have to homologate my car with its new electric motor to drive?

Knowing that this car is already registered. That I did not make any changes in the safety elements or even the bodywork.
The only thing that has changed is the way the car is powered. Basically if I had put a diesel engine instead of a gasoline engine I would have been talking about homologation.

Do you have an answer

For those who want to see what my electric car looks like: www.Code-prototype.com


You have changed one character of the registration certificate that of energy. Your car is therefore no longer authorized to drive on the public highway legally ... It must be received in isolation from the "service des mines". you put a diesel in it, it would have been the same ...

If you do not homologate it or if you do not make the necessary concerning the modifications there is can chance that the constable take you and verbalize you for that ... On the other hand if you have an accident (responsible or not) your insurance can turn against you ..If you have bumped the bumper of a twingo or flattened a doggie to its memory it will not go very far, if you teleported a fire-burner cyclist or a pedestrian who injected himself with david ghetta in the esgourdes, in a small armchair (electric they make goods) there it is another story ... Better for you not to be the owner of your house ..
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by BobFuck » 10/10/12, 11:37

It's boring this approval story, it's the same for electric bikes: if you want to install a kit or hack a revolutionary invention, you are forbidden to ride with.

I think that as long as an insurer is willing to insure you (it's up to him to examine your machine) you should have the right to drive!

Otherwise, for tires, the resistance is proportional to the Crr but above all ... to the weight. And so :

nlc wrote:Yes I did not specify, in my example it was understood that the only payload was the driver !!!


So, if the driver is green, he takes his bike (possibly motorized if it's too tiring!)

By the way, shopping with a bike is less tiring than in the car: you take the trailer, you use it as a cart (you need a 3rd wheel), you take it home, you put it in the 'lift and direct in front of the fridge ... no need to carry heavy bags, park the car in double file, etc ... great luxury! (by the way we can put the electric motor in the trailer too!)

Grelinette wrote: or an agricultural tool (harrow, plow, ...) on earth or sand, so a very high resistance coefficient!


In the days of the steam engine, we used a (fixed) steam engine with the plow at the end of a cable.

Not having to transport the tractor is a big plus for efficiency!

We could bring the method up to date with a fixed electric winch: no batteries, in short the greenest thing there is ...
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by YoBahri » 11/10/12, 00:58

Thanks for the very clear answers.
I say it should be simpler, these administrative stuff.
It is extremely effective in discouraging novices like me. I will continue to go back and forth in my garden. : Mrgreen:
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also follow my project on my website: http://www.Code-Prototype.com

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