Exploring options on electric car build

Electric cars, trucks, ATVs, NEVs - things bigger than a motorcycle.
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Joe T.   100 W

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Exploring options on electric car build

Post by Joe T. » Oct 27 2017 11:01pm

I got the bug to build a fast electric car. I have put out the word to my local used car dealers to keep an eye out for a wrecked Tesla. I’m open to other motor options. I know the Tesla motor has the power. The chassis will likely be a Factory Five 818C. This would be a cheap, light easily acquired base car.

I’m not going to worry about the chassis at this time. This very car has already been built with Tesla power. My first step will be acquiring the drive train. There is a growing community of Tesla hackers so I’m not thinking controlling the motor will be too difficult.

What would a fair price be for a Tesla motor?
Instead of thick copper wire for electric power delivery, would copper tubing work? I was thinking about copper tubing holding its shape and making a very organized electrical system. I have used steel brake line for throttle linkage for my drag car and it works great and is feather light.

Just thinking out loud for now. I have no timeline for this project. Just exploring options at this time.

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amberwolf   100 GW

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Re: Exploring options on electric car build

Post by amberwolf » Oct 28 2017 1:35am

Joe T. wrote: Instead of thick copper wire for electric power delivery, would copper tubing work?
Yes, as long as it's the same crosssection of material, it should carry the same current.

However, you'll need to insulate the pipes electrically, so they don't ever accidentally get shorted to anything.

Is there a particular reason to use pipe vs wire? Just because it's stiff and would stay in whatever shape/position you bend it to?

Keep in mind that copper work-hardens, so if it's got any unsupported lengths that vibrate over time, they may fracture at the nearest support.

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Joe T.   100 W

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Re: Exploring options on electric car build

Post by Joe T. » Oct 28 2017 9:53am

They make plastic coated copper tubing for underground use. I am assuming the price for 1/2" tubing is cheaper than 1/2" stranded wire.

I seem to remember from school, many decades ago, current traveling on the surface of the conductor. I have not researched it much since. I figured I would comment here and get a head start. You mention cross section. Obviously tubing is hollow but would have the same diameter and thus, surface area. I figured some one here would have explored this long ago.

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Re: Exploring options on electric car build

Post by amberwolf » Oct 28 2017 12:55pm

Joe T. wrote:They make plastic coated copper tubing for underground use.
Is the plastic rated for high enough voltage insulation factor for the voltage your system will run at? If it's not marked as rated for a voltage, you'd have to find out what kind of plastic it is, then what thickness, then look up what voltage that would insulate against. (or just take it as it is and hope it's enough).

Also note that some plastics have very low melting or distortion points, so that if the wiring gets warm or hot in use, the insulation could come off. The stuff used on some 18650 cells and on electrolytic capacitors is one example of that--I've seen a number of those that have heated up and split their plastics, and the 18650s have caused pack failures from shorting cells (or cells to tabs) together when that happens.

I am assuming the price for 1/2" tubing is cheaper than 1/2" stranded wire.
I don't know about the price, but 1/2" tubing won't have nearly the same copper crosssection (and thus current-carrying ability) as 1/2" wire. You have to use tubing with the same copper crosssection as the wire you'd otherwise have used. That's going to be a lot larger diameter than the wire would be, depending on wall thickness.

I seem to remember from school, many decades ago, current traveling on the surface of the conductor.
At very high frequency AC, yes (like RF). With motor control, it's still effectively all DC as far as that goes.

I have not researched it much since. I figured I would comment here and get a head start. You mention cross section. Obviously tubing is hollow but would have the same diameter and thus, surface area.
It does not have the same crosssection, meaning it does not have the same amount of conductive material, so it can't carry nearly as much current as a wire (solid or stranded) of the same diameter.

So the pipe will have to be more than twice the diameter of the wire, depending on wall thickness. (thinner wall = larger diameter required).
I figured some one here would have explored this long ago.
It's probably been tried for watercooling motors, using the tubes to carry the cooling fluid in as well as the power, but I don't know what thread it would be in. You'd probably have to search on the word "pipe" or "tube" along with maybe "copper" and "motor" to find them, and then see what comes up and sort thru it. :/

But I don't see any advantage (and more than one disadvantage) to the tubing over the wire, other than stiffness (which is usually also a disadvantage in a moving vibrating vehicle).

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Re: Exploring options on electric car build

Post by Dauntless » Oct 28 2017 2:30pm

Well now, there's a proper way to find your salvage Tesla.

https://erepairables.com/salvage-cars-auction/tesla

https://www.salvageautosauction.com/mod ... S-for-Sale

https://teslamotorsclub.com/tmc/forums/ ... r-sale.72/

But it's a whole new world, the salvage of the electric car.

https://www.teslarati.com/think-twice-b ... a-model-s/

Sounds like one of those fun and frustrating jobs, though.
Any sufficiently advanced technology is INDISTINGUISHABLE FROM MAGIC!
- Arthur C. Clarke

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