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Hi, I've just joined the forum and was looking for a tonne of advice on building an EV from scratch if possible?

I won't be using any form of donor vehicle and wish to design a bespoke EV around a carefully conceived EV powertrain. I am therefore looking for guidance on how to assemble the perfect powertrain for my project or to perhaps be pointed in the direction of an off-the-shelf solution if something like this exists?

I have spoken to a number of local companies, one of whom's suggested using 10 x Tesla Model S Modules which would provide enough power for a NetGain HyPer9 AC Motor. The problem I have with this configuration is a) weight and b) how to direct power from the motor to the rear wheels.

I've been pointed in the direction of Porsche G50-G96 transaxles which are apparently robust enough to handle the high levels of torque created by the HyPer9, but for me this is a rather clumsy solution due to the fact that I don't require 4-6 gears. Ideally I am looking for a Tesla Roadster-like direct drive system, but I am still learning about such components, hence why I'm here looking for advice if possible!
 

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Hi, I've just joined the forum and was looking for a tonne of advice on building an EV from scratch if possible?
I think the most general advice would be to understand your goals. There is no single ideal design, and you can't choose the best design and components for you until you understand what you expect of the end product.

More specifically, designing an entire vehicle - regardless of the type of powertrain - is a substantial undertaking. I think you need to understand your abilities in design and fabrication, and your budget, to have any understanding of what you can build.

... perhaps be pointed in the direction of an off-the-shelf solution if something like this exists?
One form of off-the-shelf solution is a complete powertrain from production EV... but that's optimal for one particular vehicle, so why not just buy that vehicle?

There are lots of suppliers offering packages of parts. I think those packages are mostly determined by what the supplier has to sell, rather than what would work best, and even then... best for what?

I have spoken to a number of local companies, one of whom's suggested using 10 x Tesla Model S Modules which would provide enough power for a NetGain HyPer9 AC Motor.
The HyPer9 is built specifically to provide modern motor technology for vehicles to run at lower voltage than typically used in modern EVs. Is there a reason you would specifically want to at this voltage?

The problem I have with this configuration is a) weight and b) how to direct power from the motor to the rear wheels.

I've been pointed in the direction of Porsche G50-G96 transaxles which are apparently robust enough to handle the high levels of torque created by the HyPer9, but for me this is a rather clumsy solution due to the fact that I don't require 4-6 gears. Ideally I am looking for a Tesla Roadster-like direct drive system, but I am still learning about such components, hence why I'm here looking for advice if possible!
It's not just the Tesla Roadster (which is long out of production), but the vast majority of current production EVs use a single-speed reduction gear transmission, normally packaged with a differential to make a transaxle. If you know the power versus speed characteristics of the motor, you can determine appropriate gear ratios, and whether or not a single ratio is suitable. While various production EV gearboxes would work with the HyPer9, they are even more suitable for the motor that comes with them.

You seem to be assuming a single motor driving both wheels of one axle, which requires a differential. An alternative is to drive each wheel with a separate motor; I'm not saying that's ideal for you, just that there are many choices and you need to understand your goals to choose the right one.
 

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Hi GT

The first thing to do is to decide "why" - all cars are effectively sets of compromises so "what do you want to do different"
What is your aim

Once you have done that then the rest follows on from that

My "Aim" - was "cheap and cheerful high performance with no unnecessary luxuries"

You may need to divert your aim a little to cover the realities of cost and of getting it onto the road

http://www.diyelectriccar.com/forum...dubious-device-44370p15.html?highlight=duncan

I started building 10 years ago - the device has been on the road for 5 years now
If I was starting now I would use different parts
 

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Ditto for the previous comments.

There seem to be a couple of contradictions in the original post.

You talk about the perfect power train. There is no such thing. If you want strength it will cost you in weight and size. If you want small and light it will cost you in stregth etc etc.

You also talk about not having a doner car. Yet then you talk about components from other vehicles....That would make them doner cars.

At the end of the day it is all about your set of requirements. You need to set them out very specifically:
  • Vehicle weight
  • Vehicle format
  • Driveline format (FWD, RWD, AWD)
  • Intended purpose and all the regulations that surround that purpose
  • Target accelleration
  • Target range
  • Target speed
  • Budget
Be realistic. If you set overly ambitious targets you risk becoming demotivated when you start missing targets. Once we know all these things the specifications of the required components will become clear.
 
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