Lambretta University Project

General Discussion about large electric scooters and motorcycles and other things with no pedals.
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bjreadings   1 µW

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Lambretta University Project

Post by bjreadings » Jan 14 2020 10:33am

Hello all, I'm a final year product design student studying in London.
For my final project of my degree I am trying to convert a vintage Lambretta to electric.
There are already companies that are converting these scooters, but they simply remove the original engine and replace it with a hub motor.

I want to do something different, I believe that if I can replace the crank of the original engine with a suitable motor I can power the original engine,(a similar concept to what EVwest and Electric Classic Cars are doing) this way the scooter will remain geared and not demoted to an automatic :lol: . I have found that the original output of the crank is around 10hp/7.5kw at 6000rpm at its peak power.

I've been trying to find a motor that will match (or improve) these figures. I've been brought up on petrol and pistons and have done a fair amount of research into ev motors but have realised that I really don't know a lot.

The motor that I have found that seems to be what I want is the 5kw offering by goldenmotors(https://www.goldenmotor.com/frame-bldcmotor.htm). I'm not sure if this is a suitable motor, and what variation would be best, 48v,72v or 96v. The site offers a controller and battery pack, but once again, I'm not sure this is actually what I want.

Any help from you wonderful people will be massively appreciated,
Thank you in advance Ben.

SRFirefox   10 mW

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Re: Lambretta University Project

Post by SRFirefox » Jan 14 2020 3:41pm

Step one is to lose the gearbox. Seriously. It's only going to take up volume and mass, cause headaches, and offer no real benefit over a single-speed reduction from motor to axle. If you can put the shaft of your motor where the transmission outputs to the final drive, you don't even have to worry about changing the geometry of the original vehicle. Or the output of a primary reduction if your final drive doesn't offer a large enough ratio for the electric motor.

As for motor, the QS 138 70H is a mid-drive motor capable of 10kW+ peaks with the suggested EM150S controller. Silent Enduro have used it successfully on their Husqvarna high-power dirt bike build. viewtopic.php?f=10&t=102858 There is also a thread on it here. viewtopic.php?f=30&t=93627

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mistercrash   10 kW

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Re: Lambretta University Project

Post by mistercrash » Jan 18 2020 8:26pm

There is a good reason why scooter conversions are often done with a hub motor. It is easy, and no sprockets and chain to deal with. Much quieter and leaves a lot more room in the belly of the scoot for a larger battery that will give more power and range. You can get peaks of 40+ hp with a 5kw 12'' hub motor and a proper controller. Exhilarating accelerations I tell ya.
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grindz145   100 MW

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Re: Lambretta University Project

Post by grindz145 » Jan 21 2020 1:43pm

An e-lambretta would be dope. I imagine you're interested in the non-hub motor setup because the whole swingarm is essentially the motor/gearbox assembly. I think there are some swingarm conversion kits out there that would allow you to drop all the deadweight of the gearbox. That being said keeping the weirdo twist shift handebar thing might be a fun novelty (although woefully unreliable in my experience with my Bajaj Chetak)

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