Lambretta Conversion Uni Project

[Bjreadings]

Hello. I am looking for some advice regarding my final year product design engineering project.
I am looking to convert a vintage Lambretta Scooter to electric, I am going to replace the crank of the engine with the electric motor so that the community around this vehicle can still have a geared scooter but that is now electric. I need a motor that will output similar to the original engine, I am looking for around 10hp and around 6000rpm

I want to use the 5kw (HPM5000B) motor but am unsure of what variant will be best suited, (48v, 72v, 96v?) I am also unsure of what controller and batteries would be the best for this application.

I am also worried about getting this motor in time for this project. I only have a matter of weeks to source this motor and am located in London.

Thanks in advance for any help, it's honestly greatly apprenticed.
Ben Readings, Middlesex University Product Design Engineering.

[Bikemad]

Hi Ben andto the forum.

I have just been looking at the dynomometer figures for the HPM-5000 motor and the rated speed appears to be just 3,500rpm for the 48V and 72V versions, and 3,700rpm for the 96V version.

If you need to achieve 6,000 rpm you will have to run the motor at a higher voltage than it is rated for.

The dyno figures for the 48V motor shows a maximum speed of 4,389rpm @ 48V (91.4375rpm/volt), therefore you would need to run it on at least 66V just to achieve even an unloaded speed of 6,000rpm.

According to my calculations, a fully charged 72V lithium battery (84V) should produce a maximum unloaded speed of 7,680 rpm, but this will be significantly lower if it is under load and producing torque.

I don't know what rpm the magnets in the motor are able to safely withstand, but GM state "504uH/120v Speed: 2000-6000rpm (customizable)".
I don't think you would exceed 6,000 rpm under load on a 72V pack, but it should be possible to limit the maximum rpm via the controllers programmable parameters to ensure the motor won't exceed 6,000rpm.

I think you would need to use a 72V battery that is capable of supplying at least 100A, combined with a 72V controller (e.g. VEC300-72) and you will also need the appropriate USB programming cable. 

I see there are currently 7 GM dealers in the UK shown on the Dealer Listing, so it might be worth contacting them to see if any of them carry these items in stock.

If nobody locally stocks them, I suggest that you try DeVi-motion in the Netherlands, Miromax in Lithuania, or Golden Motor Canada.

Don't forget that you will also need a throttle, brake switches to cut the power, and a suitable DC/DC converter for running the lights and horn etc. A cruise control switch is optional.

I hope the project goes well for you.

Alan