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Vespa Conversion Questions - 48V hub motor or 72V?


1 µW
Nov 11, 2022
I'm planning on converting a vintage Vespa Sprint 150. It's not a large frame like the PX so I won't have as much battery capacity. I would like to have more than 50 miles of range and a cruising speed of 45 mph. Top speed doesn't need to be much over 50, this won't really be a highway bike.

I'm planning on using the QS 3000 watt hub motor, unless I really need the 4000. Can y'all help me settle on a motor/battery pack voltage?
I have no experience with the motors you are considering and the voltage you choose affects the top speed of your scoot for a given motor wind (kv).

But generally speaking, if we’re fixing the wattage of a drivetrain, I’ve found it easier to use higher volt systems because the lower amps make for lighter, smaller components. Smaller wiring is easier to work with, lower amp breakers and contactors are easier to mount and can be cheaper.

Just 2 cents. Good luck with your build.

Perhaps you've moved on already, but I have some thoughts on your Vespa conversion. When I started converting my 1961 VBB, I had no experience in EV's so I did some research into a European scooter made by a company called UNU. Since they don't sell in the states, I copied their specs and started putting the bike together. So the relevant part here is that I ended with a 52V battery, a 3KW 48V QS motor, and a Kelly Controller. For a short while, it was a blast but I could only go 30mph, which limited my routes to and from places. Skipping the cool factor of having an electric Vespa, it just wasn't fast enough, and 48V is going to leave you with a similar top speed.

The solution for me was to rebuild using a 72V battery 28Ah, 4KW 72V QS motor, using the same controller. You can skip this expensive step by going straight to a 72V solution with the biggest motor that will fit your application. My top speed now is 54mph and my range is 24-28 miles depending on how hard you ride the throttle. You'll have to find space for more battery if your goal is to have a range of 50 miles.

There are good builds on this site from members Scusi and JimVonBaden, both building a PX. My original posts were on ModernVespa under the name Resistor. These might give you a better idea of what is possible and save you some time and heartache. Plus, more power is always fashionable.
Here’s my thread: https://endless-sphere.com/forums/viewtopic.php?f=12&t=117387

I went with the QS 260 V4 hub motor and a 12” rear. 130/70-12 tires. My motor is 3000w and I’m using for now a BTR lithium battery pack. 72v 30AH. I setup my system with 3 speeds and a Votol EM150 controller. My battery is the highest limitation but I can get up to 55mph in speed 3 and have been able to squeeze out 38 miles.