Vespa EV conversion

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jstept's picture
Last seen: 2 years 1 month ago
Joined: Friday, August 24, 2007 - 13:11
Points: 57
Vespa EV conversion

Hi, there. I just joined the forum. I have a project in the conceptual stages and I wanted to get some feedback from the experts.

I would like to convert a vintage Vespa motorscooter to a BEV. I like the looks of the drive systems offered by, since they include controller, throttle, contactor, fuses, wiring, and charger. I was thinking of using a 48V system with an Etek motor, using LiFePO4 batteries instead of SLA. Would anyone hazard a guess at what kind of power/acceleration that will get me?

I was considering getting the LiFePO4 batteries from Even though they are 40 Ah, they are expensive, and
have no included BES. How important is the BES? I'd need 15 of them to get to 48V. What kind of range will that get me? I'm seeing more attractive prices from some of the Chinese battery manufacturers, and they often include the BES. I'd like to try and fit all the batteries within the Vespa frame, so having it in several pieces gives me some flexibility in where I can locate them.

If I have to go with SLA, I don't think I'll have a problem fitting four small ones inside the frame. I suspect that my range will be substantially smaller than for the lithium cells.

A Vespa engine drives the rear wheel directly, and the rear wheel is removable from one side. The forward part of the engine attaches to the scooter frame with a pivot and is connected to the top of the frame with a spring/shock, so the whole engine acts as the swingarm. If I can find a dead Vespa engine case, I'll cut away the bits I don't need and add a mounting plate for the engine. Otherwise I'll have to build a swingarm/engine mount from scratch. The advantages to using a dead engine are that all the connection points are right where I need them and I can re-use the drum brake assembly inside the engine casing. Also a lot less welding. I might also be able to use some of the gearing inside the existing engine, although I plan to have fixed gearing.

The tire has a diameter of about 16". Will a 3:1 gear ratio work? I calculate 1200 rpms at the tire should get me to 55 mph.

I'd like to do all the lighting with LEDs, even the headlight, if I can. Maybe throw on a small amp and speakers so I can hear tunes while I ride. I assume that connecting to just a few of the series-connected batteries to pull off 12V is a bad idea, so I'll need a small transformer, correct?

Any comments on my scheme? Are there any major items I'm missing?



reikiman's picture
Last seen: 1 day 4 hours ago
Joined: Sunday, November 19, 2006 - 17:52
Points: 8447
Re: Vespa EV conversion

My first question is, do you really need to do the conversion yourself? There are several makers of EV's with the styling of the Vespa, and you can be on the road pretty quick. Electric Motorsport may even be able to help you locate an Oxygen Lepton scooter, either working or as a glider. I was talking with Todd today, and he had on display an EVT 160, 60 volt, that you could buy right now.

To answer your questions...

The range/speed is determined by the kilowatt-hours you can stuff into the vehicle. If your LiFePO4 pack ended up as 49.5 volt 40 amp-hour it would be approximately the same kilowatt hours as a 48 volt 50 amp-hour lead acid battery pack, at oh.. 10x the cost, and at 1/2 the weight. Another important characteristic is the size of the two packs... would the vehicle have the physical space to hold the pack. So for example a LiFePO4 pack weighs 1/2 the equivalent SLA pack, so with the same weight you could have a 49.5 volt 80 AH LiFePO4 pack, but who knows whether it would be the same size.

Thundersky makes a BMS so I don't know why electricmotorsport isn't selling it. It may be Todd thinks it's safe w/o the BMS. The Lithium Lightning bike is built using these cells, and doesn't have a BMS, and is a very impressive bike.

The Vespa lookalikes tend to have 48 volt 50 AH of batteries, tend to do 30 miles/hr, and tend to get 20+ miles range. They tend to be hub motors however which is a different gear ratio consideration.

LED lights... one thing you need to think about, since it will be a MOPED or even MOTORCYCLE (in the eyes of the DMV), you will need to get this registered to be legal, and you will need to ensure you are using DOT certified lighting in order to be legal. Right? That said there are LED based DOT certified lights for at least the running lights. I have heard there are DOT certified LED headlights, but am not 100% sure of that.

And a sound system sounds way cool. But would it make the bike a thief target?

- David Herron,

P.S. welcome to the board

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