Insanity? -- 3 phase battery powered MOTORCYCLE!

I had a visitor yesterday who responded to my craigslist ad about a free 200V 7.5 HP 3 phase motor. A pleasant, intelligent young man. I asked him what he was doing with the motor, and he replied that he was going to build an electric motorcycle. His plan is, apparently, to have a motorcycle based on batteries, inverter, phase converter, and a

3 phase motor drive. I just could not believe what I heard. (and still have doubts about his veracity) Am I going crazy or does this sound like a completely insane idea to you? i
Reply to
Ignoramus32687
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If he is in electronics and insane^Wengaged enough. :-)

Nick

Reply to
Nick Müller

Give some thought to this , a VFT takes 240V AC and converts to DC the rectifier side of the VFD,The VFD inverter section sees the DC and inverts it to 240 volt AC three phase. Using a VFD and supplying 240 DC from a battery bank of sufficient size directly into the DC side of the VFD you will create variable frequency AC hence variable speed.His project is very doable although I doubt if anything smaller than a car will be a big enough platform to carry sufficient battery storage.

Pete

Reply to
Pete

I might have to start proof reading before I push send , should have read VFD not VFT.

Pete

Reply to
Pete

Yes, weight and size is my main issue with that project. I asked him to keep me posted, dunno if he actually will go ahead with his project or keep me posted if he does.

If I was doing an electric motorcycle, I would use a DC motor and several small, garden tractor type batteries. I would select how many batteries are in the circuit to control voltage and speed.

I see not much reason to use inversion, AC, phase conversion etc.

i
Reply to
Ignoramus32687

Hey! Not so far fetched. We hadda a guy here in our ward a while back that modified a large block V-8 to run on steam. For his beta model, the boiler was mounted in the bed of a pickup. Production models have more efficient boilers behind the back seat of SUVs. Your guy may not be so lucky with the motorcycle though - he may run into a weight problem with all those batteries. Now, if he could put them in a little trailer to pull behind . . . hmmnnn.

Bob Swinney

Reply to
Robert Swinney

not only batteries, the motor, idler, etc all add up the weight. Weight and size are my main concern.

Regarding that steam powered V8, I am curious how come the cylinders did not rust very quickly, from all that heated water.

i

Reply to
Ignoramus32687

He could also use about 170 NiCads. :-)

Nick

Reply to
Nick Müller

Nasty question, iggy, real nasty! If you must know, the cylinder did rust up on the first stroke causing a boiler explosion. Blew the whole ass-end off of the pickup! That's when he began putting 4 inch armor plate between the boiler and passenger area.

Bob Swinney

Reply to
Robert Swinney

More sense would be to have a "series/parallel" acceleration control (just like in DC traction power applications).

With a motorcycle, battery weight is gonna be a big issue. Anything you can do to increase efficiency (including AC drive, regeneration, etc.) is a big win.

There are several companies marketing rather smartly designed electric bikes using AC propulsion and regeneration. I'm not so sure they'll ever make money but they are technologically on or ahead of the cruve.

I'm not sure what the market would be for a battery-powered motorcycle, exactly. Engine-powered bikes are already pretty energy efficient and way way overpowered for my tastes. Maybe a good-performing (in terms of endurance, not in terms of getting from 0 to 150MPH in 5 seconds...) battery-powered unit would find a market. 7.5HP would be just about the right size.

Tim.

Reply to
Tim Shoppa

Hey! I'm outta here. Gotta go mow the yard with my steam-powered lawnmower. Don't ask.

Reply to
Robert Swinney

snip

Different strokes for different folks. Going the VFD route has a lot of merit. 20 garden tractor lead acid batteries would be around 300 pounds, fit in a space 20"x32" x7" high.

Using all electronics might not be cheap but the VFD unit only weighs 20 pounds or so, is completely computer controlled with lots of feedback on speed and torque, and frees you from all the heavy duty contactors and similar.

Downside is that there is not a lot of avialable torque at low speeds where you need it the most.

Reply to
RoyJ

Sounds like he is a very lucky guy! Scary stuff...

i

Reply to
Ignoramus32687

you could just exterminate the grass with steam...

i

Reply to
Ignoramus32687

He could look at one of these

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. They're made locally and i've seen one go off a a rate of knots on the flat. One of the guys who builds them said the motor is rated upto about

70V IIRC which would be scary. The 12V system goes pretty well.

Ignoramus32687 wrote:

Reply to
David Billington

That's beyond my knowledge...

Does DC -> AC conversion increase efficiency?

And, isn't regeneration easier with a permanent magnet DC motor?

That sounds interesting.

Probably useful in very large warehouses.

i
Reply to
Ignoramus32687

He would need just 8 batteries with a 90 volt motor. I recall buying a

90 V DC motor on a flea market and reselling it on ebay. It was 1 HP, which is pretty good for a bike on a flat surface (but possibly would not push a heavy bike uphill).

Yes, that's the issue...

i
Reply to
Ignoramus32687

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jw

Reply to
jim.wilkins

Reply to
Dave

My reaction exactly.

Maybe he BSed me and had other purposes in mind. Which is fine with me.

i

Reply to
Ignoramus32687

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