DIY Electric Motor Bicycle Project

There is another alternative, to change the alternator to give out 48v, even take it out as a AC, and control it that way...

[Question already answered.]

i don't follow...

I posted a question, and then noticed it was already answered. Since posts cannot be self-deleted, I simply edited it within the 15-minute time limit.

http://www.ebay.com/itm/Wind-Turbine-Generator-2-5KW-2500W-Max-2KW-2000W-Rated-48V-60V-3-phase-AC-PM-NEW-/151062744543

Thank you very much, fine sir, love the answer, but maybe little, tiny bit price. But presiated...

Discard all the electrical BS and drive the "custom bike" directly from the B&S motor.

Put a generator on the tire if you need lights.

It is all matter of DIU lesson in combined mechanical and electrical engineering for amateurs. I think if you use 206 cc gas motor, 5hp, then you need gears, and sprockets, chain, clutch, and you don't have the pleasure to make your own electronic gadgets yourself. But if you use electric motor then you dont need all that, (just different parts).

But the question is which goes faster 206 cc motor or 300w electric motor.

And if i use pure electric power, then it is question of weight issue.

And which is more power efficient.

And i also already have bought the motor, and i do own the 206 cc motor. What a fun to be a geek..

More power to ya!

Keep us informed.

The description "48V, 3PH, DC,..., 300w" doesn't compute. 3-phase DC? Also, 300 watts ≈ 0.4 hp, which is not a very significant boost for a 206cc B&S engine, which I think is 5 hp.

Can you clarify how you intend the energy to flow under various uphill/coasting/downhill scenarios?

Here you can see similar, near identical motor.

You use PWM controller.

Interesting article, but it doesn't fully answer the energy flow question(s). As you continue to experiment, you may find out more about that. The ability to exceed the nominal 500-750W rating for brief periods makes this motor a better match for the B&S engine than what I could previously guess.

And under no load the motor is rated ca 300w. But with little modification, like bigger wires, air cooling f,example drilling a holes in the covers, then you are able to take out 450 + watts. Also by having the bike lighter that increases the capability of the motor.

The tires is very small 17" in diameter, better torque. This motor comes from a e-scooter, 70kg with batteries + 50 to 80 kg person, say average 374 pounds up to 45 km/hr. For legal reason, license and stuff, the speed is controlled. But when the bike is say 40 kg, you crank up the power and there is no speed limit, then i will put it up to 70. Theoretically.

And what happens upp hill. i will just test it out when it comes to it. Maybe i will put pedals on it also, i am trying not to, it is all question of design and style...

Thanks for the critic, appreciated...

Here guys is a cool picture for you...

Bike, like custom motorbike or bike like custom bicycle with pedals? I am very confused again, since You posted a wheel that looks like fitting a scooter.

As I read here, you will use the B&S to generate power and simultaneously charge your buffer batteries? Or just use it to charge your batteries as that?

Bringing 2 alternators, the B&S on the frame is weight that needs energy also to bring it from A to B.

I have played a bit with "assisted power motors" in the wheel(s) of regular bicycles. Unless you have far bigger types, do not expect too much of the power output.

300 Watts is still no 5 Horsepower (or 3600 Watts). And each conversion also adds up to some losses.

Definitely not following the more power to lower peak power via multiple conversion is better concept here.

As far as peak power goes 750 watts mechanical is still not much especially considering the multiple conversion you are implying plus all the added extra gear to do it with considering a typical 35 - 50 cc chainsaw engine will easily top 1500 - 2000+ watts shaft power.

The thing is anywhere a 300 watt electric motor + speed controller + 15 AH 48 volt battery system + alternator + 5 Hp B&S engine will fit the biggest most bad ass commercial chainsaw engine would also and with far less weight and size plus have far more power to boot and for far less invested cost and time to install involved as well.

I understand the e-motor is small, i get that. The thing is, this is what i got, and it is what i use. And i can always upgrade the e-motor to something bigger later on.

I appreciate the critics thanks...

My understanding: the OP plans to run the B&S at or near idle, so that it is quieter than a standard bike. The batteries allow the electric motor to run at the desired speed for traffic conditions. As he already owns the engine no outlay is required, even though a smaller engine would give a better power to weight ratio.

This set-up should be significantly more economical, as the power is stored during periods of rest (at traffic lights?) and the peak acceleration power is drawn from the batteries rather than racing the petrol engine.

We used a similar engine to drive a pump. When conditions allowed the pump to run at idle, it went all day on one fill. At full revs, it lasted less than two hours.

Thank you very much. I understand the e-motor is small, i get that. The thing is, this is what i got, and it is what i use. I have had this motor for ca 3 years, i own the alternator as a spear from a car i had. And i did bought the e-motor cheap ca 130 usd. (In Iceland everything is expensive) And i can always upgrade both the e-motor to something bigger,and i can later on if i choose to convert the bike to full motorcycle, with bigger motor, i built the frame myself with 430 mm thick steel tubes, or even go full electric. But the big picture is to build a-bike with a generator. And what i did need help with is the 12v to 48v dc converter. I was hoping to attract the attention of similar minded people, people who love putting together things, building their own pcb, soldering it to gather, and helping each other out. And maybe getting some traffic on my facebook pages.

I appreciate the critics thanks...

So are you needing to get 48 volts from a your 12 volt alternator?

If so that's not that hard and can be done a number of ways.

Internally an alternator produces 3 phase AC power the rectifies it to DC for its output.

With the AC power available a basic transformer will step up the power or a charge pump with diodes and capacitors will do it or a rewind of the alternator or modify the voltage regulator feedback circuit.

The point is getting a different and higher voltage from any common alternator is not difficult if you know how they work.

Thank you very much, i appreciate positive comments like this. I have been thinking of doing this, take out the diode bridge, take out directly AC, then crank up the voltages, then put it thru a diode bridge.

But if you want to take out directly 48v DC, is it not just question of putting higher voltage in to the rotor, and put in another regulator, then you should be able to get out higher voltages out. Am i right or wrong...

Check out 'Instructables.com' and do a search for what you're looking for, i.e. 'regulator circuits', 'electric motorcycles' you can see what others are doing and have posted...it's a good site for ideas and info. There is a chinese motor rated at 300w that can be pushed to 2500w. Met a young man here building fat tire electric mountain bike with a light weight battery pack (lithium ion @ 76v) that will do 35mph+ with a 2 hour endurance using that motor. It's derated for sale in the U.S for use on bikes.

Thanks for the comment, actually i am a subscriber to instructable and reat ther site on weekly basis, lot of good stuff over there, and i have been googling by probably 50 different words combinacion and phrases regarding to bikes, motors, electric, engineering, chemicals, tecs and science in general

If any then there is probably too much information out there, the problem is it is sometimes difficult to hit on exactly the right information you are looking for, and when you do find the right one then you have to understand the subject. My life last 5 years or so has gone to work, come home and google the internet.And learning, mechanical, electrical and chemical engineering as a layman. But when you are only a layman then it's not always easy to understand the matter. But this is why i appreciate Cr4 a lot.

And yeah it's amazing how much power you can take out from some of those e-motors, but they can be a little pricey. Maybe next step is to build my own motor.

Also this is what i love about countries like usa, how many garages engineers are out there building their own stuff, this is how great minds are born...