Hybrid Moped

gearzandgiggles · Jul 22, 2014

It begins...

I come from a background of 2 stroke karts and motorcycles. I wanted to create something which was the ultimate in fun, which to me is defined by acceleration and the time to reach that acceleration, not top speed. To obtain maximum acceleration at ALL speeds, you need a Powertrain torque band which is both flat and wide and has a high amplitude.

My plan in short is to create a Hybrid Moped. Ultimately I will build up the 2 stroke engine to be very peaky and use the low speed torque of the electric motor to fill in for lack of low speed torque. I do not care for range, fuel economy or top speed, all I want is maximum acceleration within the entire speed range.

Here is my base:

Here is my starting electric motor and wheel (thank you John Holmes)

More to come ...

silviasol · Jul 23, 2014

Interesting. I have a similar plan for my scooter(stand up). I want to have the gear on a brushless outrunner motor, then the back of the outrunner have some kind of clutch connected to a 20cc 4 stroke engine. Keep updating

gearzandgiggles · Jul 23, 2014

Batteries:

I chose the Turnigy 5S 30-40C 5000mAh, I will be running 4 in series for a 20S pack.

The batteries come with 8 gauge wire and in hind sight if I were to pick a battery again, I would choose a battery pack with a smaller thickness wire (i.e. 10 AWG) so that I could use the smaller Power Pole connectors.

I have installed Power Pole 75s.

silviasol · Jul 24, 2014

Good luck!

gearzandgiggles · Jul 24, 2014

I performed a test fit of the wheel today.

The dropout has a height/slot width of 12mm and is 53mm in length

I will need to come up with an elegant solution for the torque arm (which does not involve hose clamps)

Here are some photos of the test fit:

Alan B · Jul 24, 2014

Nice start, and welcome to ES!

Is that motor axle 12mm or 14mm wide?

waynebergman · Jul 25, 2014

Cool looking project. I am guessing when the bike is close to getting up to full speed and the little 2 stroke is spinning the rear wheel faster than the electric power you will need to still give a slight amount of power input to the electric motor just so it won't drag on the system. Not sure about this but thinking back to my DD hub I had, it liked a little bit of power going to the rear wheel so it coasted freely?

Are you thinking two separate twist throttles on the bars (one on the left side and one on the right) or how are you going to throttle the electric motor? I am guessing a thumb lever for electric but not sure what you are planning?

Alan B · Jul 25, 2014

At high ICE driven speeds, if the DD motor generates voltage greater than the battery you will have uncontrolled regeneration and charging through the body diodes in the motor controller FETs. That will occur at a speed somewhat greater than the unloaded wheel speed, so it is only a problem if higher speeds are planned.

Drunkskunk · Jul 25, 2014

This should be awesome. I was thinking I should do something exactly like this with my Pug.

gearzandgiggles · Jul 25, 2014

Test fit of sprocket to check alignment with engine, amazing awesome and no interference issues:

Also if anyone ever uses the same frame to do this again the MAX REAR TYRE SIZE IS 2.25 inches

FYI. For those who ever need to purchase bolts for you 6 hole disc mount they are a M5 bolt.

Alan B · Jul 25, 2014

Very nice looking sprocket. What's the ICE RPM/top speed estimated?

gearzandgiggles · Jul 25, 2014

Are you thinking two separate twist throttles on the bars

To start with yes and then I want a synchronized throttle for both gasoline and electric motors, which can be achieved using a micro controller and that is when the fun will start

uncontrolled charging

Again a few ways to deal with this:

1. Mechanical speed limiter
Dude look at the size of my rear sprocket
2. Electronic speed limiter
Get the road speed from the halls, input into micro and when reaching the max velocity trigger a spark cut of the engine

I bought into a Kickstarter project a while ago and I think I have just found the candidate for it...

gearzandgiggles · Jul 25, 2014

Alan B said:
Very nice looking sprocket. What's the ICE RPM/top speed estimated?

Assuming I manage to reach the engine's 11,000rpm redline the top speed that sprocket max road velocity is estimated to be 38.16743282 mph, so lets just call it 38.1674 mph AND for those of you from parts of the world where speed is measure in the CORRECT units that would be 61.4245 kph

silviasol · Jul 27, 2014

gearzandgiggles said:
Alan B said:

Very nice looking sprocket. What's the ICE RPM/top speed estimated?

Click to expand...

Assuming I manage to reach the engine's 11,000rpm redline the top speed that sprocket max road velocity is estimated to be 38.16743282 mph, so lets just call it 38.1674 mph AND for those of you from parts of the world where speed is measure in the CORRECT units that would be

38.1674 mph is correct, 61.4245 kph is just weird. Why so high?

If you run out of batteries will the engine pull you home or is it geared to high?

As for charging you may want to consider opening those packs, soldering them together and adding a pcm/bms. It is easier then you think and will make it a whole lot safer then bulk charging or a whole lot easier then charging each pack individually.

gearzandgiggles · Jul 27, 2014

After spending a weekend thinking of an elegant solution to making a dropout which could transmit the torque into the swing arm without requiring welding, I gave up.

I came up with the following rudimentary design, I designed it to be strong in tension when reacting to the engine torque, but have enough flex so that you can clamp the axle. I hope this makes sense. I will weld the top section of it onto the swing arm, leaving the bottom area free to bend.

I am having these water jet cut by big blue saw, so hopefully I will have them by the end of the week.

gearzandgiggles · Jul 27, 2014

silviasol said:
If you run out of batteries will the engine pull you home or is it geared to high?

Depends on the hill that I run out of batteries on (I live in San Francisco), so in short I don't really know yet. Hopefully the engine should be powerful enough.

silviasol said:
As for charging you may want to consider opening those packs, soldering them together and adding a pcm/bms. It is easier then you think and will make it a whole lot safer then bulk charging or a whole lot easier then charging each pack individually.

Lets just get this thing running first

Alan B · Jul 28, 2014

Looks nice.

Would be good to put a clamping bolt across the open end to avoid torque opening it up.

gearzandgiggles · Jul 28, 2014

Alan B said:
Looks nice.

Would be good to put a clamping bolt across the open end to avoid torque opening it up.

Already incorporated that into the design

gearzandgiggles · Jul 28, 2014

If I were to do this again, I would design a bespoke battery case which mounts to the chassis, however here is my initial attempt. I was actually trying to hide as much of the electronics as possible as I am going for a clean aesthetic look.

Note there will be a spacer which the seat bolts to to ENSURE that I do not accidentally squish my battery packs...

bzhwindtalker · Jul 30, 2014

Ive been wanting to try this exact setup for a long time, suscribed

danjpendleton · Jul 30, 2014

max acceleration sounds fun :mrgreen:

gearzandgiggles · Jul 30, 2014

My eBay purchase arrived today, I do not intend on using a 19" rim for my bike (as amusing as it would look). However I intend on using the hub, which amazingly appears as if it will fit. WIN.

As a note, I am using this hub as it has a 36 spoke disc brake hub. I'm sure many of you will have found that bicycle disc brakes do not have the thermal mass to cope with the increased kinetic energy.

Just need for John Holmes's rim to arrive before I test my skills at lacing a wheel.

gearzandgiggles · Aug 4, 2014

My custom designed dropouts came in today and they work great (1/2" thick steel, one per side).

I will hopefully have them welding in the week, so I should hopefully have the bike running very soon....

gearzandgiggles · Aug 9, 2014

I have a friend do some lovely TIG welding for me. My dropouts work really well in clamping the axle.

Here is a little video of my first start in electric mode
[youtube]ApahG1nIAFQ[/youtube]

waynebergman · Aug 9, 2014

Do you think you will need some adjustable stops with in the drop outs to stop the axle from sliding front to back? I think with the gas motor pulling on that left side sprocket it will slide the axle with in the drop outs. Even though you have a solution in place for the axle not to rotate with in the drop outs what about front to back movement?

Hybrid Moped

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100 GW

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10 kW

10 mW

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10 mW

10 mW

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100 kW

100 W

10 mW

10 mW

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10 mW

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