Serial Hybrid Electric Bicycle "Finished"

[fitek]

I completed my serial hybrid electric bicycle. This is my second electric bike, and I find it much cooler than the first. There's still plenty of tinkering to do, but it does work. I have to travel this week on business, but when I get back I'll get some guages on it to figure out just how well it works.

Quick rundown:
SWB recumbent made from a chain store girls bike (20" wheels) and a discarded exercise machine
RWD, 24v Kollmorgen 300W, 60:9 gearing using no. 35 chain
Generator, MY1018 250W 36v internally geared DC motor with additional 4:1 gearing using bike chain
2x 12v 38Ah gel cell batteries
No other specs such as weight available now

Thanks everyone, especially Fechter (who suggested how to hook up the generator).

Further details are on my website.

http://petervieth.com/cmsmadesimple-1.0.5/index.php?page=short-wheelbase-serial-hybrid

 

[Mathurin]

Hey that's pretty badassical.

Would be super easy to rig up a 3 speed hub on that thing for great justice.

 

[fechter]

Glad to see somebody actually tried the idea. It is not going to be efficient, but that's not the primary objective here. It would be good for bikes that go so fast you can't pedal assist anyway.

 

[fitek]

Just an update: the 44 to 13 tooth gearing between the generator and cranks really isn't enough, so I'm converting the thing to no 35 chain. The my1018 came with a no 35 sprocket, so I'm not sure why I didnt just start with that. Now it's going to be 60:9 which should work a lot better.

Unfortunately the bike was crashed twice at the end of last week and pretty much fell apart. A high speed run into a speed bump took off the handle bars, and then a subsequent fall smashed a battery box and broke off the cranks. I'm rebuilding the bike based on an old Mongoose frame with full suspension. I made the welds much beefier this time, and am thinking about adding some piping to protect the sensitive stuff if the bike is dropped.

 

[lazarus2405]

Ouch. So, the speedbumps... looks like they worked then, right?

Really though, let's see some pics.

How loud is the generator when running? And what sort of speeds and ranges are you (well, were you) getting?

Edit: I got to your webpage. Sweet indeed! Not too loud at all, but stealth isn't the point at all, now is it? How do you stay balanced when pedaling at intersections?

 

[fitek]

Ouch. So, the speedbumps... looks like they worked then, right?

Hehe, with no suspension and a really short wheelbase, hitting a bump like that at 20mph is pretty bad news. I'll see how things go with the suspension. My boss yanked on the handlebars hard when he hit it, and the wheel twisted sideways and they came right off. I knew the weld wasn't very good...

Really though, let's see some pics.

Ok, it's attached.

How loud is the generator when running? And what sort of speeds and ranges are you (well, were you) getting?

It's pretty loud for a bike. The chain routing for the drive motor also means the chain slaps against the frame a little. My LWB bent is nearly silent. I suppose you've seen it but the videos are at:

http://petervieth.blip.tv/#737029

Edit: I got to your webpage. Sweet indeed! Not too loud at all, but stealth isn't the point at all, now is it? How do you stay balanced when pedaling at intersections?

By leaning against stuff like mail drop boxes and light posts. I used to do that all the time on my road bike since the seat is adjusted so my legs are straight out at the bottom of the crank travel, so I can't touch the ground unless I get off or lean a lot.

 

[vanilla ice]

How much volts does that my1018 put out when you pedal? I was thinking one of those wide range dc-dc converters would be good for something like this since you could change cadence and the voltage will remain constant.

 

[fitek]

I had it geared so I make 36volts pedaling hard. Now that the gear ratio is going from about 3:1 to 6:1 I should be able to do double that. The trouble with the DC-DC converters is efficiency and then mostly cost. All the electric stuff for the bike cost $150, and the DC-DC converters seem to cost that much too. I'm taking the bike over to my buddys tonight to mill a new motor plate and I'll see how doubling the gearing works. It's easier just to increase the gear ratio of course, since I need to purchase sprockets anyway...

 

[vanilla ice]

I don't know man, a 1018 at 72v of rpm would fly apart methinks? You can pickup cheap surplus converters on ebay or on this forum even. I'm not sure what volt output you need to charge, but I think you can wire the conveter outputs in series because they are isolated. The converter for my lights is ~85% efficient, not too shabby.

Ah ok, I got to your webpage with the progress, I'll read up on how you set it up now, I still don't understand how its wired.

 

[fitek]

It's just wired in parallel with the batteries (2 x 12v in series) with a big fat diode on the positive lead (so the motor won't spin). The diode loses some energy but without it the apparatus wouldn't work.

Yeh I was worried about what would mechanically happen to the my1018. However, if its truly a 250watt motor, I can't apply much more than that power to it mechanically since I'm not a super athlete. I figure I might not be able to pedal hard enough to 72v. We'll see.

If it breaks apart, it was only $45 anyway

 

[fechter]

A rewound version of the MY1018 sounds like it would be perfect. If it had twice the number of turns on the armature, it would make double the voltage. Rewinding is a lot of work, but not impossible.

 

[fitek]

Good news, I decided to be bold and got a ride with the bike and pieces to my friends garage to finish it up. We got the motor mounted, but ran out of bolts for the battery boxes and I left all the brake cables behind. HMMM. It was 10pm and I was 25 miles from home (and the bike doesn't fit in his car) so I mounted up the untested lithium ion pack I was loaned Xyster style with duct tape. The thing only weighs a few pounds so the duct tape secured it to the frame. Then I got on and carefully rode about a mile to the train station. The bike got lots of attention on the train, including someone who wanted to buy it on the spot. Then I rode home from the train stop.

I'm not getting as much performance out of the lithium ion as the dual SLAs, but a quick check with the DMM showed why. 7 cells measured 3.2v, while the last measured 0.01v. I have a spare cell so I will replace the dead one.

The suspension totally rocks. No more teeth rattling riding down the sidewalk...

 

[fitek]

An update just for the record as searching google for "my1018 sprocket" finds this thread. The sprocket supplied with the my1018z is NOT no.35 as most vendors claim. It's actually some beefy bicycle chain. Will update when I figure out what the heck actually fits the shaft.

 

[Mathurin]

Ah, then that cog is probably made to fit 1/8" chain like for bmx/singlespeed. Wallmart type derailleur bikes use 3/32 chain.

 

[fitek]

Yup, you are right Mathurin. Electricscooterparts.com has it right. The shaft diameter is something really odd ball -- 11mm or 7/16", not sure what. In any case, nobody seems to sell a 7/16" bore sprocket or anything like 11mm, at least not for no. 25 chain or no .35 chain. I'm going to see if I can fit a 1/2" bore sprocket on with a set screw. If that fails, the only solution I can think of is to mill a sleeve to adapt larger sprockets. That's no fun at all and I'll probably have to start looking for another generator motor.

 

[fitek]

Hah! Finally got it. I tried putting my McMaster 1/2" bore no 35 sprocket on; but it was really really hokey. I put the "key" that keeps the original sprocket from spinning on the shaft into its slot and then tried attaching the sprocket, and that went much better, but still it looked really ghetto. I didn't think it would stay.

Rather upset I dug through my box of parts and found a 9 tooth no 25 10mm D-bore sprocket I got from tncscooters.com. It *almost* fit over the threaded part of the shaft, so I took my dremel with a really worn down cut off disc and removed the flat part in the D shape. I then secured it with the original nut. Now I need to get a no.25 sprocket to attach to my cranks and see whether this works.

 

[fitek]

Updating the original thread. This bike has gone through some revisions.

It ran great for a while with SLAs, but then at my house warming party when I moved to San Mateo I got a little out of control and drove it straight into a curb and fell over, breaking off the battery boxes and messing up some other random stuff. I pulled off the MY1018 motor to use it in my "Simple Electric Bike" which uses a bottom bracket drive.

After injuring my neck a few months ago I had to go back to recumbents. I also scored 12 Makita batteries at Home Depot. And my GF moved in a few weeks ago. So I decided to make it a tandem, but it didn't work out so hot so the rear passenger doesn't contribute any power now. Tom Kabat's driftwood SWB (http://www.woodenbikes.com/driftwood.html) is the most comfortable bike I've ridden so I copied his under seat steering and added that too. Last night I finished putting it all together except for some electronics to keep the Makitas safe from the generator.

Still needs additional yellow paint!

 

[TylerDurden]

Totally cool. What was the issue with the rear stoker?

 

[fitek]

I did the measurements for the rear rider based on my 5'11" height. My passenger is more like 5'3". She can't reach the pedals. I didn't measure too well either. *My* legs kept hitting the front seat. The frame is just too cramped for two people pedaling.

Next bike, as I keep saying, will be a trike. And it will be longer.

 

[fitek]

Quick update, extended the rear end 10" with a "custom made" rear swing arm (made of EMT... hehe). Stability is much improve. Moved the motor mount to the center now and reversed the motor direction. Less chain issues so far.

I also swapped to using a 3 speed internally geared hub on the rear as low speed torque wasn't enough on hills with two riders.

 

[LOWRACER]

Yup, you are right Mathurin. Electricscooterparts.com has it right. The shaft diameter is something really odd ball -- 11mm or 7/16", not sure what. In any case, nobody seems to sell a 7/16" bore sprocket or anything like 11mm, at least not for no. 25 chain or no .35 chain. I'm going to see if I can fit a 1/2" bore sprocket on with a set screw. If that fails, the only solution I can think of is to mill a sleeve to adapt larger sprockets. That's no fun at all and I'll probably have to start looking for another generator motor.

Hi!
Cool idea and excellent work! I've seen your videos on youtube, AMAZING!

I've sent you something, but here again:

My bike: http://www.youtube.com/watch?v=U3SAFnheRJo
And the new battery: http://www.youtube.com/watch?v=Zl9ACAbocZ0

 

[fitek]

Just to update the links for this creation,

http://hybridmojo.com/evolution/serial-hybrid/short-wheelbase-serial-hybrid/
http://hybridmojo.com/evolution/serial-hybrid/full-suspension-short-wheelbase/
http://hybridmojo.com/evolution/serial-hybrid/short-wheelbase-tandem/

The bike has had one more iteration which I never documented, but photos from the last Maker Faire suffice. Most of the changes were just to polish the look of the bike:

http://picasaweb.google.com/petersbikes/100522MakerFaire2010#5499156285440624066

There will be yet one more round of changes at least, because the cargo area (the mesh at the bottom of the frame) is actually too low slung, and in tight turns it rubs against the ground. Also, the mess had sharp edges and I ripped my pants on it, so I threw it away. I'll probably use coroplast instead.