I looked into building an e-bike a while ago, and the technology just
wasn’t there yet. A few years have gone by, and on the RC front
amazing progress has been made. I’m not sure how this has transferred
to E-Bikes yet.
What I’d like to do is create a bike that can maintain 20MPH for at
least 40 miles on it’s own. I will end up assisting it, but I like to
have the overhead. I also don’t want to arrive at many destinations
all sweaty.
I’m thinking I’ll shell out the $ for a good power system up front,
and probably start with SLA batteries. If I get the performance I
want, I’ll move on to better batteries, probably A123s. I’ve made
A123 packs in the past, and could do it again, but combining a bunch
of 36V Dewalt packs seems like it might be better for this
application. That way I can stick with the stock tabs connecting the
batteries, and the stock case, making the pack more resilient to being
bounced around. Wiring them together will allow me to add Ah, and if
desired I could double them up as well to have a 72V system. I think
a 72V system with the run time I’d want will prove to be too
expensive, not to mention too heavy, so I’m leaning toward 36V at the
moment. A system that would allow me to switch to 72V later would be
nice, but is by no means a dealbreaker at this point.
My first thought was a ready made hub motor. The problem with these
is that they are expensive, difficult to modify, and generally lack
the oomph I would like.
Another thought is a separate motor driving to the left side of the
rear wheel. The problem with this is that it loses any stealth. A
rear hub motor with panniers/saddlebags could easily hide the electric
part of the bike. A drive system separate would be very difficult to
hide. The reason I am concerned about this is the 20MPH speed limit
for electric bikes. I have no problem gearing my bike to only do
20MPH on the flats, but if I want to pour on some pedal and fly down a
hill I could be charged with an unregistered motorcycle, and all sorts
of hubbub. I have not ruled the external drive out, I’m just still
thinking of a way to make it incognito.
For separate motor systems, I’ve been inspired by 2 pages. The first
is here. http://www.electricycle.com/
The motor he chose is rather bulky, but I could live with it, or find
another motor I found more suitable.
The second is here.
http://www.recumbents.com/WISIL/shumaker/default.htm
Being into RC planes, and a former racer of RC trucks, this appeals to
me. I know quite a bit about the electronics involved, and the motors
can be amazingly efficient. The problem with this setup is that in
addition to it being very difficult to disguise, it involves a large
amount of machining/fabrication. I don’t have a machine shop, and
want to keep my build of mostly off-the-shelf parts. I don’t mind
having to fabricate a mount to attach a motor to the frame, but too
much more than that will be over my head.
So, what do you all think of my goals so far? Is 20MPH unassisted for
40 miles a reality yet? 30 Miles would do for now, with SLA
batteries, and if I get the performance I want I’ll hop up to a better
battery form to get more Ah for the extra distance.
Are there any off the shelf products you would recommend to get what I
want?
Right now I’m leaning toward something along these lines:
http://www.electricycle.com/
I’d want the batteries stored in panniers, which may have to be
modified to stay outside the chain on the left. The upside is it
would hold the batteries, and conceal the chain. I also think I would
want to go with a brushless motor for greater efficiency. One thing
that concerns me about his system is that @ 24V, with a range of only
15 miles including pedal assist. I think a freewheeling motor could
help quite a bit with that. This motor seems like an excellent
candidate http://www.cloudelectric.com/product_p/mo-36-1000.htm It’s
freewheeling, can run on 24 or 35V (perfect for when I upgrade to 36V
A123 packs), is lighter and even comes with a sprocket! A big concern
with that motor is not knowing the RPM (KV) or dimensions. They are
painfully light on details on that motor. Efficiency, KV, and
direction of drive vs freewheel would all be great to have. Size
wouldn’t hurt either.
So, I’m very curious to hear what everyone thinks. Seems the
technology is approaching where it needs to be, I just need to find
the right stuff. Hopefully you guys can steer me in some helpful
directions?
Thanks,
Dan
Hoo boy. Just go over to the endless sphere and read awhile. You can almost buy a kit these days that will do that. This forum, for whatever reason, has a lot less ebike interest and more people into scooters, large and small.
Any way, yes, its very possible. Lifepo4 batteries are not only avaliable, but some are quite reliable and sort of affordable. Sla's are not going to get you 40 miles unless you carry a ton of em, which works better on the heavier wheels and tires of large scooters and motorcycles.
For a bicycle, using a mid size hubmotor, say 500-800 watts, speeds well above 20 mph are common at 48v. For longest range though, 36v, and speeds in the 20-25 mph range work well, and even longer range can be had at 15 mph.
My own setup, a 600 watt aotema motor, often sold under the Wilderness Energy brand, goes 23 mph for 23 miles with a 20 amp hour 36v battery from pingbattery.com Two of those, and you will have at least 40 and possibly 50 mile range at the speed of whatever motor you choose. Gets expensive though, but two 20ah 36v pings will weigh about the same as a 36v 12 ah sla pack, so it's not so bad to carry. Maybe 35 pounds including some boxes or panniers to carry the batteries in.
Take a look on the sphere at Justins ride across Canada to see what the possibilites are for a long range bike. There is also a thread with a link to a video of a talk Justin just gave on his trip. The only thing between you and a long range ebike is money. The technology is totally there now. I got so stoked about Justins trip, I am going to do some long day trips, and eventually ride across New Mexico. With one ping and a 16 ah nicad, I should have 50 mile range at 15 mph, and if a plug is closer, 35 miles at 23 mph.
Be the pack leader.
36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global
I have an Electra Townie w/ a wilderness energy BD36 hub motor. With a pingping 36v15ah battery pack it has a rather long range at 15-18 miles/hr and modest pedaling. The longest ride I ever did with it was 20 miles in one go, and I stopped mostly because my butt was sore not because the battery pooped out.
In other words I'm questioning whether it's necessary to go with all these high end things you're talking about, because the low end stuff on my bicycle is almost adequate for your needs. It would simply require a motor that's a bit more powerful and a battery that has a bit more power delivery capacity than the pingping battery.
For example I'm building a new bicycle w/ a crystalyte 5xxx series motor and a headway 48v20ah pack. Unfortunately as I noted in a recent posting the pack is not usable because one cell pair arrived dead. But the combination appears it will be powerful enough for 20+ miles/hr and perhaps the range you're thinking.
I question whether SLA can give you any decent range. They have a low energy density (in kilowatt-hours/kg) and can only deliver a small portion as usable energy before they poop out. That makes them heavy for the usable energy you can use.
That one page you linked with the recumbent -- that looks really cool. It sounds like one of your values is stealth? That is, a hub motor bicycle kinda screams electric and perhaps you don't want that? That recumbent looks like it would be hard to detect the motor's presence.
With that electricycle plan.. I've heard tell of peoples spokes breaking from mounting sprockets that way. At Staton Inc they sell wheels which can take screw-on casettes on both sides of the wheel. That would allow the normal drive train on one side, the motor'd one on the other, just like the electricycle plan, but without bolting to the spokes.
http://www.staton-inc.com/Details.asp?ProductID=3191
- David Herron, The Long Tail Pipe, davidherron.com, 7gen.com, What is Reiki
Dan, 40 miles? buy a very comfortable seat. If you average 20 MPH, thats two hours?
The Wisil link is very interesting, I hadn't looked there in a while, and the triple reduction gearing was pretty extreme. If you were willing to use a "slightly" bigger RC motor, and a slightly bigger bull gear, you could get near the same total RPM reduction with two stages.
The Peltzer bike was very educational for me, as he detailed the entire experimenting process, and the design shortfalls he encountered. I believe that saved thousands of enthusiasts from replicating the same exact mistakes. He uses a double reduction, with a toothed belt on the first one so it will be quieter than a chain.
Here's a double-reduction unit with the appropriatly sized RC motor. I believe somewhere in there they said it "might" be $400 for the gear reduction module and motor:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=7180&start=810
Initially (don't laugh) I would put three deep-cycle marine batteries on a trailer (car-sized). For traction I would use a rear hub motor, or left-side free-wheeling RC-drive.
I think you would be suprised at how easy it pulls a trailer, even with a heavy battery pack. With panniers, easy to cover rear hub, the battery trailer is easily disguised as cargo.
I have heard good things about hubmotors from ampedbikes.com, and ebikes.ca as far as product quality and customer service. This would get you rolling for a fairly affordable price and actually capable of 40 miles. later, after you've saved up more money, you can swap in more expensive Lithiums of a higher voltage.