Need assistance finding a motor for my application

The Toecutter

The Toecutter

100 kW
Joined
Feb 8, 2015
Messages
1,312
I have been building an electric-assist velomobile for the last several months and it is getting close to time to order the components for my drive system. It's a tadpole trike and is rear wheel drive.

However, I haven't come across a drive system that meets my needs during my searches. I was wondering if anyone here knew of a system that would meet my requirements.

My requirements are as follows:

-at least 3 kW peak power
-pedelec system that senses torque output of rider's pedaling and applies electric power proportionally
-less than 10 lbs motor weight
-motor must be able to be decoupled from powering the trike
-greater than 85% motor efficiency during low power outputs of < 500W when operating at cruising speed(~30 mph)

The topic for my project is here:

https://endless-sphere.com/forums/viewtopic.php?f=3&t=66772

Out of everything I searched, I really like the Astroflight 3220 motor used in recumpence's build, but it has no built-in torque sensor, and I am not certain as to how I could get this motor to work with a pedelec setup because of that(I don't want to use a cadence sensor as they don't operate to my liking; I want is to base the level of assist on my torque or power output).

My power requirement means that I will have to have the motor providing power to the rear wheel in a separate system from the chain that is driven by the pedal crank. Recumpence's system can do this, but his uses a thumb-switch, instead of being a pedelec. A split-broach spline could perhaps be used for this?

There are a few hub motors by Crystalyte and others that come close to my requirements, but I would prefer a mid drive so that I don't have to deal with motor losses when under pedal-only mode. The BionX systems are nice, but are too lower power for my liking and their battery is integrated, limiting my build options too much.

My project is primarily going to be a human-powered vehicle and I'd like to be able to keep going even if the battery is drained. I just want some ass-hauling capabilities on the side for picking on cars at stop lights... and when needed, a low amount of assist for a long duration so that maintaining 30 mph all day long isn't much more physically stressful than walking.
 
If this thing can really be made to work with PAS, then it's perfect, other than the price tag! That being said, if I can figure out how to affix this to my vehicle, I may just part with the money for it...

This plus a 48V 30AH LiFePO4 pack would work great for my project.
 
The Toecutter said:
If this thing can really be made to work with PAS, then it's perfect, other than the price tag! That being said, if I can figure out how to affix this to my vehicle, I may just part with the money for it...

This plus a 48V 30AH LiFePO4 pack would work great for my project.
Click to expand...
If price is the problem, get a bbs02 or the new bbshd.
 
fredfire said:
The Toecutter said:
If this thing can really be made to work with PAS, then it's perfect, other than the price tag! That being said, if I can figure out how to affix this to my vehicle, I may just part with the money for it...

This plus a 48V 30AH LiFePO4 pack would work great for my project.
Click to expand...
If price is the problem, get a bbs02 or the new bbshd.
Click to expand...

For the level of performance, the price is no problem...

It would turn this into a $4,000 project instead of a $2,500 one though... but the idea of being able to have an electric recumbent velomobile that could accelerate up to highway speeds like a sports car, and in the state of TX, is legal without license, tags, registration, or insurance, and can be run on pedal-only mode if the battery gets drained effectively giving it infinite range at lower speeds, is too tempting to pass up... It's going to have a big, obnoxious red anarchy sign painted on the side.

It would have roughly the same top speed with this monstrous Astroflight setup as it would with a BBSO2. The only real differences between the two drives will be price and acceleration... and the BBSO2 is heavier, putting it at a disadvantage since I have to keep the total build weight under 100 lbs for it to legally be a bicycle in this state... The more free weight available, the more battery I can fit and keep to that 100 lb limit.

I would definitely have to start an Astroflight setup out de-rated to say 750W or so through the controller, and work my way up from there to find the max safe limit so that I don't kill myself during a mechanical failure, and then upgrade the components as needed before reprogramming the controller's max current limit(Dr. Bass torque arms, re-laced 14ga high tension wheel spokes, roll bar, hydraulic disc brakes, ect).

4,000W/300Nm from the Astroflight theoretically gets me from 0-50 mph in under 6 seconds... A 750W BBSO2 still theoretically gets me to 50 mph with about 250W of pedaling, without ripping the vehicle apart, but much more slowly from a stop. My long term goal for this first prototype is a human powered vehicle with car-like acceleration, that is legal as a bicycle.

I'd rather not buy two drive systems and instead get the high end system and choose to upgrade max power through controller reprogramming as the mechanical robustness of the vehicle was upgraded over time. I don't plan on gearing it beyond 50 mph, as I imagine with no front suspension, all but the smoothest roads might get a bit harrowing over 30 mph... which is the intended cruising speed.

Doing more than 50 mph or so is for a second prototype, if I do one, and should I do a second, I'd be looking at a full suspension setup with a monocoque, gearing set up go as fast as possible, maybe even triple digits... which with the right aerodynamic efficiency, the Astroflight 3210 at 4,000W would be more than adequate for, and could be swapped right over to without buying the second drive system.
 
fredfire said:
Check out http://www.tangentmotors.com/
With the cycle analyst and a torque sensor, you can add the PAS feature.
Click to expand...

With a Cycle Analyst and a torque sensor you can add the PAS feature to almost any setup, not just the tangentmotors one.


The Toecutter said:
It would have roughly the same top speed with this monstrous Astroflight setup as it would with a BBSO2. The only real differences between the two drives will be price and acceleration... and the BBSO2 is heavier, putting it at a disadvantage since I have to keep the total build weight under 100 lbs for it to legally be a bicycle in this state... The more free weight available, the more battery I can fit and keep to that 100 lb limit.
Click to expand...

The top speed is limited by the motor's power, I ton't think you will be able to get to 50 MPH with the BBS02 kit, check this calculator:

http://www.kreuzotter.de/english/espeed.htm

Avner.
 
I actually simulated 52.9 mph by inputting the following:

-Streamlined Trike(Quest)
-Rider's Height: 71"
-Rider's Weight: 140 lbs
-Bicycle Weight: 100 lbs
-Air Temperature: 68°F
-Height above SeaLevel: 1150 ft / m
-Slope of Road: 0%
-Wind Speed: 0 mph
-Pedaling Cadence: 100/min
-Offroad Tire 1.75"
-Offroad Tire 1.75"

-Power: 1,000W

If I put out 250W with my legs and the motor puts out another 750W, that's 1,000W. I currently have 20" double-walled rims with 14ga spokes on my front wheels with Maxxis Hookworm tires at 100 psi. I will probably be putting a 26" wheel with 14ga spokes and a 26" Maxxis Hookworm tire or a motorcycle wheel with a Pirelli ML75 in the rear(all comes down to what kind of sprocket set I can fit into a motorcycle wheel with my 135 mm dropouts). I intend to build a body roughly as efficient as that of a Quest, as I'm planning on a CdA of ~1.2 sq ft, vs the 0.9911 sq ft the calculator set for my selection, but the reality is I am going to make it as aerodynamic as I can and might do better than a Quest, as I'm an engineer with some knowledge of aerodynamics, and the Quest made a lot of compromises for ergonomics, visibility, and practicality, that I won't necessarily have to make. The calculator input 0.00626 for my Crr, which seems like a reasonable number.

This calculator was surprisingly close to my own calculations, in spite of the fact that it didn't let me enter my own CdA and Crr values, as the "streamlined trike" option had values similar to what I expect for mine to be.

In my own simulation using a custom spreadsheet, I'm inputting a 6 sq ft area, 0.2 Cd, 100 lbs bike weight, 0.008 Crr, 140 lbs rider weight, and 60 lbs of carry-on weight.

My idea is to go long distances at 30 mph with me inputting slightly more power that it takes to walk and the electric motor adding twice as much power to that, which should put the total pedal power input at ~100W and total motor power ~200W for ~300W at 30 mph. With a 1.2 kWh battery, I could do almost 200 miles a charge like this. With a recharge, that is potentially 400 miles of travel in one day.

If I turn the electric drive off or drain the battery, the same 100W of pedaling theoretically gets me to 18 mph, which is still much better than an upright road bike. I am capable of roughly 1 kW peak for a few seconds judging by my ability to reach 32 mph on the flat on my decrepit and dated Raleigh Technium road bike, and figure I might be able to do 750W for long enough to reach perhaps 45 mph on pedal power only in this trike once it's ready, which wouldn't be an unusual figure for a well-designed velomobile. If I want to do 50 mph, 1 kW in total is about all I need, which a BBS02 gets me most of the way there left unmodified. If I want to haul ass and f*** with cars at stoplights and do donuts in parking lots, and ride like a jackass, that's what the 3+ kW is needed for... and that's why I like this $1,800 Astroflight setup, since the stock BBSO2 won't allow enough power for that.

Best of all, this vehicle will be 100% legal to operate according to TX e-bike law as it is written, with no license, registration, insurance, tags, title, or any of that nonsense.

Get where I'm going with this yet? :twisted:
 
Keep in mind that peak power is available at about %50 of the motor's top RPM. So you will need to gear the motor for about 100 MPH in top gear to reach the 50 MPH target speed. Also I'm not sure that the motor will survive running at 1KW for extended periods.

I installed a BBS02 on a friend's mountain bike and while it's a nice package, I'm not sure it will meet your expectations.

Maybe users more experienced with BBS02 will chime in.

Avner.
 
ferret said:
Keep in mind that peak power is available at about %50 of the motor's top RPM. So you will need to gear the motor for about 100 MPH in top gear to reach the 50 MPH target speed. Also I'm not sure that the motor will survive running at 1KW for extended periods.
Click to expand...

I know it won't survive running 1 kW for extended periods. I could always set the pedelec system up to allow peak power for maybe 20 seconds, and then scale it back, perhaps giving me 500W at 50 mph while I pedal in the other 500W.

It should be adequate for travel... the only problem is that it would also be boring. I like rapid accelerations when the opportunity presents itself!
 
Put a mxus on it?
Where are you based?
 
ferret said:
fredfire said:
Check out http://www.tangentmotors.com/
With the cycle analyst and a torque sensor, you can add the PAS feature.
Click to expand...

With a Cycle Analyst and a torque sensor you can add the PAS feature to almost any setup, not just the tangentmotors one.


The Toecutter said:
It would have roughly the same top speed with this monstrous Astroflight setup as it would with a BBSO2. The only real differences between the two drives will be price and acceleration... and the BBSO2 is heavier, putting it at a disadvantage since I have to keep the total build weight under 100 lbs for it to legally be a bicycle in this state... The more free weight available, the more battery I can fit and keep to that 100 lb limit.
Click to expand...

The top speed is limited by the motor's power, I ton't think you will be able to get to 50 MPH with the BBS02 kit, check this calculator:

http://www.kreuzotter.de/english/espeed.htm

Avner.
Click to expand...

Hey Ferret. I have a 9 speed cyclocross road bike that I'm trying turn into a pedelec. Is this all I need?

http://www.ebikes.ca/shop/ebike-parts/cycle-analysts/ca3-dps.html (CA3 DPS)
http://www.ebikes.ca/tdcm-128.html (TDCM torque sensor)
http://em3ev.com/store/index.php?route=product/product&product_id=166 (BBS02 Mid drive)

Should I go for something more lightweight than the BBS02 since I'm going more for a road bike feel?

Thanks,
Lawrence

https://www.lesswrong.com/posts/o5PojLYFEWtyeo4ct/the-ai-that-pretends-to-be-human (The AI That Pretends To Be Human)
 
Lawrence,
I've never ran a pedelec setup myself.
I was planning to implement one in my GNG-Spot build at some stage using a Cycle Analyst and a torque sensor on the chain . After some riding I came to the conclusion that a pedelec setup is not really suitable for the singletrail riding I do and dropped the plan.

I'm no road or CX expert, but maybe a hub motor would suffice for your riding?
I think some hubs come with a built in torque sensor.

Avner.
 
ilikepancakez said:
ferret said:
fredfire said:
Check out http://www.tangentmotors.com/
With the cycle analyst and a torque sensor, you can add the PAS feature.
Click to expand...

With a Cycle Analyst and a torque sensor you can add the PAS feature to almost any setup, not just the tangentmotors one.


The Toecutter said:
It would have roughly the same top speed with this monstrous Astroflight setup as it would with a BBSO2. The only real differences between the two drives will be price and acceleration... and the BBSO2 is heavier, putting it at a disadvantage since I have to keep the total build weight under 100 lbs for it to legally be a bicycle in this state... The more free weight available, the more battery I can fit and keep to that 100 lb limit.
Click to expand...

The top speed is limited by the motor's power, I ton't think you will be able to get to 50 MPH with the BBS02 kit, check this calculator:

http://www.kreuzotter.de/english/espeed.htm

Avner.
Click to expand...

Hey Ferret. I have a 9 speed cyclocross road bike that I'm trying turn into a pedelec. Is this all I need?

http://www.ebikes.ca/shop/ebike-parts/cycle-analysts/ca3-dps.html (CA3 DPS)
http://www.ebikes.ca/tdcm-128.html (TDCM torque sensor)
http://em3ev.com/store/index.php?route=product/product&product_id=166 (BBS02 Mid drive)

Should I go for something more lightweight than the BBS02 since I'm going more for a road bike feel?

Thanks,
Lawrence

https://www.lesswrong.com/posts/o5PojLYFEWtyeo4ct/the-ai-that-pretends-to-be-human (The AI That Pretends To Be Human)
Click to expand...
 
I don't understand...you're just quoting yourself from several years ago. Did you want to ask a new question? Or followup on something?
 
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