ebikes.ca Hub Motor Simulator

[marty]

Would someone explain the blue, red and green lines on ebikes.ca Hub Motor Simulator. Use simple words please.
http://ebikes.ca/simulator

Battery details are:
48V 20Ah Li-ion
(13 cells)
max discharge current 60A (peak)
Go here if you would like to see battery pictures.
http://endless-sphere.com/forums/viewtopic.php?t=1170

Wheel size is 26"
Go here if you would like to see bicycle pictures. On page 2.
http://endless-sphere.com/forums/viewtopic.php?f=3&t=2688

What would be best controller and motor? Would like 30 MPH or faster, and range of 20 miles or farther.
Think I want to go 30 MPH Electric bike I got now - Bionx PL350 http://bionx.ca has top speed of about 20 MPH Would like to go faster 8) DO NOT want to go 50 MPH due to fear of falling down.
For you metric people:
30 miles per hour is equal to 48.28 kilometers (km) per hour
20 miles is equal to 32.19 kilometers

Want rear hub motor 26" wheel with 160mm disk brake, Thinking about only using one rear gear and eliminating the rear shifter? So 1, 5, or 7 speed freewheel should be fine.

Thanks all for your help with Electric Bike Project # 2

 

[TylerDurden]

It's really three charts in one.

Blue = torque:
the units are on the left, the torque diminshes as speed increases

Red=power:
the units are on the right, the peak power output is in the middle of the speed range

Green=efficiency:
This has a trick... the green line across the top represents 100%, you have to factor the units, but the line sits on the 50 of the torque units, so you can simply double the peak point on the green curve (2x41=82%)

OK?

 

[marty]

Blue = torque:
the units are on the left, the torque diminishes as speed increases

OK I understand that. Think my car works the same way?

Red=power:
the units are on the right, the peak power output is in the middle of the speed range

Is peak power output the amount of electricity the motor uses? Want to use less electricity so that battery lasts longer. Correct?

Green=efficiency:
This has a trick... the green line across the top represents 100%, you have to factor the units, but the line sits on the 50 of the torque units, so you can simply double the peak point on the green curve (2x41=82%)

I am lost on this one? But to keep it simple. A 90% efficient furnace uses less fuel then a 70% efficient furnace. Therefore it is best for the green line to be the highest at the speed I plan to ride. Correct?

 

[safe]

I am lost on this one? But to keep it simple. A 90% efficient furnace uses less fuel then a 70% efficient furnace. Therefore it is best for the green line to be the highest at the speed I plan to ride. Correct?

Yes.

It's very similiar to a gasoline motor in that there is an "ideal" rpm that the motor likes to run at. This is because the motor uses permanent magnets that have a fixed amount of magnetism. When the speed of the motor hits this perfect balance with the magnets then the motor is running at it's peak efficiency.

If you are particularly smart you will quickly realize the implications of this in that had your hub motor the ability to "shift gears" it could have better efficiency and power. There is a thread around here somewhere that talks about an SRAM 5 Speed Hub Motor that seems to be doing this.

Hub Motors are easier to use, but not necessarily the most efficient system when you think in terms of overall performance. (they only work best in a narrow speed range)

 

[TylerDurden]

Blue = torque:
the units are on the left, the torque diminishes as speed increases

OK I understand that. Think my car works the same way?

Your car has peak torque at a certain engine rpm. Your car might hit peak torque in each gear, if you drive like a maniac.

Red=power:
the units are on the right, the peak power output is in the middle of the speed range

Is peak power output the amount of electricity the motor uses? Want to use less electricity so that battery lasts longer. Correct?

The power curve represents the force generated at the wheel... like a car, the peak of power output usually is not the most efficient; but can make you go faster on the flats, in a vacuum.

Green=efficiency:
This has a trick... the green line across the top represents 100%, you have to factor the units, but the line sits on the 50 of the torque units, so you can simply double the peak point on the green curve (2x41=82%)

I am lost on this one? But to keep it simple. A 90% efficient furnace uses less fuel then a 70% efficient furnace. Therefore it is best for the green line to be the highest at the speed I plan to ride. Correct?

Bingo. BUT: you want to have a system that also provides the periodic peak power you need for any hills or drag races you may encounter.

 

[fechter]

OK, the graph will predict how much power you will consume, the torque, and efficiency for any given speed.

What it doesn't tell you is how fast your bike will go.

I think there's another part of the simulator (or another simulator?) that will tell you how much power or torque it takes to go a certain speed. This depends on slope, weight, and air drag.

You kind of need both parts of the picture.

 

[Eric G]

The speed and power calculator.I think this is the other simulator Fechter is mentioning...

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

Eric

 

[marty]

Chart

Weights of different motors:
Crystalyte 406 motor 6.5kg 14.3 LBS
Crystalyte 5304 motor 9kg 19.8 LBS
Crystalyte DC brushed motor 6.1kg 13.4 LBS
FalconEV Green Hornet 6.8kg 15 LBS

FalconEV Green Hornet looks the best to me. What do you all think?

 

[fechter]

There you go, thanks Eric.

Now you can get a better picture. I think the speed number is pretty optimistic for normal configurations, but with some aerodynamic improvements it would be close.

 

[TylerDurden]

Chart... FalconEV Green Hornet looks the best to me. What do you all think?

Depends on what your priorities are... and the chart can only tell a small piece of information, based on mfr claims.

Any one of those motors may have a high failure rate, ridiculous price, odd size... etc.

:?

 

[marty]

Chart... FalconEV Green Hornet looks the best to me. What do you all think?

Depends on what your priorities are... and the chart can only tell a small piece of information, based on mfr claims.

Any one of those motors may have a high failure rate, ridiculous price, odd size... etc.

:?

Priorities are light weight motor, high torque, low power or watts used. Please correct me if I am mixed up. Still learning about ebikes.ca Hub Motor Simulator.

One more thing that I don't understand? Why do all 3 lines, blue, red and green go to 0 at end of Hub Motor Simulator graph? Wouldn't power or watts be higher when motor is going as fast as it will go?

I just learned how to put a quote in a quote!

[quote="TylerDurden"][quote="marty"]text[/quote]text[/quote]

 

[fechter]

Where it goes through zero would be what happens on a steep downhill road. Going downhill, the bike goes faster, and the amps drop. If you go fast enough, the motor will start regenerating into the batteries and the current would be negative at this point, which the graph shows.

On an uphill, or with a headwind, etc. the motor speed drops, and the amps go up.

 

[marty]

Where it goes through zero would be what happens on a steep downhill road. Going downhill, the bike goes faster, and the amps drop. If you go fast enough, the motor will start regenerating into the batteries and the current would be negative at this point, which the graph shows.

On an uphill, or with a headwind, etc. the motor speed drops, and the amps go up.

OK think I understand? Due to real world conditions, wind, tires, rider weight, and all the things listed on the Bicycle Speed And Power Calculator
http://www.kreuzotter.de/english/espeed.htm
The bike don't go as fast as shown in ebikes.ca Hub Motor Simulator.

Could try to figure this out with math problems or do as fechter says "One test is worth a thousand opinions"

 

[Eric G]

Hi Marty,
With the sim at ebikes I find it fairly close to being accurate for my setup ( dc motor,25amp controller,36 volts,20in.wheel)if I subtract 20% from its readings.

I find the bicycle speed and power calcularor almost bang on esp. since I've gotten my Watt's up meter and compare watt hrs used over a given distance at a set speed.

Eric

 

[Dr. Shock]

Marty, I'd think the most direct way of finding out which motor is going to get you to 30 is to ask the group who's going over 30, and what setup they're using.

As far as range goes, that largely depends on whether you can lift the bike onto the rack on the front end of the bus. I'm only half joking. I think you'll find that weight is a big factor in both speed and range. I sometimes add a WE 36v SLA battery pack to my four DeWalts for a long trip. I find that it slows me noticibly even though I'm already 250 lbs. While it adds to my range, I know the weight is also working against me. I'd probably do as well without the SLAs if I dropped 50 lbs. Other things being equal, if you need more range, start with the lightest batteries you can afford and buy as many as you can carry.

 

[monster]

like fechter says the simulator only works for a given speed. so don't think that an X503 is really inefficient at 20mph because it is "designed to run at 40mph."

at 20mph you may only have 22% throttle so you could get up to 70% efficiency. the trick is to accelerate slowly to stay in the rpm that is most efficient for the motor. this is the reason why hills and acceleration drain batteries -because the speed you are at doesn't match your accelerator position and is below the "efficiency peak" speed.

 

[marty]

Enough drawing charts. Time to buy a motor!
Falcon looks the best to me :? No one seems to be selling. Did not contact Andy directly, but if it's not for sale? I no buy.
Crystalyte 406 looks to have more torque then 407 at 30 MPH. Think torque is important to make bike move? So 406 is better?
Crystalyte 5304 is heavy
Crystalyte DC brushed is lower cost
Now the competition is between Crystalyte 406 and Crystalyte DC brushed. The chart I made shows 30 MPH as shown on ebikes.ca/simulator. There is more to think about then 30 MPH. There is GETTING TO 30 MPH. I make another chart showing 2 motors at all speeds.

Crystalyte 406 = dashed lines
Crystalyte DC brushed = solid lines
Brushed motor looks good at 40 MPH only problem is no torque. Gets pretty windy at 40 MPH. I think the 406 is faster better motor for what I want to do. What do you all think? Any other morors to think about? Next question is where to buy?

 

[Ypedal]

Go with the brushless...

 

[monster]

actually im not sure i understand how to use the simulators my-self. fechter are you supposed to find the power required to reach a desired speed using the speed and power calc and then try and feed that into the ebike.ca calculator? cos how do you feed it in? do you pick a throttle setting that gives the maximum in power as the power given by the other simulator and then read the efficiency that is verticaly inline with that power maximum?

so for me an X503 at 25mph would be 50% efficient but an X505 would be also 50% efficient? that can't be right.

you could match the peak power to the other simulator as before but then read off the efficiency at the speed of the other simulator but that doesnt work for all motors?

im confused :?

 

[monster]

or do you just always read the efficiency from the point on the curve vertically inline with the peak power and ignore the other simulator?

which gives 10% efficiency difference between x505 and X503.

 

[TylerDurden]

or do you just always read the efficiency from the point on the curve vertically inline with the peak power and ignore the other simulator?

Yeah... peak power is only peak power tho. You don't always want to be there; you want to cruise in a more efficient zone, to keep from overheating.

The 'zotter calculator is just a nice tool to find your power req's.

 

[josh]

Hi Marty,

Before you rush out & possibly buy a motor not best suited for your needs:

Like Fechter & the others have said, to work out the top speed of a motor you need to know what power is needed to go x mph, and where that line crosses the red line of the motor's output power is roughly the top speed.

So 30mph needs about 6-700W minimum I'd estimate (depends how much drag bike & rider produce), so both those motors might do around 30mph or more maximum full throttle, but at that speed the efficiency (green line) is below its maximum, only 70% rather than 80% efficient, suggesting the motor is geared too high & that a lower geared & higher voltage motor might be more efficient & give better mileage per charge .

You could try different motors in the simulator & work out in the same way their top speed & efficiency, in order to pick a motor & battery & wheelsize combination which gives you best performance. Geared motors like the eZee hub motor give slightly lower eficiency than non-geared like the crystalyte, but are around 50% lighter and give higher low-speed torque/acceleration.

PS I forgot to add that geared hub motors, though lower peak efficiency than non-geared, are more efficient and higher power and torque than non-geared over a wider range of intermediate speeds and throttle settings - compare a crystalyte 408 with the eZee hub on the simulator to see what I mean - this performance is good maintaining speed & range on slopes/gradients and hillier areas .

I hope thats useful.

 

[fechter]

Yes, the simulators are confusing. It would be nice if the features of both were combined.

The ebikes.ca calculator will tell you how much power a motor produces for a given loading, but does not tell you the load. It really needs one more line for how much power the bike needs to attain the given speed (wind resistance + grade + rolling resistance). The faster you go, the more power it takes.

The kreuzotter.de simulator will predict how much power it takes to push a bike at a given speed depending on aerodynamics, weight, and grade. You should probably do the calc. for the desired top speed on flat ground and one for the the minimum acceptable speed on the steepest hill you want to climb. Once you know the watts and speed for these operating conditions, then use the ebikes.ca simulator to see if a particular motor combination is capable of making the required power at the speed used in the first calc. You can also see what the efficiency is.

If the first calc says you need, for example, 750 watts to go 30 mph, then you look at the ebikes.ca graph and see if the motor power curve is higher than 750 watts at 30 mph. If not, then the bike won't go that fast.

I don't think the simulators are very accurate for partial throttle conditions either.
I would assume 100% throttle on all these simulator graphs.

If you take a X5 or whatever motor at full throttle and start climbing a progressively steeper hill until the motor stalls, then you would follow the lines in the ebikes.ca graph. By the time the hill is steep enough for the motor to get down to 50% of top speed (even though you are still at full throttle), the efficiency is like 50%. It will be starting to generate significant heat at this point.

This is not to be confused with running at less than 50% throttle and half of top speed.

Ideally, you would want to pick a motor that will be near the peak of the efficiency curve at the most typical operating condition. If you have a lot of steep hills, you also need one that will develop sufficient torque to get you up the hill. There will be a trade-off between optimum flat ground efficiency and hill climbing ability.

 

[marty]

OK I go here http://www.kreuzotter.de/english/espeed.htm

What am I doing wrong? I see no Watts? What goes in the Pedaling Cadence Box? I am not pedaling.

 

[Drunkskunk]

you set the cadance to 0.
leave it at 90, it needs that to work. this calc wasn't realy ment for figuring motor power, so it has some querks, but it works. I came up with 797 watts for your numbers.


Somethign else to note, if this calculater says you need 800 watts to go 30mph, and your motor on Ebikes.ca shows to be only 80% efficent at 30mph, then you actualy would need around 1000 watts to actualy go 30 mph.