Electric Cargo-bike POWER system for steep terrain?

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Re: Electric Cargo-bike POWER system for steep terrain?

Post by MadRhino » Aug 09, 2017 11:05 pm

Pavement and mountain trails are 2 different worlds. The small mountain here, has trails that no one can climb on a lightweight pedal bike. In a wild mountain where hunters are going, it can be much more rough and dirty. Then, trails are deep and muddy sometimes, making them PITA to pedal even on the flat. Rock and roots gardens are very hard on a drivetrain, with alternate slip and sudden brutal traction. Believe me, there are lots of mountain trails where you don't want to ride other than downhill, or with a lot of power to climb.
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Re: Electric Cargo-bike POWER system for steep terrain?

Post by Chalo » Aug 09, 2017 11:32 pm

Have you considered maybe leaving those trails to people on foot? Just like we don't need cars driving all over everything, we don't need electric motorcycles everywhere they are physically able to go.

To put it another way, ride your motorbike on that stuff often enough, and hikers will eventually fix the problem.
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Re: Electric Cargo-bike POWER system for steep terrain?

Post by MadRhino » Aug 10, 2017 5:01 am

Chalo wrote:Have you considered maybe leaving those trails to people on foot? Just like we don't need cars driving all over everything, we don't need electric motorcycles everywhere they are physically able to go.

To put it another way, ride your motorbike on that stuff often enough, and hikers will eventually fix the problem.
With that kind of logic, you might as well tell the OP to go hunting in the city. The only part of your comment that does make sense to an off road rider is "we don't need cars".
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Re: Electric Cargo-bike POWER system for steep terrain?

Post by Chalo » Aug 10, 2017 10:34 am

The OP may have used the word "terrain", but I think he's going to be riding on streets. And he said average 9 percent grade, not 30. So the right tool for the job is not the same as something you'd use on mountain single track.

1000W is the limit for an electric bicycle used on public rights of way in Washington State. Wherever motorcycles are allowed, you can have as much power as you like in an electric motorcycle. But a motorcycle isn't a bicycle.
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Re: Electric Cargo-bike POWER system for steep terrain?

Post by markz » Aug 23, 2017 3:50 pm

Chalo wrote:He said his local power limit is 1000W. In that case, Cyclone has drawbacks but not advantages over BBSHD.
I still dont quite get this comment, what are the Cyclone 3kw drawbacks with no advantages?
BBSHD is 1000W
Edit - Ok did some digging around
C3kw - More low end torque, can take more power, but mounting brackets arent good, its like a big v-twin motor.
BBSHD - Quieter, Efficient, no freewheel means higher reliability, 52Vx40A=2100W is the max SpinMag would go, its like a high revving inline 4.

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Re: Electric Cargo-bike POWER system for steep terrain?

Post by atarijedi » Aug 23, 2017 11:15 pm

Hugh-Jassman wrote:Image

I have put too much thought into how to build one the best way for living on steep terrain (9% average). But I am still looking for the best example. I maybe the only one thinking about how bad transportation is going to get.

Living in the state of Washington I am restricted to a 1000w out put motor. And for 450 to 600lbs total combined weight, that is almost impossible. I figure I will need at least a 13:1 gear reduction ratio...for a 12-14 mph maximum.

And I believe that new motor technology is still going to be needed. Like vector control. What else?
First off, vector control aka FOC, already exists. All it does is align the BEMF phase and phase current so you get more efficient use of the current to generate torque. It will help, but not a lot. That is controller tech though, not motor tech. Having cosine/sine sensors in the motor instead of hall effect sensors makes it far easier, more accurate to control with FOC, but again, won't help out a lot. The thing that will help you out more is reading what the law says exactly.

That said, look into a high power motor with fewer turns, like someone else mentioned here. I made up a spreadsheet in excel a while ago to determine what specs I would need in order to climb certain hills in my area. I punched in your numbers, at 400lbs and at 600lbs, at 12mph and at 14mph, all at 9% grade. Power at the wheel needs to be 1497W to go up a 9% grade at 14mph carrying 600lbs, 1294W to go 12mph. When we have only 400lbs, we are at 859W for 12mph, and 994W for 14mph. This all assumes you are already travelling at those speeds before you hit the hill.

Had Oregon law been more like Ontario law, which states that the motor has to have continuous output power of 500W, you could get around it by having much higher peak loads for short periods. Maybe you can talk to a state congressman and get them to change the law so it states "continuous output power". Giving you the room for peak bursts up hills.
MadRhino wrote:I doubt that one can climb 600 lbs in steep mountain trails with legal power, not reliably. Then, there is no such thing as legal power in mountain trails. For the street, a 3 speed switch should do it. The weight is enough to require a motorcycle chain for a mid drive to be reliable up the mountains or riding rough trails.


It isn't possible, not 600lbs. 400lbs is though, just barely, and you have to already be at speed to do it.

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Re: Electric Cargo-bike POWER system for steep terrain?

Post by tomjasz » Dec 06, 2017 12:33 am

teklektik wrote:
Jul 27, 2017 1:52 pm
Here's the simulation for dual MAC8T motors assuming equal sized wheels with identical controllers. As you can see the motors are out of the controller-limited region (after the peak inflection point of the red motor curve) and so are not bound by the controller amp rating and are running at near peak efficiency even though they are climbing a 9.5% grade. This requires about 54 battery amps which should not be difficult to achieve (you want to run a single battery - avoid the control and monitoring complications of using two).

EqualWheelMotorController2wdSimulation.png
This is technique is essentially a graphical analysis that gives viable results given the constraint of equal sized wheels and identical motors and controllers:
  1. Set up for one motor/controller/wheel and run the simulation
  2. scrub the cursor until the required load power is twice the delivered motor power (2 motors, right?)
In the above example, you need 1600W to climb the grade and each motor will be loafing and supplying only 800W.

If you run equal wheels/motors/controllers you can use simple Infineon trap controllers and will get optimum efficiency under almost all circumstances using a single throttle with no special tuning. Recommend a CA3 to drive the two controllers to get throttle ramping and current throttle for smooth operation + 2WD PAS and/or autocruise if you wish... Since the drives are the same, you can use the CA to monitor the temperature of either motor and assume the other motor is about the same temperature. This gets you automatic thermal power rollback to avoid cooking the motors if you try to overtax them.
  • Remember, electric motor power specifications are in terms of 'rated power' not the actual power you run it at. So a 500W MAC can easily be run at 1500W although it will heat up and eventually overheat with this overrated operation. But legally, it's still only a '500W' motor. Do not be confused by comments about testing the output of a bike - the traffic statutes are written to facilitate field enforcement - so many cc's or so many rated Watts - not the actual hp output of a motor which an officer could not possibly measure. He needs to be able to make a decision based only a quick look at a motorcycle model plate or wattage sticker - hence the way the statutes are defined (of course there are some really confused state statutes out there, but that's another matter...)
Thanks for the great post, i have two MAC 10t motors and two EM3ev infineon 12FET IRFB4110 EM3ev Controllers (Black Case) and a CA3. Wondering what you would consider optimal power settings and battery voltage? I’m inept at using and interpreting the Grin chart. Learning but on z steep slope. Thank you.
Thanks Justin_le we're here thanks to you. All the best to the mods for their tireless work keeping it on an even keel.

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Re: Electric Cargo-bike POWER system for steep terrain?

Post by teklektik » Dec 06, 2017 3:01 pm

tomjasz wrote:
Dec 06, 2017 12:33 am
i have two MAC 10t motors and two EM3ev infineon 12FET IRFB4110 EM3ev Controllers (Black Case) and a CA3. Wondering what you would consider optimal power settings and battery voltage? I’m inept at using and interpreting the Grin chart. Learning but on z steep slope. Thank you.
The new Grin Simulator does 2WD natively so that will help you out.

Without knowing what you are trying to accomplish, it' really not possible to make and recommendations. Since you are using two identical motors with identical non-torque-throttle controllers, I'm guessing you are using identical wheels tires. That setup is inexpensive, super easy to set up, and always gives optimal efficiency when using a single throttle.

You will probably want to program down the controllers a bit - something like 35A battery current and maybe 70A phase current and zero block time (or as close as you can get). People do lots of crazy things with Macs, but impacts, jumps, starts on steep inclines with heavy loads, etc all tax the clutches so you need to hold back the phase amps and ramp your throttle with the CA to avoid eating a clutch.

The big thing will be you to figure out how much battery you can squeeze onto the frame. If you configure the two motors for 35A then they will want to pull a max of 70A so you would need a battery with a healthy C rate or else you will need to tone down the battery current in the controller/CA. A possible problem that you have is that you have 10T motors which have a low Kv and so need more voltage to go fast. As long as the bike is running in the controller-limited region of the curve (up hill, accelerating, etc) all motor winds perform the same so a Mac 8T would have the same torque as a Mac 10T - it's just that the 10T won't go as fast on the same voltage on the flat.

So - you need to figure out how fast you want to go to get your target battery voltage with the 10Ts. Then figure out what battery you can get/afford that will give you a healthy continuous discharge current. Divide that in two and that's the battery current limit (more or less) that you should use for your controllers - the CA uses an external shunt common to both controllers so that gets set to the full battery current. Macs like a phase-to-battery current ratio of about 2:1 for Infineons so set your phase current about twice your rated current in the controller. You can fiddle around with settings, but these rule-of-thumb numbers will work fine. So - as an example - if you get a battery with a constant discharge current of 60A, then you would set the CA to 60A max and the controllers to 30A 'rated' current (or a bit more - maybe 35A to get some headroom for fiddling with the CA) and set the controller phase current in the Infineons to about 2x the controller rated (battery) current or about 60A. Plug that stuff into the simulator and see what it will do.

So - as an example, if you get a 52V pack and want to climb a 10% grade you will see this:

2WdMac10T_52V_10pct.png
2WdMac10T_52V_10pct.png (91.07 KiB) Viewed 129 times

This shows 24mph up a 10% grade without overheating with a power draw of about 1600W @ 84% efficiency. The controller is set to 35A/70A rated/phase Amps (max combined of 70A/140A) but we see that on this grade the bike is really only drawing 20A+20A = 40A. In fact, we see from the plots that we are out of the controller-limited range (to the right of the peak in the red line) and so the controller setting is not even in play at top speed on this hill. The controller-limited region comes into play under even heavier load like accelerating, but at the speed/load in this example it's really the motor that's limiting things. The same setup will hit about 28mph on the flat or go up a 15% incline at 22mph and eventually overheat in an hour (lonnnng hill). To make this work, you need a battery that can continuously discharge at those battery rates (say 40-50A) and you would crank the controller or CA back down to those levels (or maybe a bit higher so you can briefly accelerate before get down to the long haul).

If you go to a 72V battery on the same grade, you get this:

2WdMac10T_72V_10pct.png
2WdMac10T_72V_10pct.png (99.1 KiB) Viewed 129 times

This is zipping up the 10% grade at 32mph and drawing about 46A from the pack. The bike should hit 37mph on the flat. But that's a pretty big pack if you are using Lion batteries.

Anyhow - hope there's enough stuff here so you can do your own What-Ifs depending on your specific terrain, loaded bike weight, funds, etc. Read my build thread - very similar to what you are contemplating.
Last edited by teklektik on Dec 07, 2017 8:04 am, edited 1 time in total.
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Re: Electric Cargo-bike POWER system for steep terrain?

Post by tomjasz » Dec 06, 2017 7:53 pm

Thanks that gives me a big start!
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Re: Electric Cargo-bike POWER system for steep terrain?

Post by wturber » Dec 06, 2017 9:24 pm

I don't see much wiggle room in the Washington State law.

RCW 46.04.169
Electric-assisted bicycle.
"Electric-assisted bicycle" means a bicycle with two or three wheels, a saddle, fully operative pedals for human propulsion, and an electric motor. The electric-assisted bicycle's electric motor must have a power output of no more than one thousand watts, be incapable of propelling the device at a speed of more than twenty miles per hour on level ground, and be incapable of further increasing the speed of the device when human power alone is used to propel the device beyond twenty miles per hour.
[ 1997 c 328 § 1.]

Note that is says, "an electric motor." That could be interpreted as being only one motor or one or more. The sentence following says, "The electric-assisted bicycle's electric motor must have ..." That seems to leave out the notion of there being more than one motor.

I'd check legal precedent before designing with two motors for Washington.
[Edit: By that I meant designing for re-sale. Designing for your own personal use is, IMO, a whole different ball-o-wax.]

About the only wiggle room I see is that it says the power output of the motor must not exceed 1000 watts. It doesn't say power draw or rated power. So you could dyno test the motor's shaft output and tune that to provide 1000 watts of measured output (+ or - some reasonable engineering error). In this way, you can bypass some of the motor and controller losses and get maximum legal motor output.
Last edited by wturber on Dec 07, 2017 9:14 am, edited 1 time in total.
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Re: Electric Cargo-bike POWER system for steep terrain?

Post by teklektik » Dec 07, 2017 8:33 am

Ignoring the nonsense about one motor which has nothing to do with the intent of the law, this law isn't too bad since it does not rely on rated motor power (normally the most inarguable constraint), clearly specifies power far in excess of that required to achieve 20mph, and additionally indicates that the power is artificially limited to 20mph so a CA is usable to achieve that end (i.e. it's not just the motor power that is limiting performance). Here you can set a CA MaxPower to 1000W/82% efficiency ~= 1200W and set the speed limit to 20mph and the bike should be legal in the absurd happenstance that a beat cop actually has a dyno in the trunk. Set that as the power-up preset. What you do with the other presets is up to you...

I'm guessing a 52V battery will do the job for you. Get something with high discharge rate cells. On one bike I run a MAC 10T on a custom 52V EM3EV battery and it's a really good ride experience. Your 2WD will go a bit faster but would have massively faster acceleration and hill climbing ability than my 1WD.

All the junior Matlock business aside your best plan is as frequently mentioned here - don't drive like a jerk and no one will care.
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Re: Electric Cargo-bike POWER system for steep terrain?

Post by tomjasz » Dec 11, 2017 5:21 pm

teklektik wrote:
Dec 06, 2017 3:01 pm

If you go to a 72V battery on the same grade, you get this:


Thinking about this option. 14S7P Battery Option 20.65 AH 30Q 60A Smart BMS. OR since it's not as much speed as 2wd traction with studded tires on ice, I could reprogram the controllers and run a 36V setup and build a custom battery. I have enough PF cells for 10s10p. All riding is on the flats, and I'd like to use the bike for Ice fishing. Walking on snow and ice is slow.....

OK off to sort what I can on the Grin simulator. I apologizer being a dullard. Old guy with aphasia and slow at calculations.

Thanks!
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Re: Electric Cargo-bike POWER system for steep terrain?

Post by John in CR » Dec 11, 2017 10:47 pm

My suggestion would be to run a 1000W hubmotor as a mid-drive, but not StokeMonkey style. Instead run a belt-drive direct to the rear wheel with the appropriate reduction. That is because for every uphill there is the same downhill on any round trip, and regen is important for minimum maintenance and optimum safety, as well as better range in mountainous terrain. It's also the quietest way to go for near silent operation, a big factor in my book. The only drawback is that a hubmotor as a mid-drive takes up a good bit of real estate on a bike, but that can be a non-issue on a cargo bike.

In choosing the hubmotor pick a high speed wind, which will give you higher rpm for the same voltage, and then gear it down more than you would with a slower motor. The reason is for greater efficiency during climbs, better regen, and better cooling at the higher rpm.

It behooves you to find out exactly what the law is. eg is the 1kw limit a rating of the motor, input power, max output power at the wheel. They are very different things.

Instead of worrying about controllers, since 1kw can be done with quite cheap controllers, you need to worry about batteries. That's where your liability risk is resides as a vendor, and the last thing you want is to have a bike you produced burn someone's house down.

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Re: Electric Cargo-bike POWER system for steep terrain?

Post by tomjasz » Dec 12, 2017 12:28 pm

No mountains, no need for high speed, I need traction and reliability. I think, given the popularity among some very active builders, single controllers for 2wd will sooner or later be marketed. Don't know if your comments were pointed towards me, but thanks if they were. They are just not inline with my riding conditions.
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