How to read Justin's simulator graphs?

[Reid Welch]

Sheepish to say, I'm not sure.

For example, this generated graph of the highest-speed 4 series motor, the 406:

Q: what is the power consumption at the maximum speed?
Is it 800W at 25mph? I just want to be sure of that.

If so, that's the same as my Unite MY1018 motor's power consumption at that speed on level ground, no wind,
as nearly as I can tell by the Drain Brain.

edit:

link to the Simulator
http://www.ebikes.ca/simulator/

edit: better screenshot installed, but,
I am still too colorblind to make out the red from the green lines.

 

[Lowell]

Looks like 500W output at 20mph to me. 71% efficiency means 705W input power. The crappy thing about the smaller hubs at low voltage is they never make enough power to get to the top of the efficency peak. Try comparing the 406 at 48v and a 5304 at 48v. Not so much the peak power, but the shape of the overall power and efficiency curves.

A 5304 with a 48V NiMH pack would make a great 30ish mph mountain bike with 85% peak efficiency and reasonable cost.

 

[Reid Welch]

Thanks Lowell, as you see now by my edit notes: I can't distinguish the red from the green in thin line form; colourblind here.

So--my question now is what is the battery power consumed at, say 25mph, rather than the Wattage developed by the motor.

Thanks!

 

[Lowell]

Thanks Lowell, as you see now by my edit notes: I can't distinguish the red from the green in thin line form; colourblind here.

So--my question now is what is the battery power consumed at, say 25mph, rather than the Wattage developed by the motor.

Thanks!

300W output at ~81% efficiency would be 370W input. That should go a long way at 25mph with a bit of pedaling.

 

[Reid Welch]

300W output at ~81% efficiency would be 370W input. That should go a long way at 25mph with a bit of pedaling.

Feh, that can't be right. See

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



And my bike would need more than that output because I'm on very wide low pressure slick balloon tires, and sit fully as upright and high off the ground as any cyclist can do. Super-non-aero.


On my bike it's about 800W taxed of the battery to get a guesstimated 550W of work function.

hmmm...any 406 users here? Report your -actual battery drain at the speed of interest, please--your drain at 25mph.

 

[Lowell]

The simulator should be right, but it doesn't predict what's actually possible on a particular bike. 300W on a racing bike is supposed to go 25mph...

 

[Reid Welch]

The simulator should be right, but it doesn't predict what's actually possible on a particular bike. 300W on a racing bike is supposed to go 25mph...

yeah, 317 to be exact, on the skinniest high pressure tires, and the rider in full tuck and none of us are running that way.

So--same number, "hands on top" of the racing bike's bars (semi upright stance), same weinie-bike, and the power requirement jumps to 440W.

And my bike is so much worse. I'm full upright and the bike is all clunky.
Whose is not? And this must require 500W at the least.

Problem with fat tires is not so much rolling resistance, but wind resistance at higher speeds than about 20mph.
So says Sheldon Brown I think it was.

 

[Reid Welch]

OH

I just now tried out the german calculator site's "Roadster" option.
I had previously presumed that meant a roadie bike.

No, it must mean more like the heavy steel cruiser bike.

The air temp was entered as a more realistic 78F (Miami)
The pedaling cadence was entered as a nominal figure
(increased cadence costs more power---windage I guess)

Here's what it says now:



Now isn't that a bucket of watts to supply?

Insofar as I can tell from the jumpy DB readings (it has no smoothing function)
this bike of mine at 25 sucks 800W from the battery.
The DB readings will be fluttering from say, 650 to 950W all the while.
The actual wattage may be a bit more or less than the 800W
I think my bike sucks.

(gotta find jokes even by line breaks).

Seriously---I'm thinking that the $45, 250W output-rated MY1018 gear motor, brushed and all,
is not such an awful lossy drive system after all,
even though I'm running it far, far over its normal mortal limits.

If a 406 should draw one hundred watts less than I do on a sub-$400US e-bike at 25mph,,,,, well, so I feel that's not a heck of a difference in relative efficiencies between two dissimilar systems.

But maybe it's more nearly 200W I pay in heating air by use of a brushed gear motor?
That's still not so bad a showing for my bike.

Here I am comparing a hugely-out-of-its-depth bargain ebike
up against an optimized single-moving-part hub motor, running at its peak efficiency point.

And there does not seem to be a big difference possible in their comparative power draws from their batteries

except...that the cheap gear motored Currie cruiser has gear motor torque across the entire rpm range; and a 406 does not.

hummm.

Something about these online calculators is screwy.

The only -sure- settlement of the question is to run two bikes,
one like mine, and one with the 406; both with Drain Brains,
preferably with identical battery packs, side by side.

The only -realistic- settlement then, is to gain some wattage report from a 406 owner, -or any Crystalite user, who also has a Drain Brain,
access to dead-flat smooth roads, no wind, and will offer his wattage figures here, of wattage consumed at 25mph

 

[Toorbough ULL-Zeveigh]

Forget the colors and just go by the shape of the curves. I'm sure there's exceptions but generally speaking for hub motors certainly they're always pretty much the same.

The easiest & the one you're probably least concerned about is the torque curve. Ideally it's a straight line sloping down. On the real curve the slope may deviate from perfectly strate, but it's always negative.

The power & efficiency curves have both a positive & negative sloping side to them. The power curve is the more symmetrical of the two. The efficiency curve has it's peak point pushed over more to the extreme right than the power peak. As well the efficiency peak typically has that little 'up-tick' in slope as it nears the top.

To make it easier to remember I use a little mnemonic aid:

1. torque is a ramp
2. power is a hill
3. efficiency is a cliff


Remember it's only a rule of thumb that seems to hold up from what I've seen thus far. If I'm labouring under any misconception or there are any significant exceptions to this then I would appreciate being set strate.

 

[Reid Welch]

Thank for that. It's a help.
But what I want to learn now, is what the 406 equipped bike typically draws from a battery
when the bike is running 25mph on a level road, in still air.

Can anyone deduce that from Justin's simulator, or from real life?

My bike seems to require 800W.

 

[TylerDurden]

I can't help w the 406 info, but regarding the graphs:

if you can distinguish the colors below, it is a simple trick to invert the original colors using your graphics software.

sorry to say you will need to pull a screenshot to do it (kind of a texas two-step), bcause inverting yer total display gets tricky.

 

[Lowell]

406 would need 48v to put out that kind of power... who's got a setup like that? Speak up and be counted (watts that is)

 

[Reid Welch]

Thanks Tyler---that helps.

Lowell, again I think we're talking different Watts?

It's not "puts out" that kind of power. It's the raw power supplied by the battery, before subtracting the various losses.

Or is that what you meant?

As a quick answer, since you have an super e-bike, and I suppose you have some metering, you might note sometime the amperage draw at 25mph and the battery voltage at that particular moment and do the multiplication?

It would be so instructive to see reports from all types here, all who can do 25 or more, just what it costs them in Watts to run at 25 per.

Thanks!

 

[Lowell]

I'll definitely do a wattage check at 25mph when I have the cells re shrink wrapped.

 

[Reid Welch]

8)
thanks guy.
And thanks again Tyler for the inversion for this colorblinded fool.

I can really see the pink line in the graph.

I hope that don't mean I'm gay

or something.

:lol:

 

[xyster]

I hope that don't mean I'm gay

or something.

It's the 'or something' that worries me....

 

[Mathurin]

Got it to show 600w out at 25mph.
600w out @ 75% eff = 800w in

With 35A controller it gets better eff, looks more like 775w in:

 

[Reid Welch]

Thank Quebec for simu-graphs
so well read by their own Math.


What does it all mean? Refer to page one. Yanks don't use the term "hoser", but Canadians all know it.

I will now hose the 406---that most efficient of the C-lyte line at that speed and loading,

because my cheap and sturdy simple low-tech old school brushed gear motor Unite MY1018 is affording
nearly identical economy at that same speed and load,
plus, being a gear motor, it pulls well across the band.

I never would've thunk it....

Huh. Needing now a bigger hose
because I want to soak the brushless direct drive crowd reallly well.
(jk, I love you spendthrifts, I am one myself)


Little geared motors forever
At $45 per pop
I can afford them even if they were not to last so long.

Let's see
when I get a good lipo pack again, how much and for how long
I can run the "250W" Unite at 800W input.

I am optimistic, you bet on that.

------------------

Now to find that proper hose and turn on the cold water.


Thanks Francois,


Reid

 

[Reid Welch]

Join the club of Hub Motor Hosers?

That's me, third one in the middle, right





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madcap verse:




Firemen deluded
firefight denuded