* * * Ebike Simulation Program * * *

[safe]

20% Slope HillClimb

Okay we take a Crystalyte5304 running at 100 volts and 80 amps and the Pmg132 running at 72 volts and 100 amps.

Then we race them across a 1000 meter (length) uphill that peaks at 20% slope. (the hill starts flat and gradually increases in slope)

First the time:


...and then we look at the speed:

View attachment 2
...and then the power output which is clearly in the favor of the Pmg132:


...finally we look at the heat produced:

View attachment 3
...so it's pretty clear that the Pmg132 has so much power compared to the hub motor that it can conquer this 20% slope with ease.

This is a case where raw power (Pmg132) is the prevailing theme.

 

[safe]

Unite Motor vs RC Motor?

If there was a racing class devoted to a 1000 watt input restriction then one might ask:

"Well, wouldn't all the bikes be exactly equal then?"

...the answer is "No". The reason is that input is not the same as output. We also have to consider efficiency. Let's compare an RC motor (Axi5345_14) verses the Unite motor I have plans to use on my Project #003.

First the Axi5345_14:


...now we look at the 1016Z3 (overvolted) that I'll be using:


...the result is as follows:

Peak power RC Motor - 875 watts
Peak power Unite Motor - 775 watts

So I would be DOWN 100 watts of power even though I would be using the exact same 1000 watts of input power!!

That sucks! The RC Motors are awesome... I'm going to have to do that one day. :? (eventually)

Note: I used Armature Current Limiting combined with Wattage Restrictions on these dyno charts.

 

[safe]

Star and Delta Two Speed Motor

Brushless motors have the potential to be rewired while in use so that you in effect "shift gears" electronically. While the controller logic to achieve this looks difficult it's also not impossible because people have done this before.

So how much of an improvement might we see in our track time using a two speed brushless motor verses the one speed?


I've set these two up as identical Axi5345_14 RC motors using a 1000 watt restriction circuit. (dyno above) The results are as follows, the two speed reduces our time by about three seconds:


...and the top speed on the downhill side of the hill is increased by about 18 mph:

View attachment 2
...so if there was a race going on between a fixed speed bike and a two speed bike there's little debate that the two speed wins hands down.

This seems a good way to go... it would be a high technical hurdle on the electrical side, but maybe there might be a controller someplace that already does this?

Anyone know of any links?

 

[Toorbough ULL-Zeveigh]

Anyone know of any links?

yes.

 

[safe]

Anyone know of any links?

yes.

Gee... so helpful... :?

Seriously... in order to really make these RC motors deliver in real world situations (uphills and downhills) they ought to have the ability to exploit the Star-Delta toggle. From a software perspective it looks like the controller needs to be able to basically "pause" in the transition and then be able to figure out where it is in the new configuration and then get back to delivering power.

This is really doable... and it makes a significant improvement over a fixed gear machine... the simulation just confirms that gearing really matters and is important... that's all...

And I'm trying to think down the road to future situations where people are trying to race these things. You know that some restriction will be involved (rules are to be expected) and so if everyone is allowed a fixed wattage value (the most logical way to do it) you then turn to figuring out how to win under this restriction.

I'm just thinking several steps ahead that's all. :wink:

 

[Toorbough ULL-Zeveigh]

Gee... so helpful... :?

well sir, you axed.
kay, here's a link with all the answers:

kidding of course, Link only has most of the answers.
This link should prove more helpful.

http://google.com


ya c, u refused to sim how much better a 5305 fares uphill.
Instead u ran the 5304 to stack the deck, knotty, gnawtty!
one hand washes the other, doncha no.
of what are u afraid that will be revealed?

alrighty, presuming you haven't found what ur looking 4 already,
if u take another simulation request of mine I'll point u in the rite direction.

This is really doable... and it makes a significant improvement over a fixed gear machine...

yeah, I know.
my ebike's been "doin' it" for the past 7000 miles.

 

[safe]

....u refused to sim how much better a 5305 fares uphill.
Instead u ran the 5304 to stack the deck, knotty, gnawtty!

The 5304, or 5304 are only slightly different.

Come on... we're talking about the mighty PMG132 which is really in a totally different league than the relatively crude hub motors. The pancake design and low motor resistance means that it's efficiency and power dwarfs the 5304, 5305. (it's roughly double the power output)

The power of the PMG132 is so much higher that it just overwhelms anything in comparision.

If you are going to have a 25 lb motor the PMG132 is simply a better motor for hill climbing or the flats.

To the PMG132 the hill in the simulation (20% slope) appears like it's not even there...

The motor resistance of the 5304 is 0.42 ohms and the 5305 is 0.5 ohms.

By comparison the PMG132 motor resistance is 0.016 ohms.

RC motors are usually around 0.02-0.08.

The PMG132 is more like the RC motors than the hub motors... (excellent)

 

[safe]

A Summary

We can conclude (based on the data in the simulations) that:

The hub motors tend to be the heaviest and least efficient of the motors tested.

The PMG132 (a motorcycle motor) equals the weight of the big hub motors, but delivers efficiency equal to the RC motors. (the PMG132 is a well built racing motor) The PMG132 produces double the power output of an overvolted hub motor.

The RC motors deliver excellent power output that roughly equals a big hub motor running up to about 100 volts. RC motors are very efficient as well as light weight.

The Unite motors deliver performance that is somewhere in the middle, but tends to have higher motor resistances and so are not great performers. (but they are cheap)

 

[safe]

The Geared vs Fixed Shootout!

Let's say that there was something like the ePower Challenge race being run at Portland International Raceway, but rather than nothing but flat you get a track with some hills in it more like Sears Point (Infineon Raceway) Raceway in Sonoma California. If the racing organization provides a 1000 watt restriction circuit for your bike in order to equalize the competition then all you have left is to figure out the MOST EFFICIENT way to use the watts you get.

So you build yourself an RC motor based machine that gets exceptional efficiency... in the 90% range.

Your competition shows up with some lousy Unite motor that only gets about 78% efficiency.

At this point you think:

"Oh I'm so golden... I've got this race locked up!"

...but wait, the guy with the Unite has decided to run an 8 Speed Sturmey Archer internally geared hub and if it doesn't blow up before the race ends he might have a chance to win.

Let's compare these two machines over the "default" track I've been using that has a hill in the middle of it. (5 meters or about 15 feet high) The track is only 200 meters long (two football fields) so the 5 meters happens in a small area. It's realistic to encounter a hill of only 5 meters. (one can imagine much bigger hills)

First let's look at the gear ratios that get employed in this little race we are doing:


...now we look at the Power Output that those gears (or lack of them) will deliver:


...and the efficiency that translates into:


...which means we are going to go this fast:


...and the heat total between the two bikes looks to be very close:


...finally we look at who "won".

The lousy Unite bike with it's 78% peak efficiency motor BEATS the fancy schmancy RC motor because the guy with the RC chose to use just one fixed gear (a big mistake):



Moral of the Story

The moral in all this is that you can't rely entirely on the technical prowess of the motor alone to increase your efficiency or power. The way to think is to do BOTH things at the same time, to improve the efficiency AND apply multispeed gearing at the same time.

My guess is that a Star-Delta electronic shifter idea would probably come pretty close to eliminating the advantages of gearing for the lousy Unite.... but one way or the other if you claim to be SERIOUS about improving the overall performance of your machine you need to think about the entire system and it's real world riding behavior in order to seek the best overall solution.

Gears can make a lousy Unite beat an RC motor.

Like the Tortoise and the Hare... :wink:

 

[Toorbough ULL-Zeveigh]

The 5304, or 5304 are only slightly different.

well, when u compare 'em that way, I don't c any dif either! :lol:
gee, I guess MENSA musta dropped its reading comprehension requirement.


btw, what was the wheel size on that run?
if ur able to stack the deck with gearing the (s)perm for optimum, that howz bout some fair play?
Give the crystalyte some similar advantage that play to its strengths.

For a complete & proper simulation, place a dual-wind 6306/6303 into a 20" dia. wheel.
And to even things up on the other side, have the PMG driven by a 275 lb. out of work insurance salesman from Peoria who's a recovering alcoholic & is going thru a messy divorce.
The hubbie can be piloted by a 90 lb. highly trained chimp, say, i dunno, Nichole Ritchie.
oh, & just keep things fair, have her in the middle of a messy divorce too.


Think ur simulator is up to the task?

A Summary

i think yer yella...
from the data collected so far it's clear.
u only pick comparisons that further ur own biased outlook to make urself look good.
This leads me to wonder if the same bias has crept into ur coding, u know, GI-GO?

I'm callin' u out...
bwaaaakk, bwak-bwak-bwak...

 

[AussieJester]

I thought the drive setup Matt was building for the rc motors will be run through the bikes gearing system Safe? Can you do a comparison between the two motors Unite and RC with the rc motor utilizing the bikes gears also? Doubtful at this stage ill continue on with electric bikes if i do the RC motor is the obvious direction to take, would be interested to see how much better it is under optimal setup ie. using bikes gears also

Cheers in advance

Kim

 

[safe]

...place a dual-wind 6306/6303 into a 20" dia. wheel.

Smaller wheels means a LOWER effective gear ratio though!

The lower gear ratio would help on the hill portion, but it would make the bike slower on the flats. I'm not sure how this helps your argument. :?

It's "obvious" to me that the smaller gear ratio would not help the weaker hub motor in the overall track time, but if you are really having a hard time seeing this I'll run a simulation with a smaller wheel.

The PMG132 is already 15 mph faster than the hub motor on the flats. (the PMG132 produces double the power output after all, you have to expect that the extra power makes the difference)

What are the 6306/6303?

Are those other Crystalyte hub motors?

(they do seem to make many models)

Possibly a better test might be:

"How many volts must the 5304/5305 run in order to EQUAL the power output of the PMG132 at it's designed peak power output?"

Maybe you might want to see that one.... maybe 144 volts would make the hub motor competitive?

 

[safe]

Can you do a comparison between the two motors Unite and RC with the rc motor utilizing the bikes gears also?

Sure.

This is the same comparison only this time the RC motor gets the same 8 speed as the other bike.

Now the efficiency of the RC motor really stands out:

View attachment 2
...the speeds are different only in that the RC motor has a little more power:


...and the race (predictably) goes to the RC motor:


When the gearing is equal the RC motor easily wins.

(and I just used the same shift points on both bikes, so the RC motors shifts could likely be improved so that it would do even better than this)

The RC motor is clearly the better motor... but if you fail to connect it with gears you lose your advantage. Excessive pride in one's motor efficiency might cause someone to make this design mistake because they don't understand the value of gearing in it's ability to improve overall efficiency.

Efficiency has two parts:

Gearing efficiency
Motor efficiency

...you need to pay attention to both types.

Note: In order to make these two totally equal I dropped the aerodynamic number on the RC motor bike to equal my Project #003 projected value. Speeds above about 40 mph are heavily influenced by aerodynamics, so without correcting for that it would not have been fair. The top speed would be less for a bike without full fairings front and rear.

 

[AussieJester]

When the gearing is equal the RC motor easily wins.

i Assumed it would it was by how much that i was curious about...Thanks for
that Safe So when are you switching to the RC motor i have seen you express interest in Matts gearbox design and hinted you would go with an RC motor one day? There is one for sale on the forum RIGHT NOWcheap if your interested? I know you like a bargain hehee...Comes with 100amp ESC too brand new never been used...I have doubts it would work without burning out ESC on my heavy ass trike with me on it towing my wheelie chair, would definitely need a slipper clutch i think...will be Unite motor for me for time being, think the next motor change will be to a 60cc china gurl motor :-S

 

[safe]

Hmmmmmm.... interesting.... I'll have to try simulating this one.

$230 shipped.

I just spent $150 for another batch of NiCads (80) and couple more chargers. Realistically I just want to get my current project completed before embarking on another tangent. The future will be with motors like the RC motor... but I've got a lot on my plate already that hasn't gotten done yet.

Once I blow up my Unite motor (which will probably happen after a few thousand miles) I'll upgrade. Plus, the little Unite has a 9:1 geardown built in, so I don't have to worry about that at this time.

This Turnigy looks like a nice motor.

 

[nomad85]

Turnigy's are ok. I dont know the exact details, but I believe they are less efficient than the axi motors, but better than the HTX motors. I would get something nicer if you want it to last and get the maximum efficiency, if you just want to try it, not a bad motor.

 

[safe]

Turnigy's are ok.

Sometimes I have to think in terms of "cost benefit" terms. Is the extra power gained with the higher efficiency motor worth the extra price? Could I get more distance by taking the $200 difference and just buying more batteries? (the Unite motor only cost me $50)

I like the idea of RC motors, but the simulation shows that the benefits of motor efficiency are about the same as the benefits of gearing efficiency. The "cheap" way to gain a better return on investment is to run your motor through your gears.

The best is a combination of an RC motor and gears.

Eventually I'm going to cave in and pay for an RC motor with all it's necessary geardown components, but it might not be right away... :wink:

 

[safe]

Comparing Efficiency Advantages

Okay, so let's say we want to ask the question:

"How much of an advantage is there between getting a more efficient motor or running the motor through the gears?"

Now that's getting to be more relevant because now we are really focusing in on the "relative" benefits gained by making one of two possible decisions.

I won't redo all the charts because they've been done already, but let's look at the result in terms of time:


...you can see that the Blue line is the Unite motor bike with gears and it delivers results that are right in the middle between the fixed gear Red RC motor and the geared Green RC motor bikes.

The "bottom line" is that efficiency gains are made in one of two ways. The gearing gives about half of the gains. The other half is the motor efficiency improvement.

Take your pick...

(or pick both)

 

[safe]

Unlimited Power?

Just to keep a sense of reality here...

If you really don't give a damn about the kind of restrictions that a 1000 watt racing class would introduce and wanted to see how much relative power the RC motor has compared to the Unite then this gives some idea of what happens. When you throw off the wattage limitation for the RC motor your power levels go up so high that it makes the Unite (running at near it's peak power anyway) look rather pathetic.

So in a "wide open power" situation the RC motors brutal power dominates completely:


...comparing apples to apples and oranges to oranges makes the question of gearing important because you are talking about equal power levels. The easiest way to improve performance is to simply increase power. And more power also produces better efficiency in many cases because a hill that might normally drop the rpm of a lower powered motor (causing low efficiency) doesn't do that with the stronger motor. The stronger motor doesn't get bogged down as easily.

In this case the full powered RC motor is pumping out 2500 watts at peak. (the others are all restricted to the 1000 watt input limit)

 

[safe]

Axi5345_14 Dyno at Full Power (36 volts - 80 amps)

 

[gogo]

Would it be safe to say, looking at the graph above, that if you were doing a lot of stop and go driving a centrifugal clutch with a 2000 RPM engagement point would help avoid a lot of motor heat and would help scoot you across an intersection quicker?

 

[safe]

Would it be safe to say, looking at the graph above, that if you were doing a lot of stop and go driving a centrifugal clutch with a 2000 RPM engagement point would help avoid a lot of motor heat and would help scoot you across an intersection quicker?

Recumpence did something he called a "slipper clutch" which was more of a way to keep his initial geardown from having troubles with the belt slipping. In general you have the right idea I think... low rpm power is not "good power" because it's mostly heat. Efficiency is always highest near to the no load rpm speed. (just a little below it)

If your gearing is correct then you get through these low rpms pretty quickly and then get into the more efficient areas, so the heat is only there for a limited time.

Motors have a thermal mass that allows short periods of excess heat to be absorbed before the motor fails. However, if you have a situation where it's a heavy load (like a steep hill) and your gearing is too high, then the sustained heating will probably cause something to fail.

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

The nice thing about a motor like this is that it produces such a huge amount of power (3.3 hp) that you have few situations where a hill might bog you down.

Power is the easiest way to solve problems... and the RC motor delivers the power without weighing a ton... I mean... 25 lbs... which in bike terms is the same thing. :wink:

 

[safe]

Chuck... you ought to download my simulation and go through the coding to look for errors.

Seriously...

In fact there are some issues that I'd like to improve and if you are interested in making those improvements then we could post a new version.

 

[mclovin]

Safe,
I downloaded you app. and was looking over the files. I'm not familiar with .gp files so I'm wondering what editor to use for making tweaks? I was able to open the files with Notepad but I'm curious to know if there is a special editor (as is the case for XML files etc.)?

 

[TylerDurden]

Safe was banned. Looooooooong story. Possible the longest story ever told. You can find him on other boards. As he states, his sim should be reviewed for omissions and errors.

For a reliable calc, check the one from swbluto: http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=6892&p=119810#p119810

For a motor sim, check http://www.ebikes.ca/simulator/

They should be a good start.