``` The Gearing Advantage ```

[safe]

There is real math behind the re-rating process

A link would be nice... that's a new term here and deserves to be explored if it's real... let's see a link!

 

[TylerDurden]

A link would be nice... that's a new term here and deserves to be explored if it's real... let's see a link!

http://endless-sphere.com/forums/viewtopic.php?p=26704&highlight=#26704


http://www.dhos.net/memory_care_clinic.php

 

[safe]

"Re-rating" is the same as "over-volting".

Sorry, I didn't download that pdf before. (then I would have know that)

The vocabulary is now cleared up for me.

 

[TylerDurden]

"Re-rating" is the same as "over-volting".

Nope.

It is a little more complicated than that.

 

[Lowell]

I certainly don't ride around at full throttle all the time, especially in the city as I would end up going faster than most of the cars. Part throttle efficiency is definitely important.

My car will do 0-60mph in under 3 seconds, and would be quicker if first gear was tall enough to hit 60. 2-3 tenths are wasted in shift time

 

[disndat]

Lowell your car is faster than my GSXR750??????I am not trying to argue with you but what kind of car do you have.Anything that I have encountered that is faster than my bike(0-60) is usually not even close to being street legal.Just curious.Sorry to change the subject.

 

[Lowell]

It's an all wheel drive Eagle Talon with a built 9:1 compression motor, individual throttle bodies, tubular stainless header, HKS 272 cams and an FP3065 ball bearing turbocharger @ 30psi boost. The engine computer is a laptop programmable unit, and I run a secondary alcohol system which allows virtually unlimited boost on pump gas.

If you have a 127hp '04+ Gixxer 750 it would be a close race from a dig, and I would pull away slightly on a roll on. The '04 750 is around 3.1 seconds 60-100mph, and I pull mid 2.9's. What I've found though is that very few riders can actually duplicate the magazine times for bikes. Often the best numbers are acheived by flyweight pro riders and should be taken with a grain of salt.

The car is 100% street legal, power windows, leather etc. and is perfectly fine at the racetrack or getting groceries.

The turbo: dual ball bearing center section and stainless steel turbine housing.

And to keep this ever so slightly on topic, I rebuilt the transmission with a different 1st gear ratio, double syncros and a few other tricks.

 

[cadstarsucks]

"Re-rating" is the same as "over-volting".

Nope.

It is a little more complicated than that.

True, differences in vocabulary do not help. I was trying to use vocab in common use here in my explanations, but I guess it was counter productive to do so.

Dan

 

[safe]

True, differences in vocabulary do not help. I was trying to use vocab in common use here in my explanations, but I guess it was counter productive to do so.

No big deal. People have been over-volting their motors here for a very long time. It's always fun to realize that someone else has invented a different terminology for the same thing. I suppose to be fully technical this is supposed to apply to AC motors and not DC, so maybe that is our way to distinguish the terms?

It's also interesting in that their chart pretty much pinpoints where the best effiency of the motor is located. We normally would be searching in the dark to find a "sweet spot" of high effiency, but using this more disciplined technique you could really be able to say:

"This is as good as this motor can run under any circumstances."

...and have the confidence to know you were probably right.

So it's a nice more scientific approach to over-volting.... um... I mean re-rating. :wink:

(the contour lines in the chart are for efficiency)

 

[fechter]

What motor is that from?
Seems to have a pretty big 'sweet spot' of over 90% efficiency.

 

[safe]

It all started here. You have to download the pdf file and then open it and search around to find it. It looks to be a big industrial motor... not something we would ever use.

http://endless-sphere.com/forums/viewtopic.php?p=26704&highlight=#26704

 

[disndat]

Lowell thats really impressive.My bike is an 07 and has 134hp at the wheel.I am not really into drag racing(the race track is more my thing)but its fun to smoke wannabes on the street with their riced out cars- just have to watch out for cops.Ok back to the topic.I think Safe is right about if you want to tinker gears are the way to go but unfortunately most people want the easiest drop in solution.They should make a universal mounting bracket for geared systems to use with any bike.That way you could swap motors,wheels etc.. really easy.Just a thought.

 

[cadstarsucks]

It all started here. You have to download the pdf file and then open it and search around to find it. It looks to be a big industrial motor... not something we would ever use.

http://endless-sphere.com/forums/viewtopic.php?p=26704&highlight=#26704

It is a 10HP 3 phase. It was used in the GM EV1 to get 100HP peak.

Dan

 

[TylerDurden]

RE power through gears on a bike, here is some info from the real world:

http://endless-sphere.com/forums/viewtopic.php?p=8750&highlight=#8750

 

[safe]

RE power through gears on a bike, here is some info from the real world:

http://endless-sphere.com/forums/viewtopic.php?p=8750&highlight=#8750

"A liberal estimate of drivetrain losses is about 8% (motor chain: 14t-46t,
new chain, perfect chainline; regular chain: 20t-11t, worst-case, with old
but non-squeaking chain, good chainline), leaving the efficiency of the
Cyclone package (motor, controller, planetary gear reducer) at about 80%.
Perhaps the planetary gear drive will loosen up with use and yield a
higher overall efficiency, especially at lower power. "

The Cyclone already uses a chain. So in this case you have chain drive (no motor) verses chain drive (with motor) verses hub drive.

Here's the problem I see...

To really get an accurate perspective on a motor configuration you need to evaluate not the "peak efficiency" numbers (which can be misleading) but the "average efficiency" in normal use. The hub motor solution has a fixed powerband and that means the actual peak efficiency is almost never seen. It gets back to this chart again... the motor + chain solution produces better results than the narrow "peak" calculation would suggest.

Yeah, the peak efficiency drops to 80% (or less depending on the motor you start with) but the AVERAGE efficiency increases. You can't expect to spend all the time at the same speed, in the "real world" your speed goes up and down a lot.

You also have to look at the kind of riding he's doing. His ride went for over 100 miles and I'd guess most of that was just long slow grinding along without any "sport" to it at all. For those of us that want "sport" the speeds go up and down very rapidly. I actually get my disk brakes heated up enough to get glazing on them because of the excessive heat. (I'm also using those high mileage pads that heat more)

Gears make LESS sense for "steady state" situations...

 

[dirty_d]

that setup you have for your gears isnt really that ideal, the the gearbox on the motor gears down just to be geared up again by the rear hub. the best thing to have would be a gearless motor with a multi speed hub that at the highest gear ratio the sprocket rotates at the same speed as the hub and at the lowest gear the sprocket rotates faster than the hub, all the ones i have seen are the opposite, at the highest speed the sprocket rotates slower than the hub and at the lowest it rotates the same speed as the hub, do they make multispeed internal hubs like ive described. it would eliminate the gearing losses in the motor gearbox.

 

[safe]

True... so true...

You can do that if you spend the $$$. The Rohloff rear hub has half of it's gears lower than 1:1 and half higher. If you are willing to spend $1000 you would not only get 95% efficiency or better you would also get a hub that is said to be completely indestructable.

So far I've spent $65 for the motor and $124 for an 8 speed hub... a complete motor package for only about $200. For me price is still a big factor.

On my project #001 bike the rear derailler was in a sense "free" (part of the bikes I bought) so that one was even cheaper...

 

[safe]

The Gearing Advantage Combined With MCL

I've been a bit lazy about this... up until now I hadn't done my homework about the combined effects of using both gearing and MCL (motor current limiting) at the same time. And the good news is that there's actually something new and interesting to learn. (you learn something new every day I guess)

If we look at the first chart we see that the efficiency advantage of using a fixed gear MCL motor verses an 8-speed is only a moderate advantage of 18%. This is actually even less of an advantage than you get with a standard BCL controller. (since the BCL is effectively correcting larger efficiency errors)

But on the second chart we see that the power advantage is a whopping 45%. That's because the natural MCL powerband is so very flat on the bottom (no low end torque) so the fact that the gears can keep things humming along just fine really shows up in the statistics. Gears and the MCL are a very good match.

Finally... and I haven't posted a chart because it doesn't really show anything... the heat is essentially UNCHANGED from the fixed motor to the 8-speed. That's kind of shocking... when you use MCL your heat is a CONSTANT no matter how you ride. If you are in the proper gear you have tons of power, but if you aren't you have no power, but also no additional heat. The very last thing to mention is that the torque is also the same between the fixed gear MCL and the 8-speed version... you can't overload the rear hub even if you tried.

MCL is really, really, really bulletproof...

MCL - Motor Current Limiting
50 Amp current limit (on the motor side)
48 volts
MY1020Z3 motor
Top Speed Estimate 50 mph

 

[safe]

I don't know if this helps much, but this is the full comparision of the stock 36 volt BCL 40 amp motor verses the same motor running with MCL at 48 volts and 50 amps.

 

[xyster]

Safe, you're only convincing yourself. Since you're already dead certain of MCL's superior utility, stop masturbating with charts and start building your perfect controller already!

 

[safe]

...start building your perfect controller already!

I spent about four hours working on the #002 Project today and since I had to keep the garage door closed in order to keep in the warmth (it was 55 degrees outside) I had to breath the fumes... not good. This week will have some warmer temperatures and I'll do my best to exploit that so that I can get some more of the front fairing done with the garage door open (fresh air). The electrical research can be done in winter, so I have a few more months before I start the MCL circuit...

It's just nice to be able to quote an actual percentage as a statistic if I'm trying to describe what I'm doing to someone. Now I can do this with a high degree of confidence of it being correct.

 

[TylerDurden]

stop masturbating with charts and start building your perfect controller already!

But we haven't heard how 50A doesn't generate heat...

 

[xyster]

The electrical research can be done in winter, so I have a few months before I start the MCL circuit...

Wonderful, we have to suffer three more months of watching Safe masturbate with charts before he gets to the exciting stuff.

 

[TylerDurden]

I blame you. He's trying to get to a gigawatt. :x

 

[xyster]

I blame you. He's trying to get to a gigawatt. :x

Oh sure, blame the victim! :wink: