SoCal Grange Race Roll Call!!!! Congrats PaulD!!!

liveforphysics said:

Thud said:

any time you can maximize your power density with voltage & never overlaod with amps....your doing it right (imho)

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This simply is not correct my friend. For our power levels <10kw, staying sub 50v has a lot of advantages. If you look at a Zero or a Brammo or a Gem car or a Think EV, or a forklift, or an electric Kart, or many many other examples, they run lower voltages than most of us do on our Ebikes.

It's really simply a matter of trading larger wire sizes to the motor for additional battery management complexity.


An exception would be if you're using a controller fitted with parts for higher voltages that would be at a severe resistance penalty to operate at lower voltages. This goes along with choosing your parts to work together as a system though, which is the key to a good performing system regardless of the voltage or anything else.

My next race bike will likely be under 60v. I think I can actually get better performance with the pieces I'm thinking of using by setting up a system there.

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OK Mr Luke, What about this..... As you raise the Kv of a motor so you can run higher rpm with less voltage you also lower the inductance of the motor at 2x the rate! So there for you start to loose efficiecny in the controller because of switching losses. And once we step into the relm of your twin turnigy motor build we find thats whats popping your controllers.... So if you were to rewind you twin turnigy motor for lower kv and inctrace the voltage to say the magic 100v you might be able to get the monster to live!

Sadly, it all balances out exactly the same.

You can rewind for half the KV, which doubles the inductance, and if you keep voltage the same, your motor becomes roughly half as hard to control because the slope of the rate of change in current is only half as steep. The penalty for that is only getting half the RPM and half the power potential from the motor. Which is exactly the same effect on both controllability and power as if you had simply cut the pack voltage in half, which also gives you the exactly same change in current over time slope (dI /dT).

If you don't want to take that losing half the power hit, you can double the voltage after cutting in half kV, but this gives you the exact same current rise times that you had before and made it so you couldn't control, only now you're stuck with only being able to use higher resistance FETs to try to get the job done.

No free lunch sadly. All balances out exactly the same, unless you want to sacrifice a hit in potential RPM, and hence potential power of the motor.

liveforphysics said:

Sadly, it all balances out exactly the same.

You can rewind for half the KV, which doubles the inductance, and if you keep voltage the same, your motor becomes roughly half as hard to control because the slope of the rate of change in current is only half as steep. The penalty for that is only getting half the RPM and half the power potential from the motor. Which is exactly the same effect on both controllability and power as if you had simply cut the pack voltage in half, which also gives you the exactly same change in current over time slope (dI /dT).

If you don't want to take that losing half the power hit, you can double the voltage after cutting in half kV, but this gives you the exact same current rise times that you had before and made it so you couldn't control, only now you're stuck with only being able to use higher resistance FETs to try to get the job done.

No free lunch sadly. All balances out exactly the same, unless you want to sacrifice a hit in potential RPM, and hence potential power of the motor.

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Uhmmmm I thought 1/2 KV gives 4x the inductance.....?

Nope. Half kV gives 4x resistance, and only half inductance.

liveforphysics said:

Nope. Half kV gives 4x resistance, and only half inductance.

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So I need to know the relationship of turns on a tooth.... 4turns vs 8 turns for instance I thought that 2 times the turns was 1/2 the rpm and I know 2 times the turns is 4x the inductance.

Also as I PM'd you I connected colossus in WYE vs delt and found.
DELTA = 8uH and 75rpm/v
WYE = 34uH and 44rpm/v

I really think you forgot something Luke. When you hook 2 inductors in parallel you get 1/2 the inductance when you hook 2 inductors in series you get 2x the inductance. So in a motor with x kv and you rewind it for 1/2 the kv you are essentially taking two inductors that are hooked in parallel and hooking them into series so you get 1/2 the rpm and 4x the inductance.....

You are the last guy in the world I want to argue with but im 100% sure im right.....

Inductance goes with number of turns squared.

Alan B said:

Inductance goes with number of turns squared.

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Yes but what about the rpm/v or more important induace vs kv relationship?

so...electric bikes ARE impossible. I allways suspected as much.

LoL^^ time to drag the CR500 out of they
Shed and forget about these silly e-bikes
Hey ThudSTeR?

KiM

Arlo1 said:

Alan B said:

Inductance goes with number of turns squared.

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Yes but what about the rpm/v or more important induace vs kv relationship?

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inductance is proportional to turns squared

v/rpm is proportional to turns

From this,

if you double the turns (maintaining the fill) and double the voltage the RPM, torque and power is the same, the current is half and the inductance quadruples.

E = L * di/dt leads to di/dt = E/L and becomes 2*E/(4*L) so the rate of current rise (current ripple) is half. The current is also half, so the percentage of current ripple is the same.

The Energy in the caps is 1/2 * C * V^2 so the capacitor energy is quadrupled. Current ripple is half so voltage ripple is half from I = C * dv/dt.

Let me know if any of this is wrong.

Alan B. This is what Im trying to say to luke. So because you have 4 x the inductance with only 2 x the voltage you have 1/2 the current ramp angle so the fets have a better chance surviving. With the same motor rpm and power output!

I'm not saying Luke is wrong here. I think he has the force on his side...

There are many factors. I don't think we have covered them all yet. The larger voltage swings at the FETs increase dissipation a bit. 100V FETs are not as good as 75V FETs. At the end of the day the "improvement" from 90V vs 60V may net essentially zero, which is Luke's point.

What im getting at is one thing the fets need to turn on and off for pwm 1/2 as often giving less switching losses.

Arlo1 said:

What im getting at is one thing the fets need to turn on and off for pwm 1/2 as often giving less switching losses.

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True, but the voltage has to swing twice as far and so it takes twice as long each time, so maybe that cancels out too.

LEt's see more racing footage!! Cmon, I saw Lyen holding a camera from the stands, lets more videos and pictures posted.

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Absolutely, here are the pictures (warning: bandwidth intense):

Here are the videos:

Zombiess 20" 9C 18 FET 4115 24S Lipo night before test run:
[youtube]6Z-KScBCnQs[/youtube]
[youtube]ak2QWTNIWCw[/youtube]
[youtube]0ERE_a0rI_I[/youtube]

October 22nd race event:
[youtube]YTfp5EtwO9E[/youtube]
[youtube]bNoxYsrCiX0[/youtube]
[youtube]ge01XPhUNmY[/youtube]
[youtube]QkgYcRIpJTk[/youtube]
[youtube]d85vhbGx_Lk[/youtube]
[youtube]4ua_HHm6uWU[/youtube]

Zombiess with 20" 9C/18 FET 4115 controller/30S Lipo 126V against 24 gasers (2 strokes 50cc engine motorized bicycles). I witnessed he kept passing almost anyone in front. He managed to get 7th place although he started last which I believe he was one of the fastest in that race:
[youtube]YadYnFWqG7g[/youtube]

[youtube]9vQatpAgfn8[/youtube]
[youtube]I33563Q-yUY[/youtube]
[youtube]b6tPoePAHr0[/youtube]
[youtube]30-DN7jffRI[/youtube]
[youtube]_kF1VaTb604[/youtube]
[youtube]IEXo0E1UY6Q[/youtube]
[youtube]rkqit0keX5o[/youtube]
[youtube]d5MZjTm2pq0[/youtube]
[youtube]tR6caAswH7o[/youtube]
[youtube]EWTqnbeO3Nc[/youtube]

Thanks, that must have took awhile to load to the tube. Would on my connection anyway.

Nice to see Aiden's big smile, and great photos of the bikes details.

Huge thanks to all the ebikers who helped make the event a success!

The Official SoCal Motor Bicycle Racing Oct 22nd Grange Race Results.

eBike: 12 lap Final.

1st #109 PaulD
2nd #116 farfle (Rider Aiden)
3rd #100 liveforphysics Luke
4th #111 Evoforce Ed
5th #117 Dan Hanebrink

DNF: #113 zombiess #105 SoSauty

4 Stroke < 50 cc: 12 lap Final.

1st #98 nashmoto 50 cc Honda G4 shifter kit with Nuvinci hub
2nd #16 Bigboy Timm 50 cc Chonda
3rd #3 scotto- 50 cc Huasheng Q Matic

2 Stroke: 12 lap Final. Was run with the 4 Stroke 50 cc Class.

1st #1 magrider
2nd #5 Jim Rust
3rd #86 Rodney
4th #33 bairdco
5th #98 nashmoto 4 stroke 50 cc Honda shifter kit with Nuvinci 1st 4 Stroke
6th #32 Flying Dutchman
7th #29 Karen Hicks
8th #67 John Piston Bikes
9th #16 Bigboy Timm 49 cc Chonda 2nd 4 Stroke
10th #75 pistonbike greg
11th #95 Kyle
12th #55 Tim
13th #58 Ron VanLaar
14th #59 Headtrama
15th #3 scotto- 50cc 4 Stroke Huasheng Q Matic 3rd 4 Stroke
16th #22 DuceDave
17th #35 Tristen Brown
18th #66 Brokenpedals
19th #96 NoStyle Sin
20th #60 oldbiker

DNF: #57 PistonBikeRob was 2nd for the first 5 laps.

Mid Range + < 11 hp 12 lap Final.

1st #6 Jonathon Wolf 200c Harbor Freight CVT
2nd #69 Easy Rider 11hp water cooled Morini
3rd #15 culvercityclassic Jeff 200c Harbor Freight ???
4th #3 scotto- 212c Harbor Freight CVT
5th #81 agk Bryan 200c Harbor Freight CVT
6th #19 Flex Man 200c Harbor Freight CVT
7th #17 Bigboy Roland 88 cc Chonda 1st Mid Range Class.
8th #12 msrfan 5 hp Briggs & Stratton 2nd Mid Range Class.
9th #34 AirEd 200c Harbor Freight J/S
10th #48 Briggs Biker 5 hp Briggs & Stratton 3rd Mid Range Class.
11th #84 Oppanoia 5 hp Briggs & Stratton 4th Mid Range Class.
12th #80 agk Blayze 79 cc Harbor Freight 5th Mid Range Class.
13th #72 Ghrebes 5 hp Briggs & Stratton 6th Mid Range Class.

DNF: #11 Samford&Son 5 hp Briggs & Stratton
DNS: #74 Chris Tomahawk Tuning 14 hp Moped won the race by a large margin.

ULTIMATE RACE of All the Classes: 12 Lap Final.

1st #109 PaulD ebike
2nd #116 farfle (Rider Aiden) ebike
3rd #6 Jonathon Wolf 200c Harbor Freight CVT
4th #3 scotto- 212c Harbor Freight CVT
5th #69 Easy Rider 11hp water cooled Morini
6th #1 magrider 66 cc 2 Stroke
7th #19 Flex Man 200c Harbor Freight CVT
8th #17 Bigboy Roland 88 cc Chonda
9th #67 John 66 cc 2 Stroke
10th #32 Flying Dutchman 66 cc 2 Stroke
11th #95 Kyle 66 cc 2 Stroke

DNF: Lap 6 #100 liveforphysics,
DNF: Lap 11 #81 agk 18 hp Harbor Freight

UNLIMITED RACE was cancelled due to #100 & #81 DNFing.

awesome pics and videos! this is a blast.thanks everyone for info and coverage.

Great stuff MBR. The small 4 strokes were competitive with the mid 4 strokes. There's a crowd of 200+cc CVT equipped HF now, good luck staying up with their mods. The e-s are finding ways to become competitive, yet only a few fast and reliable.

What strikes me is all the classes have a pretty big fast/slow spread. Fast/slow e-bikes, fast/slow 2 strokes. Fast/slow <11hp. The ultimate was fast fast

Hey MBR,
Keep up the great work. I know it's a lot of work but you have pulled it off again.
I hope to join you in April 2012 at the Grange with another eBike.
Cheers to you, Roy

Hey thanks a lot to Lyen for posting and recording all those great pics and videos. I really wish I could have been out there on the track now!!