Graph: Amps Required To Maintain Different Speeds

[xyster]

Test conditions:

no pedaling
batteries at 80 volts
level ground
dry asphalt
250' above sea level
minimal weather-related wind
normal upright riding position on upright bicycle
5304/24" wheel
2.125" F / 2.4" R wheel width
72V 35A controller

 

[Beagle123]

That just shows that at higher speeds the wind is king. I'd imagine from the way the graph flattens out, that you reach a point around 50mph where it almost doesn't matter how many amps you add, you ain't going any faster!

 

[Lowell]

~40 amps at 85v is over 50mph for my bike.

 

[BiGH]

and that is why i'm going to most likely source a 5303 motor on a 26" rim as opposed to a 5304 motor on a 24" rim

 

[eP]

Hi BiGH

and that is why i'm going to most likely source a 5303 motor on a 26" rim as opposed to a 5304 motor on a 24" rim

Keep in mind Lowell reach the controller's limit at that speed. So you cannot much load the same controller.

When you use the same rim you need the same torque, but for 5303 you need 1/3 more current for the same torque than you need at 5304.
So you get the same voltage sag at motor side as the 5304 has 1/3 more turns than 5303. But at higher current you get higher loss, so if you are at the contr. limit 5303 cannot put out even the same power as 5304 can.

5303 could be the same or better efficient at 20'' or less rim if you compare to 5304 at 26'' rim.

5303 could draw more power from controller if the low source voltage is the power limit. When the max current is reached at WOT you cannot get more power from the controller.

Regards.

 

[Ypedal]

I beleive Lowells controller allows more than 40 amps..

but i agree with the above in general.

 

[BiGH]

eP - that was a very well written post thankyou.

Ypedal - Lowell's modded his for 60amps

 

[Lowell]

Hi BiGH

and that is why i'm going to most likely source a 5303 motor on a 26" rim as opposed to a 5304 motor on a 24" rim

Keep in mind Lowell reach the controller's limit at that speed. So you cannot much load the same controller.

When you use the same rim you need the same torque, but for 5303 you need 1/3 more current for the same torque than you need at 5304.
So you get the same voltage sag at motor side as the 5304 has 1/3 more turns than 5303. But at higher current you get higher loss, so if you are at the contr. limit 5303 cannot put out even the same power as 5304 can.

5303 could be the same or better efficient at 20'' or less rim if you compare to 5304 at 26'' rim.

5303 could draw more power from controller if the low source voltage is the power limit. When the max current is reached at WOT you cannot get more power from the controller.

Regards.

Interesting how you seem to know more about my speed controller than I do. For the record, the current limit is set just over 80 amps. 81-82 amps to be exact. The limiting factor on my bike is batteries. They're only rated for 3C drain which is 56-60amps. That will be changing soon though as I will be upgrading to 90V+ at 80 amps down low, and hopefully around 50-55A at speed. Should the stator burn up during testing, I'll be upgrading the controller to 150V and replacing the 03 with an '04 wind.

 

[BiGH]

awesome looking forward to your future mods.

i was just basing it off the 60amps on what was written in one of the threads on your bike - which i have to say i've read a few times love that bike...

 

[Lowell]

awesome looking forward to your future mods.

i was just basing it off the 60amps on what was written in one of the threads on your bike - which i have to say i've read a few times love that bike...

Sorry, that previous post was directed at eP, who stated my bike is limited by the speed controller, when in fact it is limited by the batteries.

At one point I was running 60 amps, but that wasn't enough to keep ahead of traffic

Glad you like the bike, I hope the info I've posted helps people out with their own creations.

 

[BiGH]

Glad you like the bike, I hope the info I've posted helps people out with their own creations.

*cough*main inspiration*cough*

seriously, i'm looking at making a pushbike that is closer to a motorbike than a pushbike (thats what the MTB and roady are for atm) and so far your bike is basically exactly what i'm looking for.

i'm planning on starting out however on 72v with a 40a setup. Prolly using 2 or (more likely) 4 Evtech 36v packs, it won't give the insane performance your bike has, but should be enough for my intended purpose (commuting at decent speed).

However now the cannon motor is on the scene, might look into doing one of them on a flat bar road bike (should fit) with 72v.... i've got dealers looking into more stats now

 

[eP]

Interesting how you seem to know more about my speed controller than I do. For the record, the current limit is set just over 80 amps. 81-82 amps to be exact. The limiting factor on my bike is batteries. They're only rated for 3C drain which is 56-60amps. That will be changing soon though as I will be upgrading to 90V+ at 80 amps down low, and hopefully around 50-55A at speed. Should the stator burn up during testing, I'll be upgrading the controller to 150V and replacing the 03 with an '04 wind.

Sorry for my bad assumptions again. ( Before i've assumed wrong your's rim size).
It wasn't my intension describe yours controller or batteries at detail.
For the motor it is almost no difference what exactly limiting your average current.

You can see i'm writing relatively long posts ( for my poor english) so i try cut them as far as possible. So take this (my bad assumption) as a form of short - for the sake of lack of time to writing all thing detail.
My point is still the same - x5404 is more efficient than x5303 at the same rim if you push controller/batts to the limit.

Cheers

 

[BiGH]

but wouldn't it mean that even tho it was more efficieint, it would be at a lower speed?

ie:
for a given voltage / amperage a 5304 motor will give a lower speed, but a better efficiency

for the same voltage/amperage a 5303 motor will give a higher speed, but lower efficiency.

 

[eP]

but wouldn't it mean that even tho it was more efficieint, it would be at a lower speed?

ie:
for a given voltage / amperage a 5304 motor will give a lower speed, but a better efficiency

for the same voltage/amperage a 5303 motor will give a higher speed, but lower efficiency.

You could push push the load to the limit at almost any speed (it depends on: current limit, battery voltage and windings resistance Rm).

And again: efficiency depends on motor's current, windings sag, and what i called working voltage: rpm/kv )

 

[Beagle123]

This post is directed to everyone who's put up a thread about their bike:

Please put a link to your bike's page in that little footer that appears at the bottom of each post. When I read your comments cough*Lowell*cough I'm dying to see the bike you're talking about.

For example, I tried to find Lowell's bike, and he has over 700 posts so I can't find it.

It seems to me that each of us should have a "home page" for showing our project.

I plan to put up an extensive one myself.

Just click on "Profile" at the top of the page to add it.

P.S. I got the idea from xter, but don't hold it agains me.

 

[Lowell]

Good idea, I'll find my old posts and list them.

 

[BiGH]

most of the bikes (with some stats) are in the "pictures and videos of bikes) (including lowell's).

There isn't a lot though. I agree - beginning to think that we should have a thread called "members rides" and another called "projects" for in progress projects.

I'm thinking also of a single thread with a ridgid database structure (or a page would be better) that has specific stats.

kinda like:

Username: BiGH

Base bike: Avanti Barracuda
base bike type: MTB
Motor: C-lyte 5xxx
controller:
battery capacity and voltage: 72v
battery type: EV-Tech 37v15a battery * 8
battery chem: LiPoly
Link to Picture: xxxxx
...
...
...
u get the idea!

 

[Kyle]

Hey xyster,

It looks like you have the perfect rig for a Fairing test.
It would be good to look at the power consumption differences.
At the speeds that you can run, I know that we all would learn something.

Thanks
Kyle