Re: [ElectricMotorcycles] " Motor Load and DriveLine Losses - Observations and Questions" ListServ Digest, Vol 18, Issue 12

Tue, 13 Mar 2007 07:07:22 -0800

Both chain drives and belt drives can be 95%+ efficient, but both must be adjusted and aligned properly. O-ring chains that most street bikes will have as stock these days will consume more power than a non o-ring chain. It is much easier to change ratios with a chain drive. Chain drives require some slack, and the losses will be high if they are too tight. There is not really any power lost because of the chain slack, at least until it starts jumping teeth.
There is not necessarily any HP consumed by rotating things - a wheel in the absence of friction (space for example) would rotate forever with no power input. Angular momentum is conserved exactly like linear momentum. The weight of the wheel, sprocket and chain, only effects the acceleration, not steady state power requirements, except through higher rolling resistance for a higher weight bike. 


That equation on the page you referenced is just the ratio of HP to 
torque, and has nothing to do with drive train losses. It also takes a 
fair bit of work to get from there to  torque or HP required to 
accelerate the drive train.


Kevin Caldwell
Courtenay, BC

Lauren & Nathan wrote:


the next thing to look at could be whether running a belt drive could 
also aid in power transmission. no slack=no power sag when you twist 
your throttle
measure the weight of your rear wheel, sprockets, disks, chains etc, 
and you could use an equation to find out how much horse power is used 
to turn all this at certain tourque/rpm measures



http://www.ajdesigner.com/phphorsepower/horsepower_equation_rotating_horsepower.php 


they could help you out



Message: 3
Date: Sun, 11 Mar 2007 14:29:28 EDT
From: [EMAIL PROTECTED]
Subject: [ElectricMotorcycles] Motor Load and DriveLine Losses -
Observations and Questions
To: [email protected]
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset="us-ascii"


There is thread on the EVDL about what are the normal drive-line 
losses in a
Front Wheel Drive car. It got me thinking, so I put the Ninja un the 
center

stand and did some tests for you to comment on.


Test 1 - Bike on center stand, measured motor amps, falls quickly to 
~29.5

amps at about 1500 rpms. Is this normal?


Test 2 - Bike on center stand, removed read disk brake, no change in 
motor

amps consumed. So far so good.


Test 3 - Bike on center stand, removed all drive line loads (e.g. no 
chain
or rear wheel or bearing losses) 19.5 amps. This seems to be a lot  
just to

turn over the ADC 6.7" motor?

Things noted during the tests....

- I can turn the motor with my hand on the shaft with moderate 
effort. It

doesn't turn as easy I thought.

- the motor makes a small squeaking noise when (un powered by hand) 
turning
slowly. Is this sound the brushes rubbing or do I need to suspect 
bearings? I

don't suspect any issues, just curious.

- I found that the chain was too tight and the alignment is not 
perfect. I
have some motor mount bolts that need to be addressed to get the 
alignment

perfect.


Any thoughts of suggestions appreciated. Any other tests that I 
should try?




Mike  Bachand
Denver Electric Vehicle Council (DEVC) - Colorado Chapter of the  EAA
1994 Kawasaki Ninja EV



Message: 4
Date: Sun, 11 Mar 2007 17:03:07 -0400
From: "BadFishRacing" <[EMAIL PROTECTED]>
Subject: Re: [ElectricMotorcycles] Motor Load and DriveLine Losses
-Observations and Questions
To: "ElectricMotorcycles" <[email protected]>
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset="iso-8859-1"


I've tried similar things with my twin etek setup.  Started with just 
the motors spinning.  Then added the transmission.  Then added the 
rear wheel. No one thing was a big amp drag, but they all add up.  So 
I think all is well.



But one thing I also notice is that with the brushes removed (easy to 
do on the etek), the motor turns over a lot easier by hand.  I'd say 
there's more drag due to the brushes than the bearings, etc.  Don't 
know if you could do the same, pop the springs off of the brushes.  
And Yes, I've got squeaking from the brushes too.



Plus realize that you're powering the series field, even with no load 
on the motor.


Darin
BadFishRacing


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

Message: 6
Date: Mon, 12 Mar 2007 10:08:40 EDT
From: [EMAIL PROTECTED]
Subject: Re: [ElectricMotorcycles] Motor Load and DriveLine Losses
-Observations and Q...
To: [email protected]
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset="us-ascii"

Thanks For the input Darin.

I guess in all the data I forgot some conclusions.


1) Unlike the car folks, dragging disks (assuming a properly aligned 
rear

wheel) don't seem to be much of an issue on an electric motorcycle.


2) Despite my search for a range killer in my direct drive line  the 
chain,
wheel bearings etc. account for only 10 amps or so and that seems 
acceptable.


- Mike B.


Mike  Bachand
Denver Electric Vehicle Council (DEVC) - Colorado Chapter of the  EAA
1994 Kawasaki Ninja EV



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