All this wondering about To Transmission or Not To Transmission has got me
wondering myself again.
My last EM, I used the transmission, and it was pretty neat.
I retained the original clutch and original transmission and using a two
stage contactor controller, it got around town fairly good on two small
batteries.
But it was not very fast. Might of been the 12V Baldor motor with not much
torque capabilities that was the problem, but I will never know.
The 1966 Jawa was sold, to a Jawa Fan and he let me keep all of the electric
stuff.
Tomorrow, I pick up my next project, a 1966 250 Harley Davidson Sprint.
The original stock weight of the Sprint was around 220 pounds.
I plan on going with (2-4) 6.8 HP double ball bearing winch motors.
But I am torn on using the tranny or not. I learned a lot from using the
tranny on the Jawa.(Sprocket on the new crankshaft was too small, ect.)
Really would like to keep that original bottom end that says "Harley
Davidson" on the side.
Might try just two motors to start with and retain the transmission.
If I don't like the performance, then I will go with 4 motors and no
transmission.
Each motor will handle 500 amps for a bit, and times 4 should get me off the
line pretty good.
I have the batteries that will handle the 2000 amps and plan on putting them
low to the ground on the frame.
They are long and skinny and should do good with the Sprint.
Just two of them for now, and see how it does at 24 Volts.
And of course, a contactor controller.
Check out my web site now and then the progress I make on the 1966 Harley
Sprint.
And as always, I will be building it "On the Road", as I travel for work.
Jack.
"When in doubt, Convert"
www.poormansev.com
----- Original Message -----
From: "Jeffrey Blamey" <[EMAIL PROTECTED]>
To: "ElectricMotorcycles" <[email protected]>
Sent: Friday, April 04, 2008 12:01 PM
Subject: Re: [ElectricMotorcycles] CVTs vs trannys and power shifting
My personal pursuit of a CVT or std.trans was to keep the motor rpm
up, current draw reasonable and sacrifice some speed going up a hill,
similar to the little car with a little engine, or a cyclist
conquering steep hills. Now I know electric motors have this flat
power thing going, but if we're trying to maximize our range I think
the transmission can make a difference. EVs cars trucks do use the
trans and not just because it is there, but because of the ability of
the trans to multiply the available power.
The trans should prevent precious amps from turning into heat (waste).
If you live on the flats a single speed is probably okay. The two
times I have done 21 miles on a charge had few hills in the mix, more
like very gradual rises. Now if you could extend the wheel base (oops
I am the one doesn't like that, shoot!) move the swing arm back to
accomodate the smallest separate trans (sportster, brit bike) and use
two gears maybe the range can be stretched a little?
Jeff
On Thu, Apr 3, 2008 at 6:55 PM, damon henry <[EMAIL PROTECTED]>
wrote:
Once you spring for a Zilla, the point is moot. The only reason for a
transmission is to try to get good acceleration and a high top end out of
a
moderate motor controller combo. A Zilla has plenty of overhead to
accomplish this with a single motor... unless of course you are talking
about Killacycle type performance. I don't think anyone on this list
has a
bike that even the lowly Z1K low voltage (156 volts) model couldn't make
scary fast from 0 to 80+ mph. The problem is most on this list are
dealing
with 48 or 72 volt controllers in the 300 to 400 amp range and a single
gear
ratio which means you have to choose between good acceleration or a
higher
top end. Multiple gears could give you both with a much smaller cheaper
controller.
Don't get me wrong, think your solution is the correct one because it
is
the least complicated least space solution. I just don't think multiple
motors and parallel shifting are necessary on anything short of a drag
bike.
If you really want more performance forget the transmission and buy a
stronger controller with a motor that matches. Any of the common 6.7
inch
series wound motors and above should be up to the task of dealing with
more
powerful controllers.
damon
________________________________
Date: Thu, 3 Apr 2008 20:36:30 -0400
From: [EMAIL PROTECTED]
To: [email protected]
Subject: Re: [ElectricMotorcycles] CVTs vs trannys and power shifting
I think if you look closely you'll see a sport bike transmission is so
tightly packaged you won't have room to fit covers and seals to close it
up.
Not to mention carving away the engine side of the cases and mounting the
resulting metal potato.
How about a completely different approach - why not get the effect of a
transmission with electronics? A Zilla controller will properly
(important
concept) shift two motors from series to parallel and back. If you have
two
motors they can each be smaller than a single motor. I'm thinking the
ADC
5.5" series looks promising. Jim Husted might be able to dig up
something
even more suitable.
There are a number of advantages with this idea. More comm area,
"shifting"
is ultra smooth because there is no change in rotational speeds, and the
mechanical implementation is WAY easier. It is no doubt pricey (less so
if
you scrounge), but you might spend more in custom machining and reworking
to
adapt a transmission. It should be pretty easy to get a two-motor setup
to
work well first time out.
One important consideration: The S-P shift can be made automatic for
cars
(senses current draw and shifts at a programmable point), but you want it
to
be manual on an EM. The shift results in a step-change in rear wheel
power
that could mess with your traction. Better to treat it like a normal two
speed transmission that you shift, just like any other motorcycle.
Except
there are no gears.
When you think about it, this achieves exactly the same thing for an EM
that
a gearbox does for an ICE. Gears on an EV are not typically the best
solution. When we use them it's usually only because they came with the
donor.
Chris
On Thu, Apr 3, 2008 at 2:25 PM, john fisher <[EMAIL PROTECTED]> wrote:
> As to using a sport bike trans, that would be an idea. The only
> oiling for the trans is a splash oil. The shafts run on ball
> bearings. So if you could enclose the case, you'd be all set.
yeah I was assuming enough skill to be able to close up the box to keep
oil
inside.
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