I'm thinking about my BMW motorcycle conversion. It has a fixed 3.36
ratio, but will probably weigh less than yours as I only need about 25
miles range. I don't need extreme acceleration, but I don't want to bog
the motor down too long.
- SteveS
Shawn Waggoner (FLEAA) wrote:
Jeff is <200lbs and gets 45-50 miles on his. Mine is unknown so far as when
we had it running in January we only rode it for short distances. I am >200
so we'll see how it impacts range with my, er, load.
As far as 48VDC goes, I think they would run really well on 48 or 72VDC. The
top end might be a little less, at least with current ratios. We tested
several ratios before settling on this one. Any lower and the torque at full
throttle is too much for a street bike. It would definitely surprise people
the first time they rode Jeff's. Go the other way and the launch was pulling
too many amps for too long, and wasn't as much fun to ride.
Hope that helps!
Shawn
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of SteveS
Sent: Monday, May 05, 2008 2:40 PM
To: ElectricMotorcycles
Subject: Re: [ElectricMotorcycles] two motor2
What kind of range are you getting? How do you think the motor would
perform on 48V?
- SteveS
Shawn Waggoner (FLEAA) wrote:
I agree with Jeff on the heavier Series motor idea. My bike is almost
finished. (I was working on it at Jeff Patterson's shop last
weekend...sorry
I have been remiss on posting any details on the project) The Patterson
Cycle bikes weigh approx 620lbs on a custom steel frame and use 6 AGM
batteries - currently I'm using 6 Discover Energy EV24A batteries. Jeff's
original bike was the same specs just different batteries. When he used a
standard ADC 6.7" 4 brush motor it would get incredibly hot after 5 to 10
minutes of riding - 10 minutes and you couldn't touch it. We worked with
Jim
Husted to design a motor for the bikes. The current motors (in his and
mine)
are 7.5" 8 brush series wound motors. They are awesome, after riding till
batteries were tired, the motor was only warm. The current setup is using
an
Alltrax 72VDC 450A controller and roughly 5:1 ratio on the sprockets. The
bike has great acceleration and a top speed of 67 MPH (actual - not
calculated). These 7.5" motors are wonderful for the heavier bikes. I
certainly would prefer to wire one motor and have one controller for a
street bike than two motors and or controllers - lots of extra space and
wiring.
You will need to check with Jim, but I think the motors are right around
$900 or so - cheaper than 2 PMG's an only one set of contactors and one
controller.
I took some pictures after the work on Saturday and will get them posted
soon...
Thanks,
Shawn
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Jeffrey
Blamey
Sent: Monday, May 05, 2008 1:43 PM
To: ElectricMotorcycles
Subject: Re: [ElectricMotorcycles] two motor2
Having over 1300 miles on the PMG-132 in a light(er) bike aprox.
440lbs and a <200lb rider I find the heat generated in the motor to be
controllable with the small fans and shroud I made. Where am I going
with this, oh yeah. If I were trying to build a bike based on a
heavier frame I would opt for a larger motor, like a D&D or if you
have deeper pockets one of the smaller Warps or a custom motor from
JH versus a dual Etek or Dual PMG (2 PMGs will set you back roughly
$1600 so why not do the series wound and have the thermal mass to
handle the required power dissipation under acceleration).
Jeff
On Mon, May 5, 2008 at 8:04 AM, SteveS <[EMAIL PROTECTED]> wrote:
I get the idea of the two motor system, but how does compare to using a
larger single motor? I imagine a single larger motor would be easier to
install and control. The larger motor would deal with the low speed
torque
need, but I wonder about what happens when you get up to speed? Would a
larger motor be less efficient?
- SteveS
dale henderson wrote:
The advantage of a transmission is more power at low speeds while at the
same time reducing the power needed. But once you are up to a cruising
speed
the transmission does not any help except for allowing the motors to
operate
at high efficiency at more than one speed. The disadvantages of a
transmission are increased drag, or lower overall efficiency and
increased
weight.
The advantage of a two motor system is that a second motor is often, if
not always, lighter, smaller, simpler and more efficient than a
transmission. The disadvantage of a two motor system is increased power
requirement.
Here is another way to look at it: if your main concern is high
efficiency
at a particular cursing speed [e.g. highway travel] then longer you
travel
the less efficient a transmission becomes and conversely the more
efficient
a two motor system becomes. A transmission only increases efficiency
during
acceleration once you are at a steady speed the transmission reduces
efficiency in terms of drag and weight. While a two motor system is only
less efficient during acceleration, so if you have little acceleration
and
a
lot of steady speed then two motor system is overall more efficient.
Here is a very simple model; if it gives good results then a closer
examination would be warranted: take a 25-mile highway trip, we'll give a
¼
mile acceleration; more simply a 100-mile trip with 1-mile acceleration.
At
any give time the motorcycle needs X power. A transmission is 5% less
efficient than a non-transmission so over 100 miles it will take 100
miles
*
.05 = 5 units more power. The two motor system will take twice the power
at
acceleration 1 mile * 2 = 2 units more power. But if you are commuting in
stop and go traffic then a 40-mile commute might have over a 1 of
acceleration. So a transmission is 40 * .05 = 2 units and a two motor
system
is still 2 units. So if your steady speed is more 40 times longer than
your
acceleration then a two motor system is more efficient. But if your
steady
speed is less 40 times more than acceleration then a transmission is more
efficient. A closer study is needed and results will vary based on
rider/bike/weight/route/etc… but I think it will be clear that in short
city
travel a transmission is more efficient, but in longer highway travel a
two
motor system is more efficient. But since an electric motorcycle has a
finite range and can't be filled up at the pump then it should be built
to
be the most efficient for the longest-range option. Hence once you get an
electric bike going over 50 miles on a charge [i.e. lithium] and you have
some plans to travel on the highway then a two motor system is the best
choice. Further with a 100+ mile range, city travel never be a concern,
even
with the lower efficiency of the two motor system, but when a long trip
on
the highway is needed the two motor system will shine as it will give you
more range than a transmission.
harry
Albuquerque, NM
http://www.austinev.org/evalbum/1179
http://geocities.com/solarcookingman
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