Steve,
I really like the swing arm mount idea for an Etek having seen and ridden
the results. The obvious benefit is a more useable space for batteries. The
less obvious reason is that chain/belt tension is now constant and can be
carefully set for max efficiency. With my motor setup the swing arm movement
causes wide variations in chain tension and I suspect that this results in a
measurably less efficient final drive. In particular this is a big issue for
belt
drive set ups according the engineers at Gates.
Again remember that Bidwell uses a ratio of about 10 to 1 to mitigate the
Etek heat / amp issue. He continually reminds me that my ratio of 3/4 to one is
too high, but sometimes I need to go faster than 65MPH. I did move the ratio
up once dropping the front sprocket from 12t to 11t (the rear is a 45t), but
more is probably needed and would likely increase my range.
Battery and range for my Ninja.
Optima Yellow Tops (AGMs) for performance (400 amp Curtis that really does
draw the rated value). The original batteries (before Johnson Controls bought
Optima) were labeled 65 amp hours provided range in the low 20 miles on a warm
day with a fairly deep discharge. Jon Olsen a fellow DEVC member was an
engineer at Optima and calls my original batteries hand built.
The new battery pack is somewhat unknown as a couple of the batteries were
not in their original plastic wrap and I do not have a load tester available.
These are somewhat surprisingly labeled at 55 amp hours although the
manufacturer says they are the same battery. My range is now perhaps 13 to 15
miles
at the same level of discharge. I suspect that Johnson Controls may have
degraded performance as they commercialized the manufacturing of Optima the
products post acquisition. The engineers at Optima told me that the reduced aH
rating was simply to make the specs more realistic to the actual performance.
Several other people have indicated that the "new" Optimas are not as robust
as
the originals. I do live within a few miles of the Optima office where the
originals were created so some made there way into the local EVs..
Having said this about the batteries keep in mind that the reduced range
while typical with other EV motorcycles with Optimas is not based on any
actual
measurements of the old verses new batteries under load. What I really need
is to get some telemetry instrumentation to use while riding that will allow
me to see each battery. Then of course time to purchase a (100 amp?) load
tester and make sure that one of my current set is not falling off early.
How is that the battery instrument panel project coming along? Does anyone
know?
I have one mystery issue with the new batteries. The performance is a little
different. the strange behavior is that at about 45 MPH (perhaps 3000 rpms?)
the electric motor hit a sweet spot. It feels like the motor pulls harder
(like a load has been reduced allowing the motor to rev more freely). I have
not
idea what to attribute this to except possibly a drive-line (mis) alignment
or potentiometer issue . Nothing was changes except the batteries. Any ideas
about how to diagnose or potential causes would be greatly appreciated.
Mike Bachand
Denver Electric Vehicle Council (DEVC) - Colorado Chapter of the EAA
1994 Kawasaki Ninja EV
