Dirt-E Bike
Kawasaki KE-175 Conversion - Part 3 ...
(Paint & Assembly)
The previous
section was heavily electronics based and covered hacking a YK42-x
controller...
After running
numerous bench tests at no-load the Brute-Force x-Tender (BFx) had zero issues
and is ready for testing on the Dirt-E.
I was just about
to start mounting the hardware back on the frame when it occurred to me that
once this was assembled I'd likely not want to take it apart to paint later.
So the frame was
partially stripped and painted with a couple of coats of good old gloss black.
The battery rack
had space added for 2 additional cells that would now bring the Voltage up to
72V.
Additional
1/4" #20 all-thread was welded to secure each battery.
...and painted.
So were the
fenders...
This is just a
brush-on job, since I wanted to paint the bike, but not get into a major
ordeal with covering up the shop to get a spray finish.
Though I did want
to apply some simple stencils to brand the project.
The lettering is
cut on the mill with a 0.020" cutter into cheap mac-tac.
Unfortunately
there was a bit of spray-by under parts of the stencil so I'll have to do some
touch-up after the fact.
The blower mount
for the motor is a section of (clean) 6" PVC drain tile from our septic system
repair, and 2 (two) layers of fiber-glass mat.
The fit to the
motor is very snug, and didn't require the large ring-clamp I'd bought to secure
it.
The cooling fan
has a simple air filter to keep the motor clean and has a bead of caulking
applied to ensure as much air hits the brushes as possible.
A slot is cut to
allow the mount to pass by the motor wiring and the fan is oriented to have it's
wires at the same side.
The retaining
straps are a bit fancier than the straight band that is holding the center 48V
pack.
Originally the
band and all-thread were poking into my shin and caught the laces of my boots.
The bike almost
fell over with my foot caught on the pegs, so I couldn't put-off fixing this.
Obviously the new
electronics has to be mounted some how, but I hadn't thought that through as
well as I could have.
The foam blank
here is being routed out to form a pocket for the boards to sit in.
Rather than lose
half a day setting up the tool-path I just ran this through free-hand on the
mill.
As crazy as it
sounds the brds are only held in place by "Hot-Glue".
About 4 sticks of
glue, but it is very secure.
After having to
re-position the AWG #8 cables a few times nothing has let-loose.
If the brds have
to be removed from the foam, it would need to be replaced, but that's a quick
job.
I think I have
everything where it should be and have started to think about wiring and a cover
for the electronics.
As you can imagine
there has been lots of sitting on the bike and just seeing how it feels...
...the answer is
heavy, the sixth and seventh batteries have added another 25lbs to the front
end.
This will be the
controller cover, or at least give it some shape.
I tried a couple
of different shapes, but they were either too complex to assemble or wouldn't
clear the heat-sink of the BFx controller.
I was going to
take pictures of it being fiber-glassed and painted, but thought that they'd
look about the same as the other images and would save you the bandwidth and
time of viewing them.
Between painting,
assembling and layering the fiber glass, I've been undergoing an education in
analog meter technology.
The meter to the
left is one of many that I bought dirt cheap, all the same...
1 milliAmp 85 ohm
meter.
It can be
configured as either a Volt Meter or an Amp Meter.
The stock 15V
scale was removed and scanned to make a custom face plate.
The images above
are the 2 scales that I set on for the Dirt-E, 0 to 40Amps and an expanded 62 to
82Volt scale for the batteries.
The meter can be
configured/wired to accommodate the scales shown, but I haven't finished that
yet, but did want to place the meters before wiring in the rest of the parts.
The cover was
drilled and parts mounted for placement.
Not exactly what I
was after but it's more than adequate for now since everything is still largely
in "Test Mode".
The
pre-charge/Main switch, Motor Temp and blower switches are all functional.
The motor is
cooling down after a hard run that pushed it up to 97 degrees F.
Obviously I don't
have an inkjet printer (their way too expensive to run), so hand coloured the
"Red Zone".
All things
considered, the wiring is much neater than I thought it would be.
The controller
cover may appear flimsy, because it is...
...but the 2
layers of fiberglass make it about as strong as a plastic waste paper basket.
It's been dropped
a few times and seems to have enough flex so that it can be pushed and
manipulated into place against the heavy wires inside.
And this is where
it sits for now...
After numerous
test sessions of 5, 10 and 15 minutes under varying load conditions everything
has been holding-up well.
The rear wheel is
off the ground (a safety measure while wiring in the controller), and handy for
determining how the motor and controller behave on the bike.
The motor temp sensor is
mounted into one of the exhaust holes drilled in the front casting.
Prior to mounting
the controller onto the foam base, one of the 3 (three) shunts were removed
dropping the effective current limiting function to 26.6Amp from the factory
40Amp setting.
Predictably the
motor was displaying a sharp rise in heat approx 2 to 3 degrees F per 30sec
sample when run at full speed no load (just the rear wheel in mid air)... So a
second jumper was removed dropping the current limit to 13.3 Amps @ 72V... The
no-load heat rise dropped slightly, so I ran a few shorter tests with a moderate
and progressively heaver load applied by riding the rear brake.
The motor can
climb into the mid ninety degree F mark from an ambient temp of 60F in under
10minutes of load testing. The controller isn't breaking a sweat as it records
absolutely zero rise in temp over ambient. Which is a major hurdle completed in
that it has started to be effectively load tested.
So the Dirt-E will
sit over the holidays while I finish the meters and consider whether to drop the
voltage to 60V and how to have a greater resolution of control in the current
limiting function of the controller.
The current motor
a MY1020 750W unit may require some additional work, if it's going to stay with
this project. The issue largely is it's internal resistance. By Over-Volting the
motor to twice it's rated voltage of 36V to 72V it's generating too much heat to
be a reliable power plant.
I do have a second
identical motor, if I was to cut and extend the rear swing arm by 8" or so
I could mount both motors in parallel with a common drive shaft effectively
reducing the current draw on each by half.
Also I have a
MY1020 (non-gear reduced) motor rated for 1200watts that has heavier copper
wound on it's armature, unfortunately the output shaft would have to be taken to
a machineshop that can cut the drive teeth into it's shaft to mate to the gear
reduction unit, or I could re-wind the existing armature with a heavier gauge of
wire to effectively lower it's resistance and increase it's low-end torque.
Certainly, I'm
very pleased with the performance of the BFx controller part of this project as
it will be useable on other EV related projects in the spring, but as far as
offering any gains on the Dirt-E it's questionable given the heat issues
surrounding the current motor.