Dune Bug-E
Controller/Wiring/Road Test -
Part 5 ...
May 2010
Part 4 was focused on the drive
train and the rear swing-arm assembly, and a lot of misc detail work on the
front ie; brakes, steering, seats and wheels...
With the motor & wheels
removed, the rear-end was blasted with a coat of primer and painted the standard
camo colours...
This base coat will be
re-painted yet again with grasses and local foilage as spring progresses and
they become available.
The cross-bar that the shock
mounts are welded to had a second bar with braces welded into place (not clear
in this image)...
Both Battery Banks were
installed, and a pair of tie-down straps cut, bent and drilled to fasten them
into place.
The 3KVA UPS/Charger is
installed into it's racking and bolted into place.
The image to the right are the
"Electronics" that will control the motor...
After surveying the market and
numerous Emails, I ultimately ordered a Kelly Controller's KD48500 Controller
w/Main Contactor, F/R Contactor and foot throttle assembly.
Although I'd implied earlier on
this page (or perhaps the Endless Sphere Forum's) that I'd be revisiting &
upgrading and PicOx Open Source controller for the Dune Bug-E, the reality is
that I'm running out of time if I want to make use of this unit before the snow
flies again.
The foot throttle assembly as
bolted down, is reasonably comfortable (considering how cramped the quarters are
within the cabin).
If I could find fault with this
unit it would only be the poor fit between the pedal assembly and the Pot-Box
itself.
To make a secure mount I had to
wrap the shaft with some electrical tape and cut open the "C" in the
pedal casting so that it could be tightened down and remain secure.
The shop was cleared, swept, and
wiped down to clean-up the layer of metallic dust that has accumulated over the
last few months.
The welder, clamps, and misc
materials are stored away, and the bench re-configured for the wiring of the
controller...
The documentation that came from
Kelly was clear and easy to follow.
One feature I wanted to
incorporate from the beginning of this project was the ability to run the motor
controller and/or the 3KVA Inverter independently, as well as charging the banks
individually as required.
The image to the right is of the
"Toolpath" used to cut out a series of 1/4" Nylon pieces that
would be laminated together with 4 heavy copper buss-bars to form a switch
assembly.
The Nylon was cut at a 45 inch
per minute feed rate using a 0.062" end-mill bit. By cutting at 0.020"
per pass the cutter never clogged or missed a step.
Cutting the pieces out on the
CNC Mill.
The cuts were made to a depth of
0.220" leaving 0.030" to be trimmed out with the band-saw and a sharp
exacto-knife.
This shot is of the switch
partially assembled.
The 3/4" by 3/8th"
buss-bars are notched such that the small nylon spacers that allow a gap for the
Knife to swivel in are securing the buss-bars from moving once the switch is
completely assembled.
The "Hot or B+" lines
from the Battery banks are bolted to the Knife-Bars.
The Buss-bars had
"V-Cuts" machined to mate to "Wedges" that were machined in
to the Knife-Bar edges, to maximize the contact area when engaged.
For now the knife switches are
secured in position by simple rubber bands.
This has been working very well,
and most likely will remain.
This is a view from the back of
the controller with the cable harness that ties the keyed ignition, throttle,
brake sensor and Fwd/Rev switch.
All Load carrying cables (from
Battery banks thru the controller onto the motor) are AWG #4 welding wire.
Each cable end is crimped and
soldered to a homemade brass end lug, taped and labeled as assembled.
The charging circuit to the
battery banks is AWG #8 with an Anderson connector that can be pulled either for
servicing or if things go wrong.
For now I've just mounted the
Fwd/Rev Switch and Keyed Ignition on the original dash-brd.
This will eventually be replaced
with a wood console and a pair of analog meters to display the Voltage (State of
Charge) on the Battery Banks and a Current meter, as well as a Temp sensor that
will be mounted on the motor.
At this point the Dune Bug-E is
up & running, and has had 8 or 9 test drivers without any issues ie;
intermittent power of general failure while driving.
The Home Brew High Current
switch was one area that I'd had concerns about but they proved needless.
The slip differential in the
rear-end will be welded or fixed to approximate a Posi-track or solid rear
drive, as there is no flex in the frame or swing-arm, so one of the rear wheels
is prone to getting hung-up spinning in the air...
The Kelly Controller is still
set at it's factory defaults, as there was a gap in communications between me
and the Kelly Sales Staff regarding an SCI to RS-232 adapter that allows the PC
to talk to the controller.
Given that the controller is
rated at 48V 500Amps the usage has been on the "Light Side" for fear
that I damage the motor. Ideally I'd like to dial-in a bit more responsive
throttle over the full arc of it's movement (the first 1/4 of it's travel is
dead), and set an upper limit of 200Amps initially on the controller, until I
add a temperature monitor to the motor to ensure it doesn't over heat.
While I have the gear-box dis-assembled,
there is a slim possibility of re-gearing it internally for a much higher
top-end. Presently it has tremendous torque in all three forward gears, but is
far slower than I'd calculated. After reviewing the spreadsheet I found that I'd
made an error in one equation that grossly over estimated the top speed of the
buggy. If re-gearing internally is not an option, I'll add a jack-shaft and
sprockets to bump-up the speed with an aim towards a 35 to 40Km/hr top speed in
3rd.
(Video
to be posted by May 10th 2010)