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Alan Kilian - Plymouth, MN
Web Site: www.pobox.com/~kilian/
- Type: Industrial Robot arm.
- Purpose: Try and control a HUGE robot arm.
- Controller: UNIMATION 6-axis servo controller.
- Software Development Environment/Methods: RS232 Serial-port
- Sensors: None
- Actuators: 6 large electric motors with encoders.
- Height, width, length: 6 Feet tall 4 Feet reach
- Weight: About 80 pounds.
- Power source: 120 Volts AC
- Speed: Maybe 1 foot-per-second
- Construction history: See: Puma 560 progress page
- Type: Electric motor scooter
- Purpose: It takes me 15 minutes to walk from my parking place to my office.
- Controller: One big FET
- Actuators: One big motor
- Height, width, length: About 30 inches long, 15 inches wide and 30 inches tall.
- Weight: About 25 pounds
- Power source: 14 10.8 Volt NiCd packs for a total of 151.2 Volts.
This is 126 individual NiCd cells.
- Speed: 8-12 MPH
- Operational description: Get on, turn motor on, watch out for pedestrians.
- Future Enhancements/Plans: None
- Status: Resting for the 1999/2000 Winter. Returning Summer 2000
Date: Sun, 14 Mar 1999 20:37:24 -0600 (CST)
I have been working on a design for an electric scooter that I can
use to get from the parking lot I have to use at the U of M to my
office. It's about a 12-15 minute walk, and if I move to a cheaper
parking lot, it would be about 25 - 30 minutes.
I built a triangular platform from plywood with three 10 Inch diameter
rubber tires from Ax-Man to use for experiments.
Jeff and Ron helped me try out a large DC electric motor with about
a 3:1 V-belt pulley speed reduction. I sat on the platform holding
the motor, and applied 24 Volts DC to the motor, and I didn't go
anywhere. Jeff and Ron then pushed me to see if the motor could keep
me going once I got started, and it didn't work either.
So I looked about on the WWW for electric scooters, and found a
place that sells them for $500.00 but they didn't tell me how large
a motor they used. I eventually found a place that sells a motor that
you attach to your bicycle, and they had a 220 Watt and a 440 Watt
version. These are 0.3 and 0.6 Horsepower motors. So that told me
I went to Ax-Man to find some larger motors, and came away with one
rated as 1/8 Horsepower. 130 Volts DC and a 1.0 Amp draw. So the
Volts * Amps is about a 1/6 HP motor. This also had a 4:1 wormgear
reduction that claims to run at 500 ROM output.
Now if I direct drive a 12 Inch diameter wheel at 500 RPM, it will
go 17 Miles-per-hour. Which is faster than I want to go. I'd like
about 10 MPH, so if it has enough torque to get me going, I'm in
So I bolted on a 10 Inch diameter wheel from the triangle platform,
and built a 1-diode 120 Volt DC power supply with an extension cord
to the 120 Volt AC plug in the wall, and tried it out. It didn't have
enough torque to get me going, but if I pushed off, it could keep me
going! So I them built a full-rectifying and filtered DC power supply
that ran at about 150 Volts DC, and tried again.
Now I was kneeling on the platform, and either Jeff or Ron plugged
the thing into the wall, and the rubber wheel started spinning
against the carpet, and I took off like a rocket headed for the brick
wall! It was great. Burnouts in the basement.
So now Jeff is giving me a pile of NiCad packs to make a 120 Volt DC
battery to try, and I found a nice two-wheel scooter at a place
called Sport Mart in Golden Valley or maybe Plymouth for $50.00 that
has steering, and brakes. I'll adapt the motor to drive the rear wheel
directly, and bolt on the batteries, and we'll see how fast it goes.
Then I'll have to design a 120 Volt PWM driver for speed control.
I'll keep you up to date on progress.
If you are interested, here are the motor numbers:
Bodine Electric Company
130Volts DC 1.0 Amps 1/8 HP
11 Lb-In 500 RPM 5:1 gearbox
0.625 Inch shaft with flats.
Avaliable at Ax-Man St Paul store (At least) $50.00
If they only use uppercase alphabetic letters, that Type field
can handle 308,925,776 types of motors!
Date: Fri, 26 Mar 1999 10:58:27 -0600 (CST)
Subject: Thursday 3/25 kilian's house
Another fun day at my house last night.
I worked on getting a 130 Volt DC NiCad pack built. I had a metal
case from a stepper motor driver that didn't work, and it was EXACTLY
the right size to hold 12 10.8 Volt 1700 mAHour NiCads with cardboard
spacers and everything.
Run wired up two bricks of 6 batteries, and then taped them all together
with Electricians tape, and we had a nice little bomb!
We then needed to charge them! We hooked my 150 Volt CD power supply
then I had at the last meeting to a bathroom light fixture with a
single 60 Watt light bulb in it. We wired the light fixture in series
with the power supply so that the light bulb would limit the current into
the battery pack.
When we plugged it together, we got about .6 Amps into the batteries, and
it quickly went down to 0.25 Amps. So I screwed another bulb into the
fixture, which reduced the resistance by half, and the Amps jumped up
again to about 0.5 Amps. A few minutes later we were at 0.25 Amps again
as the batteries got their initial change, and their voltage came up to
normal. So I screwed in another bulb and we came up to 0.5 Amps once
again. It stayed there for over an hour while the batteries were
charging. the batteries didn't get even warm to the touch. The would
take about 4 hours to charge at that rate. I will build a little
constant-current charger with two settings on it: 0.5 Amps and 0.2 Amps.
If I charge at 0.2 Amps I can charge them forever and not damage the
batteries and they will take about 14 hours to fully charge which is
just fine for me. I can plug them in when I get home, and they'll be
ready the next day.
Now it's on to mechanical to get a wheel on the motor, and that unit on
the scooter. What fun!
Date: Fri, 2 Apr 1999 16:14:17 -0600 (CST)
Kilian's robot shop of smoke!
Another fun night at my house last night.
I cut some aluminum for the electric scooter to hold some
bearing blocks for the rear wheel/motor. I made some blocks to pound
the shaft out of some bearings I got from the AxMan also.
Then we went on to the batteries. I had stopped at Radio Shack and
got 15 Amp and 20 Amp fuses and a fuse holder to put into the
battery box. I wasn't sure just how much current the motor would draw
under load, so I bolted on a 6 Inch diameter pulley, and while the motor
was running, I pressed the edge of the pulley into a 2X4 board to generate
a load. With no load, the motor draws 0.7 Amps. With a reasonable load
it draws 1.5 Amps, and with a really large load it draws up to 4.0 Amps.
So I thought a 15 Amp fuse would be fine. But Ron noticed that the back
of the package said 15 Amp Slow Blow and the front said 15 Amp Fast Blow.
But he 20 Amp said Fast Blow on both sides. I thought that a NiCad could
produce 20 Amps to blow the fuse, but I wanted to check.
So I installed a 20 Amp fuse, and Ron swiped the two wires together.
Remember that this is a 130 Volt battery, so 20 Amps is 2600 Watts.
Well it made a big bright flash! and when Ron hit the wires together again,
it made another bright flash! Every time hi did it, it still flashed,
so we were not blowing the fuse. We thought that maybe the current pulse
was too short, so I decided to short the wires together for a long time.
First I went upstairs and got a Fire Extinguisher and gave it to Ron.
I set the battery in the middle of the concrete, put one wire on the
floor, and held the other wire over the top, and stepped on the wires
to short them together. And then things got exciting!
There was a strange FUFF noise, and sparks, and a blue ball of plasma
or whatever blasting out of the pack, and then nothing.
The battery produces 1.5 Volts according to the meter.
The fuse was still good!
Using the meter, I found out that one of the top two battery packs didn't
produce any voltage, but the other 11 packs seemed fine, so I unsoldered
the to pack, and took it off.
There was a hole blasted clean through the plastic coating, and a hole
blasted through the coating on the pack beneath it! Big charred metal
bits, and molten blobs left one pack, and entered the other pack.
Using another pack that I had cut the plastic off of, we figured out that
there is a temperature sensitive sensor wired in series with the battery
pack that open up at 70 Degrees C that had been vaporized.
Jeff has the packs, and will take some photos and scan them in and put
them on the tcrobots.org web page.
I replaced the two packs, and put in a 2.5 Amp fuse and I think we'll
be fine from now on.
I'll keep you up to date on progress.
Be careful out there,
Date: Fri, 7 May 1999 09:54:29 -0500 (CDT)
Another good Thursday at my house.
I was disappointed with the performance of my Dual LM555 based motor
speed controller, so I was going to try a Basic Stamp using the PWM
command. It sounded like overkill, but I just don't like fooling around
with analog stuff. Especially 555s. Jeff said something like Oh come on!
a pair of 555s should be just fine. Why don't you have Ron look at it.
Well Ron redesigned it, and moved a few components, and it works great!
That's why he's an analog guy and I'm not.
I did some machining, and the scooter is getting closer to running.
I have the motor and main driveshaft supported by two bearings all on
a plate that can be bolted to the rear frame of the scooter.
I need to make two plastic adapters to get the wheel on the main driveshaft
and things will really be rolling. Literally.
I have some doubts about the strength of one end of the main driveshaft
where I have a 0.5 Inch diameter aluminum shaft inside a bearing.
It doesn't seem like a 0.5 Inch diameter aluminum shaft will hold me up, but
I'll try it, if it breaks, I can bore the shaft out to 0.5 Inch and insert
a steel shaft, and everything will be good again.
The battery was down to only 97 Volts DC ??????
Last week I changed it until it got hot, so what happened?
The battery is 108 NiCd cells in series for 129.6 Volts DC nominal,
and I know that NiCd's have a very flat discharge curve, so the voltage
stays up around the rated value until very near the end, and then they
go flat very fast, so I don't understand this.
At 97 Volts DC that's only an average of 0.9 Volts per cell.
So I charged it up again, and it was at 141 Volts DC after running the
motor for a while. I put a note on it listing the voltage, and I'll
measure it every night for a few days to see if it self-discharges
faster than it should.
The one explainable possibility is that after I charged it last week,
I might have left it hooked up to the charger, but unplugged the AC
from the charger, so maybe the charge leaked out through the filter
capacitor, or the Diodes in the charger. Who knows?
That's it for now.
Date: Sun, 9 May 1999 22:05:31 -0500 (CDT)
Well it wasn't a good weekend for the scooter.
I started by discharging the battery pack through a bank of 60 Watt
120 Volt AC lightbulbs.
First I used one bulb, and it drew about 500 milliAmps or so for 15 minutes.
Then I used 4 bulbs which drew about an amp.
After about 13 minutes, the voltage started to drop off very quickly. I
stopped after about 14 minutes when the voltage got to 100 Volts.
The first discharge should have been about 125 milliAmp-Hours and the
second should have been another 250 milliAmp-Hours but the cells are
rated at 1700 milliAmp-Hours, so they weren't fully charged.
So I decided to charge them. I charged using 1 60 Watt bulb in series with
a 170 Volt DC source, and got about 600 milliAmps into it at the beginning
dropping off to 300 milliAmps after 15 minutes.
Then I used 4 bulbs in parallel and got about 1 Amp draw. This is about
0.6 C charging raet which should be fine for about 2 hours or so.
I came back in 1 Hour 20 Minutes, and the current was at zero.
So I figured that somehow I had blown the 2-Amp fuse I have in series with
the batteries. Nope.
The battery pack read about 3.0 Volts DC. !!!
So I figured that my meter went bad. Nope, it measures a 12-Volt battery
All the packs in the cluster read 0.05 Volts except two which read 1.2 Volts
What is going on?
I took apart a pack of nine cells, and they all read 0.05 Volts.
How does a NiCd cell do this? I never charged them for more than 3 hours, and
I never charged faster than 0.6 C.
Is there something about using a 170 Volt supply on 130 Volts worth of
I don't know what to try next. It looks like all the cells are blasted
somehow. They all look fine. Not bloated, leaking or anything. Just
Would these be the symptoms if I had somehow charged them backwards?
Date: Fri, 14 May 1999 14:22:55 -0500 (CDT)
I built a new battery pack last night, and am charging it at 0.1C
(170 milliAmps) to make sure it gets a proper charge, and then I will
discharge it under a 0.1C load to get the pack's capacity, and then
after another recharge at 0.1C, I'll discharge it at my anticipated
rate of between 1.0C and 1.5C to get another reading on the pack's
I'll keep you all informed.
On to the "Other" pack.
I am pretty sure that I charged the pack backwards.
- My charger is connected to the battery with clip-leads and a meter
to monitor the current in a big Rat's nest looking mess.
- Whenever I wanted to check the pack's Voltage, I would disconnect
all the clipleads, reconfigure the meter for Volts. (And if I didn't
reconfigure for Volts, the meter's fuse would go Blammo, so I was
focussing on this) and measure the pack's Voltage.
- Then I would again reconfigure for Curremtn measurement, and reconnect
the mess back together again.
- I'm a software Guy.
- When I charged using One 60 Watt bulb in series, I got 500 milliAmps
and the bulb was medium-bright.
- When I charged the completely dead NEW pack using One 60 Watt bulb in
series I get 180 milliAmps and the bulb was not illuminated, but gets
- There was some greasy or oily liquid in one of the pack's wrapping that
might have been electrolyte.
So, I looked in my "Battery Bible" _Handbook of Batteries_ Second Edition
by David Linden 1995 McGraw-Hill ISBN 0-07-037921-1
(Sorry about that wrapped line, but That's the way the URL bounces)
and He says that reversal causes gas and electrolyte to leave the cell,
but that this just reduces the capacity of the cell, it doesn't ruin it.
So I'm going to put my Effort where my Mouth is, and rebuild the original
pack using the original 108 cells, and try to charge it, and then discharge
it and measure the capacity.
I'm betting on the pack working fine although at a reduced capacity.
I'll keep you all informed of course.
Any bettors out there? Which way are you willing to bet it will turn out?
Date: Fri, 28 May 1999 14:42:49 -0500 (CDT)
It's time for another update on my Electric scooter story.
Batteries: I don't have my Lab notebook here at work, so
I can't give you the gory details of charging and test
discharging. So I'll give you the high points, and save the
details for another posting. Old batteries that have been
reverse-charged until all cells read zero Volts can be
recharged, but some of them don't survive. Some recharged
back to normal Voltages. I have not done discharge tests
yet. New batteries charge normally, and discharge found one
pack that dropped it's Voltage way before the others, so I
replaced it, and will try another discharge test again later.
Scooter: I actually rode it last night!!!
I finished up the mechanical assembly, but the PWM speed controller
was not quite ready for prime time. It works, but the box with
grommets for wires etc isn't ready so we decided just to wire
up a momentary switch to apply power directly to the motor from
Also I didn't have a place to mount the battery case, so I put it
into a backpack and wore it.
We got everything together, made sure the motor went the right
direction. Reversed the motor wires, and again made sure that the
motor went the right direction.
Then we went out to my front yard for a test drive.
I live in a suburb, and there are no street lights so it's pretty
dark at night. It was 11:45 PM before we got everything together,
so it was dark.
I started scooting down my driveway, and then I hit the power
button just for a second, and MAN this thing has power!
Hey, Hey, HEY!!! It's still running even though I'm not pushing
the button!!! I hit the brakes, but I didn't hook up the rear
ones yet, and I can't stop. I took a turn at the bottom of the
driveway and I'm now driving on a dark street at Midnight with
no way to turn off the motor. I pushed the button a few times,
and the motor slowed down enough for me to jump off, and lift
the handlebars so that the rear wheel was off the ground.
So now I'm standing in the middle of the dark street at midnight
with a spinning rubber tire that I can't really see between my legs,
and I have to hold this thing at shoulder height and walk back to
the driveway so that Ron or Jeff could unplug the battery.
And the switch is starting to smell bad.
Actually, I was glad that the switch was burning, because it was then
adding some resistance to the circuit, and that's why the motor slowed
down enough so that I could use the brakes enough to get off the
Ok, no damage done to anything other than the switch which has melty
electrical tape on the connectors since it got so hot.
So we decide that maybe a household light switch is a better idea
since it can do 125 Volts at 15 Amps, and I only have a 3 Amp fuse
in the battery pack. Rewire and we're on our way again.
I go up a slight hill this time. Man I'm really moving. Maybe 7-10
Miles-per-Hour or so. This is great. I turn off the switch, and
no change in the speed. Arghhhhhhhh. I look at the switch, and I can
see really pretty green explosions going on INSIDE the switch that
is lighting up all the way through the switch's plastic parts.
This switch is not supposed to be translucent. The sparkles stop
when I try switching the switch a few times, but I'm still going.
Fast this time.
Without my bike helmet.
In the dark.
Away from home.
With eight pounds of batteries in a nice rectangular box lined up
with my spine.
So I yell out "I'm in trouble here." and go up to an intersection
and make a nice skidding U-turn only hitting one curb and start
rolling back to Ron and Jeff.
With the brakes on full-blast (Front brakes only you know) and
dragging my slipper (No need for hiking boots right?) I got slowed
down enough for Ron and Jeff to grab the thing and hold it up in the
air while the battery plug got pulled.
Now there wasn't any reason to use a bike helmet or boots since
there wouldn't be anyone there to see anyway. Except maybe the TV film
crew taking footage of me as I'm laying in the front seat of my
neighbor's car after blasting through the side window RIGHT?
Ok, we thought about it for a while, and thought HEY!!! we forgot to
install a flyback diode on the motor! Duh, that's why we are blowing
So we install one, and the same thing happened again. Fused switch.
We don't really understand what's going on with the switches, but
we think that there's something about DC vs AC that makes switches
blow up. Maybe it's that the current goes to zero every 120th of a
second with 60 Hz AC.
When we broke apart the switches post-mortem, Ron says "Look, 125 Volts
15 Amps AC ONLY" on the house light switch.
Well, I really need to design an emergency power disconnect that can
be pulled from up at the handlebars, and physically disconnects the
You know the NEDRA (National Electric Drag Racing Association)
has a rule that you have to have this type of device, and I thought
it was silly until last night, now I know that they are right.
See: http://www.nedra.com/rulebook.html#2_8 section 2.8.3 and 2.8.5
Next week I'll try to get more mechanicals going to mount the batteries,
motor speed controller and emergency disconnect.
Be careful out there.
And wear your helmet.