Videos of the working Kart

Videos of the Kart, working as planned:

Future Projects

Potential Future Projects



Carbon Fibre lightweight Kart, Double RC motor powered

• Carbon fibre chassis (for all mounting points, disk brake, etc)
• Lightweight rear wheel (Alloy, BMX wheel) + front wheels (Jogger pram alloy)\
• Lowly geared, for stupendous take-off power.
• Hydraulic rear disk
• Double RC motor + controller + special programmable servo driver
• 48V 10AH (sprint cart - short run time)

......-> New skill ... of carbon and vacuum formed carbon chassis parts
......-> Safe ... because carbon used in "not too high-speed" machine
......-> Can show the RC mount and gearing system, on Endless-Sphere. Orders ?

BMX with carbon fibre mounted twin RC motors

• Lightweight carbon fibre mount, being "covert" (enclosed, invisible)
• Lightweight twin RC motors (fan cooling)
• 48V 40AH (spring BMX, short run time ... covert in water bottle)

......-> Improving skills ... at vacuum forming carbon parts
......-> Can post pictures on Endless-Sphere, and maybe get orders for the parts
......-> Safe ... because "high-speed" machine ... but frame etc is all professinally made


Carbon Kick Bike Scooter with RC motor

• Lightweight carbon fibre kick bike
• Work on CVT transmission ?

An electric car

• #

09/09/2009 Progress

EV Charger

• Thoroughly checked Schematic and PCB against Breadboard (ie that identical)
• Re-created PCB with throttling control circuit.
• Created 5 x shunt circuit on a small PCB (in Eagle, free version) ... so to have professionally created (at a cost of under $30.00 for 2) by futurlec Australia. Saves printing, ironing, and drilling. Mainly the drilling (don't want to do that !).
• Following are images of the PCB, and the Schematic:

• Ordered from Futurlec. Lets see how we get on !
• DMM turned up today.  It is a Digitech QM1548, 40,000 count.
• Very useful, very good (very accurate) DMM. 
• Tested it - and very happy with result.
• Testing the Shunt circuit, there is a change of around 12mV up to 1.3A shunting.  This will do fine !
• This indicates I should select the "turn on" of the shunting, for 4.1 volts ... so the maximum possible "top out" is 4.22V, even if everything goes wrong with it.

*** Things to do ***

Things to do

1. Shunt charger
2. Create LVC circuit
3. Create better Kart Control (no heat dissipation, stable voltage, has LVC circuit)
4. Emergency panic switch.

=== Shunt Charger ===

1. Receive boards.
2. Test.
3. Assemble.
4. Test.
5. Use.

=== LVC Circuit ===

1. Check there is 12V switched from Kart control.
2. Single circuit, operating from that voltage.
3. Actually turns off Kart control (ie connected to ground, or power wire, or "stop" switch)
4. Has "Low Voltage Warning" LED, which lights for 30 seconds only.
5. Completely terminates power (no residual leakage).

=== Better Kart Control ===

1. Switch-mode power supply ("Buck" supply ?)
2. Thoroughly tested circuit
3. Single, smaller relay ?
4. Includes LVC within the circuit
5. NOTE ... easy connection when the lid is connected (ie whole thing comes off, for easy connection of new wiring etc).

Future Improvements

Front Stub Axles

-> Buy cheap 6803 bearings through eBay.
-> Bearings arrive.
-> Attend looking for bolts with 17mm shank (for front stubs).
-> If cannot find any ... then call steel supplier http://www.buau.com.au/ for 1020 17mm steel
-> If cannot find any, then consider here: http://www.smallparts.com.au/ $50 RSH170A ........ or change to 20mm bearings.

Later

-> Get the plug finished.

-> Create the female mould.

-> Create cart shell (fibreglass).

-> Create cart shells (final - fibreglass / carbon)

-> Create push bar.

-> Create axles.

-> Add all hardware to the cart, and finish !

08/09/2009 Progress

EV Charger

• Further experiment ... 60cm of 10A power cable is OK (after balance taps - does not affect outcome).
• This means shunt balancer does not need to be located directly on the balance taps.
• Further experiment ... Close connection between sense resistors and power source improves outcomes.

• Decided definitely not mount on the Kart itself.
• Decided definitely 2 x PCB.
• Created new PCB, with close connections. 5 channels per board. With space for further control circuitry (ie BM6 mounting, and RSP-1000 control.

• Control circuit must "latch" ... otherwise it will cycle between "on" and "off".
• All Jaycar double throw relays (ie simple solution) require 12V.
• All Farnell relays are $11.00 +++ and come from the UK only.
• Designed a latching circuit using a dual optocoupler.

• Created the dual optocoupler latch on the breadboard. Works !! Hooray !!
• Tested optocoupler latch with remainder of circuit. Works !! Hooray !!
• Tested optocoupler latch with RSP-1000-48 power supply. Works !! Hooray !!
• Thoroughly tested ... with "Shunting" and "Over-current" output. Good !
• Over-current operates the optocoupler at 1.3A. This, as it turns out, is fortuitous ... because it is the level at which the shunting isn't so accurate (because of the resistance effect of the balance tap wires).

07/09/2009 Progress

EV Charger

• Got 3 x 10W 4.7ohm resistors.
• Using resistors, did thorough "burn it" test at higher currents.
• After much experimentation, discovered that:

........TL431 works perfectly !!

........Breadboard resistance affects voltage control (ie allows "drift").

........Crucial to have no resistance between source, TL431, TIP137

.......and source

• Even further analysis, shows that it is the resistance of the balance wires that fouls up perfect balancing.
• Simple hook-up wire is sufficient to give bad enough readings, that the "Shunt Balancer" loses accuracy at around 1.4 Amps.

• Even further analysis (and testing) shows that the shunt balancer is much more effective if the balance wires are connected FIRST AND FOREMOST directly to the +ive into the TIP137, and the ground from the resistor.
• THIS WILL MEAN A RE-DRAW of the PCB permitting the largest possible traces directly to the TIP137, fuse, and primary resistor.
• Also, Futurlec boards are $8.00 each, $16.00 to set up ...
• ... so really can easily spend an extra $8.00 so to spread out the components, with larger traces, and order two boards instead of one.

06/09/2009 Progress

EV Charger

• On Friday, learned "Eagle" ... which will allow me to design a PCB that can be emailed to a manufacturing house (Futurlec) and manfactured cheaply.
• Completed a new PCB, fitting (amazingly) into 100mm by 80mm board.

• !! BIG NEWS !!
• Plugged in the RSP-1000-48 charger, and adjusted it to 41.6V, and it charged the whole pack incredibly quickly. Amazing !
• Only problem is ... it magnified (slightly) the wrong-balance of the cells. So from 16mV unbalance, one bank now has 36mA unbalance.
• This is (of course) still quite good, but it is enough to make the "Fuel Gauge" registered unbalanced cells, making an annoying beeping for driving.
• Important, now, to get the shunt balancer working as soon as possible.

Optocouplers

Best datasheet source is: http://www.fairchildsemi.com/an/AN/AN-3001.pdf

Key things to know:

=== Threshold ===

• Starts at 1.0v, and 0.1mA
• Best at 1.2V, and 10mA
• Effective resistance at that = 120 ohms
• Long term life is reduced above 10mA.

=== Resistor calculation ===

• R = (Vapp - Vforward) / Iforward
• R = (4.1 - 1.2) / 0.010 = 290 ohms !

=== Threshold adjustment ===

• Threshold can be adjusted by putting resistor in series:
  

• === or, redrawn so it make sense to a newB ===
• BUT NOTE ... values are not 2.2K and 2.2K (which don't make sense).
• Instead (for example) R2 could be 240 ohms (2.4V / 0.01 A) ... and R1 would be 170 ohms (4.1-2.4)/0.01.
• This would mean total circuit resistance (when LED on) of 250 ohms (170 + parallel 240 and 120) so total circuit current of 4.1/250 = 16mA. R2 gets V/O = 2.4/240 = 10mA of the current, and the LED gets 2.4/120 = 6mA of the current.
  

03/09/2009 Progress

EV Charger Progress

• Worked out adjustment of circuit (potentiometer wrong on breadboard).
• Tried the "off" circuit ... and fried a transistor (darn !)
• Therefore - definitely decided to use Optocoupler.
• Read all about optocouplers (see seperate post, under subject "Optocouplers")
• Ordered 40,000 count multimeter (to accurately set charger, and balance circuits).
• Ordered terminal blocks, and opto-couplers.
• NOTE - PCB board was too expensive. Almost half price at Jaycar.
• Started work on new PCB for balance circuit.

02/09/2009 Progress

Charger

• Created the "Shunt" circuit.
• As I "wind up" the voltage into the circuit, current is conducted ... but the voltage seen by the battery does not remain the same (which is what I expected).
• When I measure with the ammeter, the current seen by the battery remains the same ... so even when the system is "balancing" ... there is still current sucking into the cell which is at full voltage.
• How does this balance cells ?
• Thinking ... and carefully doing calculations (see below)

• The trick is to do calculations on a number of cells at the same time (not just one cell).
• As the "Shunt" circuit conducts, it actually reduces the resistance of the "Cell" ... thus decreasing the voltage drop across the cell (in comparison with other cells).
• The current in the circuit actually goes up.
• So the supply voltage to other cells will go up.
• The voltage reference and power transistor, should "balance" the circuit at the selected voltage.
• According to my calculations, the current through the balancing transistor should always be negligible, because the circuit effectively "balances" on the edge of the voltage selected.
• What I need to do now ... is test the circuit in parallel, with dummy loads (and check that it does, indeed, fix the maximum voltage at the cell terminals).
  

Testing

• Created test board ... of simulated cells etc.
• Turning up the voltage ... means shunt sends power away, keeping voltage constant (almost !).
• The TL431 does have some drift (as per its specifications).
• Changing the 120 ohm resistor in the voltage divider circuit before the TIP137, does make a slight difference (a slight improvement in steadiness of voltage).
• Reducing the resistor to 0.5ohm from 1.0 ohm makes a large difference in stability at higher amperage (up to 0.5Amps).
• Over 2.5amps, the circuit becomes completely unstable (TIP137 swamped ?) and voltage runs away.
• Therefore, it will be critical to have careful "back up" safety strategies.

01/09/2009 Progress

Kart progress today

Things I wanted to do today (AND GOT DONE !)

1. Finish all major wiring
2. Wire in "start" and "Stop" buttons, and fuel gauge.

• Created connector, for wire to Fuel Guage.
• Installed connector and fuel gauge wiring.
• Remove additional wires from balance board.
• Carefully check for short circuits.
• Hook balance board to batteries. Any heat ?
• Glue controller PCB into box.
• Screw in Kilovac relay.
• Screw in "stays" for battery.
• Screw / bolt in "strap" for battery top
• Screw in Kart control box.
• Created "wiring harness" wires for: (a) positive, (b) ground to kilovac, (c) kilovac to controller.
• Determine which is the "lower" 5 cells, for reading.
• Solder in "header" pins for lower 5 cells.
• Drill holes and cable tie in balance board.
• With screwdriver and wire cutters, install: [] relay wires, [] Positive, [] negative, [] precharge, [] fuel, [] Start, [] Stop
• Test operation.
• Cut "7 way" header socket and solder onto "easy board"
• Cut fuel wire, and solder into "easy board".
• Tested operation.

31/08/09 Kart Safety Features

Checklist

[ ] Safety "Kill" switch is big and red and very easy to hit.
[ ] Safety "Kill" switch is directly connected to Kilovac relay (no intermediate electronics)
..........for fool-proof cut-off.
[ ] Brakes have microswitch, connected to controller (ie to shut-off controller).