Sunday, 21 December 2008

The Kogan Agora Android phone dosn't have an accelerometer!

The Kogan Agora Android phone doesn't have an accelerometer! This means some of the augmented reality apps wont work to full advantage and I can write my EV performance calculator.
I think Google should specify a minimum hardware specification for devices to ensure all the apps work properly.
Might cancel my order and a t-Mobile G1 in the US if I am there before it appears in Australia.

arrg

Saturday, 20 December 2008

CO2 output and charging using Coal Power Generation

We have to be very skeptical when reading reports from 'experts' and 'scientists' to check the author does not have a conflict on interests. 

I did the math on this a few months ago and here are the results. 

In 2006 Munmorah generated 1,416Gwh of electricity, the most since 1942. Given that Munmorah emits 1.065 tonnes of greenhouse pollution for every megawatt hour of electricity generated, it would have produced about 1.5 million tonnes of CO2 in 2006,about 1% of NSW’s total. 
Munmorah power station old and very inefficient is http://www.greenpeace.org/raw/content/australia/resources/reports/climate-change/switching-from-coal.pdf 

FYI only - Redbook figures are in = gm/km. 

Thermal efficiency of coal Australia 33.3% in 1988 
Newer plants are 53% for UCC generation. 
http://www.australiancoal.com.au/cleantechAus.htm 

Greenhouse gas emission could be reduced by 20% by modernization. 

1.065 tonnes of ‘greenhouse pollution’ per megawatt hour 
= .000001065 tonnes of CO2 per watt hr 
= 1.065gm/Wh 

If my ute does 200Wh per km = 200*.000001065 = 213gm/km based on coal generation. 

Mitsubishi i-Miev 123Wh/Km = 123*.0001065 = 130gm/km based on coal generation. 

Compare that to a rough average of about 2.3kg/L 
http://www.comcar.co.uk/newcar/companycar/poolresults/co2litre.cfm 
-> 230gm/km for a 10l/100 vehicle 

Conclusion: an EV charging from power generated from Munmorah will have about 8% less CO2 output. 

This excludes transmission losses are about 7.2% http://en.wikipedia.org/wiki/Power_line so we are about on par. 

If you charge using a modern coal fired power station, you are winning with your EV, if you use real green power you have won. 


Petrol energy = 31.2 MJ/l 
If my hilux ICE did 10l/100km 
then it would use 312MJ of Petrol 

According to Google, 1 megajoule = 0.277777778 kilowatts hours 
so I have used 86.6kWh of Petrol to travel 100km 

My EV Hilux will use about 200*100=20kWH to travel 100km 

Sanity check. 20/86.6= 23% efficient ICE. A bit high but in the ballpark. 

Monday, 15 December 2008

Fuses, lots of fuses.

This weekend was spent making up fuse boxes. I purchased 60 FHM3AG fuses from Pacific Components .

26 of these are to connect to the outputs of the 13 chargers. These (actually 24) of them are mounted in 2 ABS boxes on clear acrylic. The final 2 will be inline as they are only +-12 volts.

Each alternate fuse has 48 volts between them so before inserting the fuses I will glue some clear plastic sheet between them so they dont short when fumbling with fuses.

<<13122008.jpg>> <<13122008(001).jpg>>

I started test charging one set of batteries and unfortunately the charger let the magic smoke out of the output electrolytic capacitor and a diode also ruptured. I have replaced the cap and diode, but the charger still has some problems. Back to e-crazyman on eBay if I cant fix it.

Another smaller ABS box has 6 fuse holders for the heater and the 12 volt power supplies to charge the accessory battery.

<<13122008(002).jpg>>

Tuesday, 25 November 2008

Monday, 24 November 2008

Productive Magazine - free edition

Here is something a bit different. In my day job I manage a knowledge management application for a multinational. (can I use manage twice in one sentence). There is a new publication that caught my eye. It is good reading for anyone into productivity or just getting things done.

Take a look at http://productivemagazine.com/editions/

Sunday, 23 November 2008

12 volt battery installed

When I bought my batteries I ordered 5 additional as spares. Rumor has it that the failure rate is about 1 in 30.
I have used one of the spares as the 12 volt battery for the accessories. To fasten it I bought some 6mm threaded rod (600mm zinc plated for $2 from Hardware and General) .
I cut it to length and bent about 30mm on one end 90 degrees. The bent end goes through a 6mm hole drilled in the base where the original battery went.
The battery is sitting on a rubber mat. The threaded rod and the hold down clamp are covered in heat shrink to prevent any possible abrasion.


All battery interconnects are installed and wiring done.

This weekend I installed the battery interconnects. They are made from copper sheet, cut into 12mm strips and drilled. All the straps are n shaped so they will allow a little battery movement. This is to prevent the battery terminals from working loose.


The cables are 16mm^2 . Overkill but free. The contactors along the side are double pole. These are used to break the battery bank into 12 x 48v blocks and on 24v block. This makes it save to work on. I tested each contactor separately with my cable shears at the ready in case I had made a terrible mistake. Thankfully they were not required. Across any contactor there can only be 48v max so it is safe to work on. The stainless steel battery clamp strips are covered in heat shrink to give as much insulation as possible. Each battery has the zener-resistor balance circuit connected across.

Next step is to put the +- 300v cables and interconnects to the VFD into orange plastic tube. and begin connecting the controls. (throttle, reverse lights, direction switch and VFD display. Then the chargers and fuse holders for the chargers.

What to do with 25 empty battery boxes?

Make a robot of course!

Saturday, 15 November 2008

Try and get google to find this page better

Malcolm Faed
Electric Vehicle
Hilux
Greensaver
Malcolm Faed

Batteries Installed

Today I installed the batteries and cut and drilled copper bus bars. Also put heatshrink.

I need some stainless steel bolts to attach the bus bars and the balance circuits. The screws and nuts that came with the Greensavers are too short and have cheap plated screws.

Here are the photos.

360kg of batterys almost make my Vitara pull wheel stands :)

Batteries bolted down
One set of 4 batteries connected. I need to buy some new bolts for the terminals to do the rest.
The battery balance circuits are attached to the 4 batteries in a set.


Thursday, 13 November 2008

IEEE lecture by L Roy Leembruggen


I attended a lecture at the IEEE tonight . Details here

There was a very good turnout for the presentation this evening. And quite a few AEVA members as well. Many of the IEEE members were keen to hear about the various conversions underway after the main talk.

Andrew brought his motor bike along that drew a good amount of interest.

I should have printed some AEVA 'business' cards to had out.

Roy gave an excellent talk on his various EV designs and also briefly descried a business he is setting up and was receiving expressions of interest for people to become a part of the company.

He described various sized family vehicles as well as buses of all shapes and sizes, including a double decker the size of a B Double.

Unfortunately there is not a web site. I found this by google that discusses some of his projects. http://eclipsenow.blogspot.com/2008/08/double-decker-trams.html
http://eclipsenow.blogspot.com/2008/10/aussie-car-company-should-run-roll-out.html

Sunday, 9 November 2008

Battery box and VFD installed

While I was away last month Geoff from GT Tooling built my battery trey.
Yesterday I installed it and the VFD in the tray. Beneath the trey there are 4 stainless steel square tube cross members to help support the batteries, act as spacers for the bolts to the trey structure and to support the VFD.


The contactors are visible on the posts vertical supports. The connections will be the same height as the battery terminals.

Each threaded rod will be covered with heat shrink to prevent the batteries from being abraded in case they come in contact.

All components of the battery trey are stainless steel.

Next weekend I hope to install the batteries and start connecting them.

The interconnects where practical will be made from copper strip. The rest will be 16mm^2 cable with appropriate lugs crimped on.

The straps to hold the batteries down will also be covered in heatshrink to provide additional insulation to the Battery Balance Circuits.

Emissions ICE vs coal generation

I did the math on charging using an inefficient coal fired power station as a worst case example.

Essentially the CO2 emissions are about the same for an ICE for a similar weight vehicle.

So, even using power from a modern coal fired power station, the environment is winning. Also the point of combustion is away from populated areas.

Long time no post

After being away on holidays and for work for a month it is time to get back into the ute build.

Tuesday, 23 September 2008

Sparky Bro going nuts on my balancing scooter. aka segway

We had a very pleasant visit from Sparky Bro and his family this evening and enjoyed discussing EVs and industrial AC conversions in particular. Before leaving he had to have the mandatory ride on my scooter. :)


50 x balance systems.

Here are a few snaps of my battery balance system construction. they consist of 2 x terminals, 2 x 6.8v Zeners and one 4.7 Ohm resistor. Each series is encased in clear heatshrink.



Under construction. The wooden block is a jig for aligning the pieces for soldering
Completed units - no heatshrink
Completed units, with heatshrink.




Monday, 22 September 2008

Batteries Arrived - port and final costs.

I picked up my batteries from the port last week.

3 tips if you go to the ports.
1. Wear a fluro vest
2. They don't load vans with a forklift
3. You are not supposed to break down packages for loading.

None of this was a problem but I will keep it in mind if the is a next time.

So... the final outcome

55 batteries AU$2290.48
Bank Fee AU$ 20.00
GST and Duty AU$ 423.77
Customs Agent AU$ 137.5
Port Fees AU$ 248.05
TOTAL AU$ 3119.08
or $56.72 each. 

They came in Under $60 so I am happy.

Now  to call about my battery box.



Tuesday, 9 September 2008

Donate button

Not to be outdone by Kearon of EV Capri I have added a donate button.

Instead of paying money to offset your greenhouse emissions to an anonymous company, how about donating it to me. :)

Comments please?

I figured out why no comments were being left. The option was turned off.

Please comment all you like!

De-Bogan

I have removed the tinting from the windows to make the Hilux look a bit less bogan. I can see into the windows now. When it was on the road I would wave at friends and they wouldn't even be able to see me.

It was not has difficult as I had expected. After using a blade to peel off a corner, the rest peeled of reasonably easily. Then  I had to remove the sticky. The trick is a good blade handle designed for scraping and lots of sharp blades. I used about one blade per window. 99% of the sticky was removed this way. For the last few smears, I washed the windows with a cloth dampened with eucalyptus oil, and finished with window cleaner.

The rear windows demister didn't work anyway so I scraped the elements off at the same time as removing the sticky. I found and aftermarket demister on eBay that I will probably install.

More photos to follow.

Friday, 5 September 2008

Tuesday, 2 September 2008

Heater Install

Here are the details of the heater install.

The heater is designed to run 4 ceramic elements in parallel at 240VAC

I will be running the 4 elements in series at 600VDC. If they were purely resistive this would amount to about 800W.

But these are PTC so I expect the output will be a bit higher.

The element has been installed in high temperature RTV compound into the main air duct from the fan.

The relays for the heater are only able to be energised when the fan is on.

<<30072008.jpg>> <<30072008(002).jpg>> <<23082008.jpg>>

A thermal cut-out on the heater, connected to the relays coil will also be installed for protection in case of over heating.

Parts for battery balancing

Here are the parts for the battery balancer.

They are all available from http://www.rockby.com.au

For the 50 batteries, there are:

·       100 x 5mm Terminals

·       100 x 6.8v 5W Zener Diodes

·       50 x 4.7R 1W resistors.

I will make up a jig to assist soldering them all quickly and accurately.

After completion they will be encased in heat-shrink.

<<12082008.jpg>>

A few notes

  1. My batteries are on a ship on their way from China. Should arrive mid October.
  2. Spent Saturday installing the dashboard and stereo. Gotta have good sounds!
  3. I have located all the important wires in the loom and designed the necessary opto isolating interface. (Reverse, Tacho and Speedo)
  4. I have permanently wired the brake vacuum pump to the ignition
  5. Sent plans for battery box to Geoff for fabrication.

Daddy's Helper

With toolbox in hand.

Engine Mount and Driveshaft installed.

This is the view looking up from under the vehicle.
The aluminium block holds the inductive pick-up. (Thanks Geoff)
The drive flange is the grey part.
The Universal and sliding spline are bolted to the drive flange.

I spent ages looking for 10mm x 1mm pitch bolts. I should have gone to Toyota first. They were just a couple of dollars each!



This is the rear mount that attaches to where the gearbox used to attach.

Sunday, 10 August 2008

Cyclic test result for 20Ah Greensavers

I have cycle tested the Greensavers and plotted the capacity. The results were disappointing HOWEVER please see the explanation from Greensaver. It seems I over discharged them. I probably incorrectly assumed the 100% discharge point was indicated by the "Discharge Characteristic Curve" in the data sheet. (see previous post for data sheet)

Director of R&D, Greensaver: "Two comments on the cycle life test result: (a) The cutoff voltage was too low. Overdischarge will cause low cycle life. It is suggested that the depth of discharge is limited to 80%, and the cutoff voltage is set at 11.4 ~ 11.5V.
(b) The average discharge currents were relatively high. In this case, the recharge current is suggested to choose the same rate of high current to improve the cycle life of batteries."

Point 2 would be difficult to implement due to the cost, size and primary current of chargers.


The capacity is normalised to 1Ah discharge as varying discharge currents were used. This eliminates the effect of the Peukert factor at different discharge rates. The 'waves' are caused by slightly different end point volatages at different currents.

Tuesday, 5 August 2008

The Driveshaft

Here is the assembled driveshaft.

The shaft is a 2 piece unit. The forward section (closest to camera) has been extended and a sliding yoke fitted.

The near end attaches by 4 bolts to the drive flange on the motor.

Motor installed

The motor is installed on the mounting plate.

<<19072008.jpg>>

Batteries Ordered

Last week I ordered 55 x Greensaver SP20-12 batteries. 50 to install and 5 spares.

I need to design and build the battery box next!

Cost per battery should be a little under $60 each including landing taxes.

Drive Flange and speed sensor

Thanks to Geoff O'Toole for your fantastic machine work.

Here is a photo of the drive flange assembled with the inductive pickup (AE1-AP-4A) from AutomationDirect.com.au.

The speed sensor is used to provide feedback to the controller for closed loop operation.

<<18072008(007).jpg>>

The Drive Flange has been machined, drilled and tapped to accept a Hilux universal joint.

Thursday, 17 July 2008

Greensaver battery inter cell balance - After Discharge

To satisfy Tuarns (and my) curiosity, I discharged the battery to 11.5v at 20A, let the battery rest, then measured the individual cell voltages. Following are the results.

+
2.0919
2.0966
2.0994
2.0985
2.1004
2.0957
-

Average = 2.097083
Standard Deviation = 0.003079
Range is from 2.0919 to 2.1004 difference = .0085 volts (0.406%)

Again the battery seems to be well balanced.

Wednesday, 16 July 2008

Thanks Dom




Actually I am waiting to get the engine mount back from the sand blasters and painters, bit it looks good hanging there. :)

Tuesday, 8 July 2008

Greensaver inter cell balance

Greensaver have been very helpful in providing technical details regarding their batteries.
They provided the following diagram of the top of the cell including the interconnecting links.



I drilled 5 holes in the top of the battery according to their diagram and measured the voltage of the 6 individual cells. The battery is measured at full charge. This battery has been (unfortunately) over discharged about 35 times and is only about 1/2 new capacity. A battery that has been cycled like this should exhibit significant imbalance between cells if the cells are not almost identical.



The results below are measured with a meter (not pictured) with 4 decimal places:

Cell : Voltage

+
1: 2.2402v
2: 2.2456v
3: 2.2452v
4: 2.2541v
5: 2.2490v
6: 2.2458v
-

Average cell voltage is 2.2466 volts. This is 100% charged including some surface change.

The standard deviation is .004616

The range is from 2.2402 to 2.2541. A difference of 0.0139v (13.9mv) or 0.6205%

I am not an expert in battery chemistry but this seems to be quite good.

Comments welcome.

Brake Vacuum Pump and Manifold complete

The brake vacuum pump and associated fittings are installed.

The pump is quite quiet. At higher vacuum the vibration is less.

From left to right:

1. T goes to brake booster and to the vacuum tank. (Aluminium drink bottle from Katmandu)
2. T and vacuum cutoff swithch
3. T and vacuum gauge
4. One way valve
5. Vacuum pump.

I bought the brass fittings (5/16") from ENZED


Monday, 23 June 2008

Controls and centre console

I have inserted some trim plastic from a wreck into the gearbox and coin tray holes in the centre console.

I have fitted a forward, neutral, reverse switch and the display/keypad for the motor controller. I am VERY pleased how these worked out.




ahhh progress.

Throttle Pot Installation

On the weekend I installed the throttle pot.

I fabricated what was needed from scrap aluminium. All in all I am happy with how it turned out. Placement in the engine bay is a little awkward due to the limited length and the stiffness of the cable.



The rubber dust boot should be pushed back over the cable shroud.

Thursday, 19 June 2008

ICE Removed & Weight loss

The ICE is now removed from the Hilux.

Electric motor and ICE side by side


The curb mass including Driver and a 1/4 tank of fuel was 1340kg
780kg on the front Axel and 560kg on the rear. (58%F 42%R)


There was a total of ICE components 285kg removed
This leaves a vehicle mass of 1340 - 75(me) -285 = 980kg before installing electric components.

Wednesday, 11 June 2008

Danfoss VLT 6042 for sale.

I have upgraded the VFD and have the original one looking for a home.

It is a Danfoss VLT6042 30kW 380-500v unit. It is in an IP54 case.

It has the DC bus option so it can be powered directly from a ~600v battery pack. According to Danfoss it can be lighted by (~20kg) removing the AC input filter components.

The Danfoss tech may also have a PCB to upgrade it to a VLT5032.(lower number, higher spec)

See here for images

Here is a link to the Specifications and Manual. (look for the VLT 6000 HVAC)

It is suitable for a conversion where you will retain the gearbox in a larger vehicle or a small vehicle with direct drive.

Please drop me a line if interested. (m.faed at ieee.org)

Regards,
Mal.

12 Volt Power Requirements

The maximum 12V power requirement for the vehicle is just under 50A. After replacing the bulbs with LEDs this will be reduced significantly.

Power Requirements:







Accessory Current Draw Include in Max total

Incadessent LED

Brake 3.2
x
Fan 1 2.7


Fan 2 4.2


Fan 3 6.9


Fan 4 12
x
Idicator L 4.5


Indicator R 4.2


Hazzard 8.9
x
Park 3
x
Headligh L 12.1


Headligh H 13.4
x
Wiper L 3.3


Wiper H 5.5
x
Demister 0.2
x Faulty
Dome Light 0

Needs Bulb
Total Draw Amps


46.2

12 volt charger mods.

I am using 2 x 'off the shelf' 230v to 12 volt 25A switch mode power supplies for my 12 volt system. One is powered from 0 to +300v and the other from 0v to -300v respectively.

As a consequence 2 modifications were required.

1. The feedback circuit needed changing to increase the adjustable output to 13.8V. This was done by tracing the voltage divider circuit and adding the required resistor in parallel with an existing resistor.

2. The 20 ohm bleed resistor needed removing in order for it not to discharge the battery while the vehicle is not being driven.

The image below shows the modifications. (zoom in for detail)




The completed power supplies have been installed into the Variable Speed Drive where some of the AC filter components have been removed. The device between the power supplies is a 50A circuit breaker that will be used for the 12V protection. The Power supplies will be wired in parallel.



The maximum 12V power requirement for the vehicle is just under 50A. After replacing the bulbs with LEDs this will be reduced significantly.

Battery Balancing the cheap way

I have installed a zener diode - resistor battery balancer on my 'self balancing scooter'



There are 2 x 6.8V diodes and a 5 ohm resistor across each battery.
(Thanks again for the info from Tuarn)

The Lead Acid batteries at rest are about 13.3V at new and fully charged so no power is lost when the batteries are not in use.

The Zener voltage must be greater than the battery full charge voltage

The idea is that the more voltage there is across a battery, the more current is bypassed that chargers lower batteries.

This worked surprisingly effectively.

The batteries before installing the balancer were from 12.5 to 14 volts at 'full' charge.
After balancing they were all within a few millivolts of each other, even after some discharge.

I was concerned that the bypass current may effect the automatic charger cutoff point as the batteries became fully charged however the charger still functions properly.

Given Zener voltage = 13.6
Maximum charger voltage = 15.2
Bypass resistor = 5 Ohms

The maximum current through the resistor is (15.2-13.6)/5 =.32A
The maximum resistor power dissipation is .32 * (15.2-13.6)=.5W

My ceramic 5W resistors are overkill. I will use 1W resistors in the vehicle system.

Maximum zener power dissipation will be 6.8V * .32A = 2.2W

The long awaited 20Ah Greensaver Test Results

Greensaver 20Ah Battery Testing

Apparatus:

Microprocessor controlled battery discharger and charger.

4 x 1 Ohm 200 watt resistors. Hard wire configurable.

Relay to switch between 2 discharge currents

Microprocessor calculates V, I, Temp, Ah, Wh and Peukert Factor.

Readings are taken every second and logged to the serial port of a computer for graphing.

After discharge, the battery is automatically charged.

The discharge cutoff voltage is programmable.



The negative figures in the LCD indicate that the battery is being charged.


I know, it looks like a weapon of mass destruction :)


Goal:

To determine the Peukert effect of the 20Ah and 27Ah Greensaver battery.

The reason for perform the test is because the specifications state a low Peukert factor fro these batteries and I wanted to verify this before purchasing a pack of 50 batteries.


Results:

Discharge curves. (note glitch in V5 between seconds 3 and 12. As this is only a 9 second occurrence, it does not affect the overall result.

Peukert Effect:


Conclusion:

The average Peukert factor of 1.105 is low compared to other batteries that are usually greater than 1.13 for batteries of similar capacity. The calculated Peukert factor from the 20Ah specification sheet is 1.07. My tester is probably not that accurate but is sufficient to confirm that the battery performs close to specification.


Given this result, if Lead acid batteries are used, they should have superior performance under load and give a long service life.


Original discharge data is available in an Excel sheet upon request.


Next steps:

I also have a 27Ah battery that will be tested next.

The high current wiring will be upgraded to allow testing at 40A

The discharger will also be reprogrammed to continuously charge and discharge a battery to determine de rating over time.


Charging:

The charge curve for the 20Ah battery is below.



Thursday, 29 May 2008

How to lower rolling resistance? Suggestions welcome

After reading Tuarn's post in the AEVA forum I got thinking more about lowering the rolling Resistance.

I had considered these ideas at different times but Tuarn rolled them up into one nice post.

Lower viscosity oil in the diff will be a must. As per Tuarn I will look for 55W75.
Setting the tow in will be important. Lower the better within reason.
Tyre pressure is a given. I will try and locate the Rolling Resistance specs for my tires.

Now the tricky part. How do you minimise brake drag. The rear drums are self adjusting and the front are disk brakes. Neither lend themselves to tweaking. Any tips and suggestions welcome.

At some point I will get some 'moonie' hub caps / wheel covers. Partly to reduce wind resistance and partly for looks.

Update - Batteries - Tester - Diff - Steering - VFD - Tray

It has been a few weeks since my last post so an update is in order. photos to follow.

1. I received the Greensaver batteries (20ah and 27ah - 2 hr rate). The port chargers were unbelievable! These would have to be the 2 most expensive batteries in Australia! Lesson learned about sea-freighting goods

2. I have built a micro controller based charger / discharger. It will measureand log to a PC the following aprameters during discharge and charge Volts, Amps, Watts, Ah, Wh, temperature and the all important Peukert factor. It uses 4 x 1 ohm resistors. The resistors can be wired differently to vary the test current. I am waiting an LCD from Futurelec and a charger from ebay's ecrazyman.

3. I have bought a diff from pick'n'payless . It is a 5.125 ratio from a Hiace van. All going well I will install it this weekend. This gives a theoretical top speed of 94km/hr at 4000RPM

4. I also bought a manual steering box from pick'n'payless for installing this weekend.

5. Better VFD. I bought a better Danfoss 5042 VFD off ebay. So, if anyone wants a Danfoss 6042VFD in an IP54 case I have one looking for a home. I have removed all the AC components from the cabinet to minimise losses and will feed it DC directly to the soft charge circuit.

6. The ute has a tray back which was way too wide for the body. To tidy up the looks I have narrowed the tray to be the same as the body (100mm off each side) and shortened the back. If I need sides I can get them from the manufacturer which is encouraging.

At the moment the carport looks like a car wreckers yard, but things should start coming together in the next few weeks. I am still waiting to borrow an engine hoist from my neighbours.

Monday, 12 May 2008

Tray off and ICE ready for removal

I have removed all things petrol from the vehicle and am ready to lift the engine out as soon as I get the hoist from my neighbour.

The brakes look OK. The diff needs replacing. Just as well I planed to change it to a lower ratio.

The next few weekends will be spent fixing up the body paintwork and surface rust spots.


Friday, 2 May 2008

Band I just found - Abney Park

I just found this Steampunk band called Abney Bark.

here is their album to play while you read :)

Monday, 28 April 2008

Greensaver batteries on order

I have ordered some sample Greensaver batteries. A 20AH, a 27Ah and a 12 volt charger.

I have also ordered 4 x 1 ohm 200w resistors for building a battery analyser. I am workon on the Bascom AVR code at the moment to check their capacity at different loads. The Peukert fact er of 1.09 for the 20Ah unit seems a little too good to be true but if it tests out after many cycles then they are great value for a bit over USD20.

Wednesday, 23 April 2008

Speedo

I have been browsing the workshop manual for a 93 Hilux / Tacoma and checked the vehicle and it has an electronic speedo. This is brilliant because I wont have to retrofit one.

The speedo just requires a 4 pulse per revolution input from the shaft.

There is a pulse output from the Danfoss VFD that is programmable. I will also be able to adjust the VFD output to compensate for the change in differential ratio.

This setup will require that I use closed loop control to have an accurate speedo.

Monday, 21 April 2008

Vehicle Purchased!


I have finally purchased a vehicle for the conversion.


It is a '92 Extra Cab Toyota Hilux ute (Tacoma Pickup for our American viewers). Model is a RN90R.


The good:
The right price for Sydney. These vehicles are about $2000 more expensive in Sydney. I payed $4k for it. The body is straight apart for a ding on one guard.

The interior is in good condition apart from the drivers seat that will need replacing.


The Bad:
It looks like it is from Mad Max as it has been painted black and has very dark tinted windows
The tray has no sides
The black respray is peeling off in places.
It has done 330,000km so I can not really sell the motor


To Do:
Replace drivers seat and various trim pieces inside.
Remove interior for cleaning. (I did this on the weekend. I just need to wash the carpet.
Investigate re-paining the body white or touching up bad paint job.

I took it to the local tip to put on the scales. The kerb weight (no driver or fuel) is 1250kg. A little more than I expected as it has an aluminium tray back rather than a well side. The GVM is 2050 allowing 800kg of load.

The rear axle has 41% of the weight. I will mount the motor as far forward as practical in order to maintain the balance.

I would still prefer to remove the gearbox. There is a 5.29 ratio differential available (existing is 4.1) from an early Hiace. This would give a final drive ratio a little high than third which may be acceptable. The top speed would be about 80km/h which is adequate for me.

Saturday, 5 April 2008

Battery Balancer

I have been thinking about how best to balance my chain of batteries, all 50 of them.

As there are 50 units the price could be quite significant.

Ideally a microprocessor based system would be implemented with isolated sensors on each battery however at this time it is cost and time prohibitive.

There are 2 alternatives I have seen the first would place 15V Zener Diode in series with a light bulb or suitable resistor across the battery. When a battery exceeds 15 volts, the Zener and lamp would bypass current proportional to the over voltage. This would be the simplest to implement.

Another alternative is a more aggressive voltage clamp described here.

The clamp voltage will have to be above the maximum charge voltage from the chargers and the regenerative braking.

Under regen this is 15 volts. Under charge this is about 15 volts but will need to be measured on the charger.

Obviously this solution will only work under charge but should be sufficient for now.
I will test it on my self balancing scooter first.

Thursday, 3 April 2008

Greensaver Silicon batteries

I have just been reading about these batteries.




They seem to cope better than Lead Acid on high discharge. Here are the specs of the 2 models I am interested in.

27 Ah



20 Ah