Mazda 121 Auto EV

Registered

2010-10-20T20:32:00.000-07:00

Well the car has finally been registered. After a 12 week delay comprising 7 weeks to receive the approval letter from Qld Transport and 5 weeks waiting for an inspection, it is done.

Of course Murphy's law came into play when I took it for the final inspection at the QT depot at Zillmere. When they checked the brake lights it turned out that one of the bulbs had blown while driving it to the inspection and when I tried to blow the horn it also didn't work. That turned out to be a loose connector. Luckily the inspector was a human being and allowed the vehicle to pass.

I have been doing some testing of the acceleration of the car and have been tweaking the motor controller settings to improve the acceleration. Unfortunately I improved the acceleration to the point where the front transmission mount broke. I have ordered a new mount and will put it in next Saturday.

While waiting for the part I am manually balancing the battery pack. I have made a single cell charger from a PC power supply that is capable of puting 40 amps into a cell. I am also using a high power resistor 0.22 ohms 150 watt to bring higher voltage cells down to a lower value. Unfortunately with these cells the voltage tends to bounce after charging and discharging. ie the voltage may rise to 3.4 volts when charging but when you remove the charger it goes back down to 3.38 volts after a few minutes. So there is a lot of waiting involved. Once I get it roughly balanced I will let the BMS do an automatic balance at top of charge.

I have also put a small DC pump onto the high pressure port of the auto transmission to try to keep the clutches engaged when the motor is not spinning. This partially works but I am drawing atf from the cooler loop which creates a vacuum in this loop to the point where the pump stalls. I will have to draw the fluid from the transmission sump, so it needs another outlet brazed into the sump to connect to.

Ian Bartie is also making an ATC (Automatic Transmission Controller) to replace the vacuum modulator in the transmission. It will control the pressures and gear change points in the transmission electrically from the motor controller. The device comprises a model airplane servo which drives a pin into the box via a cam mounted on the servo shaft. When the motor current is high the controller will drive the servo so that the pin moves into the transmission and out again under low current. This should simulate exactly the effect of engine vacuum on the vacuum modulator. Testing on the existing vacuum modulator showed that moving the pin only 1mm gave a change point from 2nd to 3rd gear speed variation, from 40 km/hr to 80 km/hr.

Ready for Rego

2010-07-10T01:46:00.000-07:00

Well it's finished. Last Monday the certification engineer did the final inspection of the car and it passed!!!.

He now has to write a report to Qld Transport and include the NCOP14 check sheet. It will then take 3-6 weeks for them to approve the vehicle and forward the approval docs. A roadworthy certificate will also probably be required. I can hardly wait.

I have a few shows lined up to display the EV. The Alternative Technology Association are having an EV open day at Albion. I won't be registered by then but I will be borrowing Graeme's (Suzi Springwood) trade plates to get it there (~1Km). I have also been asked to display it at the Green House at the Woodford Folk Festival at Christmas.

I have still got a fair bit of fine tuning to finish the car. The auto box still lurches if you accelerate quickly from stopped. I will have to include the electric pressure pump to keep the clutches engaged and this will stop the lurching. The gear change points are set about the right speed now but it still changes gear a bit hard. I have to come up with a simple way to drive the vacuum modulator push rod so that it goes in by 4mm under full throttle and pulls back out when idle. I am thinking maybe a model servo connected to the pushrod through adjustable linkages. The servo input can be modified to take a variable DC voltage instead of the normal pulse train by removing the integrator circuit in it's front end. It can the be driven from the throttle pot.

There is also some noise problems with the BMS causing random alarms and also fine tune the State of Charge calculation.

2010-06-23T04:06:00.000-07:00

Yet another long weekend spent working on the car. My wife will be very happy when I finish this project.

The new handbrake cable was fitted and adjusted. Wired the motor speed sensor to the controller and fit a cover to the controller bus bar connections.

The heater is controlled by a solid state relay which I operate from an illuminated switch mounted on a blank plate where the ash tray used to be. It produces a decent amount of heat and I think you could use it to heat the vehicle as well as demist, although it uses a lot of power.

I got to use my new MIG welder to make the battery hold down bracket. MIG really makes welding simple.

I had a final read of the NCOP14 regs to see if I missed anything and it turns out I did. I forgot about the requirement to disable the vehicle while its plugged into a power point. I haven't run any cables from the fuel flap for a switch. However the charger does output 12vdc onto 2 of its control terminals while its powered up. I will use this to operate a relay which will isolate the 12v feed to the contactors. The relay will also drive an input into the BMS master to start the charge cycle.

There is also a clause in the regs about having an audible and visual alarm if the brake vacuum is low. I am not sure what other people have done with this, so I might see if I can get away without it for the moment. It's a bit stupid as there is no requirement for this in the original vehicle.

I drove the car down to the AEVA meeting last week and it was well accepted. I found out when I got there that one headlight (connector disconnected) and both tail lights were out (blown fuse). The automatic worked very well and I was able to drive very slowly into the hall under perfect control. The controller has really good low speed control due to its current feedback loop.

I will be ready for the engineers inspection later this week so fingers are crossed. The final thing before registration will be replacing the windscreen as it was cracked when I bought the car.

2010-06-07T04:17:00.000-07:00

I got the charger back from repair installed it and charged up the battery. On the weekend I fitted the power socket behind the fuel flap, wired it up, finished tidying up the battery wiring, fitted some plastic sheet into the battery box lid and fitted the lid.

The back seat was then installed and at first it didn't fit. A piece of trim under the seat was fouling the battery box lid mounting bolts. 5 minutes later after the jigsaw had its way with the trim it all fit
with nothing to spare.

The hand brake cable no longer fits so I took it to ATS Cables to get a special cable made. Thanks to Graeme from Suzuki Springwood for the tip. I will pick it up tomorrow and install it tomorrow night.

This will finish the rear section of the car.

What's left?
Wire motor speed sensor
Fit a cover to the controller bus bars
Fit and wire heater switch and test heater
Make and fit a hold down bracket for the aux battery
Fine tune vacuum modulator push rod length
Fit BMS master into dashboard
Fit Asus EEE PC into dash
Fit warning HV stickers to relevent bits

Getting Close

2010-05-29T05:47:00.000-07:00

I haven't been updating the blog lately due to work pressures.

I've taken the car for a couple of laps around the block. It had very good acceleration but the gear box wasn't changing gears properly - too high revs and hard changes. It didn't have any vacuum on the vacuum modulator and this caused the problems. When I connected the vacuum up it changed low and soft. The rod from the modulator into the transmission was changed for one 3mm shorter and it changed OK with no vacuum.

Had a setback when I connected the wrong cable to the battery charger. It blew up the charger and the BMS. I fixed the BMS but the charger had to go back to China for repair. It's due back next week.

Most of the 12vdc wiring is complete. I just need to wire up a switch to turn on the heater solid state relay. The DC DC converter was mounted into the dashboard with anderson connectors as connections and flexible orange conduit for the 144VDC input. Tomorrow the dashboard goes back in.

The battery boxes need a final tidy up and a perspex sheet mounted inside the lids to protect the terminals. I hope to get the car ready for final inspection in 3 weeks.

2010-02-21T01:24:00.000-08:00

Today we had a group effort with 2 other members of Brisbane AEVA helping out with the build. Thanks very much to Greg and Jim for your assistance.

Today we worked out where to mount the charger. As it is a fully sealed unit we decided to mount it under the rear of the car beside the spare wheel well. There is a large recess there where the muffler was previously and it means that the charger will not take up any of the luggage room in the car. A couple of steel brackets and it's now mounted solidly under the car.

We also fitted a number of units to an aluminium plate in front of the batteries. The controller, main contactor and precharge resistor were mounted on top of the plate and a sealed aluminium case was mounted under the plate for mounting terminal strips for connecting to the controller and contactor.

The BMS slave boards were mounted in 2 sealed ABS cases one on the rear battery box for 25 cells and one on the front box for 20 cells. The slave boards are 16 cellls per board and the wiring to the cells will be done in 1 sq mm double insulated cable with a 1 amp 3AG waterproof fuse in each wire. The 4 slave boards are then connected by 2 buses (master and slave) back to the BMS master system which will be mounted under the dash.

Battery Boxes Completed

2010-02-15T03:13:00.000-08:00

The battery boxes and motor mount are complete. It took 3 solid days welding and grinding then 2 days painting. Another few hours putting them into the car and I am ready to start wiring. The rear box just fits under the rear seat with about 5mm clearance and the batteries can be maintained by removing the seat (4 bolts) from above. The front box holds 20 batteries and is mounted across the engine bay. The controller contactor and fuse is mounted in front of the batteries on an aluminium plate.

I've mounted some sealed ABS cases for the contactors, fuses and BMS slave boards and run the battery cabling from the rear battery box to the engine compartment in "flexible" orange underground conduit. That stuff is not very flexible and it was a painful experience.

Replaced the bonnet and closed it to see if the battery box fitted. There is only about 2 mm clearance in one spot so I will be doing a small amount of panel beating under the bonnet to give a bit more clearance.

Next weekend more wiring.

Charger Arrives

2010-01-14T03:49:00.000-08:00

I received the charger. It's an Elcon 2KW charger with profile for 45 off Sky Energy cells.

The vacuum pump also arrived along with fuses, contactors, cable etc.

Tomorrow I am getting a steel fabricator in to measure up for battery boxes and motor mount.

I just got confirmation form the certification engineer that I don't need to use a big red switch. The new version of NCOP14 allows for isolation of the battery via 2 contactors operated from the ignition switch.

Parts have also arrived for my battery management system. It is a processor based system using a PIC chip for each cell, mounted externally from the cells, 16 per board. The master does coulomb counting and shows SOC for the pack and remaining distance to travel.

Batteries

2010-01-03T04:07:00.001-08:00

The batteries arrived just before Christmas. 45 off Sky Energy 100AH cells. I spent a few hours bolting them into groups of 5 using the mounting plates provided.

Its pretty scary wielding pieces of uninsulated metal around the terminals of these cells as they can put out over 1000 amps each.

I have now finished my open source DC controller and it is all set to be tested at high voltage.

I am waiting on fuses and contactors before wiring up the whole battery pack.

For a BMS I am going to use another open source project from http://www.batteryvehiclesociety.org.uk/forums/viewtopic.php?t=1245

Motor Installation

2009-10-18T04:45:00.000-07:00

After 3 long months of waiting the gearbox, couplers and adaptor plates arrived. At first try the coupler did not fit so back to Geoff for some fine tuning. When it came back everything fit ok so I fitted the adaptor plate to the motor then the coupler and after a lot of time sorting out the right bolts and lining up the motor on the hoist I fit the motor to the gearbox and tightened all of the bolts.

Next I lifted the motor gearbox into the car and bolted it to the front and rear transmission mounts. I the refitted the drive shafts to the transaxle and remounted the wheel hubs and steering arms. I then connected the output of the oil pump to the input to bypass the oil cooler in the radiator, as it will no longer be needed. The majority of the heat generated in an auto transmission is from the torque converter and this is now gone. I filled the transmission with atf and I was ready for a test run.

I put the transmission in D and connected the motor to the old starter battery and hey presto the wheels started turning. There was a very short delay between when the motor started turning to when the wheels turned, maybe 1/4 second. I don't know what this will feel like when driving yet but I have some ideas on fixing the problem.

2009-09-03T02:22:00.000-07:00

I installed the ceramic heater core in the heater unit and put the dash back in. About another 4 hours work all up. I am still waiting on the coupler and adaptor plate for the motor / gearbox. This was bad timing as I gave it to Geoff to convert just before he went on leave. I should get it back next week if all goes well.

I have been working flat out on a design for the motor controller over the last few weeks. It's an open source design and I am just doing a bit of fine tuning and the final board layouts. Beta testing of the unit is almost complete with no major issues. http://ecomodder.com/forum/showthread.php/paul-sabrinas-cheap-144v-motor-controller-6404-224.html

Its a long read at 224 pages and growing. Paul has done a fantastic job with the design. We are arranging a bulk buy of parts for Aussies, see http://www.aeva.asn.au/forums/forum_posts.asp?TID=1160&PN=1

2009-07-18T02:02:00.000-07:00

Dashboard gone
Dashboard removed

Removed heater core

Being a glutton for punishment, I decided that the next thing to do would be to replace the heater core with an electric element, as there will be a severe lack of hot water in the car after the conversion. I sourced a 120 VAC ceramic heating element from a guy in the USA who sells them to EVers in Australia.

The removal of the dashboard took about 4 hours and is possibly the worst part of the whole job. Without the manual I think it would have taken 8 hours. The most dangerous part of the operation was removing the air bag. Apparently they can go off with very little provocation, hmmm very similar to a woman. Next is removal of the steering wheel using a steering wheel puller, $20 from Supercheap Auto. The instrument panel was removed and I noticed that the front panel was cracked. It looks like a trip to the wreckers for a replacement.

While I was disconnecting some of the wiring connectors I noticed a non standard unit wired into the ignition wiring. It turns out it was an aftermarket engine immobiliser and remote keyless entry. The wiring was very poorly done with wires cut and twisted, no connectors and no solder. As I didn't get the remote control when I bought the car I removed the unit and restored the wiring to original. Finally after removing the dash & the aircon unit I got to remove the heater unit. The heater core will have to be modified to allow the mounting of the electric element into the old core frame.

I sold the old engine on Ebay this week. I listed it last week and it sold for $1.50. It turned out the guy who bought it didn't check where the engine was. He was in Adelaide and I am in Brisbane - go figure. Anyway he defaulted, I relisted and sold it for $100 to a local. He also took a lot of the other bits I didn't need, so I won't have to dump them.

2009-07-04T03:46:00.000-07:00

The plans have evolved a bit more now. The automatic transmission is now on it's way to Sydney so that Geoff from GT Tooling can make the adaptor plate and coupler. The plan is to remove the torque converter cut it open and use the internal splines to create a coupler. The secret is to recreate the normal transmission fluid path from the centre of the pump shaft back to the outer shaft where it returns to the transmission. He is also going to make a plate for the rear of the motor to mount the air conditioning compressor and power steering pump

The other problem to overcome is that the transmission clutch for 1st gear will not engage if the transmission pump is not operating ie when the car is stopped at lights etc. I am going to do some tests when I get the transmission back to see how long the pressure remains in the box after the motor stops turning. This should be proportional to how good the seals are. Geoff has suggested that an accumulator connected by a solenoid valve could be used to apply pressure instantaneously to the box when the accelarator is pressed. The logic behind this may be a bit hard to apply and it may be restricted by how fast the clutch can operate compared to the motor.

The other option is to use an electric pump operated from a pressure sensor to keep the pressure up to the clutches. The pump would only operate when the pressure drops below the point at which the clutch would disengage. To make this more efficient, the pump could also be turned off if the brakes are applied, so that when you lift your foot off the brake the pump starts and by the time you apply the throttle the clutch has engaged (if it engages fast enough). Either way there is a bit of testing to do before I proceed any further.

I have settled on a controller for the project. I will be building the controller myself from an open source design see link http://www.paulandsabrinasevstuff.com/evmotorcontrollers.html
It is a 144volt 500Amp controller and it meets my requirements for power. Parts have been ordered andshould be delivered within 8 weeks. Construction should take a few more weeks after that.

For batteries I will be using Lithium Iron Phosphate batteries from Thundersky. I am still tossing up between the 90 Ah and the 160 Ah batteries. I was going to try to fit all of the batteries under the rear seat where the fuel tank was but the available space is just too tight to fit all of the 90's in the one spot. Depending on which battery I can afford at the time I will mount some under the rear seat and some in the engine compartment. I calculate that I can probably get about 90 Km range from the 90 Ah batteries and about 160 Km from the bigger batteries.

I am looking at 2 different battery management systems. The 1st is an open source processor controlled shunt device which has over & under voltage protection. The 2nd option is an active powered system where a small power transformer feeds each cell independently and the amount of current to each cell is controlled by the state of charge of the cell. This gives the best balancing but is limited by the size of 45 transformers and the addition wiring to each cell. The main advantage with this system is the simplicity. I will have to get a few batteries and do some testing to see which way works best and is safest.

ICE Removal

2009-06-14T03:39:00.000-07:00

Transaxle ready for a cleanup

Anyone want a 1300cc Mazda ICE

Empty engine bay

Out with the ICE

The electric motor (Impulse 9) was delivered last week.

On Saturday I pulled the axles from the transaxle. This was hard going as the axle nuts wouldn't budge even after soaking in rust remover and using a 600mm break bar. In the end I removed the wheel hubs with the axles attached. The manual said to pry the axles out using a pry bar but I found using 2 bars one on either side more effective. I then loosened all of the engine mount nuts and made sure the engine was free of everything holding it in.

Today I removed the engine. I hired an engine crane and it popped out with no problems at all. I had to disconnect the air conditioner condenser because the return pipe was in the way.

I then removed the transaxle from the engine.

2009-05-24T04:14:00.000-07:00

Got back into it this afternoon and removed the entire exhaust system, battery, radiator and disconnected most of the engine wiring and the air intake.

It was hard going at first with lots of rusted nuts in hard to reach places. I then decided to take out all of the easy stuff first and the extra room it gave me let me easily undo the difficult nuts and bolts. The auto gearbox has an oil cooler built into the bottom section of the radiator, so I will have to get an aftermarket oil cooler to fit in it's place.

2009-05-23T02:19:00.000-07:00

The workshop manual arrived this week and so I started the dismantling phase this afternoon. I was dying to get started early but family duties took precedence in the morning.

I drained the fuel tank by removing the fuel pump and syphoning the petrol out, then removed the fuel tank and all of the fuel lines. Next to go was the fuel filter and the carbon canister. This is really a dangerous operation as petrol keeps spurting out of the lines as you remove each part. I made sure I had a couple of fire extinguishers nearby ready to go and cleaned up each spill as it happened.

The exhaust system is next so I started off by giving each nut a good spray of CRC to try to free up the rust. It worked on the catalytic converter nuts but not the rear join. So tomorrow I will use a grinder to cut those off.

Well here goes nothing

2009-05-19T02:59:00.000-07:00

The conversion of a 1998 Mazda 121 automatic hatchback to a plug in electric vehicle has officially started.

I bought the donor vehicle last weekend had it weighed, measured the ground clearance on each wheel and put her up on stands so I can start work removing all of the bad stuff. Engine, fuel tank etc.

I have ordered the workshop manual so I will wait till it arrives before proceeding. It still has a nearly full fuel tank so 1st thing to do is to syphon it out before removing the tank. I have to be carefull here as it would be very embarassing to set the car on fire under my wooden house. It turns out I have to lift the rear seat, remove an inspection plate, remove the fuel pump connector, start the car and wait till the engine stops to release the pressure in the tank. I can then remove the fuel pump from the tank and siphon the fuel out. This is going to have to wait for the weekend. What happened to the good old days when you could just bung a bit of garden hose down the filler pipe, a quick suck, lots of choking and out comes the fuel.

The plan for the car so far is

Netgain Impulse 9 DC motor - on order

45 off Thundersky 90 AH Liffepo4 batteries

everything else is still flexible