It's out!Dave and the MX-5BMUs complete!BMU PCB stackMiddle battery boxesFitting cellsChargerElectrical DiagramAt the Brisbane AEVA festival
OwnerDave Keenan, cobuilders Mike VanEmmerik, Jeff Owen
LocationBrisbane, Queensland Australia map
Web/EmailWebPage email image
Vehicle1990 Mazda MX-5
Original engine 86 kW. Cost of conversion $42,000.
Time taken 4.6 years. Weight increase 33%.
MotorAsea Brown Boveri 3GAA 131 008E 3-Phase AC
Industrial induction motor, 130 kW peak
2 pole, 132 mm dia, 470 mm long.
DrivetrainStandard 5-speed manual gearbox and clutch.
3.636:1 diff in place of stock 4.3:1.
Controller Tritium Wavesculptor200
180 kVA 750 Vdc (Tritium is a Brisbane company)
Batteries218 CALB/Skyenergy SE40AHA, 3.30 Volt,
Lithium Iron Phosphate, 28.8 kWh
System Voltage720 Volts
ChargerElcon 2 x TCCH-417V-5.5A-CAN
Heater2 x 500 W ceramic PTC heaters
DC/DC ConverterMeanwell 2 x HLG-240H-15A
InstrumentationOriginal instruments repurposed. Tacho can be
cycled to display r/min, power, torque, traction-
voltage, auxiliary-voltage, diagnostics. Oil
pressure displays battery stress.
Top Speed121 MPH (194 KPH)
Acceleration0-100 km/h in 7.5 seconds. 0.25 gee in first gear.
Range81 Miles (130 Kilometers)
Watt Hours/Mile356 Wh/Mile
220 Wh/km
EV Miles
Start:148,109 Miles (238,307 Kilometers)
Current:153,100 Miles (246,337 Kilometers)
Total:4,991 Miles (8,030 Kilometers)
    As of 7/16/2015
Seating Capacity2 adults
Curb Weight2,976 Pounds (1,352 Kilograms)
Unladen 1350 kg. Fully laden 1530 kg.
TiresUpgraded to 195/60R14 86H, Yokohama BluEarth AE01,
240 kPa front, 260 kPa rear.
Conversion Time4.6 years. Started Feb 2009, compliance plate Sep
2013, upgraded to full power Sep 2014.
Conversion CostAU $50,000 including original vehicle.
Vehicle $8,000 Batteries $14,000 Controller
$7,000 Motor $2,600 Chargers $1,400
DC/DCs $500
Other parts $16,500
Additional FeaturesReplaced manual steering with power steering
Kept existing air conditioning
Upgraded brakes to NB model 250 mm disks
Upgraded to NB8B 3.636 differential
Suspension upgrade: Yellowspeed Dynamic Pro Sport fully adjustable
coilovers, 8 kg/mm front and rear.
Rollbar: Automotive Plus, single hoop torque box.
Attempting to produce a sporty conversion with better performance
than the original.

2009/Apr: the engine is out. Still considering two lithium battery
options: 40AH Thunder Sky, or 30AH China Power (high discharge

2009/June: Sky energy batteries ordered weeks ago; controller
arrived; motor almost ordered (just waiting for final options). Motor
will take 5 weeks to manufacture and 9 weeks (!) to ship.

2009/Oct/13: Batteries arrived months ago; started battery racks. BMS
PCB design completed and prototype arrived. Motor ordered and now due
late December.

2009/Dec: Having completed an analogue BMS design, we're now
considering a redesign using a microcontroller per cell. Three
battery cages are welded (no cells installed yet).

2010/May: Decided to switch from industrial controller to Tritium
Wavesculptor200. Motor has arrived, and we have a plywood "adapter
plate" for measurements.
Completed the digital BMS design; testing prototypes. Almost complete
on 5 battery boxes.

2010/July: Installed potbox.
2010/Nov: Tritium controller and motor are home from dyno testing
2010/Dec: Installed custom flywheel.
2011/Jan: Got the motor running from 24 VDC.
2011/Feb: Driver Controls is talking to both BMS and charger, cutting
back charger on over-voltage, and detecting all BMUs (Battery
Management Units) in bypass.
2011/Mar: Motor coupled and installed (still needs final balance)
2011/May: still tweaking BMS. Using industrial fibre.
Chasing measurement glitches.
2011/June: First drive with one battery box (28 cells; 93V). Video:
WebPage .
2011/Sep: All battery boxes complete and painted. Now concentrating
on getting the car ready for the Brisbane EV festival.
2011/Oct: Air conditioning bracket completed, also mounts vacuum
pump, starting contactor boxes. Power steering pump mounted. Three
battery boxes installed. Frame for mounting two under-bonnet
contactor boxes made and painted. Three contactor boxes completed;
controller pre-charges and connects to the pack with the key-switch
now. It moved under its own power for the Brisbane AEVA festival.
2012/Jan: Three battery boxes (of 8) are complete. Still chasing
possible BMS comms problems. Had setback with pre-charge resistor
exploding: adding thermal cutout, redesigning 12 V wiring.
Repositioning motor controller to allow space for two more contactor
2012/June: BMS testing is complete, final PCBs have arrived, parts
about to be ordered. Motor controller repositioned. Started
installing cells into next battery boxes. Boot floor reinstalled.
2012/July: BMS parts arrived, started loading components using a
frypan and a rework station (the latter mainly for the bypass
resistors). Two more battery boxes are ready for BMUs.
2012/Sep: The BMUs are finally manufactured. Starting the last
battery boxes in earnest; installing BMUs in all boxes.
2013/Jul: All battery boxes complete and installed, but B half-pack
not wired in yet
2013/Sep: New brake rotors and pads
2013/Oct: Added 2.9L of vacuum reservior
2013/Oct: Registered!
2014/Sep: Upgraded to 750 V motor controller, reconfigured pack to
720 V.

See also our AEVA Member's Machines page:

code by jerry