For registration in NSW Australia every electric vehicle conversion needs a 12 Volt battery to power the ancillaries, primarily the hazard lights. But it is also pretty convenient for powering pre-charge circuitry and contactors when starting the car. In MR02EV I recently upgraded to a Drypower 12V 22Ah sealed lead-acid battery.
When converting MR02EV to an electric vehicle a lot of weight was removed with the petrol engine and then put back, mostly in the form of batteries, which affected the vehicle stance. I just did not look right.
After upgrading the main battery pack in MR02EV to 310 Volts of Nissan Leaf battery modules charging with my 5.5 Amp TC Charger was very slow. So I jumped at the chance to purchase a second hand 16A, 3.3kW, Brusa NLG513 charger.
When I bought the 1989 Toyota MR2 that was to become MR02EV, it was pretty un-loved. Especially the wheels which had been painted with white house paint. I could have refurbished them, but I never did like the originals so started looking for alternatives, which started a minor obsession with wheels and conflict with my Wife (cars can do that)!
Motor controllers for electric vehicles like the TIM600 in MR02EV typically have a large internal capacitor bank on their input with very low Equivalent Series Resistance(ESR). As such they require inrush protection when first powering up to prevent a large current spike which can damage components – most commonly, welding contactors shut or blowing fuses.
In MR02EV I use a ZEVA Smart Precharger which is designed with a 2-stage soft start to limit inrush current via a resistive circuit that charges up the inverters internal capacitors before automatically closing the main contactor when the process is complete.
Every gas vehicle on the market uses a belt driven alternator to generate 12 Volts DC to run the accessories (fans, pumps, headlights, heaters, etc). MR02EV has no alternator so a Chennic DC-DC converter is used to convert the 370 Volt main battery pack voltage to 12 Volts.
I have been driving MR02EV for about 4 years using a battery pack consisting of 56 Thundersky lithium-ion cells totalling 201.6 Volts and 12kWwh; it has served me pretty well. Initially my driving was in city traffic 0 – 60 kph so performance was not an issue and the 70 kilometre range was more than adequate.
Because Electric Vehicles do not have an internal combustion engine there is no traditional vacuum source to supply the brake booster, so a vacuum pump and vacuum flask is needed. In fact it is mandatory for registration of the vehicle.
The modified Corolla gearbox which is now a 2 speed was finally installed into MR02EV (see earlier posts for details on the modifications).
MR02EV has been a registered road going vehicle for 3 years and covered about 12,000 kilometers in that time, mostly through commuting to work and running around town. It’s a fun car to drive. But right from day one the gearbox has been plagued with problems, excessive noise and excessive backlash, which has just gotten worse over time.
In April 2013 an Automotive Engineer certified MR02EV as road legal, I obtained a vehicle safety compliance certificate (an engineering certificate) and was able to legally register the car in NSW Australia. Following is an extract from the engineer’s report which gives you a flavor of the information required.
I purchased an MES-DEA Type 70/6E vacuum pump at the same time as the MES-DEA inverter and motor, also from Metric Mind. Because an EV does not have an internal combustion engine it does not have a traditional vacuum source to feed the brake booster and needs a 12v pump like the 70/6E.
I have a Degree in Electrical Engineering from the University of Technology Sydney and am employed in Broadcast Television Industry. My hobby is the (continuing) modification of MR02EV. I am also the National Treasurer of the Australian Electric Vehicle Association.