Imagine a car that you can largely build yourself
– or have a company convert for you. A car that uses near silent electric power,
and is recharged by simply plugging into a power point. A car that allows you to
start from a rest in first or second or even third gears, such is its torque. A
car that costs literally cents a day to run – but also has a range equivalent to a
car with only a 5 litre petrol tank.
Welcome to the world of converted electric
Nathan Bolton has an electric car – and a new
business. The car is his beautifully converted 1992 Hyundai Excel Sprint and the
business is Convert Ur Car, based in Sydney. Bring a car to him and make
available AUD$21,000 to $25,000 and you’ll be able to drive away in a car that
plugs into a power point.
We had a detailed tour of the Excel and got to
briefly drive the car. First, the tour.
The Excel has lost its petrol engine (which,
incidentally, had leaking valve stem seals), clutch, radiator, exhaust and fuel
tank. It retains the standard gearbox and driveshafts.
Bolted to the gearbox input shaft is 83hp Advanced
DC electric motor, designed specifically for electric cars. The motor is
attached to the gearbox by a custom 25mm alloy plate and the shafts are joined
by what Nathan calls a third generation fully balanced flex coupling. The
motor/gearbox combination is supported by the original engine mounts, with the
left-hand one flipped upside-down and using a welded adaptor made from 5mm steel
Also under the bonnet you’ll find seven of the
fifteen lead-acid batteries that power the car. The 8V, 170 amp-hour batteries
are Trojan deep cycle designs. Each weighs 28kg, giving a total on-board battery
weight of 420kg. The underbonnet batteries are mounted in a cradle constructed
from 25 x 1mm angle section steel. The cradle is supported at the front by the
original radiator mounts and at the rear by the firewall.
The power supplied to the motor is varied by a
Curtis pulse-width modulated controller. The accelerator cable, which was
shortened to suit, connects to an underbonnet potentiometer that in turn is
connected to the Curtis controller. The controller allows anything from a tiny
motor output right through to full power – it is a stepless system. A main
‘on-off’ solenoid is also mounted under the bonnet and complements an emergency
‘off’ switch located in the cabin.
Vacuum for the braking booster is obtained via a
12V Rietschle Thomas vacuum pump that evacuates a reservoir made from PVC pipe.
The pump is triggered by a pressure switch, so braking vacuum is always
A normal 12V battery supplies all the conventional
car systems; this battery is topped-up by a dedicated Statronics DC/DC
Moving towards the rear of the car you’ll find
that the back seat is now gone and a neatly carpeted, plywood enclosure is there
instead. At the very back of the car the fuel tank and its surrounding metal
have been cut out to make room for the rear battery box, which contains eight
more batteries. This compartment, which is supported by another angle steel
subframe, uses forced air ventilation, with this air exhausting through two rear
The box that’s located where the rear seat once
sat contains a large Zivan NG3 smart high voltage battery charger that’s has an
output of 18 amps at 120V. The charger, which draws 19 amps from the mains power
socket, takes six hours to charge the battery pack. Note that most mains sockets
are rated at 10 amps, so a dedicated high current socket needs to be installed.
Next to the high voltage charger is a 12V charger for the on-board 12V battery.
This enclosure is also forced air ventilated, with these fans running when mains
charging is occurring.
From the driver’s seat you’ll see a 600 amp
emergency ‘off’ switch and an aftermarket style Curtis LED bar graph battery
level gauge. Not visible is the resistive heater that replaces the original
To support the extra weight of the batteries, new
heavy duty springs have been fitted front and back. These custom KMac springs
are teamed with Pedders dampers. The rest of the suspension – and the brakes –
Workmanship on the car looks excellent – the
wiring is neat and well thought out and the packaging has been well
After the tour, it was time to hit the road.
Nathan turned the key, selected second gear and pushed down on the accelerator.
Accompanied only by a high-pitched whine from the motor speed controller, the
car moved off. There’s no tacho and so the point at which to change up a gear is
largely a matter of experience and watching road speed. The electric motor can
be felt to drop a little in power as it passes its peak and that’s the max motor
speed at which to change gear. Once moving, the motor speed controller becomes
Performance from the passenger seat felt adequate
– but no more. Nathan says the car gets to 60 km/h in 10 seconds. The ride
quality clearly reflected the high sprung mass – bumps were well absorbed but
the oscillations of the heavy duty springs were not quite quelled by the
Then it was time for my turn behind the wheel. I
selected first gear and put my boot into it – only to have my neck snapped back.
There’s a reason that Nathan starts off in second gear....
However, even in first gear, the initial
acceleration was really only a jerk off the line, rather than being sustained
and strong. The change to second gear felt rather odd, not because the car was
doing anything wrong but because no clutch is used. The rotating mass of the
motor’s armature is so small that the synchros in the gearbox can easily do
their job, making up-changes a no-brainer. Think of it like a semi-automatic,
rather like the old Porsche Sportmatic system or something like the Mercedes
A-class clutchless manual.
At the local speed limit – 70 km/h – the car felt
smooth and quiet. Thoughts of vibrations coming from the motor/gearbox coupling
were quelled – apart from the NVH you’d expect from the suspension and body of a
1992 Excel, the car felt very good. The road undulated and I lifted off so as
not to exceed the speed limit downhill. But the car would have none of that – it
kept rolling happily along. Unlike commercial hybrid cars and the one other
electric car I have driven, Nathan’s Excel does not use regenerative braking. I
really noticed its absence – regen is not only more efficient but also provides
excellent real world braking.
We then confronted another hill and Nathan
nervously suggested from the passenger seat that with two people onboard and
with the steepness of the upcoming hill, a down-change would be required. But he
need not have worried – again, the synchros did their job fine. You wouldn’t
want to go from fourth to second gear at 80 km/h, but with a touch of driver
sensitivity, the clutchless manual is absolutely fine.
Doing a U-turn showed that the extra mass of the
car and a lack of power steering are not a good low-speed match – the steering
was heavier than most people would today expect. The lack of air conditioning
was also a downer – Nathan says he can fit a dedicated electric motor to run the
compressor but that range will noticeably suffer.
And its range which is really the Achilles’ heal –
even on my short drive, the battery level gauge dropped one full bar (out of
perhaps 10). Yes the road was hilly and yes I was using full throttle quite a
lot, but they were real world conditions. Nathan quotes range at 60 kilometres
but suggests that acceleration starts to fall away after only 30 kilometres.
That initially sounds ludicrous (even petrol scooters have more range than that,
don’t they?) but so much depends on how the car will be used. Many people have a
daily work commute of less than 30 kilometres and in this time of climate change
awareness, it would be an unlikely workplace that wouldn’t make available a
So that seems to make the niche clear – a
commuting car that has almost no fuel cost. But then again, unless you start
with a more modern – and so expensive – car for the conversion, you also have
little luxury and safety. Maybe the best approach would be to begin with a small
car that originally was of high quality but has dropped a lot in value – get one
with a defective engine and then away you go.
Driving a car that’s been converted to electric
power is clearly not for everyone, but for some people such a car could be an
absolutely ideal commuter. Electric for weekdays and petrol for weekends...
Contact: Nathan Bolton, Convert Ur Car, 0417