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 cars
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 plate.
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 available.
A normal 12V battery supplies all the conventional car systems; this battery is topped-up by a dedicated Statronics DC/DC converter.
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 facing pipes.
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 heater core.
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 – are stock.
Workmanship on the car looks excellent – the wiring is neat and well thought out and the packaging has been well accomplished.
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 inaudible.
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 aftermarket dampers.
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 recharging socket.
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...
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