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The Solectria DW Electric Car

Driving an electric car

by Julian Edgar

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Shouldn't every car be like this?

I sit at the traffic lights, the radio playing and the engine silent. Not 'quiet', but totally silent. The light turns green and I push my foot down past the halfway point at which acceleration begins. The car smoothly moves away, the engine now only a faint whine that changes to a higher pitched - although still barely audible - scream as speed briskly grows. There are no gear changes, there's no tacho to watch - the car simply builds in speed as the engine climbs its flat power curve. It's a feeling of an elastic, flexible and refined powertrain. Now the traffic in front is slowing, and I lift my right foot into the zone of regenerative braking. As progressive as the throttle in a normal car, the regen braking allows nuances to be played in decel - and all the time that the car is slowing, energy is being poured back into the battery. It is only when the car is at a walking pace that the regen braking switches off and the hydraulic brakes need to be applied. And then again the car sits stationary, silent and using no power except that required for the brakelights and the radio...

Thank God no other car is like this!

The centre console switch is turned to 'Power' and my right foot is buried. Despite this, I'm crawling up this long hill at just 60 km/h. That's it - flat knacker. The red 'out' LED on the dash is almost continuously lit - showing the current being drawn from the battery pack, it normally it flashes at just a slow rate. Above it, the Battery Level amp-hours display counts up like the spinning wheels in a poker machine - before my eyes I have seen it move from 10 to 20. When it gets to 45Ah, the battery pack is flat... The tiny electric motor is struggling to drag this monstrously heavy small car up a medium grade. Finally - finally - the hill is climbed. I have just used up one-quarter of the range - all over less than a kilometre of a hill. It's as if someone just banged a 1-inch punch through your petrol tank and has been letting it all drain away...

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We've been reading about them for years - electric cars. The electric car predates the internal combustion engine car, and in fact electric cars once held the land speed record. But then, just as now, electric cars had a major problem: batteries. They weigh a lot, and their energy density (how much grunt they can pack into each kilogram) is also low. Basically, petrol has a helluva lot of energy in it considering how much room it takes up and how much it weighs. Batteries, despite the oft-promised claims of enormous breakthroughs, don't come within a bull's roar of petrol. And that means that electric cars have always had a very limited range and have also been heavy vehicles. Sure, in some cases those are relative terms, but in the case of the Solectria Daewoo Cielo that we were lucky enough to drive, the compromises remain obvious.

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Converted in 1998 by US company Solectria (in conjunction with GP Batteries) for use in Singapore and Hong Kong, the 1200kg electric Daewoo uses Nickel Metal Hydride batteries that are said to have a capacity of 90 amp-hours (Ah). (However, there's some confusion here - the car we drove had a capacity of about 45Ah.) These develop 240V and power a DC/AC converter that in turn drives the AC motor. In addition, there's a DC/DC converter (rated at 57 amps) that powers the conventional 12V car electrics - the radio, horn, lights and so on. To provide vacuum for the hydraulic brake booster, a dedicated vacuum pump is fitted, while a 1.34kW electric motor is used to drive the air-con compressor as required. Finally, a high voltage heater element can be activated for cabin heating - this and the air-conditioning work in conjunction with the normal Daewoo HVAC system.

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There are two battery packs, one located under the bonnet and the other where the fuel tank used to be. Luggage intrusion is kept to a minimum - the boot still has full depth, although a black box (the battery charger) takes up some room on the left. This charger is used when the car is plugged into the wall socket - the traction battery can be charged at 12 or 15 amps. At the slower rate, a full charge takes 12 hours, while with the juice turned up, a full recharge will take proportionally less time.

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Inside, the car looks conventional Daewoo except for the panel that replaces the gear lever, and the dashboard instruments. In front of the driver is the LCD Battery Level meter. As mentioned above, this confusingly counts upwards - it starts at zero (or even a little in negative numbers) and increases as you use the juice. Above it are green and red LEDs, both of which have a variable flashing rate. A red LED shows when you are using battery current, while a green LED indicates when power is being put back into the battery - either because you're plugged into the wall or using regenerative braking. When the green LED is lit, the Battery Level meter counts in the opposite direct from its normal disheartening trend upwards. To the right a large warning sign indicates that the handbrake should be applied when the vehicle is parked. Finally, a row of three LEDs is present to one side of the instrument panel. These show:

  • when the battery charge is complete,
  • when you're starting to run very low in battery power,
  • and when you're so low that the computer has shut down the car.
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The panel that replaces the gear lever contains the main driving controls. A large knob allows the selection of Reverse, Off, Economy, Normal and Power modes. Above that is the heater switch, and to one side is a switch that disables the regen braking. This is supposed to be done when the road is slippery, presumably because some people are so harsh with the pedal that the wheels can lock-up.

And that's it for the internal changes over a Cielo.

In practice the red and green (ie "out" and "in") LEDs are a poor indication of current flow. They flash, but what does the flashing mean? If slower flashing equals better, pulling over by the side of the road and switching off would be best of all! Better to have a long bar-graph of LEDs, half red and half green, with perhaps a white centre LED. That way, you could see just how much current you were pulling (or putting back in), and also when you were freewheeling down a hill. The latter's quite hard to work out - take you foot right off the accelerator and the car slows rapidly as the regen braking operates.

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Aaaaah, that regenerative braking. I loved it. The regen braking is quite strong - we didn't measure it but I'd guess that you can decelerate at 0.5g without touching the hydraulic brakes. The integration of the accelerator and decelerator into the one control works superbly - and when you think about it, it's the obvious way of placing the controls. In city traffic you need never touch the conventional brake - in fact, except in an emergency and after the speed drops to only a few km/h, a good driver will not even use the hydraulic brakes. The progression, feel and travel of the 'accelerator' during regen braking makes you realise just how bad conventional brake pedals are - there's no 'stepping on a lump of wood' feeling; instead you can adjust stopping distances with as much subtle control as you normally apply to acceleration. And all the time that you are slowing, juice is flowing back into the battery packs....

And you need every little bit of regen juice you can get. Initially we drove the car around in 'Economy' mode, but that gives very slow acceleration indeed. Then we swapped to 'Normal', got bored with that and jumped to 'Power'. And a leap it is too. DAT Racing were as pleased to put the electric car on the chassis dyno as we were to have them dyno it. In Economy a power of 9kW was generated at the wheels. Yep, nine. In 'Normal' mode the power rose to 13kW, while in 'Power' it peaked at a giddy 24kW!

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However, when compared with a conventional petrol-powered car, these figures are quite deceptive. An internal combustion engine developing 9kW does so at only one point in its rev band - in Economy mode the electric car developed 9kW from 20km/h road speed through to 50km/h, and then about 7kW up to 100 km/h. So 9kW of electric power is probably the equivalent of a petrol engine with, say, 18kW. Still not impressed? Oh well.... The 45kW peak recorded in 'Power' mode was in fact a peak rather than constant reading, but the meaty torque curve (in all modes peak torque is at low speeds) meant that performance was quite punchy up until about 70 km/h.

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In fact, when we were returning the car we had a chance to drive it hard - we'd previously fully charged the battery. In Power mode, the radio playing and being driven as hard as you would in a conventional car being squirted through traffic, the Solectria used one-quarter of its battery capacity in less than 10km... But driven like this it was fun - the lack of driveline inertia, the quick response and the seamless, elastic feel to the development of power made it nothing like as boring to drive as you'd expect.

In fact, take away 300kg of mass and triple the range, and we'd just love it.

But then, weight and range are the problems with electric cars, aren't they....

www.solectria.com

Thanks to Peter Yates of Gerard Industries - owner of this car - for making it available to us.

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