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S. Muralidhar

THE French gave it their best shot, the US is still struggling to make it universally acceptable and many other countries have dabbled with the subject building unviable prototypes. But electric vehicles have not made it to the roads in big numbers.

Electric passenger vehicles have yet to merge attributes such as affordability, practicality and drivability in as seamless a fashion as cars that run on petrol and diesel. Zero-pollution, electric vehicles (EVs) have, as a result, remained just niche products catering to a focussed group or continue to be just experimental prototypes, while their more practical cousins — the Hybrids — are making steady inroads into the mainstream world of automobiles.

But one Indian company, which manufactures electric cars, is egging on to try and make them bridge the gap with petrol and diesel driven cars. From being a hesitant, fledgling manufacturer of one electric car model that lacked finesse, the Bangalore-based Reva Electric Car Company's line up has now grown to three models, offering fit and finish that edges close to regular cars and even creature comforts such as air-conditioning and climate controlled seats (much more difficult in an EV). The company is also on the threshold of launching a sporty cabriolet version.

The Reva has not been a runaway success in the conventional sense of the term. But the cute, super compact electric vehicle, which comfortably seat two adults and two kids, has its own fan following amongst the environmentally-inclined, and even the practicality-loving and cost-conscious car buyers in the country.

Electric vehicles have not been a big success in markets such as the US, where consumers have been pampered with the extreme practicality and luxuries that gasoline powered vehicles have been able to offer.

EVs also suffer from a few inherent disadvantages that are unique to them and continue to dog their attempts at reaching the levels of usability that traditional passenger vehicles offer.

Some of their biggest minuses are underpowered performance, the heavy weight of batteries, which consequently drags the performance even further, poor driving range per charge of the batteries and inability to offer all the devices that gasoline/diesel powered cars offer since they will drain the battery and charge needs to be saved for the main purpose of driving the car. Globally, automobile manufacturers are still grappling with the task of reducing the size and weight of batteries, even as they try to pack in more power.

Ironing out the minuses

In the Reva, the company has attempted to address these disadvantages by incorporating a number of safety features and warning devices that also go on to making the car more practical and usable.

To counter the general perception amongst people that EVs are not safe, the Reva has incorporated safety features like the steel space frame, side impact beams, dent-proof ABS body panels, a low voltage system, and a dual-braking system.

Another common worry for potential customers is the fear of running out of charge in the middle of the road. To reassure customers the Reva incorporates a number of warnings to ensure that the customer gets ample warning signals in the form of a warning display on the instrument panel. For example, when the charge is down to 35 per cent, the Reva automatically slips into economy (E) mode. At this point, the "Low Battery Light" is programmed to come on, thanks to the pre-programmed software in Reva's Energy Management System (EMS) and motor controller.

These warning signals ensure, as far as possible, that the customer is adequately warned of insufficient energy in the power pack. When the charge in the power pack reduces to 25 per cent state-of-charge the "Low Battery Light" starts flashing. Further, at 15 per cent charge, the Reva automatically switches to Limp-Home Mode, limiting acceleration and speed, enough to help the user reach home or the nearest charging point.

Other safety features and warnings provided include door-ajar chimes that are heard if the user has opened the door and left the key in the ignition and/or if the handbrake is not engaged.

The car will not move if the system is plugged in for charging. It also has a full-throttle-disable facility that prevents any run-off of the car, in case the accelerator pedal is pressed accidentally.

The absence of an engine and other mechanical parts in the front bonnet area also facilitates a large crush zone in the event of a frontal collision. The spare tyre, designed to be at front, further helps in reducing the effect of an impact.

Electric features

At the heart of the Reva is its electric motor, which is comparable to the engine in a conventional car. Unlike other engines that are driven by hydrocarbon fuels, the rating of the Reva's motor cannot be calculated using conventional methods.

There are no gears either to make its performance comparable to conventional cars. The Reva has a 13 kW separately excited DC motor that offers a high torque of 70 Nm at zero speed.

When in use, the motor converts the energy stored in the power pack into mechanical motion. The high torque electric motor ensures fairly quick acceleration. The power from the motor is delivered to the wheels through the trans-axle that propels the vehicle. While braking, the motor acts like a generator (regenerative braking) and recharges the power pack, somewhat like what happens in Hybrids that combine gasoline or diesel engines with an electric motor.

The Reva derives its driving power from a power pack (instead of fuel), which consists of eight 6-Volt EV tubular type lead acid batteries. The pack of batteries attains 80 per cent state of charge in quick-charge mode in under two-and-a-half hours. A complete charge is achieved in less than seven hours and gives a range of 80 km.

The power pack has been housed beneath the front seats, which lowers the car's centre of gravity, thus increasing the safety of passengers. Charging the Reva is simple, just plug into a 220 Volt, 15-Ampere socket at home or at work. A full charge only consumes just about nine units of electricity.

The Reva has an on-board charger, which converts AC into DC power to charge the power pack. The charger is computer controlled with an in-built stabiliser and auto shut-off mechanism, so that there is no risk of damage from fluctuations in voltage or from a possible overcharging of the batteries.

The smart charger's output is connected to the power pack ensuring that optimum current and voltage is maintained at all times.

Reva also has a computerised motor controller that regulates the flow of energy from the power pack to the motor keeping it in direct correlation to the pressure applied on the accelerator. It ensures perfect speed control and optimum use of energy in both forward and reverse directions.

The brain of the Reva is the Energy Management System (EMS), which monitors and controls all the vital functions of the car. The EMS is a computer-based system that optimises charging and energy output of batteries to maximise operating range and optimise performance. The system also predicts the available range for a given state of battery charge and is a standard feature on the Reva.

In addition to these functions, the EMS also maintains an electronic log of the vehicles performance and enables service personnel to run diagnostic checks on the car to access service information about the car.

The Reva is offered in three variants — Standard (non-a/c), Air-conditioned and Classe. Priced at Rs 3.1 lakh (on-road) for the base variant and Rs 4.05 lakh for the Classe variant, the Reva is not exactly very affordable. The non air-conditioned base variant has a driving range of 80 km on a full charge, while the other two air-conditioned variants will give you about 60 km.

Despite being an unconventional electric car, the Reva does not come with duty exemptions or waivers for individuals, though some institutional buyers like public sector undertakings, Government departments and educational institutions can get Government subsidy. The Reva can be a good second car for the average city-based `office-goer' or businessman. You may not be the first off the block at the signal with this car, but the Reva offers a practical peak speed that will be sufficient in city traffic.

The Reva will continue to be a car that many will want to own, but will be hesitant to buy. The high cost of ownership due to the stiff price will make it unattractive for many first time car buyers. The car's limited range will also be an issue for buyers whose usage will not be restricted to just commuting within the city.

But the Reva will be the cheapest car to run within the city. Even if we take a peak electricity tariff of Rs 7 per unit, the cost/km for the Standard variant works out about Re 0.75 and one rupee for the air-conditioned variants. That is an extremely low running cost when compared to the average Rs 4 per km that other small cars can muster.

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