The e-up! points way to VW’s electric future

  • 24-Feb-2014 07:49 EST
VW01-14 20_e-up!.jpg

The electric motor and gearbox of the VW e-up are manufactured by the company at its components plants.

Exclamation points are sometimes scattered like self-seeding grammatical saplings through the pages of company press releases. Often unwanted, unwarranted, and unnecessary, they may be a desperate PR ploy to introduce energy into prose struggling to extol the alleged virtues of what is a dull product.

So Volkswagen’s cheeky decision to use an exclamation point in association with the name of its little Up! was a risk. In fact, there is nothing dull about the finely engineered successful four-seat sub-compact—3540 mm (139.4 in) overall length—hatchback launched for MY2012, so VW got away with its use.

But now the exclamation point has been used again for the electric version of the car—the e-up! (future references dispense with !).

For those entrenched technology doubters who remain unconvinced by the pure electric solution to alternative motive power, the e-up! bolsters their negativity in two crucial areas of measurement: its short range and high price. Range is about 160 km (99 mi) and price varies according to market, but in the UK it is £24,250 or £19,250 including Government EV grant.

For those doubters able to see beyond these—at present—very serious minuses, the practical little e-up may help to generate an automotive epiphany on the rugged road to powertrain reformation.

Leaving aside the caveats of range and cost, VW has provided the e-up with a level of performance, packaging integration, and electronic control technology that together provide an integrated solution.

The basic elements of the car are the use of a compact AC electric motor producing a maximum 60 kW (with 40 kW continuous output) and 210 N·m (155 lb·ft), driving the front wheels through a single-speed gearbox, weighing 16.3 kg (35.9 lb) wet. An 18.7 kW·h lithium-ion battery weighing 230 kg (507 lb) is integrated into the car’s floor in such a way that it does not intrude into passenger or luggage space. It has 204 cells providing a total 374 V. The car’s power electronics module weighs 10.5 kg (23.1 lb).

It takes 9 h to recharge the battery from a regular domestic supply; a wall box is an option and providing a 3.6 kW supply could recharge a completely discharged battery in 6 h.

Overall weight of the e-up is 1139 kg (2511 lb) against 929-940 kg (2048-2072 lb) for an internal combustion engine (ICE) up.

Apart from its packaging, the particularly interesting facet of the e-up is its choice of economy profiles and regenerative options. This may appear to be a little confusing at first experience but in fact both are driver-intuitive in use.

There are two profiles: Eco and Eco+. The former limits peak power to 50 kW, cuts air conditioning output, and reprograms accelerator response; the latter saves even more energy consumption by trimming maximum power to a modest 40 kW, disabling the air conditioning and heating systems, and applying further reprogramming of the accelerator response.

In both profiles, maximum power of 60 kW can be accessed by the driver when necessary via an accelerator sensor operating in a similar way to an auto transmission kick-down switch. However, if the battery charge has dropped into the red sector of a dashboard instrument, power may be limited automatically and maximum output cannot then be selected.

A really significant aspect of the car’s powertrain control systems is the subtle use VW has made of regenerative braking input. There are five modes: D provides normal driving without any regeneration, but modes D1, D2, D3, and B (braking), deliver progressively increased regeneration; when selected, all except D1 cause the brake lights to illuminate. Brake-light illumination is dependent on deceleration. In B there is no deceleration until battery charge can be added—from approximately a 90% charge level. Brake lights illuminate at a vehicle deceleration rate of 1.3 m/s² and deactivate at less than 0.7 m/s².

Control of the modes is via the transmission selector. The driver pushes or taps the lever to the left or right, respectively, to select or deselect a level of regenerative braking. Pushing to the right and holding the selector for a couple of seconds selects the regular D mode.

B mode is selected by pulling the lever rearwards; with foot off the accelerator pedal, the effect is of strong braking. Maximum braking effect is 0.35 g.

An electromechanical brake servo was developed for the e-up. It uses “brake blending” to produce mild braking via the electric motor’s natural retardation effect but stronger braking via the motor and the car’s hydraulic braking system, while also providing some regeneration. The electromechanical actuation also helps ensure consistency in pedal feel and power.

This Automotive Engineering editor experienced the car over a 40 km (25 mi) route of mixed urban, low, to very low speed roads, main routes with a 100-km/h speed limit, and on a motorway.

VW’s research has shown that B mode is used by the majority of drivers. This editor found it useful in slow moving or stop/start traffic, but D2 or D3 made for smoother progress at higher speeds while still producing a useful return to the battery. With deft use of the system, it was possible to see the range increasing.

At the start of the test, the e-up (fully charged) battery indicated a possible range of 158 km (98 mi). This dropped quickly in the initial phase of the drive when the regeneration system was not used and maximum acceleration was employed to join traffic, and also to accelerate hard from standstill at several large roundabouts. No attempt was made at economy driving; the car was driven in the same manner as its ICE sibling. Air conditioning was used and the highest motor output selected.

At the end of the 40-km test route, the battery indicated a 64-km (40-mi) range remaining. Best possible could have been 118 km (73 mi), figures that demonstrated the necessity for a driver to become “eco-minded” and use the energy recuperation supporting technology.

Best performance of the e-up includes a 0-100 km/h (0-62 mph) time of 12.4 s, which is quicker than the most powerful 55-kW (74-hp) ICE up, which needs 13.2 s. The 80-120 km/h (50-75 mph) time of the e-up is 10.5 s, 5 s quicker than the ICE car. Top speed is 130 km/h (81 mph).

The electric car is highly responsive, its added weight not proving detrimental to ride and handling. The powertrain is exceptionally quiet.

Both powertrain and its ancillaries, including power electronics, of the e-up indicate the direction that VW will take with regard to forthcoming models. These include this year’s e-Golf, and plug-in hybrid Golf (due early 2015), together with hybrid versions of other models.

A hybrid version of the up, called TwinDrive, was shown at last year’s Tokyo Motor Show. It incorporates an 830-cm³ two-cylinder turbodiesel engine with electric motor, technology from VW’s exotic XL1. A hybrid version of the Polo supermini is also planned.

This year the VW Group as a whole is scheduled to offer 14 models available with electric or hybrid drive. If public demand is sufficient, up to 40 new models could be fitted with alternative drivetrains, said Prof. Dr. Martin Winterkorn, CEO of Volkswagen AG: “We have developed the know-how for electric motors and battery systems at our own component plants; we have recruited 400 top experts for electric traction and qualified almost 70,000 development production and service employees in this new technology, the biggest electrification training program in the industry.”

The VW Group’s annual R&D budget tops €7 billion, with electric programs and projects taking a “significant” chunk of that.

VW expects the overall performance figures of its new alternative energy models to make the “point” about the efficacy of electric power via demonstration and explanation, not exclamation.

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