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First drive: Plug-in Prius progresses

Plug-in problems: Toyota's electric future is clouded by technology issues.

Toyota accelerates Prius III PHV trial, but production is still way off

27 Jan 2009

TOYOTA has accelerated its petrol-electric plug-in hybrid vehicle (PHV) trial program from 2010 to the last quarter of this year, but ongoing issues will prevent full production for up to five years.

These include battery, pricing, durability and packaging problems, as well as infrastructure obstacles as a result of monumentally increased load pressures on the power grid.

This is according to US national manager of Advanced Technologies Group at Toyota in America, Bill Reinert, speaking to the Australian media at the Prius II PHV drive day in Los Angeles earlier this month.

Employing a host of new technologies including the introduction of lithium-ion batteries to replace the more conventional nickel-metal hydride (NiMH) battery pack that is the basis for today’s Toyota and Lexus hybrid vehicles, the PHV program will be launched in the US and Japan on an experimental basis in the recently unveiled third-generation Prius.

These trials will not include Australia for now, meaning the Prius III will be launched in the middle of the year using a variation of the outgoing model’s petrol-electric Hybrid Synergy Drive System, which according to the company is “over 90 per cent new”.

About 500 Prius III PHV vehicles will be leased to fleet and government agencies in North America and Japan. Around 150 will be heading to the US.

Running on purely electric mode, the Prius III PHV should have 20km of range before the regular 1.8-litre four-cylinder Atkinson petrol engine takes over.

However, this depends on how much compromise the consumer is willing to make on performance, cost, comfort, convenience and entertainment systems, according to Mr Reinert.

This compares to the maximum 10km range of the all-electric range prototype Prius II PHV test mule fitted with an NiMH battery pack, as assessed by the Australian media, although that figure is variable and controlled to best preserve the hardware.

The lithium-ion batteries heading for the trial Prius III PHVs are to be built by Toyota as part of its 60 per cent equity in the Panasonic EV Energy Co battery plant joint-venture with Panasonic.

Toyota says it is doing its PHV research to develop “more advanced, compact and powerful battery systems … that results in substantial gains in fuel economy and a major reduction in total tailpipe emissions”.

8 center image Mr Reinert said lithium-ion eventually would replace NiMH batteries for reasons of efficiency, performance, packaging and reliability, despite the massive and ongoing issues that Toyota faces. Translated into today’s dollar terms, switching from NiMH batteries in the Prius II to lithium-ion would add between $5000 and $5500 to the price of the vehicle.

“Right now, it would be about $US500 ($A770) for every electric mile (1.6km) you drive,” said Mr Reinert, who then revealed some of the problems: “Do they work in 45 degrees Celsius? Do they work in minus 20 degrees Celsius? Will they be made 99.99 per cent reliable? “Can you make these lithium-ion batteries in a large format with great repeatability? Can you get the cost down?” Battery cooling, which is essential to reliability and range performance, remains another obstacle for lithium-ion battery applications to overcome.

“A lot of manufacturers now have to provide complex heating and cooling for the batteries to take care of temperature strains,” he said.

“That’s a parasitic load, so if you buy one you have to pay for that, and you won’t see any advantages – it won’t air-condition your house, for example – it’s going to sit there and heat or cool your battery and it is going to run for 24 hours a day and seven days a week whether your car is being used, parked or charged.” Range is a further issue, Mr Reinert admitting that about 10km will probably be the average everyday range of the Prius PHV for the foreseeable future.

"We figure in the real world you are going to get between two-and-a-half… to four miles (four to 6km) per kiloWatt hour," he said.

“Other (manufacturers) rate (theirs) much higher. And you can get it much higher, but the reason why (they) are getting much higher (figures) is that they are not running their PHVs in what we call ‘hotel’ mode – your heating, your air-conditioning, your demister, your radio, and so on.

“And all the safety equipment we run on the car like anti-lock brakes, power steering … all these are power loads that are competing for the electricity onboard.

“So to say you are going to get eight or even 10 miles per kiloWatt hour (is possible) … but only if you drive at 35mph (50km/h), and if it’s on a flat and steady surface and if you do not accelerate very fast. There are a lot of ifs.” Mr Reinert went on to say that a PHV’s battery – which lives in the boot area where the spare wheel normally lives in a regular Prius – adds weight that is “like an anvil in the back” that needs extra structural strength and bracing to accommodate it, along with appropriate increases in braking and suspension to cope with these, bringing on significantly more mass for the battery to drive around.

In the case of the Prius II PHV, there is about 45kg of extra weight on board.

Finally, upgrading the power grid is recommended, according to Mr Reinert, since many centres use immediate post-World War 2 electrical feed stations that are not designed to supply the modern household with all the latest audio, entertainment and comfort demands on electricity, let alone the recharging of millions of extra vehicles.

“The feed to your house is (probably) undersized, the feed from your pole to your transformer is (probably) undersized, the transformers are undersized, the sub-stations are (probably) undersized, and the feed to the sub-stations are (probably) undersized,” he said.

“So it is not a trivial issue to think about these things in a holistic manner, if you start to worry about the electrification of cars and the charging of cars.”

Drive impressions:

DRIVING the Plug-In Prius (PHV) is a fleeting thing – and not just because the vehicle is eerily quiet and absolutely smooth as it whooshes forward in pure electric mode.

Compared to the regular Prius II that will be replaced in Australia with the all-new model unveiled at the Detroit motor show earlier this month, the Prius II PHV has an all-electric range of about 10km, can travel on pure electricity at a maximum speed of 100km/h instead of about 35km/h, and weighs 1360kg – 100kg more than usual.

Our drive was limited to just 3km in light LA traffic, and quite frankly, finding the differences between this and the regular 2003-2009 second-generation Prius petrol-electric hybrid took up most of those precious minutes behind the wheel of the electrified Toyota.

The steering still felt as disconnected as it normally does in a Prius II the acceleration seemed strong but then the petrol electric motor kicked in as we depleted our charge and suddenly, the fossil-fuel burning Toyota felt just like any other vehicle.

We did feel the extra weight of the old-school nickel-metal hydride battery pack nestled in the boot area where the spare wheel normally resides, and so the Prius II PHV felt even heavier than the non-plug-in version.

And then… it was all over. All electricity was gone. The petrol engine chugged away smoothly and quietly without re-energising the batteries as the regular nickel-metal hydride batteries would have been in a regular Prius II, and we started to wonder about the biggest disadvantages of driving an electric vehicle that – in most parts of Australia at least – requires carbon-spewing coal to power up the electricity grid, thus virtually negating all the benefits of going plug-in hybrid in the first place.

We are confident many of the limited range (up to 20km in the 2010 Prius III PHV test cars), high cost (upwards of $5000) and heavy packaging issues will be addressed eventually.

But as long as driving a plug-in hybrid means that we are merely moving the pollution from the exhaust pipe to the power station pipe, then going for a plug-in is simply not the answer for now.

Read more:

Toyota tests plug-in Prius in UK

Prius plugs in


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