Thursday, 11 September 2008

Toyota Plug-in Hybrid Prius is pathetic

Take a look here (video) for the trial of a plug-in hybrid Prius. I must say this really exposes the feebleness of this car's "green" credentials. This is "news"?

It has only six miles of electric range. Yes, SIX. It then takes 1.5 to 2 hours to recharge the battery.

The Prius has always been a monumental dud, but works as an eco ego trip for the owner, who can prance about in a cloud of smugness exhibiting how green they appear, but in truth they are not in the least. Dust-to-dust carbon output, if you worry about such things, is higher than a Hummer, due to the highly complex powertrain.

The Prius has a complex powertrain as it is a parallel hybrid, in that it has both the electric motor and petrol engine mechanically connected to the wheels which, in my view, overcomplicates matters enormously. The petrol engine runs when the electric motor is not powerful enough or you need more range than a trip to your, erm, nearest petrol station. In truth there is no need to have such a feeble electric motor, but I suppose if it were any more powerful the range of the Prius in electric mode would be even more pathetic. It is a shame, however, for such a feeble motor is, unfortunately, incapable of absorbing much in the way of regenerative power. The excellent Mini prototype by PML Flightlink, which I blogged about some time ago, showed what a series/plug-in hybrid could be and the true extent of the energy that can be reclaimed from braking. The Mini has four 160bhp motors, one in each wheel and no friction braking. The 640bhp is needed for the motors to absorb the energy peaks in braking, giving 200 miles range in electric-only operation. In other words the Prius is literally throwing away energy. Not only that, the Mini uses a 250cc motorbike engine to hum away in a corner somewhere to give it 900 miles in total range, such is the effectiveness of the regenerative braking, series layout and motor control technology. Remember, this Mini with a 900 mile range from a 250cc engine has 640bhp on tap. 

The lesson here is that a series plug-in with a small, efficient generator is far preferable to some complicated parallel dinosaur compromise like the Prius. There is no need to keep the petrol motor connected mechanically to the wheels unless you are in the thrall of the various Mafia that runs Engine Management Unit, transmission, brakes, cam profiles and exhaust modelling fiefdoms and related ricebowls - all of which will have little to do of an evening once the ideal steady speed of the generator is arrived at, for who needs a motor that is "responsive" and "flexible" with high revs but low down torque when all it needs to do is convert fuel into electricity as efficiently and as smoothly/quietly as possible? All these roles will become far less glamourous, boys, so get used to it. 

Talking of glamorous, the PML technology has been chosen for the new Electric Lightning



This is nothing fundamentally new in concept, for Ferdinand Porsche was involved in one of the first series-hybrid electric sports cars...back in 1908. It could do 70mph, faster than the Prius can today. What makes the Electric Lightning an advance is the light, efficient and highly intelligent hub motors, removing the need for friction braking and the safe, rapid-charging and dense-enough battery technology, which is getting better by the day.

If you want to really understand how people can move to plug-in hybrids, give them a vehicle that actually makes SENSE, otherwise you just skew the results to suit your own parallel agenda.

UPDATE: Patrick, in the comments, reminds us of the EV1 by GM. This is an interesting though depressing situation. GM had, IIRC, a majority shareholding in the battery company that had some nice patents around NiCad battery packs, giving a range up to 150miles. They sold that shareholding to Chevron. I suspect this was not part of an "oil conspiracy" directly, just that GM feared its servicing revenue would be whacked, and correctly, so it decided to sell on to the last company that would want to see the battery tech widely adopted. While this was going on, Panasonic produced batteries that either used or infringed patents now held by Chevron. These batteries were installed in a Toyota RAV4 EV, fully electric vehicle. It had 120mile range, costing around £2 to recharge. Yes, £2. Most of us could survive on 120miles for a commuter car and the RAV4-EV could be upgraded to contain a small on-board generator to take over when battery power flagged, i.e. 95% of our journeys would be electric with overnight recharging and the rare long trips would be assisted by the on-board generator turning the RAV4-EV into a series hybrid. Chevron sued Panasonic and Toyota and the RAV4-EV production was rapidly halted. The chap "liveoilfree" on Youtube has some vids of him trolling around in his 2 RAV-EVs and, in particular, reviewing the Prius and its barking mad powertrain.

3 comments:

Patrick Vessey said...

Another vehicle that shouldn't be forgotten.

Roger Thornhill said...

They even made a series hybrid version which is a no-brainer.

Forget the "oil" conspiracy, to me it is the near total lack of routine maintenance, i.e. the parts scam.

Simon said...

The one mile pathetic battery in the Prius is why they were allowed to be sold when they were. Seen many 640 bhp electric minis on the road? That you an fill up from your plug at home at only 5% tax. No Well I wonder why. Hell you could even charge it from solar panels, it's clean but they really only want to approve lead acid or other under achieving electric cars that will put people off them. Simon