Early next year, devotees of the Toyota Prius will have their chance to go a step further into greenness. Thatís when the Prius PHV, a plug-in hybrid based on the current Prius architecture, will be introduced.
(To see related content, about the Chevy Volt, go to Drive for Innovation and follow the cross-country journey of EE Life editorial director, Brian Fuller. On his trip, sponsored by Avnet Express, Fuller is driving a Volt across America to interview engineers.)
Design News recently had an opportunity to drive a pre-production version of the Prius plug-in, and the good news is that itís a sensible alternative-fuel vehicle.
First, it should be noted that, as a plug-in, this Prius is half hybrid and half electric. It differs from other plug-in vehicles in that it employs a relatively small battery. At 5.2kWh, the Prius has a battery capacity thatís about one third that of the Chevy Voltís 16kWh and about one fifth that of the Nissan Leafís 24kWh.
There are pluses and minuses to Toyotaís strategy. First, letís look at the downside: The Prius has an all-electric range of just 13 miles. If youíre looking for a vehicle thatís more electric and less hybrid, this isnít it.
The upside, though, is big. Yes, the range is just 13 miles, but the smaller-battery strategy has efficiency written all over it. Smaller means less mass, which translates into greater fuel economy. Thatís particularly important when the driver has exceeded the 13-mile range and the depleted battery is basically dead weight.
It also means the recharging time is a fraction of what weíre hearing from competitors. Instead of an eight-hour recharge at 220V (as is the case with the Leaf), the Prius plug-in recharges in about three hours at 110V or 1.5 hours at 220V.
The 110V recharging setup is a huge advantage, not only in terms of availability, but also in terms of cost. During the week we tested the vehicle, we recharged in three hours twice from a 110V outlet. Thatís very important in terms of cost, because it means owners donít need to get their garages rewired at $2,000 a pop.
The biggest advantage of the smaller battery, however, is initial cost. Toyota engineers told us that more range would have translated into about $500 per design mile. Hereís another way to look at it: Numerous estimates have placed lithium-ion battery cost at between $750 and $1,000 per kilowatt-hour. In terms of initial cost, that converts to between $15,000 and $20,000 to get an extra 20kWh.
During our test drive, we got the advertised 13-14 miles of range. When we drove within that all-electric range, our vehicle estimated its own fuel efficiency at 99mpg. It should be noted, however, that even when we drove within the electric range, the vehicle autonomously shifted back and forth between electric and hybrid modes. The main reason was acceleration. When we stepped deep into the accelerator, the car shifted into hybrid mode for about 10 seconds until a constant velocity was reached, and then it switched back. After a low-speed, 4.3-mile circuit, the vehicleís dashboard display claimed it had been in EV mode 75 percent of the time and in hybrid mode for the remaining 25 percent.
A longer drive was a different matter. As soon as we reached 60mph on a local expressway, the car shifted into hybrid mode and stayed there. The shift was seamless. During a 155-mile ride, the vehicle was in all-electric mode just 4 percent of the time. The fuel efficiency was still impressive, however, coming in at 56.6mpg.
The key to this carís success on the market, of course, will be its cost. Unfortunately, Toyota hasnít announced an exact figure. During an interview with Design News, Toyota engineers hinted at a possible figure hovering at around $26,000 or $27,000. But itís probably safe to say the ultimate entry number will be higher -- possibly landing between $27,000 and $32,000 before tax credits.
The bottom line is that this is a sensible alternative-fuel vehicle for someone who has a short commute to work. Some owners will be able to drive all week in the electric mode simply by recharging every night. Then, when the weekend arrives, they can depend on the car to switch silently to hybrid mode for greater range.
13 miles certainly doesn't get you very far, yes. And even during those 13 miles the engine isn't completely off all the time.
However, if you tend to make a lot of short trips at low speed, the engine would be off almost all of that time. Short trips are very desirable to target, however, because tend to really drop your mileage. That, since gasoline engines run especially inefficiently at low speeds, or at idle. Or before/while warming up.
On a somewhat-related note, I've seen discussions of the Volt of the nature of, "I wouldn't buy this thing because, I can't fit my 50-mile commute into the nominal 40 mile pure-electric range of the car." Well, OK, but isn't burning 10 miles of gas a big improvement over burning 50 miles worth of gas?
As distances here are expanded compared to other parts of the country, <13 miles doesn't get us very far. I didn't mention in my post that I sold the Prius 2002 because it had no trunk. My needs changed, so I bought a used 2002 Aerio SX (Suzuki) hatchback (in 2004) that has good carrying capacity. Put $7k in the bank. It gets a measured 29-30 mpg, losing 1 mpg when the A/C is on.
Air conditioning certainly does take a bit out of my 2009 Prius' mileage, but thankfully not to the point of keeping the engine running all the time. Then again, here in Austin, it's only 100 degrees at 9:30PM! :-)
Rob: Automakers are definitely considering battery replacement, and are trying to make it part of the buying decision. GM offers an eight-year, 100,000-mile warranty on the Volt's battery. The fact that they did so indicates consumers are asking about it. However, my guess is that most consumers aren't asking about it until it comes time to plunk down the money. Nissan actually interviews prospective buyers of the Leaf to make sure they understand the issues associated with the performance and care of an electric car.
I think that full-production EVs are still new enough that a mentality related to battery replacement has not yet to emerge. However, I think the expectation is that you simply won't need to replace traction batteries for a normal expected lifetime of the vehicle - say, 150Kmiles. As for whether it will really happen that way ... I guess we'll see.
For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? Thatís where the ďsmartĒ machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This discussion will examine whatís possible with smart machines, and what tradeoffs need to be made to implement such a solution.