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Toyota Reveals Third-Generation Prius; 50 mpg

12 January 2009

2010prius_2
The 2010 Prius. Click to enlarge.

Toyota Motor Sales (TMS), USA, unveiled the third-generation Prius hybrid vehicle at the 2009 North American International Auto show. The new version of the world’s top-selling hybrid vehicle (more than one million sold in 44 countries) offers better mileage ratings and enhanced performance, as well as new design features.

The first-generation Prius, which was EPA rated at 41 mpg US combined city/highway, was replaced by the current model, which is EPA rated at 46 mpg US, combined. Using a combination of technologies, fuel efficiency was increased to an estimated 50 mpg US combined for the new Prius.

Hybrid components like the inverter, motor, and generator are now smaller and lighter. An exhaust heat recovery system, exhaust gas recirculation, and an electric water pump contribute to a more efficient hybrid system with a net horsepower rating of 134.

The battery module carries over from the tried-and-true technology from the current Prius. Engineers applied enhancements throughout the entire vehicle to achieve 50 miles-per-gallon, more consistent efficiency in real-world driving, and further reductions in CO2 emissions.

Electric power consumption has been reduced through the use of a more efficient air conditioning system and new, optional LED head lamps. Internal tests show that Prius’ zero-to-sixty acceleration time has dropped from the previous generation’s mid 10-second range to 9.8 seconds, making it comparable to that of an average mid-size sedan with a 2.4-liter engine. This is in response to customer expectations for better every-day performance. In short, the entire Prius package has been made more efficient from overall power consumption to output.

—Bob Carter, Toyota Division Group Vice President and General Manager

The new Prius also features what Toyota is calling a “Solar Moonroof”. A small array of photovoltaic cells automatically powers a ventilation system on hot days. The system allows fresh air to circulate into the vehicle, cooling down the cabin so that the air conditioning doesn’t have to work as hard, thereby conserving power.

Preliminary 2010 Prius Powertrain Specs
Engine 1.8L I-4 with VVT-i
Engine power [hp (kW)] 98 (73)
Torque [lb-ft (Nm)] 105 (142)
Motor power [hp (kW)] 80 (60)
Motor torque [lb-ft (Nm)] 153 (207)
Net power [hp (kW)] 134 (100)
Emission rating SULEV (w/ AT-PZEV)
Battery pack NiMH
Est. combined fuel economy 50 mpg US

A larger and more powerful 1.8-liter Atkinson-cycle, four-cylinder engine powers the new Prius. The larger engine helps improve highway mileage. By making more torque, the new engine can run at lower average rpm on the highway. When operating at lower rpm, the new engine uses less fuel. Mileage is especially improved in cold-start conditions and at higher speeds.

Use of an electric water pump and a new exhaust gas recirculation (EGR) system also contribute to the engine’s efficiency. The 1.8-liter Prius engine is the first Toyota power plant that requires no belts under the hood for better fuel economy and less potential maintenance.

The patented Hybrid Synergy Drive system in the 2010 Prius is 90% newly-developed with significant improvements over previous models:

  • The transaxle is lighter in weight and reduces torque losses by as much as 20% compared to the previous model.

  • The inverter, which converts direct current to alternating current, has a new direct cooling system to reduce size and weight.

  • Taken together, the inverter, motor and transaxle are smaller and 20% lighter.

  • A newly developed electronically controlled regenerative braking system has been adopted, with control logic optimized to enhance regeneration.

2010priusb
Under the hood of the 2010 Prius. Click to enlarge.

The new Prius will offer three alternative driving modes. EV-Drive Mode allows driving on battery power alone at low speeds for about a mile, if conditions permit. There is also a Power Mode, which increases sensitivity to throttle input for a sportier feel, and an Eco Mode, which helps the driver achieve the best mileage.

Dimensionally, the new Prius has the same wheelbase as the current generation. Overall length is slightly increased by 0.6 inches, in part by moving the front cowl forward. Designers preserved the triangle form of the current model, but made alterations to the overall profile, pillar position and angle. The overall height of the Prius is the same, but the roof profile is altered by moving the top of the roof 3.9 inches to the rear. This emphasizes the wedge shape, and also allows for enhanced rear headroom and improved aerodynamics.

The new Prius received more wind tunnel hours of testing than any other Toyota vehicle yet. By focusing on the shape of the body, underfloor, wheelhouse liner and shape of the wheels, the designers of the new Prius were able to reduce the coefficient of drag (Cd) value to 0.25, compared to 0.26 for the previous model. The airflow under the car was studied extensively. Engineers made changes to the shape of the fender liner, front surface of the underfloor, and added a fin at the rear floor cover to increase linear stability.

The next-generation Prius is built on a new platform, which enables improved handling stability, quieter operation, and collision safety. The suspension consists of front struts and a rear intermediate beam design, as before, but handling stability is advanced by improving the stabilizer layout, higher caster angle and tuning the bushing characteristics. Disc brakes are now used on all four corners, replacing the front disc/rear drum brakes in the current model.

Weight was saved through use of aluminum in the hood, rear hatch, front suspension axle and brake caliper and super high-tensile steel in the rocker inner, center pillar, and roof reinforcement. To meet customer expectations for everyday performance, zero-to-60 acceleration has been improved to 9.8 seconds, more than a second faster, in internal testing.

Better-performing sound insulation, working with improved vibration damping, has been installed in various locations to reduce road noise.

Toyota will use plant-derived, carbon-neutral plastics in the 2010 Prius. The newly-developed plastics, known as “ecological plastic,” will be used in the seat cushion foam, cowl side trim, inner and outer scuff plates, and deck trim cover. Ecological plastic emits less CO2 during a product lifecycle (from manufacturing to disposal) than plastic made solely from petroleum; it also helps reduce petroleum use.

Sales of the 2010 Prius will start simultaneously in both the US and Japan in late spring, followed shortly by Canada and other countries. Toyota forecasts first full calendar year sales in the US will be around 180,000 units.

We expect a large portion of this volume to come from current Prius owners. That’s because more than 90 percent say they will buy another Prius.

—Bob Carter

January 12, 2009 in Hybrids | Permalink | Comments (31) | TrackBack (0)

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Comments

wow no belts! unbelieavble! belt free engine!!!

wow rear discs! WOW

It sounds like the engineers got a chance to do a lot of things they wanted to do before but couldn't because they were constrined by schedule.

I just hope they didn't make too many changes all at once - it increases the chances that you'll have manufacturing problems in the first year.

I wonder if they were able to supress the electrical whine that you get when the battery recharges on soft braking or during a coast. Maybe the improved sound insulation covers it up better. Anyway, you only hear it when the radio is off and there is no other traffic on the road nearby.

I would have liked the option to buy a bigger battery pack (2x, 3x, or 4x), but I suppose that will have to wait until 2012.

But it's not a plugin. Why not? Why is it you can buy a conversion kit to convert it to a plugin but Toyota will not offer this simple technology as an option? Can someone confirm this, is the European version a plugin?

I wonder if they've fixed the power steering so that it actually feels like the steering wheel is connected to something ... the complete lack of steering feel and limp suspension turned me off the outgoing model. If not, the Insight is supposed to have better driving dynamics.

Not too exciting - but making a good car better often isn't.
Price ?
I wonder about the wording Gen 1 "was EPA rated at 41 mpg US combined ... current model, ... EPA rated at 46 mpg US, combined. ... estimated [sic] 50 mpg US combined for the new Prius.” Probably will be EPA rated at 50 or very close. ?
Either way they seemed to have made both acceleration and mpg better.
“preserved the triangle form” What triangle form?
“We expect a large portion of this volume to come from current Prius owners That’s because more than 90 percent say they will buy another Prius.” Right, when I have a car that I like, I trade it in.
I hope they sell to new buyers. But no matter, the trade ins will still be on the road.
No Wait – voices just told me Big Oil will buy them up and give them to GM to crush.

“Toyota forecasts first full calendar year sales in the US will be around 180,000 units.”
That’s 1.5% of US vehicle sales. Arghh.

It's not plug in because there is not enough battery to plug in.
Hymotion's $10,000 battery pack is bad ROI.
The car is not engineered to handle too much all electric driving. You can only drive upto 35 mph without the gas engine, and the amount of power and acceleration you get with the battery only is somewhat weak.

Wait until 2012 when the engineers can get it right.

The rather modest increase in mileage indicates diminishing returns for refining the Prius as we know it. That was to be expected.

It sounds as if they really made the car nicer even if the fuel economy is roughly the same.

Big advances now will come from different battery chemistry and drive train and plug-in recharging.

Even so a lot of makers would love to have an equivalent of the outgoing second-generation Prius in their dealers showrooms.

Two years ago Toyota's head of Prius development said that the 2010 Prius would have 9-miles of EV range.

This 1-mile EV range is a real U-turn from that, and I wouldn't be surprised if the 3rd generation battery is actually smaller (in kWh terms) than the 2nd generation battery!

I think that this new Prius is a wonderful evolution form the previous version. A 10% increase in fuel efficiency increase while also improving on handling AND performance is no small feat. The current Prius was already a very drivable car, and this new incarnation will be an even greater pleasure to drive.

Things i really like:
* Smarter use of breaking energy
* The radar "distance keeper" in combination with cruise control !!!
* LED headlights (no more garage work to replace a bulb!!)
* lower RPM on the highway
* Lower drag (even less wind noise)
* Green switch (optimized fuel efficiency)

Can't wait to go test drive it!!

Ps. I would have loved a Prius 3.0 with a smaller engine, bigger motor and LI-ION and plug in, but alas, the American consumer :-)

It has a flying buttress! Woo-hoo! I'm sold :_>
http://priuschat.com/forums/members/danny-albums-2010-toyota-prius-official-toyota-photos-picture950-42-10-prius.html

Batteries Are Hard. I'm not going to buy the first year that the plugin option is generally available (2011; 2010 availability will be severely restricted as a beta test).

Those of you disappointed by the lack of PHEV option, read:
 
MIT Technology Review
Tuesday, January 13, 2009
 
Toyota to Deliver Plug-In Hybrids
 
The new Prius is designed so that its battery pack can be swapped out for a plug-in lithium-ion battery.
 
http://www.technologyreview.com/energy/21951/?a=f
 

I think they have done an admirable job of continuous improvement. Now being in the 3rd generation, they are way ahead of everyone else in this hybrid technology. As is the tradition, american companies will now try to "leapfrog" and hope in this way to regain a competitive advantage. That may work, but the risks of failure are higher. The option is being plug in ready is great, although I did not see any particular place prewired for an outlet.

Progress continues incrementally. The Ford Fusion took a big step forward over HSD, and and this Prius is a small step too. Call it HSD Version II.

But it is easy to see that HEVs are reaching the end of the large expected improvements. Dual-mode HEVs wil improve highway mileage but it appears that 50+/60 mpg is about the maximum to be achieved in a "c" or larger segment car.

If you want more fuel economy you wil have to go to Parallel/Series PHEVs, and pure Series PHEVs like the sedan versions of the VUE dual mode PHEV, or the Volt architecture.

Fortunately, that is probably more than enough to fracture the OPEC cartel, and drastically reduce petroleum demand.

Is any manufacturer considering the Miller cycle for their hybrids? I haven't seen one except for Subaru's aborted plan. I would have thought that this would be the most efficient gasoline powerplant, and turbos are cheap these days.

Does it seem odd to anyone that both Ford and Toyota have both significantly increased the size of their hybrid engines? I'm perplexed.

I read where Toyota was asked about that and what they said was basically this...at highway speeds (an area they wanted to improve mpg) the larger engine was more efficient since they didn't have to rev it as high to produce the power needed and that was why they went with it.

With Ford, while it could be the same explanation, I think its really Ford deciding its cheaper to lift the drive system from the Escape Hybrid with virtually no changes and drop it in the Fusion Hybrid - then only make 25,000 of them, so people won't be able to get them.

They are saying the larger 1.8L engine will run more slowly and therefore be more efficient.

Hmmm the new engine has the increased bore of 80.5mm which will typically have more friction than the earlier 75mm. More likely the reason has to do with a cost reduction by using the same engine as the Corolla.

The Prius was never underpowered, too bad they are moving it in a power hybrid direction. For those who put on large mileage out on the highway I see the advantage now shifting towards the new Honda Insight with its 1.3L.


@Stan - Don't expect series hybrids to be ANY more efficient than a series/parallel or dual-mode when operating in gasoline mode. The most efficient way to get mechanical power from an engine to the wheels is through a gear-to-gear transmission without converting to electricity first. Series has its place (and facilitates plug-in operation) but my view for the foreseeable future is that the mechanical drive train has to be maintained to give best efficiency in highway operation. It's more efficient to go engine -> gears -> wheels than go engine -> generator -> rectifier -> battery -> inverter -> motor -> gears -> wheels.

I believe GM has been saying the Volt is expected to get 35 mpg US when operating in gasoline mode ... unremarkable (and to me, unsurprising).

The beauty of the Prius powertrain is that it can operate in parallel mode, or almost-series mode, or almost-all-mechanical mode. I will bet money that it's not going to get significantly more efficient than this ... except by chucking out that gasoline engine and substituting a diesel!

@JC - Most of these hybrids are using an Atkinson cycle, which is (more or less) a Miller cycle but without the supercharger to gain back the power lost by the loss in volumetric efficiency. The net effect (effective expansion stroke longer than effective compression stroke) is the same.

@T2 - this new Prius is scarcely what you call a "power hybrid" ... Increased bore size with lower RPM adds up to not much difference in friction. And the definition of "underpowered" depends on your perspective; a Prius is not, and was never meant to be, a quick car.

No question the base engine designs are being taken from other models in the interest of cost control. Nothing wrong with that.

- Brian P I agree it's not yet a power hybrid but this move from 104Hp to 134Hp with the GEN III that's more than an incremental step in my view. And you would think that with a million sales or so that the Prius would at least get its own engine else what's the point of introducing a hybrid Corolla ? The HSD system or, to put it more accurately, MG1 needs an engine of constant torque over a wide rpm bandwidth - this automatically eliminates the diesel from contention by the way. An engine with higher max rpm, say 6000rpm but with orig 82lbs-ft torque, would place max power point currently at 51mph also higher as well. Not good. Therefore the transaxle gearing would need increasing from the present ratio of 4.113 towards something higher so that MG2 and the ring gear approach 7200rpm, up from 6000rpm, at 100mph. All this is purely speculation but it's fun. Any comments ??

As I have written before although the philosophy behind Prius seems more about it being ultra low emission than actually having good mileage, the improved mileage comes about anyway from having that smaller 1.5L engine with the Atkinson camming.
For what it's worth my Toyota Echo with virtually the same 1NZ-FE engine already achieves 51mpg on the highway, just not as clean. But I admit that when it comes to town driving the Prius will clean the Echo's clock.

- Mark and TM regarding your need for more energy storage.
The Prius is less about the utility of being an electric car and a lot more about the utility of it being an electric transmission, despite the efforts of those misguided souls who would try to turn it into one with $12,000 of computer laptop batteries. An electric vehicle it is not. It is what it is. It is in fact a shining example of what you can do if you replace the conventional multi-ratio gearbox and clutch (19th century technology) with an electrical transmission that partially decouples the mechanical connection of the engine to the wheels.

For those not in the know. It is from the help of two powerful servomotors MG1 and MG2 followed by a single fixed gear reduction equivalent to something between conventional 3rd and 4th gear and with no clutches whatsover, that allows the engine to rotate at any speed no matter what the speed or direction of the wheels happen to be.
In real life that means a small 1.5L engine is capable of propelling a midsize hatch as if it were a 2.4L. Sure the 21kW battery assist of effectively 28Hp can help also, but most of the time the engine just simply speeds up when extra power is needed and spins back down again afterwards.

Since the torque fluctuations - as when the driver of a conventional car "rows" through the gearbox while accelerating - are not present, many people gain the false impression that this is a slow car. Gradually declining torque as you accelerate rather than in chunks that rock you around is going to be the hallmark of 21st century powertrains.

All that aside TM writes -The car is not engineered to handle too much all electric driving. You can only drive upto 35 mph without the gas engine, and the amount of power and acceleration you get with the battery only is somewhat weak.

I agree the 50Kw electric motor (now to be 60kw with this GEN III) is disadvantaged by the 21Kw HV battery, but this servomotor does not have a continuous rating at its full 50Kw output anyway, have you seen how small it is ?

Clett - Two years ago Toyota's head of Prius development said that the 2010 Prius would have 9-miles of EV range
I know you know the Prius battery holds only 1.3Kwhr. A hundred dollar 72AHr lead acid battery holds 0.9Kwhr. So you're wanting the Prius to drive 9 miles on less than two conventional batteries ? The NIMH battery is even less than this since deep discharges are inhibited. That one mile is conservative but there are probably a few uses for it that will save gas in the long run so why not, electric mode will save owners having to play tricks to prevent the engine from starting. Being 3 minutes at a stop light a mile from home and the engine kicks in can be frustrating when it kills your mileage figure for the trip.

For every person who wants the car to be more active in electric-only mode there is someone else who won't buy the hybrid because of a possible battery failure after ten years. That possibility must be why the manufacturers have refrained from opening themselves up to further vulnerability on a replacement being necessary. At the moment there is no real competitor to the Prius for Toyota to take unnecessary risks.

@T2,

I simply disagree.

When all motive power is derived from the electric motor at all the varying speeds required, the ICE can run at essentially a constant speed as a generator. ICE engines can be tuned to as much double their efficiency in such single speed applications. Provided that the ICE is sized to be at a partial load in such conditions. HCCI operation is coming from the labs rather soon, and perfect for Series architecture. That would enable the Series ICE engine to deliver 42-45% thermal efficiency, versus low the 20s in variable speed operation. Even assuming Atkinson cycle operation, that you would see in a parallel/series design.

In the HSD drive implementation, there is a double energy conversion now losing some 20% of the efficiency since there is only a single planetary gear-set.

I recall GM saying the Volt is expected to produce not 35 mpg when the ICE is operating, but rather closer to 50 mpg. Substituting electrons for oil molecules, has led many to calculate the fossil fuels MPG equivalent, is some 322 mpge, for the Volt.

But we do need to answer the need for Petroleum substitutes, as there simply is not enough to power a Worldwide advanced civilization for an indefinite amount of time. The problem is, and has been for thirty five years, to develop substitutes for the only Oil market still growing, Transportation. All other oil markets are static or declining. Ground Transport is by far the majority consumer of that economic sector.

The coming Electrification of
Ground Transport removes the last and only impediment to providing an advanced lifestyle to the entire Planet.

Excuse me T2. The above post was in response to Brian P instead. Sorry for the error.

Brian P,

The ordinary Cruse uses a standard 1.4 liter engine without hybridization, but with turbocharging. It is expected to produce 40 mpg with no hybridization operation at all. The European Focus is now doing somewhat similar.

I would expect that with primitive parallel/series hybridization that you could achieve the 50 mpg that the Prius III produces.

But if you add constant speed at partial load operation tuning you can do better. Constant speed at partial load, is conducive to extensive HCCI operation, you have indeed achieved the equivalent to diesel operation except in a much lighter engine block.

Even without HCCI, tuning for constant speed operation, with equivalent Atkinson cycle operation, would produce a better BSFE than the larger 1.8 liter that the new Prius has.

I fail to see why a Volt couldn't/ wouldn't easily achieve 50 mpg in such circumstances, if the Prius can do so. When HCCI comes, it should jump to even higher fuel economy numbers.

Brian & Stan. Your discussion of the series v. parallel drive trains makes sense. To me the fundamentals of the series come out stronger.

Here is what Brian correctly said about the parallel:

"It's more efficient to go engine -> gears -> wheels than go engine -> generator -> rectifier -> battery -> inverter -> motor -> gears -> wheels."

I believe Brian omitted the fact that a parallel must both power paths in order to operate in both modes. But the serial hybrid does not need the mechanical path of engine -> gears -> wheels.

The serial should come to weigh less and cost less.

I'm guessing, like Stan, that the simpler serial arrangement allowing the optimization of the ICE size and a nearly constant speed will prevail.

The series-hybrid promoters love making the constant-engine-speed argument. I do not dispute that this can be an advantage, but must point out that except at the *one* speed at which the power demand to drive the wheels matches the power output from the engine, this arrangement MUST involve charging and discharging the battery. There is a significant energy loss involved with discharging and charging a battery. With lead/acid this process is about 85% efficient at best and that's only at low charge/discharge loads (and I realize that other battery technologies are planned but they will have a similar effect). Also, the effect on battery life of constantly charging and discharging has to be accounted for. These losses can easily be made up by NOT charging/discharging the battery (or keeping it to a minimum) and instead accepting a *slight* loss in engine efficiency by running it "off-design" but at a power output that more closely matches demand ...

For what it's worth, I have the BMEP map of a certain VW diesel engine, and if one accepts a 15% drop from the best possible BSFC, the possible range between maximum and minimum power output within that constraint is about 5:1. If the battery charging/discharging losses are accounted for, when one considers the WHOLE vehicle as a system, it's more efficient to let the engine speed and load vary if the power demand is within this range.

And this does not account for the losses in the generator, rectifier, inverter, and motor, which will surely be greater than the losses in a gear-to-gear transmission.

I still maintain that the engineers who designed the Prius do, in fact, have their heads screwed on straight (by allowing for almost-all-mechanical drive during motorway conditions) - and further, the designers of the Volt also have their heads screwed on straight (by allowing the engine/generator speed to vary SOMEWHAT according to vehicle power demand to minimize battery charge/discharge losses).

Remains to be seen how the Volt will do in charge-sustaining mode compared to the non-hybrid Cruze. I betcha if you take both cars and drive them down the road at a constant motorway speed, the Cruze will do a little better due to fewer losses in the powertrain ...

Regarding HCCI, every case of this that I have heard of thus far, only allows HCCI operation at relatively light engine load, and thus far this has been true of both the gasoline and diesel based HCCI concepts. BSFC is normally best at relatively high engine load (for gasoline and diesel), not in the regime where HCCI has thus far been proven possible.

@Ken - I left it unsaid that a parallel hybrid must provide both paths. The planetary dual-motor-generator arrangement used by Toyota (and Ford) and the two-mode arrangement used by GM, Chrysler, Mercedes and others don't have any particular difficulty providing both paths; this is scarcely an obstacle. All of those can transmit engine power straight through without encountering charging/discharging losses.

It remains to be seen whether a serial hybrid will cost less to build. The big money is in the batteries and the power handling equipment, not in the gearbox that a parallel-hybrid must have.

-Brian P wrote : The series-hybrid promoters love making the constant-engine-speed argument. I do not dispute that this can be an advantage, but must point out that except at the *one* speed at which the power demand to drive the wheels matches the power output from the engine, this arrangement MUST involve charging and discharging the battery.

As a series hybrid promoter it annoys me too when I see that disinformation written also. Union of Concerned Scientists website - are you listening ?

The energy should be kept in the fuel and used at the rate required ; not by this intermediate storage implementation with its churning losses (even with the more efficient Li-ion cells).

My own vision goes beyond, with the batteryfree or 'virtual battery' concept. This totally avoids the use of "boutique" energy storage and power delivery. For a lot less money you can install a significant amount of racing technology (forged crankshafts for example) that will allow a much lighter and powerful 2 cylinder to exceed the performance of current 4cyls but be lighter and have less moving parts and consequent friction.

How would that 'batteryfree' work ? Well, initially the main bus is energised to 150vDC using the power of a couple of 6 volt lead acid batteries so that either MG1 (to borrow Prius terminology) can be used to start the engine or so that MG2 can be energised providing a 'one mile' low speed 20km/hr electric- mode capability. The rest of the time, with the engine running at the appropriate speed, energy flows from MG1 to MG2 at the level required. Not so in the Prius where except during brief acceleration periods, the electrical power flow is from the traction motor, MG2, back to MG1, the generator. This reversal of power when cruising the Prius is necessary to force the engine to work high torque/low rpm. Always working hi-torque low rpm is the tenet of series hybrid operation also.

At 50mph the Prius HSD "circulates" about 33Hp even though only 8Hp is produced by the engine and 6Hp gets to the wheels. That's why Prius is not so good in hiway as it might be. It's because of those very real losses generated by the transfer of 33Hp of "imaginary power" between its electrical machines.

A series hybrid, on the other hand, only transfers between its electrical machines what is actually is needed at the wheels so its electrical losses are considerably lower when cruising. Whether you can make sense of any of this depends a great deal on your level of education. When the Chevy Volt appears you're going to see that effect hopefully we'll get some converts.

Heretical mode as some Prius advocates refer to it can be found in the 'Prius_Stuff' Yahoo group. See posts around Aug 2001 with Graham Davies holding court ! Then there's post #12022 which gives a link to the DOE 1984 teardown of the Gen II HSD.

As Nasa's Mike Griffin said, we need to be knowledgeable so we can say "Yes if......then that's possible " rather than adopt a "NO, because... " type of culture.
T2

Brian: you obviously know a great deal about the tradeoffs of serial and parallel. And so do some other commentators.

You are right that battery costs are a dominant factor, especially at the moment. If they remain too high then the design with lesser battery requirements must prevail. I'm guessing battery prices will fall rapidly.

I am dubious that the costs for the power handling equipment gives advantage to either technology. Both serial and parallel must handle the same sort of electrical conversions. Admittedly the serial would deal with more power.

If you have an old Pius, is your piusness diminished by the new Pius.

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