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Food for Thought: PiP a preview of the future of Prius?

Discussion in 'Other Cars' started by Tideland Prius, Oct 27, 2016.

  1. Tideland Prius

    Tideland Prius Moderator of the North
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    With the launch of the Gen 4 Prius and the imminent launch of the Prime, I've been thinking about where the next generation Prius could go. Of course there's been a few articles about Toyota contemplating about eliminating the hybrid system for Prius and simply offering a PHV powertrain as standard equipment.

    This has me thinking. What if the PiP was an experiment for the 5th Gen Prius? I'm not saying it was intentional but it could be seen as a byproduct of the PiP.

    Let me explain.

    Toyota has repeatedly said that squeezing out each further mile per gallon of fuel is getting increasingly difficult. It would require either lots of research, expensive materials or other compromises that they're not willing to take yet.

    How dense of a battery can the hybrid battery have to be to function as a hybrid without a plug? And how small of an engine can Toyota fit into the Prius and maintain cargo capacity, performance and driveability?

    While a series-parallel hybrid has worked well for Toyota, what if they started focusing on a series-hybrid like the Volt or i3 REx? They can make the engine function closer to a carnot cycle and use electric motors or the PSD to convert work into potential energy or for torque multiplication to offset the lower output of the engine.

    This way, they can make a thermally efficient engine and rely more on the battery.


    So, how dense of a battery can Toyota install in a hybrid vehicle such that a system similar to the one I've described can be feasible and therefore eliminate the need for a plug?

    Of course, there's probably going to be a PHV version (assuming the Prime does well) for those who want more power and longer EV range.
     
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  2. bisco

    bisco cookie crumbler

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    you lost me.:p but i'll follow along to see if further discussion helps my pea brain.
     
  3. iplug

    iplug Senior Member

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    When Toyota first hinted at the 5th generation Prius going all-in PHEV it seemed plausible, but largely conjecture at that point. But now seeing rapid improvement in PHEV costs (witness the Prime), this seems very doable.

    For those who remain Toyota enthusiasts but want the latest cutting edge eco tech, the liftback Prius platform has been a bit hampering. Both the PiP and Prime are constrained to a significant degree by the "liftback first" structural format. With the liftback format as priority one, the plug-in models have had to play second fiddle with Toyota having to figure out where to work in the PHEV battery, what size/capacity, and all the compromises that follow including on cargo and seating space, suspension, etc.

    But design the Gen 5 Prius with PHEV as a standard feature, and suddenly there is much more flexibility to maximize the most appropriate battery placement, size/capacity, etc.
     
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  4. bisco

    bisco cookie crumbler

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    are you suggesting sedan?
     
  5. iplug

    iplug Senior Member

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    No, it would be about building the 5th gen Prius around a PHEV system/battery instead of the other way around. The fit, finish, and performance could be significantly improved.

    And as the Prime shows, it's shouldn't cost too much more to do so with current PHEV price improvement trends.
     
  6. bisco

    bisco cookie crumbler

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    i was hoping that was going to happen with gen 4. sigh...
     
  7. john1701a

    john1701a Prius Guru

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    I thought the upcoming flip was easy to see. Apparently, it's not... yet.

    Think about what happened with the computer industry. Where are all the desktop computers now? That format which once dominated the market has become quite rare. Those high-priced portable devices have very successfully replaced them. They have even been supplemented with smaller version now depend upon for routine communication.

    Intel announced quite a number of years ago that they would stop producing desktop processors, that 100% of what they'd offer would be a portable design. Have you looked inside a new desktop computer? It's actually a notebook with a large case, lacking a battery and a screen. Mission accomplish. The desktop we all grew up with is now long gone.

    Hybrids will follow a similar evolutionary path. Offering a plug and some degree of EV operation will be the norm, hopefully by the next generation. Plugging in will become so convenient, there won't be any need to further push HV abilities. Prime offers a rock-solid 50 MPG following depletion. Prime also addresses every need related to EV operation.

    Lowering cost a little more, while also improving energy-density a little more, is all it should take to make the plug part readily available for everyone realistic.
     
  8. bisco

    bisco cookie crumbler

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    but isn't this thread premise about not having a plug?
     
  9. drash

    drash Senior Member

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    Not sure its the density of the battery that matters as much as the amount of energy they can get into the system in the most efficient and fastest way possible. Is it Toyota's free piston engine linear generator (FPEG)? Or a turbine similar to what Wrightspeed is trying to put in big rigs? Wireless charging will probably grow faster than what most people are thinking and even with their losses is still far more efficient than localized mechanical generation. Of course there is also cogeneration in which you might have 2 or more systems putting electricity into the battery. If Toyota can grow car top solar panels from 50 watts to 160 in 6 years can they triple it again in the next 6? And now that wireless has a standard, you might have a situation where both can feed the battery at the same time.


    Unsupervised!
     
  10. iplug

    iplug Senior Member

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    My bad, think you're right. I need to stop skimming here.

    I don't see efficiency evolving much more without making the 5th gen Prius PHEV standard.
     
  11. bisco

    bisco cookie crumbler

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    that's why i'm trying to understand tide's post. i think he's intimating that there might be a way to efficiently charge a larger, more advanced battery from a more advanced engine and hybrid system, without plugging in.
     
  12. Tideland Prius

    Tideland Prius Moderator of the North
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    Well yes and no. I was thinking what will be the future of hybrids and is a PHEV basically the "destiny" of hybrid vehicles. The Europeans seem to think so as a number of them only had one generation of hybrid and went straight to PHEV for Gen 2 (Porsche, BMW and MB). Could be European fuel economy laws but they took the PHEV plunge first with Toyota bringing up the rear.

    So I was thinking, is there a way to keep costs low (which is pretty much where Toyota is with the hybrid system) while increasing fuel economy? Cause a hybrid vehicle's battery cannot be too large unless there's a way to charge it via regen or engine. That means the engine power has to increase or conversion loss has to be reduced further or MG1 needs to be more powerful or all of the above. There must be a certain battery capacity where it becomes more feasible to recharge the battery with a plug. Solar panels can work too.

    Or should we just give up on hybrids and continue pursuing PHEVs for Prius (and leave hybridisation for other vehicles yet to be hybridised)
     
  13. wjtracy

    wjtracy Senior Member

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    Tell you what, gimme a PiP body style/cargo space and a Prime engine technology, and gimme whatever (smaller) battery size fits in the PiP battery port and I am good. I have little interest in a reduced interior space in order squeeze a crapload of batteries in there.

    Here is what I want:
    High MPG (OK with Gen4 thats fine)
    Ability to Plug-in if needed
    No Cargo Space give away
    Use of car as energy home generator
    Possible use of off-grid solar power as the next way to reduce dependence on both gaso and grid power
    Wireless charging
    Cost effective (not paying a lot for the above)

    Already where Toyota is on gaso MPG is good enough for USA. Start to look more at giving owner the way to conveniently inject electrons to the battery.

    The problem with what I said above is: that is not exactly what U.S. Gov is subsidizing. U.S. is asking for a crapload of batteries to reduce interior space, so that 's the rub.
     
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  14. Tideland Prius

    Tideland Prius Moderator of the North
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  15. bisco

    bisco cookie crumbler

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    agreed. problem is, gov and mfg have lost focus. they're trying to turn everything into a bev, which is a huge mistake.
    it's like people who say, 'i'm buying a volt because it goes 50 miles in ev', even though they only drive 25 miles a day.
    everything has become 'how much battery can i get for my dollar'.
     
  16. Trollbait

    Trollbait It's a D&D thing

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    Honda's dual motor hybrid system is a series hybrid most of the time. Except at highway speeds when it is more efficient to clutch the ICE into the drive train.
    The Audi A1 E-tron prototypes went from one engine speed to three because occupants didn't like the steady engine hum that wasn't tied to road.
    So will be interesting to see how Nissan's system works out, and whether it is something that will work in North America.
     
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  17. wjtracy

    wjtracy Senior Member

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    ...and also as Dianne Whitmire states, it seems to be a 95% solo drivers in Plug_ins, and this scales up to the ideal Plug-in being front seat only with decent space. So bottom line we do not yet have a family car plug-in, except PiP which was severely criticized. But you gotta start somewhere, just hoping we see more space in future 8 kwhr batt size....and they can cut that back to 6 kWhr as far as I am concerned.
     
  18. Tideland Prius

    Tideland Prius Moderator of the North
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    Right, basically at the speed where the engine can power the wheels at its most efficient rpm. Makes sense.

    So then Honda is already showing us the potential of this setup, since the Accord, according to the EPA, gets mileage nearly identical to the Gen 3 even with a larger engine and a heavier car.
     
  19. Trollbait

    Trollbait It's a D&D thing

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    It is also because the inefficiencies with pure series operation become greater with faster speeds. Enough that a more complicated drive train and control software becomes worth the investment.

    With a plug a series hybrid makes sense but having reduced costs. So the inherent inefficiencies is balanced against that and operation off grid power.

    PS: there is now a thread for this Nissan system in news
     
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  20. bhtooefr

    bhtooefr Senior Member

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    Really, I'm thinking serial hybrids aren't the way to go.

    You've got the added conversion losses of all torque going through an electrical path. You've got the added weight of having to have an MG1 large enough to absorb all engine power, and an MG2 large enough to deliver maximum power. You've also got a bigger inverter, due to having to convert more power.

    Meanwhile, a power split device, especially with a one-way clutch on the ICE ala the Gen 2 Volt, the Prius Prime, and I believe the Pacifica Hybrid, should be lighter - you have smaller motors, a smaller inverter, and the addition of as little as one planetary gearset for directing ICE torque to the wheels. And, of course, there's the fact that ICE torque is directed to the wheels more efficiently.

    If you want to run the ICE at one fixed RPM and load point, you can do that with a power split device no problem - just run it at that fixed RPM and load point, holding it there with MG1. (You will need the MG1 sized to handle that, though, so it'll be bigger, but MG2 doesn't necessarily need to be sized for full power.)