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NiMH vs Li-Ion battery - what's the deal?

Discussion in 'Gen 4 Prius Technical Discussion' started by pakitt, Apr 6, 2016.

  1. goldfinger

    goldfinger Active Member

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    Lithium ion has better charge efficiency than NiMH. Car Battery Efficiencies
     
  2. EngMarc

    EngMarc Member

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    I’ve driven the Gen 4 and wasn’t impressed. It’s bigger, bulkier and has the same problem - it runs the engine all the time even when driving slow just to warm it up and warm the water up to heat the cabin!

    I’ve written Toyota many times on this. The same phenomena causes one to get in the low 20’s for mileage when driving 1-2 miles on short trips daily when it’s moderate to cool outside. There’s plenty of batter power and I turn OFF the cabin heat, yet it still runs the engine constantly - shame on you Toyota.

    They seem to be running scared after the accelerator law suit and just recycling 2009 technologies with only minor changes. Yes, it has a carbon fiber hood - whoopee! And yes, it is a bit lower - whoopee again!

    Why not take off 1000 lbs and get nearly 100 mpg by doing some real engineering instead to just tweaking old technology that was innovative in 2000 but really isn’t competitive in 2017.

    Maybe we are spoiled but I’ve driven a Tesla and will probably drive a ELR and i3. There isn’t a Toyota competition for any of those vehicles.

    I am going to add up the total cost of driving my Prius and see where it places in comparison to other vehicles. I still contend that my SMART car at a solid 38 mpg combined was a more economical and efficient vehicle. And, it never had door dings - the outside panels are ABS plastic. Try that Toyota for cutting down weight!
     
  3. Tideland Prius

    Tideland Prius Moderator of the North
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    At 1-2 miles, you're better off with an EV. No car is going to get good mileage at 1-2 miles. In addition, the Prius runs the engine to get the catalytic converter up to temperature to reduce emissions.

    Also, plastics introduce another set of problems. They expand/contract more than steel, requiring larger panel gaps. Larger panel gaps increases drag by turbulent eddies caused by the larger panel gaps. With ultra high tensile steel, I'm not sure plastic has that huge advantage any more.
     
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  4. bisco

    bisco cookie crumbler

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    have to disagree here, the pip would be perfect for your driving.

    on another note, i can't believe you've written to toyota that much, and they haven't changed how the prius operates. shame on you toyota.
     
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  5. bhtooefr

    bhtooefr Senior Member

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    Another thing is, once the engine starts, it needs to get to temperature, to drive off contaminants in the oil (gasoline, water). So, you can prevent an engine start by driving gently, below 20 mph, not running the heat... until the engine starts.

    In your case, I'd almost say your best bet is to force the engine start to happen as soon as possible, then it might actually shut off by the time you're to your destination. However, a PHEV or BEV product would be better suited to that short of a commute.
     
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  6. alanclarkeau

    alanclarkeau Senior Member

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    I think you're looking at the wrong car. To reduce weight by 1000 lbs - you'll end up with a puny 2 seater, which isn't what Prius is. You want an electric SMART, but that'll not come in your 1000lb less than a PRIUS.

    The cheapest TESLA here is 4 times the price of PRIUS, i3 is about double the price. The i3 is only marginally lighter than a PRIUS. Prius has a much longer range than an i3, with a range extender.

    If you want the heater running, you have no option but to run the petrol engine - (unless you were to use a heat pump A/C which would add to weight, complexity and battery size). And, once the engine starts, it will run till it is at operating temperature. If I park mine with the A/C off, and temperature set to "LO", and have a full battery (which I generally do as I have a down-hill run to home), it will run a kilometer or 2 before the petrol motor starts. BUT, if I have the heater set (ie 12 deg outside temp and have it set to 23 from the previous afternoon), it will start the engine immediately - because you essentially told it to.

    PRIUS is a good car, very fit for the purpose it is made - your needs aren't what a PRIUS has in mind - you sound like you need something else.
     
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  7. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Marketing methods are different between the BMW i3-REx and Prius. Due to a happy accident, I bought a used 2014 BMW i3-REx for the same price as a Level 3 Prius with similar safety features. The 2014 high price led to generous lease arrangements and those end-of-lease BMW i3-REx are coming out at the same price as a new 2016 Prius. The decision BMW i-3 REx vs 2016 Prius was 60/40. With the 2017 Prius, that decision might have gone differently.

    The i3-REx is 110-180 lbs lighter than the 2016 Prius with 138 hp vs 121 hp Prius. As for range, the i3-REx refuels too.
    I agree that the 2017 Prius with TSS-P makes a lot of sense. A Prius Plug-In also looks good for short trips. But right now I am planning a 700 mile trip that will determine the fate of our remaining, 2010 Prius.

    Bob Wilson
     
    #147 bwilson4web, Aug 21, 2016
    Last edited: Aug 21, 2016
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  8. bhtooefr

    bhtooefr Senior Member

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    It's also worth noting that the Prius Prime does have a heat pump, specifically to make the heat situation when the engine's cold better.

    However, 1000 pounds lighter than a Gen 4... the heaviest that can be is 2080 lbs, and a 2080 lb 4-seater PHEV (because that's really what you're asking for, a plug-in experience) car is going to be something with a full carbon fiber monocoque, really, to even hope to meet modern safety regulations. I mean, yes, the Mitsubishi Mirage ES manual is 2018 lbs, but once you add 4 kWh of battery (really the minimum to be a PHEV), and a hybrid powertrain, you'll be well over that 2080 lb limit, in a terrible car.

    An i3 REx actually has a CF monocoque, although it also has a much larger battery. Its curb weight is 3130 lbs, heavier than any Gen 4 (that isn't the Prime). (I'm also of the opinion that the i3 REx, for most users, is too much of an EV, not enough of a hybrid - most people don't want to stick to a 65 mph limit on road trips.)
     
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  9. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Source? Wiki reports: BMW i3 - Wikipedia, the free encyclopedia

    Curb weight 60 A·h: 1,195 kg (2,635 lb)[6]
    60 A·h: 1,315 kg (2,899 lb) (with range extender)[6]
    Fortunately, not my problem.

    Bob Wilson
     
    #149 bwilson4web, Aug 21, 2016
    Last edited: Aug 21, 2016
  10. bhtooefr

    bhtooefr Senior Member

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  11. bwilson4web

    bwilson4web BMW i3 and Model 3

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  12. kithmo

    kithmo Couch Potato

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  13. bhtooefr

    bhtooefr Senior Member

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    BMW i3 with Range Extender - Features & Specs - Specifications - BMW North America
    is an interesting one.

    2899 lbs unladen according to DIN, 3064 lbs unladen according to EU.

    EU unladen weight includes 75 kg of driver+belongings, and 90% fuel. US is no payload, but 100% fluids.

    Neither of those are US specs, though... but the previous i3 REx spec page that I linked was a 2016, not a 2017, so it doesn't have the bigger battery.

    As far as suddenly losing power, that's due to the US tuning that only starts the REx at 6% battery, and cannot be told to start it earlier. Thank CARB's BEVx regulation for that. With coding, it can be set to the European specs, which are (IIRC) 15% battery for the REx to automatically start, and a hold mode allowing it to be started at as high as 75% battery.
     
  14. alanclarkeau

    alanclarkeau Senior Member

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  15. alanclarkeau

    alanclarkeau Senior Member

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    Unfortunately, here, there are very few used i3s, and they're about $60k (Gen 4 Prius about $38k).

    What realistic range will an i3 give with a Range Extender? Here, there are very limited charging facilities, even in major cities, so for extended touring, it would essentially be running on Range Extender once the initial battery charge was depleted.
     
  16. john1701a

    john1701a Prius Guru

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    Shame on you for complaining without researching. Sorry, but sometimes it's best to confront directly. In fact, that's how a few of our best advocates have emerged... from a misunderstanding based on incomplete information. So, it's worth taking the time.

    In this case, you make no reference whatsoever to the reason for the warm-up process. It's to reduce emissions by getting the engine up to optimal operating temperature as quickly as possible. The supposed waste of gas you witness is actually the cleanest way of achieving that. Traditional vehicles attempt the same thing, but they cannot deliver as well lacking an electric motor which provides a buffer.

    You also made no reference whatsoever to battery recharging or longevity. Do you really expect great overall efficiency and a pack that never needs replacing with the suggested operation of not warming up? A cold engine not only operates in an inefficient and dirty manner, it also has to endure greater wear. Toyota has went to extremes to optimize that process.

    You have made no reference to the rest of the market either. Toyota offers the best hybrid system available. It's most efficient, most clean, and most affordable. That's just among no-plug offerings too. The upcoming Prius Prime not only resolves all of your complains, it should also score the highest efficiency rating (estimated at 120 MPGe).

    You can consider yourself schooled, no worries about having been unaware of some information either. Making it personal sometimes really is effective. Just take the time now to study what's being posted for your benefit. Notice how others are also taking the time to make sure you have a thorough understanding of design & intent too. We all end up better off by exchanges like this.

    What do you think now?
     
    #156 john1701a, Aug 21, 2016
    Last edited: Aug 21, 2016
  17. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Fortunately the European models can start the range extender at 75% SOC. There is coding that allows enabling this on the USA models. That is how I got it to go 463 miles including climbing from 710 ft up a 2,800 ft pass on I-40.
    When the SOC reaches 75%, enable the range extender engine and you'll have at least 80 miles before needing to refuel the engine. It isn't clear if the European versions also have the full tank capacity but I'll ask in the BMW forum.

    Sorry, I can't help on the end-of-lease price for BMW i3-REx. What shows up is random.

    This is what I found today under the "completed" listings: BMW i3 -series | eBay

    The problem with multiple standards is making sure we're using the same measuring stick. I used Google to hunt down the curb weight but obviously, it isn't clear there is a single standard and Google may be reporting different metrics:
    I checked two EPA sites and found "Test Car Data" has weight 'groups' needed for the dyno testing. Argonne does not have the 2016 model test data, yet. So I checked Car and driver:
    My assumption is Car and Driver uses a standard weight protocol for their tests.

    Looks like I'll have to head over to a truck stop scale.

    Bob Wilson
     
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  18. bhtooefr

    bhtooefr Senior Member

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    The European cars have full tank capacity by default, it's just the US ones that limit it (to keep REx range shorter than battery range, to satisfy California, to get BEVx tax credits).
     
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  19. bhtooefr

    bhtooefr Senior Member

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  20. bisco

    bisco cookie crumbler

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    apparently, you haven't read his 'manifesto' letter to toyota.:p
     
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