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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. alanclarkeau

    alanclarkeau Senior Member

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    This was something which was very unclear when I was researching - I tried to find out how far an i3 would travel if it had no effective charge, but a full range extender tank. BMW's information on their website only kept coming up with "COMBINED" 0.6 L/100km, but no information with no charge.

    Prius was front runner with my research, so I went that way instead without fully investigating the i3.

    I'm suspecting that in 3-5 yrs when I hit the market again, the scenery will be VERY different, not only i3, but just about every manufacturer chasing that PHEV market in various forms. And battery technology is likely to have changed in that time too, with Li-ION having matured, Aluminium batteries may(?) have become the new tech - or something else altogether different - research is moving at an astounding pace.
     
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  2. Trollbait

    Trollbait It's a D&D thing

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    Without a plug, the Prius is still just an ICE car at the end of it all. If the traction pack SOC is full when charged, you might get a mile or so out of it on EV mode with very gentle driving. Then on the return trip, the ICE will run harder to recharge it. The battery simply isn't large enough for extended pure EV driving, and without a plug, it will burn gas to replace the charge in the battery.

    Every car gets worse fuel economy on short trips. Even plug ins pay a price in not completely warming up tires and bearings. An non-hybrid ICE would likely only return 10 to 15 mpg in the same conditions.

    It's because of CARB and BMW wanting or needing their ZEV credits. The wrong party is being sued.

    The European spec tank is maybe 0.9 gallons more than the American one. Big considering the we talking about a tank around 3 gallons, but not enough for most to think of the i3 REx as a highway cruiser.

    The ICE only range should be that combined consumption times the tank volume. With just the minimal charge in the battery, the car will be limited on speed and on performance.
     
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  3. wjtracy

    wjtracy Senior Member

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    Hey Marc I give you my 2-cents as a fellow Pittsburgh native...just got back from the 'burg yesterday.
    Keep in mind, Prius is a 50-state car so we are all getting CARB-certified vehicles last time I checked. There was some discussion a few years back that FORD Fusion Hybrid for example has had CARB and non CARB versions for sale, so the non-CARB version was possibly less MPG hit when cold. There were also some Gen2 and Gen3 warm-up electronic hacks to get back some of the cold MPG lost. Believe we are still looking for a Gen4 owner willing to be the first to try the hack trick. But I am under the impression Gen4 and Prius v are much improved over Gen2 warm-up MPG hit.

    PS- Thanks for Pirates closer Mark Melancon now if we could just get a few batting averages over 215 maybe we get somewhere.
     
  4. apt49

    apt49 Junior Member

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    What is charging efficiency? It must be a formula determined by the ratio of output to input variation, where the highest quotient you can get is 1 (100%).
    This article is from 2010 and if I am not wrong, the author takes consideration of references before 2008 .

    Assuming that the author is correct,
    1) It seems that the most advanced Li-ion batteries had almost a not to distant from perfection efficiency 10 years ago.
    2) He does not mention if those NiMH batteries being benchmarked are prius batteries to begin with.
    But even if these are definitely prius batteries, which gen prius batteries are? Are these the NHW20 prius NiMH batteries or the older NHW11 NiMH batteries and how these compared to ZVW30 NiMH prius batteries ?

    A member of admins, Tideland Prius uploaded a picture on his post #215 on the thread below, stating ZVW50 NiMH battery has a better charging performance by 28% compared to ZVW30 prius. But I have no idea if this is relevant to charging efficiency.

    Reference
    /Prius Eco 58 MPG vs Prius 54 MPG - What's the difference? | Page 11 | PriusChat
     
  5. goldfinger

    goldfinger Active Member

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    You are correct. It takes extra unrecoverable energy to charge the battery. There's energy lost in transporting ions and breaking chemical bonds. Charge efficiency is somewhat intrinsic to the chemistry.

    This article is talking about time rate of charge or C. C is mainly a function of construction. Construction has obviously improved.
     
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  6. bhtooefr

    bhtooefr Senior Member

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    The other thing is, as far as NiMH, my understanding is that going past 80% is where it starts to get really inefficient to charge, so stopping there helps the efficiency.

    Which, 80% is where Toyota stops charging NiMH...
     
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  7. apt49

    apt49 Junior Member

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    So as I understand, if charging efficiency is the time rate of charging, then "Tideland Prius" photo is about efficiency charging too.

    Which means that
    IF "Tideland Prius" photo is correct (2016 NiMH 28% better than previous NiMH prius) AND ZVW30 prius supposedly had the same efficiency charging as the battery in your old link (66%) THEN
    0.66 X 1.28 = 84.45% charging efficiency.
    Which means that probably NiMH battery has better charging efficiency than Li-ion!
     
  8. alanclarkeau

    alanclarkeau Senior Member

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    TOYOTA doesn't seem to say anything about it, except:

    "and the nickel-metal hydride HV battery is lighter and more efficient"; and

    " It has increased cooling efficiency and the regeneration range.".

    in the document - THE NEW TOYOTA PRIUSTHE REBIRTH OF THE PIONEER
     
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  9. Trollbait

    Trollbait It's a D&D thing

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    Which is likely in comparison to the old NiMH battery.
     
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  10. Felt

    Felt Senior Member

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    Trollbait - In layman's terms, what can you tell us about the cabin heating system that does not rely on ICE heated radiator water. I believe the new Prius Prime will have the system .... do other manufacturers utilize the system? It it significantly more costly? In really cold climates .... is it not as effective (a house heat-pump is not as effective).

    (I know my question is not related to batteries ... but I saw your post and thought you might return and find my question)
     
  11. Trollbait

    Trollbait It's a D&D thing

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    All I know about a heat pump is that it is an air conditioner that can run in reverse. Moving heat around is more efficient than making it when you don't have waste heat from something else running. Heat pumps do need for there to be some heat in the outside air. When that heat gets too low, the heat pump won't be able to warm up the space. But too cold for some house units would be considered quite cold. Years ago, I saw one advertised to work down to 0F. I wouldn't could of one for a car to be that effective. Winter will be the time to burn off old gas for those with EV utilization in a PHEV.

    The Prime's uses technology that is more efficient, and may allow it to work down to lower ambient temperatures.
     
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  12. Tideland Prius

    Tideland Prius Moderator of the North
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    Yes. Our talk with the engineers say that the gas-injected heat pump system in the Prius Prime is effective to about -10°C. Below that, they figured it's more efficient to burn fuel, run the engine and use the waste heat from that. I hope this means that those in milder climates will benefit from lower engine run-time. (And even those that experience bitter cold temps can benefit during spring/autumn transition periods).

    Here's an article from InsideEVs

    Advanced Heat Pump Comes of Age in the New Prius Prime. Would this be a good option for Model 3 or the Bolt EV??
     
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