Featured Toyota’s Redesigned Aqua uses a new Bipolar Nickel-Hydrogen Battery

Discussion in 'Prius, Hybrid, EV and Alt-Fuel News' started by drash, Jul 21, 2021.

  1. Trollbait

    Trollbait It's a D&D thing

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    This is the footnote to the 2 times current increase, "Compared to the previous-generation nickel-hydrogen battery, the all-new bipolar nickel-hydrogen battery delivers 1.5-times greater output per cell, and packs 1.4-times more cells in the same-sized space; together, this leads to a total output increase of approximately two-fold."

    In the above footnote, and elsewhere in the press release, they refer to the current Aqua's NiMH pack as nickel-hydrogen. In technical terms, the names mean the same thing. Switching to nickel-hydrogen now is more about messaging to support Toyota's hydrogen FCEV efforts, as these have had a political set back in Japan.

    The references to increased out seem to be about the pack's current.

    NiMH generally performs better in the cold than Li-ion. Since it wasn't stated otherwise, the bipolar pack likely has the same limits as the old one. Mainly that it has to be kept in a narrow state of charge range for long life; the 40% to 80% NiMH hybrids currently use. Considering Li-ion's wider usable charge range and higher amperage per cell, a pack of the same size would likely still out perform this new NiMH. Then the basic bipolar concept can be applied to Li-ion for similar gains.

    A good question. The move to prismatic cells was partly because they offered better heat shedding within the pack than the original cylinderical. Maybe this new Aqua will use a loop from the A/C to help cool the pack, like the Rav4 Prime and other hybrids do. Ford has gone to liquid cooling for the Escape and Explorer hybrids.
    Europeans went with diesel because it was cheaper per mile, and they were concerned with carbon emissions for some time. A gas car made for fuel economy can't match the diesel there, and gives up low end torques. When diesel fell out of favor with the public, car buyers there had no qualms about buying gas hybrids. This new battery will likely only benefit Toyota sales, as they are the only ones still using NiMH in cars.

    Want more hybrids in the US, support higher CAFE targets. I don't see a fuel or carbon tax coming along to push hybrid sales through fuel costs.
     
    #21 Trollbait, Jul 22, 2021
    Last edited: Jul 22, 2021
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  2. Rmay635703

    Rmay635703 Senior Member

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    This whole thing reminds me of the old Tripolar Lead Cobalt batteries that used to go into hot climates and space craft.
     
  3. hill

    hill High Fiber Member

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    IIRC - hasn't there been at least one manufacturer that has done away with some of their lead batteries, & in stead, use the large lithium pack, via dc-to-dc step down transformers?
    .
     
  4. drash

    drash Senior Member

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    Makes you wonder if it will cause confusion in their targeted markets. Buyer: Here’s a car that has a nickel-hydrogen battery that I fill with gas from thousands of places. And here’s a car I have to put hydrogen in. Hmmm. “Hey salesperson, why do I have to put hydrogen in this car when this car already has it?” Salesperson: <blank stare> Uh….

    The NiH2 batteries I worked with usually demonstrated during testing in excess of 40,000 cycles at a Depth-of-Discharge (DoD) of 80%. That was in the 90’s. One of the main reasons they were originally installed in the space station before they switched to Lithium recently. It’s one of the main reasons NiH2 was selected over NiCd and NiMH. IIRC the EVAs (spacewalks) they performed on the space station to replace the battery usually were at about the 40,000 cycle mark. I watched a couple of the EVAs and winced each time it was performed.

    This is a small battery going into a small car so this might be their Prius or test mule for further NiH2 installs.


    iPad ? Pro
     
  5. Trollbait

    Trollbait It's a D&D thing

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    "It differs from a nickel–metal hydride (NiMH) battery by the use of hydrogen in gaseous form, stored in a pressurized cell at up to 1200 psi (82.7 bar) pressure.
    ...
    The nickel-hydrogen battery combines the positive nickel electrode of a nickel-cadmium battery and the negative electrode, including the catalyst and gas diffusion elements, of a fuel cell."
    Nickel–hydrogen battery - Wikipedia

    From the details provided, I don't think this is a true nickel-hydrogen battery Toyota is putting in the new Aqua.
     
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  6. Richard2005

    Richard2005 Member

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    Yes, the current Aqua has NiMH and the fact they refer to it as 'nickel-hydrogen' is evidence that the new battery is still NiMH. Also they do not refer to the new battery as NiH2, so this also suggests they are using 'nickel-hydrogen' to describe NiMH. This is confusing and may well cause them to revert back to referring to the new battery as 'NiMH'.

    Also the new Aqua grade B, is rated 35.8 km/L (84.2 mpg) under WLTC, however this model does not have the new bipolar battery and Toyota have not released fuel efficiency for all the other models that do have the new battery. So it will be interesting to see the impact of the new battery on efficiency.
     
    #26 Richard2005, Jul 22, 2021
    Last edited: Jul 22, 2021
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  7. Richard2005

    Richard2005 Member

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    Yes it would appear to be a test mule. I would assume they would use this in the Gen 5 Prius.
     
  8. telmo744

    telmo744 HSD fanatic

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    Wow, everbody was laughing at Toyotas stubborness in NimH...
     
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  9. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Not me!

    Unlike LiON, NiMH batteries are free from irreversible chemical changes that over time reduce capacity. Also the new construction reduces dead weight and extra parts.

    Bob Wilson
     
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  10. Trollbait

    Trollbait It's a D&D thing

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    Somebody is probably already working on bipolar Li-ion.
     
  11. Richard2005

    Richard2005 Member

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    Yes Toyota keep their cards close to their chest and so its not always easy to understand their strategy. I came across a US research paper from 2001 talking specifically about the benefits of bipolar NiMH and its looks like Toyota have now implemented that proposed solution. What we don't know is how much cheaper bipolar NiMH is compared to an equivalent Li-Ion. Toyota make 2.5 million hybrids annually and its growing at 15% per annum and so any saving they an make on the battery is worth a lot. ie If they can shave $100 of the battery cost, that equates to a $0.25 billion saving.
     
    #31 Richard2005, Jul 29, 2021
    Last edited: Jul 30, 2021
  12. Trollbait

    Trollbait It's a D&D thing

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    Finding any recent cost quotes for large format NiMH is difficult, but they aren't cheaper than Li-ion. Other plugless hybrid makers would be using it otherwise.

    Last cost per kWh quote I saw for NiMH was in the $400 to $500 range. BASF acquired Ovonic, and made a statement about potential energy density improvements to NiMH in 2015. They were hoping to get the cost under $150/kWh, but there isn't any news since then.

    Assuming Toyota has gotten down to that $150/kWh figure, their press release said nothing about lifecycle improvement. The batteries are still going to be limited to a narrow state of charge range to ensure a service life in the car. For the car companies that have made large scale investment into L-ion, like Toyota once did for NiMH, have kWh costs closer to $100; some maybe under that soon. Because of Li-ion's wider SOC range, a comparable NiMH needs to be 50% larger.

    Even if Toyota manages to make bipolar NiMH for the same cost as Li-ion, the pack will cost more because of the larger size. Which is also needed to get a pack performance approaching that of the Li-ion.

    Of course, once they get all their NiMH battery switched over, these will save Toyota money there. I don't think the savings will be enough to expand NiMH production though, based on what we currently know of the battery.
     
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  13. Richard2005

    Richard2005 Member

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    I think that for small hybrid batteries, NiMH must be comparable or cheaper than Li-Ion otherwise Toyota would not have developed a new NiMH battery and just switched over to Li-Ion.
     
  14. hill

    hill High Fiber Member

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  15. Trollbait

    Trollbait It's a D&D thing

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    Toyota really likes squeezing every penny out of an investment. Look at how long they kept the 4 speed automatic in production. Toyota started development of this battery years ago, when Li-ion was higher price. Sounds like converting current NiMH lines to bipolar is low cost, which will let Toyota make further use of their NiMH invest. Even with a unit cost more than Li-ion, they save versus changing the lines over to Li-ion, which will also require new investments into the supply lines to those battery factories.

    Toyota is also supply limited on Li-ion for plug ins. Which they need for meeting the various EV programs around the world. Making high power Li-ion packs for hybrids means less high energy packs for plug ins. Toyota is balancing the cost of NiMH against that.

    No one else is using NiMH in a hybrid. The original switch to Li-ion may have been over supply concerns, but enough time has passed for those companies to have ensured their own supply of NiMH. Instead they opted to go with Li-ion, which gives the same performance for less weight. The investment into Li-ion production for EVs has now given it a cost advantage.

    It isn't going to Australia.
    2022 Toyota Prius C (Aqua) revealed for Japan, not for Australia | CarAdvice

    Like the original Aqua to Yaris hybrid comparison, the new Aqua is a little bigger; around 2 inches in the wheelbase.

    Europe never got the Aqua because of import taxes, and the US isn't even getting the Mazda Yaris anymore. Near term, it doesn't look like the new Aqua will leave Japan. Maybe that will change when production levels of the new battery increase. More likely, the new battery just goes into other hybrid models.

    The US would need small cars to return for the Prius c to have a chance of coming back.
     
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  16. Rmay635703

    Rmay635703 Senior Member

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    Or it could be NIMH handles
    Abuse
    Cheaper BMS
    and extreme temperatures

    much better than lion
     
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  17. austingreen

    austingreen Senior Member

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    Actually cheaper bms is the only advantage there, and bms prices have fallen greatly in the last decade. I would be surprised if when designing a car that will be in production to 2028, if lithium plus bms is not less expensive per unit. Still short term toyota has Nickle chemistry capacity and not lithium, and it will cost money in the short term to expand that. Nickle chemistries (bipolar and nimh) will charge at a lower temperature, but why not warm up the cabin, lithium will still charge at -10 C, and let that heat warm the battery.

    lion for a given usable energy or power will be lighter, smaller, and lose less power when not in use. Operating temperatures for discharge are similar - neither likes to operate over 100 degrees, but Toyota puts these hybrid batteries in the car. Lithium hybrid batteries are more expensive than liquid cooled lithium plug-in batteries.
     
  18. Richard2005

    Richard2005 Member

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    Toyota's have to be simple, low cost and work well in all environments .. so maybe NIMH is overall better at meeting that goal.
     
  19. Richard2005

    Richard2005 Member

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    Yes supply lines, expertise and NiMH production will also be important factors. It will be interesting to see whether this new battery replaces the current NiMH and Li-Ion in their other hybrids. Also I wonder whether they will use Li-Ion or bipolar NiMH in the new Tundra Hybrid.
     
  20. Trollbait

    Trollbait It's a D&D thing

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    Toyota is using Li-ion and NiMH interchangably at this point. Last half of 2020 had them putting Li-ion into the Rav4 hybrid for the US instead of the NiMH, likely form a supply disruption. Even though the only technical reason they have given for choosing NiMH over the other was better cold performance in cars with AWD.
     
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