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Prius Battery Replacement (GenII) Like you've never seen - NEW Cylindrical Cells

Discussion in 'Gen 2 Prius Main Forum' started by 2k1Toaster, Jul 17, 2017.

  1. ericbecky

    ericbecky Hybrid Battery Hero

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    I like the concept.
    The real question is whether the car will tolerate superior for the long term.
    I would think so. As you say... All signs point to Yes.
    I don't really need a pack in any of my Prius at the moment, but I would love to install one of these packs just to be able to say I did it. :)
     
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  2. fotomoto

    fotomoto Senior Member

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    giphy.gif
     
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  3. ericbecky

    ericbecky Hybrid Battery Hero

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    I've certainly spent my money on more frivolous batteries and tools than this.
     
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  4. sub3marathonman

    sub3marathonman Active Member

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    I, as a long-time, though not as well-respected :) member here, I will second that. Really there are just a few people doing this that I'd be interested in.

    I'm going to say too that in this case, to me 14 batteries seem a lot better than 28. I really don't understand the propensity, such as with Tesla, to go with many, many small modules instead of larger ones. As you get the most benefit with the initial step, cutting the number by 50%, it seems pretty logical.

    But I was wondering a couple more details that I haven't seen.

    How much is shipping, maybe a chart could be posted somewhere for people in various locations?

    Is it possible to return the poor battery, either to 2k1toaster or somebody else, for a bit of a refund? This would bring the cost down, as people are comparing it to Toyota where you have to turn in an old battery. I'm also wondering about how much the old battery could be worth.

    I will say, for me the timing is pretty excellent, as I've been trying to get by at least for the summer with a 2005 w/ 100K miles, where the battery pack is going bad.
     
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  5. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    Thankyou both. :)

    Just to be clear, there are the same number of cells. There are just less battery modules.

    For example this is a stock Prius battery module that I have labelled the 6 individual NiMH cells in. At a 1.2v nominal voltage that makes this battery module 7.2v nominal.

    oem_numbered.jpg

    In comparison look at this photo of mine I've labelled:

    IMG_20170513_011313_numbered_cells.jpg

    Look at the circled areas and you can sort of see a seam there. That's where the cells join. They are electrically welded together, but they are individual cells, just like the Toyota pack. And then mine snake around as indicated making 12 * 1.2 for 14.4v battery module voltage.

    The benefit is not fewer cells, it is fewer independent cells. These cells are manufactured at the same time and then welded together as soon as the casing is sealed and then wrapped. It makes it all one unit basically. In the Toyota version they do the same thing but with 6 layers of batteries with a single casing over them all, no welding. But then all these independent battery modules of 6 cells get assembled into a full pack later where they won't be as well matched.

    Additionally, these 11 welds is sealed and should last indefinitely without corroding or changing. This is also true of the Toyota pack where the 5 internal connections should last indefinitely. But when you add 2 Toyota packs together you get an extra external connection where you use a busbar and two nuts. Eventually these generally corrode and start to look like this:

    corrosion.jpg

    That is less good than a nice internal clean connection and that's where the problem come. This will increase the effective resistance of the pack as that is no longer a great mechanical connection leading to a not so great electrical connection and it will only get worse. That connection will get hotter, that cell will get hotter, that corrosion will get worse, etc.

    Now as to why Tesla uses so many tiny cells, there are advantages there too and Elon himself has made similar claims and reasons to what I am saying here. You need to keep in mind that a battery cell is not a uniform homogeneous blob of energy. There will be spots that are more dense or have more carrier holes and those will act differently than a place that is different. That's just how a battery is made, we aren't perfect yet at making batteries! So if you have a large battery and this uneven density is right in the middle of the pack, then what? Now it has to heat up ALL the surrounding battery goo until it also gets hot so that the heat can get to the outer walls and then hopefully to some thermal solution like active cooling in the Tesla or passive fan cooling like in the Prius. By making the cells smaller, that uneveness is more contained and can be managed separately much more effectively. You can also pack the cells more densely, look up "circle packing" and there is an entire mathematics field dedicated to trying to make circular pegs fit in square holes with minimal waste.

    Here is a now public (I had to check!) image of Tesla's battery pack:

    gbslide1aug2016.jpg

    This is a gross simplification, but hopefully makes some sense. :)

    When Toyota designed the Prius packs in the mid 1990's they could not have envisioned what has happened to battery technology today. That's what we're taking advantage of here. We are using newer denser NiMH cells that take up physically less space allowing for air gaps and increased cooling while maintaining the same overall watt-hour capacity. We have the advantage of 20 years of learning over the original pack style that are in all the Prius packs!

    As of now, I am hoping to be inclusive of shipping within the continental USA. I hate paying for shipping, so I carry that forward to my products.

    As mentioned above, you will need your OE cells if you ever plan on making a warranty claim or disposing of your original pack to get a Toyota certified core charge returned.

    Having said that, I personally would sell your old cells on eBay and when you need another battery in 2030 and want to use the Toyota dealership buy 28 dead modules off of eBay. The cycle completes. :)

    I as of now have no use for batteries. I am trying to sell my hundreds of genuine Toyota modules on eBay and Craigslist now! I accumulated quite a few during testing lol.

    An old junk battery (even just 1 cell bad) on eBay is usually in the few hundred dollar range. I saw one on ebay not too long ago for about $300. But please remember you are keeping your old HV ECU and everything else in there except the battery modules themselves, the main wiring, the bus bars, and the safety covers. Even the old safety disconnect switch remains your original. The part of all that that has value to be sold are the batteries themselves which you can sell on eBay for $30 to $40 a battery all day long, $840 minimally in recouped costs if all were good. Realistically 1 or more cells will be dodgy so lets say you can only sell 26 of the modules and recycle the other 2. That's still over $700 in recouped moneys after eBay and PayPal fees.

    Send me a PM if you want to be a tester.
     
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  6. rbdigital

    rbdigital Hybrid Family Father

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    As more of these new generation packs replace the old generation packs, used battery modules will become less expensive. Supply vs demand.

    Posted via the PriusChat mobile app.
     
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  7. ericbecky

    ericbecky Hybrid Battery Hero

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    "Having said that, I personally would sell your old cells on eBay and when you need another battery in 2030 and want to use the Toyota dealership buy 28 dead modules off of eBay."
    Ha, ha. This is exactly what I thought of after I posted my other "keep your modules" comment.
     
  8. TMR-JWAP

    TMR-JWAP Senior Member

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    So what kind of connection is used on the ends, where they snake? Under where the caps are? Going by only appearance, one could say that you actually have 3 modules with 4 cells each?

    Aren't these already being offered by another hybrid battery company out west somewhere? We had a small discussion about them earlier because they had specialized in Honda's but started offering Prius batteries using the Honda design. Is that you?

    I'm also not quite sure I understand what you mean about the Panasonics. They are all serialized and are typically sequential in an undisturbed pack. Certainly you would consider them to be fairly tight in their tolerances.

    Also confused by your comment about cooling. The battery pack has very defined flow paths for cooling air flow. The majority of heat is NOT removed at the thin edges, as a flow path for air exists between each module by design of the sides of each module. The cooling fan forces air into a plenum above the modules and then it's guided/forced down between the modules and then exhausted out from the bottom plenum. The gaps between modules is large enough to do the job, yet small enough to ensure the entire plenum is pressurized to ensure flow through every module gap. Too large of gaps will cause reduced cooling at the end of the battery farthest from the fan. Kind of like laying a garden hose on top of one end of a grating. A grating with small holes will allow the puddle to expand to a large size, allowing water to pass through many holes. A grating with large holes will just dump the water down the nearest holes.
     
  9. TMR-JWAP

    TMR-JWAP Senior Member

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    bumblebeebatteries.com
     
  10. bisco

    bisco cookie crumbler

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    see posts #12 and 19?
     
  11. Sam Spade

    Sam Spade Senior Member

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    I said it SOUNDS LIKE, not that it was necessarily.

    AND......your reputation and credentials are not necessarily known by everybody who reads that post.

    Read it again with some objectivity as if you were "Joe Blow" who just joined the forum yesterday.

    A simple one or two sentence recap of your qualifications in the field would have been MORE than enough.
    Having that mentioned somewhere in the post might have quashed my comments before they were made.

    Sometimes people who run off on a rant at the least sign of a challenge often appear suspect too.

    I can only go by what I read........and each post pretty much stands on it's own.

    I meant no personal insult with my comments.
     
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  12. TMR-JWAP

    TMR-JWAP Senior Member

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    Guess I missed connecting the dots on those. Just watched the video on #12. It's interesting.

    The design is interesting. I like that the terminal covers are heavier and the sensor wires are heavier also.
     
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  13. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    Welded.

    Not me. And no *these* are not offered by another company. There are 2 other companies producing a style similar to this in China that some people in the US have used. I am not aware of any real US distribution of them, but I know they are around here and you can get them shipped here. Ceba and Yabo were the two big names. And I believe you are right they started making Honda cylindrical cells since those packs died so early in their lives, it was good money.

    But these cells are made by a completely different supplier. The plastic I am getting from the factory that Ceba uses under an agreement with them. Slightly modified for me although I just learned they may be "upgrading" their own kit lol. So my guess is we will use the same plastic kit. But the cells will be completely different. I already have my manufacturer customizing the appearance so there is no confusion in the field.

    I measured the other batteries and they came up under half the capacity as claimed.

    The serialization occurred after production and during characterization from my discussions with Toyota engineers. Old stale information though.

    Yes all true, however in practice this pack stays noticeably closer to ambient than the stock pack. I haven't found the dimpled system of the Panasonics to help much. When I look at them with my FLIR camera (a $12K FLIR with 464 x 348 IR pixel resolution and 5MP optical resolution) these cells are noticeably cooler after the same run. I live in the mountains so I've done some pretty strenuous testing. :)
     
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  14. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    No insult meant here either. I was and am genuinely interested what you think sounded like hollow claims, and I will try my best to defend against them.
     
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  15. The Electric Me

    The Electric Me Go Speed Go!

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    I'm surprised this product originates from China.
    Because what everyone seems to be missing is that going from the original modules to these cylindrical modules is going to entirely mess up the Fung Shui of the battery compartment.

    Seriously though?

    This "might" be great for Prius Owners. But I'd want to sit back and get some real world results over a period of time.
    Also, I would say, it's been my observation that Prius seems to have quite a lot of owners that are qualified and actually enjoy the project. But for a LOT of owners-probably the majority, even a pretty straight forward kit battery assembly and swap is a pretty daunting maybe even dangerous project.

    I don't think this is an answer for everybody..."yet".
    It may be an unfair idea as well, but I'm also always cynical and suspicious when a new design, years after the fact is sold as being "superior". Nobody as far as I know, has a patent on cylindrical battery module shape. So somewhere in the back of my mind the cynic in me says "If It's Better? Why hasn't Toyota or Panasonic done it a long time ago?" . It's the same feeling I get when I see some late night commercial for a product I slip into my air intake that is suppose to improve my gas mileage by 25%.

    But, I concede sometimes...the best way, isn't really discovered until later. But I still proceed with a high degree of skepticism.

    But I'll watch for more threads related to this option, with hopeful and open minded interest.
     
  16. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    Once installed it can't be seen from any of the doors, so maybe that helps offset it? :)

    Agree. It is meant for the moderate level DIYer or perhaps pack rebuilders in the future. Everyone wants to wait for real world results over a period of time, that's why the guinea pigs who want to help with this will receive a heavy discount to be a first adopter. :)

    Toyota did go with cylindrical cells originally. In the 1992 version of the Prius, they were cylindrical. The problem is that 25 years ago we didn't have the technology to put the same energy density into a smaller pack like that, so they made their own prismatics with Panasonic.

    Now there is momentum behind the design, there is no reason for them to change it. They have already invested in everything from the R&D to machining and assembly along with a healthy service/parts arena. The change to lithium in the newer models is the next change, I have a feeling they won't be going back to the previous models for retrofits.

    Tesla famously uses cylindrical cells for many reasons but the designs came about completely differently.
     
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  17. a_gray_prius

    a_gray_prius Rare Non-Old-Blowhard Priuschat Member

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    I'm a little surprised that nobody brought up my primary concern with this battery, which is its resistance to thermocycling and exposure to high temperature. While it may have been tested under strenuous conditions and performed as intended, there's a confidence in the Toyota batteries that comes from the fact that millions of them have been time-and-wear tested by being in running cars.

    I'd also argue that Tesla uses cylindrical cells primarily to leverage the massive R&D manufacturers had already put into them for laptop use.
     
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  18. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    The chicken and egg problem. Batteries aren't magical, and the goo inside will be similar to the goo in the stock cells. Both will die in heat. And this gets less hot, so win. As I have continuously said, wear testing is no substitute for estimation and research, but all the signs show that it will hold up, including accelerated aging models.

    Yes. But there are lots of quotes from Elon about the advantages of cylindrical cells floating around.
     
  19. GasperG

    GasperG Senior Member

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    I also think that there are differences between NiMh as there are differences between Li-Ions. I mean my battery have seen 62° C and did not die, Toyota ECU uses battery power normally until around 50°C, how will these cells deal with 50°C giving out 10C (~10 kW)?

    Enthusiast can keep the battery temps down, with driving style, not shutting down the car immediately after going down the steep hill and constantly monitoring sensors, but if this pack gets to a normal user this could be an issue.
     
  20. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    Please don't spread FUD.

    Yes there are lots of differences in battery chemistries. Even a small change like the metal makeup of the terminals can have a profound effect on the cell overall. These are high quality cells. They have been tested at high temperatures, which were artificially created by running up and down mountains and high speed getting the pack to charge and discharge basically continuously. They have also been in a lab quality temperature chamber with load tests performed both at high temperatures and low temperatures.

    Additionally the 3 thermal sensors are still on the pack. The Toyota firmware in the HV ECU is actually extremely flexible. This is why a pack can be essentially dead and still make the car move with no indication to all but those intimately familiar with the Prius. NiMH charging relies upon temperature readback from the cells themselves to figure out where you are on the charge curve. And the Toyota ECU will limit the pack current depending on the temperature of the pack (both hot and cold) as well as the voltage of the pack (about 180VDC) and the largest cell imbalance of the pack. Toyota did an excellent job on the firmware.

    These cells don't have billions of miles behind them, but there is no reason to make them sound scary.