Rainbow Prius Hybrid Powered by Lithium!

Discussion in 'Gen 3 Prius Accessories and Modifications' started by jacktheripper, Dec 24, 2019.

  1. TMR-JWAP

    TMR-JWAP Senior Member

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    What you saw is a battery with lithium chemistry and voltage curve being used in a system designed for an NiMH chemistry and voltage curve. I think everyone understands that lithium has a much flatter curve over the course of it's discharge. The flatter curve fools the car controls into thinking the battery has not discharged as much as it really has. This is what causes/allows this battery to use 80% of it's capacity before the car thinks it's at the bottom of the control band. In reality, the remaining charge is significantly below the normal (42%) bottom control level. It's likely at 10% or less remaining capacity when it decides to start the engine to recharge. As long as there are no problems with the engine starting, everything is cool, right?

    One of the great things about lithium battery cordless tools is they deliver full power over the entire range, but unfortunately, then they just shutoff with no warning.

    What has more power available? a 6500 mAh NiMh battery or a 6500 mAh lithium? Aren't they going to be the same if used in circuits designed for them?

    If you were to install a new Toyota battery or 2k1's battery, and instead of controlling between 42% and 62%, the circuit was calibrated to control between 10% and 90%, then yes, you would get the same result driving around your neighborhood since it would be using 80% of it's charge range. What you wouldn't have is the (42%) safety margin that Toyota designed into the system. If you installed the lithium battery into the same circuit (controlling between 10%-90%), you would be dead on the road before it ever got close to reaching the 10% lower control point.

    I seem to be the only one asking/discussing what safety margin is actually available on top and bottom of the control range. Seems like everyone else is walking around with stars in their eyes.

    Is this battery working well? Certainly. To me, it's just like the guy who drives his car for 2 days while the fuel tank level is blinking one dot and then he finally goes to the gas station. It works just fine until that one time it doesn't. Then he's on the side of the road.

    Someone with more knowledge of this lithium battery please prove me wrong. Show me how my thought process isn't correct.
     
  2. JohnPrius3005

    JohnPrius3005 Junior Member

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    As a Prius owner, driver, and amateur tinkerer, I'm happy to see new, alternative batteries being made available. These new batteries have each involved their producers in a lot of hard work, tests, and development, and real world beta testing. And I have great respect for anyone who works on any Prius batteries professionally. I cannot say the same about those random sellers who try to sell used cells/modules with minimal life left in them, or cells without a known age and mileage history. So, hats off to Jack and Toaster. Thanks guys. We all benefit from what you are doing, and we learn from these debates.

    Two battery related things I've noticed I'd like to have with my Prii: more battery power available (so the ICE is used less), and more battery capacity available (so that on long downhills that "wasted" regen power goes into charging the battery). But I'm still really stoked to get around 50mpg+
     
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  3. jzchen

    jzchen Senior Member

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    I'm not gonna be able to prove you wrong. You are correct. If it's simply a Lithium module with no electronic logic board we'd probably getting reports that the car stopped on them, but there is a board inside, and reports are of no problems. So maybe what you're asking is a trade secret...

    My 12 V LiFePO4 also has a BMS board inside. My 12 V has a backup cell. I press a button and I can start my dead car without AAA. MAYBE there's a backup cell. It gets activated at a certain V drop. I could certainly see someone able to implement that vs having to manually press a button as in my case. Maybe this provides the juice to start once the main cell is depleted.

    Just a guess on my part....



    moto g(7) power ?
     
  4. jacktheripper

    jacktheripper Active Member

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    allow me to point out couple of points that you've missed.

    1. Lithium runs at a much higher efficiency, 99% to be more precise with these high quality cells, that means most of the braking kinetic energy goes back to the battery instead of dissipate into heat like NiMH, that's why you see in @TheChip racing video that the lithium pack only reach 104F at the end of session compare to NiMH ended up at 140F. And also in my Gen2 EV range test video, the battery charging at a much faster and efficient rate every time I hit that downhill session, running cooler and running efficient all contribute to better MPG, would you agree on that?

    2. Lithium has minimum self-discharge compare to NiMH, I am sure lot of you have experienced with seeing the red energy bar after just parked their Prius for a couple of nights, with NiMH the energy is basically draining away even during your sleep, with Lithium you parked the car for half year and it won't even drop a bar on you.

    3. Lithium is designed to be deeper discharged without damaging the cell, try to do 80% deep discharge with NiMH and you will very quickly runs into memory effect and see the overall capacity drop like crazy, you could exercise the NiMH to get it's capacity back but it's only a temporary solution, that's why Toyota only allows 40% discharge with NiMH chemistry, but not on their Lithium line-up.

    Best,
    Jack

     
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  5. jacktheripper

    jacktheripper Active Member

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    @TheChip my friend Photoshop your racing photo to make it looks faster :D
    and please keep on torturing the battery!!
    upload_2021-4-11_20-31-23.png
     
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  6. TMR-JWAP

    TMR-JWAP Senior Member

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    1. I would agree that you are exaggerating. The NiMH batteries generate very little heat under normal driving conditions. It's not a significant enough difference to worry about. The examples you're using is like the spark plug commercials that claim a 5 horsepower increase but fail to mention it's on a race engine at 8000 rpm, which 99.9% of users will never see. 99.9% of drivers will never have their car on a race track. I have no idea where or how your sensors are mounted. I can make a battery read any temperature I want just by relocating sensors or how the internals of the module are located compared to the sensor location.

    2. Once again, I will agree that you are exaggerating the amount of self discharge. I purchased 2 brand new Toyota NiMH batteries that had been sitting on a shelf about 2 years due to a Toyota parts department shutting down. TWO YEARS. They worked absolutely perfect. I had a OEM original 2005 battery that had 235k miles on it, had a single module replaced with no additional work performed that then sat un-used on my garage floor for a year. We installed it in a white 2005 that had a failed battery and it fired right up and I drove that car for a year before it got run off the road and totaled. The example you use about draining to 2 purple bars overnight or 2 days or three days or four days is a prime example of an older battery that is starting to experience early signs of failure. It is in no way the characteristic of a healthy battery. You're comparing apples to oranges. The amount of self discharge between a new NiMH and your new Lithium will be insignificant.

    3. True or not, what relevance does this have to the topic?

    4. I'm all for your battery and hope it works out well for you and everyone who uses it. What I'm tired of is the exaggeration. This is not some miracle energy solution. It's a battery design that fools the car, and it apparently does it pretty well. But people/potential customers deserve to know the real truth on how it works, possible negatives, along with the positives.
     
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  7. jacktheripper

    jacktheripper Active Member

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    dang.. I actually feel like you are exaggerating your miracle NiMH batteries, you must be the luckiest guy in the world!

     
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  8. TMR-JWAP

    TMR-JWAP Senior Member

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    You were right!! I was way exaggerating!! Now that I looked back at the thread, one was only 22 months old and one was only 19 months old when I purchased them!!

    For Sale - New in crate Toyota Prius replacement HV Battery | PriusChat

    And a previous post on the 'garage floor battery'.

    If I change only the bad cells/modules in the battery, how long would it last? | PriusChat

    One thing you may notice, is I have no reason or desire to blow smoke up anyone's acts. I also have no problem trying to clear up the smoke.
     
    #408 TMR-JWAP, Apr 12, 2021
    Last edited: Apr 12, 2021
  9. ChapmanF

    ChapmanF Senior Member

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    I was a little bit surprised one time when I got around to doing the math.

    It's common to see people reporting results from Dr. Prius or the like, including the battery ECU's computed internal resistances per block. On the NiMH it seems not unusual to see figures around 21 milliohms.

    With 14 blocks in the battery, that works out to an overall internal resistance of about 0.3 Ω. Which doesn't sound like much, but:

    In a 100 amp acceleration or braking run (which I do see from time to time in my car), that's 3 kilowatts lost to heat, a/k/a 4 horsepower (and 3 kW is a darned substantial heating rate for the battery's air cooling to carry away).

    At 50 amp acceleration or braking (which I see quite often), I²R is still 750 W, a good solid HP being wasted.

    At 20 amps, a charge rate my car often targets when charging the battery while just sitting still, it's about 120 W of heat, wasting a sixth of a HP or so. It's that exponent in the I²R making it so much more significant at the higher currents.

    Do we have numbers for the effective internal resistance of the lithium packs?
     
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  10. royrose

    royrose Senior Member

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    I also agree that the self discharge of Toyota Nimh batteries is minimal. When my 2010 Prius was 4 years old I worked abroad for a year. A friend was supposed to drive it occasionally but hardly ever did. The 12v battery died but the hybrid battery was fine and still is at nearly 12 Y.O.
     
  11. mjoo

    mjoo Senior Member

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  12. jzchen

    jzchen Senior Member

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    Well, that 235k mi battery that needed one cell swap to be healthy again, that’s common?
     
  13. Giugrilli

    Giugrilli New Member

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    Hello, can anyone tell me if this battery replacement is available for the Toyota Auris 2011 HSD ?
    (maybe it shares the same battery type with a Prius of a certain year)
    If so I'd be interested in the replacement.

    Thank you in advance.
     
  14. jacktheripper

    jacktheripper Active Member

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    Hi @Giugrilli yes, Toyota Auris Hybrid shares the same powertrain and batteries as the Prius.

     
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  15. Giugrilli

    Giugrilli New Member

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    All right! I just bought a lithium battery pack!
    Keep up the good work!
     
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  16. jacktheripper

    jacktheripper Active Member

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    Thanks Giugrilli !
     
  17. bisco

    bisco cookie crumbler

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    how much was it? manufacturer?
     
  18. tony_2018

    tony_2018 Member

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  19. jacktheripper

    jacktheripper Active Member

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    pre-order start shipping next week !
    like Elon said, prototype is easy, production is hard !!
     
  20. jacktheripper

    jacktheripper Active Member

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    upload_2021-5-13_15-38-15.png upload_2021-5-13_15-37-54.png
     

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