youtube video of replacement of nimh with lifepo4 hv batteries

Discussion in 'Gen 2 Prius Accessories & Modifications' started by donbright, Sep 13, 2020.

  1. donbright

    donbright Member

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    (

    ( sorry just realized this should be in the addons / modifications section.. can it be moved? )

    anyone seen this?

    this person just replaced their traction battery with lifepo4 (lithium iron phosphate) cylindrical batteries in place of the nimh (nickel metal hydride) prismatic batteries without any additional battery management system.

    apparently the cells have 6 amp hours 3.2 volts, he says the full capacity is twice original, so ~2.6 kilowatt hours instead of ~1.3 kwh.

    apparently he uses 10 cylindrical cells per block, in 2 parallel 5 series. i.e. one block was originally two nimh prismatics with 6 cells per prism, he has 5 sets of 2 lifepo4 cells in parallel to replace each block. so since there are 14 blocks in the prius thats 140 battery cells total.

    he apparently wired each pair for a lithium BMS but he hasn't used it yet and is relying on the toyota bms to shut everything down if there is a voltage differential.

    apparently is having temperature issues, with the metal case on his temps are higher than with the case off.

    mechanical stability is ... zip ties. ... i do not think i would ride in this thing but i am wondering what the experts think.
     
    #1 donbright, Sep 13, 2020
    Last edited: Sep 13, 2020
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  2. Prodigyplace

    Prodigyplace Senior Member

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  3. bisco

    bisco cookie crumbler

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    no one has accomplished a lithium replacement to my knowledge. dr. prius has been working on one for quite a while, with no success.
     
  4. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    Using the Toyota BMS that is geared for NiMH with Lithium of any kind is asking for a fire to burn your car down. It will work just fine 99% of the time because of the 40% to 80% limit if you can keep your lithium range also in the low end range. But there are corner cases that the NiMH system has no problem with that a lithium system will overvoltage and make fire, or under-voltage and kill.
     
  5. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    This guy has been running one for about a decade.
    Antiscab's NWH10 Prius plugin Lithium conversion - AEVA Forums

    There are now dozens of Honda conversions to lithium from NiMh.

    Lithium conversions are still a DIY science project.
     
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  6. donbright

    donbright Member

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    thanks for the link..... looks like Antiscab spent 8 years (off and on) and still hasnt got it working properly. problems with straight lithium swap seem to include differing internal resistance, heat issues, differences in charging algorithm, max amperes batteries can take on regen... etc...
     
  7. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    Check out what the Honda guys are doing. There are some bright people over there working together to come up with a replacement for OEM honda packs.

    LTO cells as NiMH repacement | Honda Insight Forum
     
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  8. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    I have wanted to try a lithium conversion for years. It's the pesky 1% that keeps getting in the way.;)
     
  9. bisco

    bisco cookie crumbler

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    it's a fools errand
     
  10. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    Yeah I've been contacted by some of them too. And they have ignored my warnings. I won't even sell my NiMH to fit into a Honda IMA system. I have owned these systems, I know these systems. The Honda IMA system is severely crippled and it treats the battery extremely poorly. Toyota beat them to the market with a good hybrid. They made the Insight, first gen, and Toyota released the Prius right away and blew em out of the water. Scrambling to compensate for what they thought was a great lead in technology, they robbed life from the batteries to play the higher instantaneous mpg. Our civic hybrid had 3 brand new replacement packs under warranty. Everyone I know with an IMA system, had a replacement pack under warranty at least once. And their "fix" years later was to basically reduce the useful range again just like Toyota did from the start to preserve pack life, but the mpg's dropped significantly.
     
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