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LifePO4 12V Drop-in(retail); Anyone actually tried?

Discussion in 'Prius v Main Forum' started by Onlooker, Sep 29, 2024 at 7:18 AM.

  1. Onlooker

    Onlooker Junior Member

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    I searched forums many times, valuable data is sparse. I see some building their own BMS free systems, and those even updating traction batteries, but surely there are a few people who have tried dropping in retail/cheap LifePO4's, any issues?

    More specifically I'm wondering about the Prius's response to a BMS 'cutoff' while underway, any glitches/fried ECU's or otherwise? Temperature and other issues I can handle.

    Here's the scary theory; THe Prius HVDC-12vDC feeds 'whatever it is set to'(?) amps into the battery to charge it at 14.5v(seems to be number from my tests with stock AGM); Once a LifePO4 gets charged it switches itself off to protect itself... There would be a momentary surge of voltage(amps? maybe not with no-where to go) as the DC-DC throttles down; Under even cheap solar installations this might cause an inverter alarm/reboot due to over-voltage but usually the charge controllers maintain the set charge voltage(14.5, at 0current or whatever the current load is minus the battery(BMS disconnected)); The battery would stay in that state until voltage drops to where it detects it is 'needed/provide current'.. This can cause BMS shutdown/voltage spike loop that isn't pleasant...But I digress...

    I guess I'm going to try it regardless, but if anyone has actual experience with a direct swap with a LifePO4 or even regular Lithium with!! a BMS, would really like assurances or negative experiences as I could do 'plan B' with a system paired(for DC-DC surges) off a poor, but functional existing AGM/SLA to act as a buffer(kinda wasteful), my main interest is 24/7 power for a micro-camper I am doing with my 2014 Prius v'.

    If project continues I'll create a new post with my setup for anyone interested in such things.



    Thanks

    P.S. Side note, has anyone disconnected the 12V battery suddenly underway or in 'ready mode'? Similar idea, what did car do?
     
  2. MAX2

    MAX2 Member

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    After turning on the "Ready" mode, the 12V battery was disconnected and replaced with another one.
    This saves the settings of the various systems.
     
  3. Onlooker

    Onlooker Junior Member

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    Thx. That's a good sign it's not totally 'crazy'; If the battery that was disconnected was 'low' and taking a high current at the time, then it would be similar to LifePO4 BMS triggering.Odds are, a bad battery would act much like a fully charged 'good battery and jump/rest at 14.5v when disconnected absorbing very little current (to cause a voltage spike I'm 'interested in').
     
  4. jzchen

    jzchen Newbie!

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    Yup, I have one installed. No problems as the battery accepts the 13 - 15 V range specification of the charging system...

    EDIT- Got one off eBay from a Chinese seller back in Oct 2018, so going on 6 years. I am planning on updating the thread next year, 1 year, 2 years, 4 years would be next year. After that I'll see if it lasts another 8 years before my next bump...

    CPH2551 ?
     
    #4 jzchen, Oct 5, 2024 at 12:06 AM
    Last edited: Oct 5, 2024 at 12:14 AM
  5. Air_Boss

    Air_Boss Senior Member

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    Which supplier? Are they still selling the battery?
     
  6. Onlooker

    Onlooker Junior Member

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    Often times they put the basic stats(ah rating, max charge current) on a sticker on the front of the battery, but if you can find the make/model might be useful to know the BMS that survives this.. Was it one that fit in the battery compartment, or placed elsewhere?
    Amazon Links I am posting are showing up as site 'preview' and not showing with "Hmm. We’re having trouble finding that site."
    Anyone else seeing that? Pasted link to battery I'll be trying, bought off amazon.. Here it is again:

    and again:


    and a screenshot(testing):
    screenshottestupload.png It will not! fit in the battery compartment .
     
  7. jzchen

    jzchen Newbie!

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    Thankfully eBay still has record of the sale. Just find the cheapest 46B25R LiFePO4 IMHO.

    But the seller I bought this specific battery from is 2014littleflower2014 .

    I had trouble because it had mounting lip on the bottom which I explained to them as "edge". (Their English wasn't good).

    My son went to do research at the NIH in Bethesda, MD. The car sat for 2 months with little to no use. I just needed to jump it with a NOCO, they charge so fast....


    CPH2551 ?
     
  8. jzchen

    jzchen Newbie!

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    Here's one, doesn't have the backup start function but if you have it in the trunk not sure need it...

    850CCA 40AH Group 51 Lithium Car Battery LiFePO4 Car Audio Auto Replacement | eBay

    Be sure you verify it has the skinny/thin JIS terminals. (I believe they come with adapters. I bought a similar 46B24L for my son's Honda Clarity not very long ago. I'll check in the morning because his needs the SAE terminals).

    CPH2551 ?
     
    #8 jzchen, Oct 5, 2024 at 3:16 AM
    Last edited: Oct 5, 2024 at 3:21 AM
  9. jzchen

    jzchen Newbie!

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    eBay let me take a screenshot... Screenshot_2024-10-05-00-24-55-95.jpg

    CPH2551 ?