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

Discussion in 'Prius v Main Forum' started by Onlooker, Sep 29, 2024.

  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?
     
    #1 Onlooker, Sep 29, 2024
  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.
     
    #2 MAX2, Sep 29, 2024
  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').
     
    #3 Onlooker, Sep 30, 2024 at 12:51 AM
  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?
     
    #5 Air_Boss, Oct 5, 2024 at 12:20 AM
  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 .
     
    #6 Onlooker, Oct 5, 2024 at 1:18 AM
  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 ?
     
    #7 jzchen, Oct 5, 2024 at 3:10 AM
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  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 ?
     
    #9 jzchen, Oct 5, 2024 at 3:25 AM
    Air_Boss and Onlooker like this.
  10. Onlooker

    Onlooker Junior Member

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    It has survived initial testing... Peak amperage I saw was ~67amps; The battery terminals read 13.8+ while the 12V car cig. PriusConversionLiFePO4Test1.jpg plug read 14.6/14.7v ... As battery took a charge it's terminal voltage got up to about 14.3v and ~30amps when the BMS clicked itself 'off' to protect it... nothing noticeably negative occurred, traction's DC-DC converter seemed to just throttle down.. I was stationary, next tests on the highway... Only 'negative' I saw was the BMS turned itself back on repeatedly, accepting 30amps, then shutting down again moments later.. I attribute this to uneven cells in the battery telling the BMS it could 'take more'... 20minutes or so later, BMS seemed to stay disconnected a 'long time'.
     
    #10 Onlooker, Oct 5, 2024 at 5:15 PM
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  11. jzchen

    jzchen Newbie!

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    @Onlooker You purchased a deep cycle LiFePO4 battery. The eBay sellers do sell those also but they don't like to sell them for automotive starting applications. Whenever I inquire about one, (they are usually cheaper than the starting type), they always sell me a starting type, which have "capacitors" of some sort to support cranking a starter. If you buy a smaller size battery such as the 46B24R/L then they ask if you have a larger engine size than 2.0L then add an extra capacitor for about $10-$20. For my son's Clarity it is a 1.5 L engine so I did not purchase that option. (I believe it doesn't use the 12 V to crank the engine similar to the Prius).

    For the wife's Panamera it takes a huge H8 or Group 49 if I recall correctly. I tried to purchase a deep cycle battery because the CCA/CA was substantially larger than the AGM already but they still sold/sent me a starter type. I'm not going to argue over 10% more cost at $6xx price range as long as it works, which it has. For that car I was replacing AGMs approximately every two years. Now I barely remember the size...

    I hope it works out for you and thank you for sharing your testing. I never went that far just saw the matching specs in the little booklet that came with my first one, and moved on with the install. I think all the eBay sellers source them from the same manufacturer or something. I do not believe I have purchased from the same seller twice, but one confessed to me they are all the same, (just different storefronts). I usually sort by price and pick the cheapest one, say with "dual battery" or "emergency start". That was January when I bought the 46B24L for the Clarity. It is in the engine bay so I got the function this time. (I'll try to take a picture as the sun is coming up)...

    CPH2551 ?
     
    #11 jzchen, Oct 6, 2024 at 9:40 AM
  12. jzchen

    jzchen Newbie!

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    #12 jzchen, Oct 6, 2024 at 10:09 AM
  13. jzchen

    jzchen Newbie!

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    For the Prius v- I was very happy that they were answering my concerns over the weekend. (I honestly thought I would have to wait until Monday to get an answer about the bottom mount ledges). But they answered very quickly through the weekend. (That's an unforgettable experience). Eventually they asked me if I could make it work somehow. I went to Home Depot and got some washers, (maybe a longer bolt as well), and got to snug it down although not flat on the bottom.

    I was told for smaller batteries they install JIS terminals and include adapters, (brass rings). I was promised that the next batch would not include "edges". Don't misunderstand that was originally the word I used to try to explain the issue of why it would not drop in fit.

    They still do install JIS terminals AND include the ring adapters (as of late January my last purchase of one). Size shown is 46B24L (for a 2018 Honda Clarity PHEV). IMG20241006080608.jpg

    CPH2551 ?
     
    #13 jzchen, Oct 6, 2024 at 11:13 AM
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