Check Hybrid System Stop The Battery In a Safe Place

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Dave1UK, Jul 2, 2026 at 9:24 AM.

  1. Dave1UK

    Dave1UK Junior Member

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    So went to start the car today and got the message in the title.

    Own a basic cheap 12V battery/alternator checker so checked the 12V and it showed as OK and low, the car did start/fire up as well.

    Proceeded to run a diagnostics code check and also the Dr Prius App. Got the results attached in the photo.

    Done a bit of Googling and on the Dr Prius App, the red for DELTA SOC 4.50% means unbalanced cells/deterioration of a cell/s?

    The hybrid battery in the car is a reconditioned battery, I bought the car with the battery just fitted as the previous one was acting up however the warranty on this "new" one ended several months ago. I'll check the fan/air vents for the hybrid battery but I did clean the area/fan also have a "dust" guard fitted for the system near the back seats so doubt it's being clogged or anything. Based in the UK and we have had some high temperatures past few weeks up to 33 degrees Celsius (probably doesn't help much).

    What are the next steps I should take?
     

    Attached Files:

    #1 Dave1UK, Jul 2, 2026 at 9:24 AM
  2. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    Warranties WILL do that. :unsure:

    You've done the dusting and cleaning - SO....now your choices are (1) playing 'whack-a-mole' by cracking into the battery pack and replacing the offending cell or (b) replace the battery....maybe with the second or maybe third cheapest one available instead of the cheapest.

    I am not familiar with the availability of remanufactured batteries on your side of the pond or what your long term plans are for the car.....

    BEST....
     
    #2 ETC(SS), Jul 2, 2026 at 10:14 AM
  3. Dave1UK

    Dave1UK Junior Member

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    I can't complain about the warranty as it outlived it by a year after expiration.

    I intend to keep the car and run it into the ground for now, battery options/price wise where I am, they seem to sell them on a basis of warranties based on months elapsed/mileage. So for example:

    6 month warranty/10,000 miles £400.
    6 months warranty/unlimited miles £500.
    12 months warranty/25,000 miles £600.
    12 months warranty/unlimited miles £700.
    18 M £800.
    18 M U £900.
    24 M £1,000.
    24 M U £1,100.
    36 months warranty £1650 - brand new battery.

    Now the current one was the 6 month £400 one, which lasted 18 months (till now). I don't think they measure voltages or are able to estimate the life length with those prices, it seems to be pot luck but they will just warranty it whichever comes first. I don't need mileage warranty just lifespan anyway.

    On eBay battery modules go for about £28 each with 2 months warranty.

    I'm competent and don't feel uneasy about replacing the modules, my only concern is it just a swap or do I need to cycle/balance the batteries etc? Will I need to invest in some new equipment for that etc?

    What sort of a prolonged lifespan can I be looking at by just replacing the one module for £28, just a swap out before deciding the replace the whole pack?
     
    #3 Dave1UK, Jul 2, 2026 at 10:41 AM
  4. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    Easy, Cheap, Long Lasting......
    Pick two and add a dash of luck.

    SO.....My uneducated GUESS:
    (Street Price: tuppence)
    If you need a 'quick fix' and you're the least bit handy with tools then you can replace the cell.
    MAYBE even get two with the foreknowledge that you will be cracking the case again and again.
    I do not pretend to know the ins and outs of things like VAT, tariffs, cell availability, or if the new battery pack uses lithium (LiFePO4) battery packs, the original Nickel-Metal Hydride (NiMH) setup - or some combo thereof.

    This may be a "buy once, cry once" occasion.
    Buy a new battery with the newer gen LFP cells and you should be good for 4000 charge/discharge cycles and if you buy the whole battery it will come with the warranty you mentioned.

    If money drives the decision maybe keep playing 'whack-a-mole.'
    When I drove Priuses in my job Nickel-Metal Hydride was the only option, and it was a GOOD option based on the longevity of the G3 batteries - so I would not get wrapped around the axle about this versus that chemistry.


    Disclosure: I've never actually replaced a Prius or rebuilt one but I am familiar with the process and I watched several YouTube vids on it back when failing traction batteries used to be the biggest monster under the bed for Prius owners.
    Now?
    It's head gaskets.
    By the way....
    You mentioned 33°C not being good for the traction battery.
    Since I'm a relatively uneducated colonial I had to think about it and do the math.
    (33°C × 9/5) + 32 = 91.4°F

    92-degrees in freedom units isn't terribly hot
    It only seems that way because London is cooler and wetter than most parts of the US.

    It's important to keep the battery vent fan clear but, again.....92-gegrees isn't 'battery-eating' hot.

    AGAIN.....
    MY Opinion.
     
    #4 ETC(SS), Jul 2, 2026 at 11:42 AM
  5. ASRDogman

    ASRDogman Senior Member

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    The BEST thing to do is replace it with a NEW Sodium Ion battery pack.
    If you just keep replacing blocks with used block, you are not solving the problem.
    And at the very least, you'll have to balance the pack.
     
    #5 ASRDogman, Jul 2, 2026 at 11:54 AM
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