hv battery dying?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by unluckyduck, Jan 10, 2022.

  1. unluckyduck

    unluckyduck New Member

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    Hello smart people. I have been reading PriusChat threads for months now, but I just now made an account. I know very little about cars (except what I've read here), so I appreciate your patience and understanding.

    The other day, I was operating my 2007 Prius normally when the following warning lights turned on:
    • The triangle of death
    • Brake system warning light ((!))
    • VSC: Vehicle stability control
    • (!): tire pressure (but this has been on bc I know my front right TPS is shot)
    • I can't remember if the ABS light came on, but it may have.
    When I was parking the car at the mechanic, my power steering failed as well. Luckily the lights came on close to home. I forgot to take a picture, like a dummy.

    Anyways, they ran the computers on it and diagnosed a dying hybrid battery. I did not get a chance to see the trouble codes. After doing some further research here on PriusChat, I am reluctant to dish out the money for a replacement until I know FOR SURE that this is the problem.

    Here is why it may in fact be the hybrid battery (besides the obvious computer diagnostic):
    (1) The mechanic noticed that my Prius wasn't following the usual cycle with the electric/gas motor upon starting the engine.
    (2) I have experienced weird fluctuations in battery power/capacity within the last week.
    (3) My car has 147,000 miles on it with some change, and I drive it ~80 miles a day. I assume that the current hybrid battery is the original (I bought it from a private seller and have no access to that info). They do tend to fail around this time.

    Here's why I am second-guessing myself:
    (1) I took my car to the Toyota dealership for a diagnostic A MONTH AGO, and they detected no milage drop and no battery issues.
    (2) The dealership DID notice that my water pump was seeping, and it looks like these warning lights could be triggered by a failed water pump.
    (3) Perhaps the failures are linked to a 12V battery failure? The only potential symptom of that is that my AUX cord plugin hasn't worked for some time now.

    What I plan on doing is (1) self-testing the 12V battery when I get home from work today and (2) asking the mechanics to run the computers on my car again so I can see the trouble codes. Thing is, will the trouble codes even show up this time if he cleared them?

    Based on the info I shared, do you think it is, in fact, a hybrid battery failure?
     
  2. unluckyduck

    unluckyduck New Member

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    [​IMG]
    this lovely cocktail of warning lights came on in my 2007 prius this weekend. in case you can’t see the image, we got:

    (1) triangle of death
    (2) vcs light
    (3) brake light ((!))
    (4) check engine
    (5) the car with the ! on the monitor

    the car has 147.6k miles and ran well until this weekend, lmao. i bought it used at 132k; no history. i assume this is the OG hv battery. i drive ~90 miles a day to commute to and from work.

    my 12v battery isn’t the strongest, but i did the vehicle signal check self-test and it looks like it’s still going. (12.1v before unloading, 11.8v after unloading, 14.4v upon starting)

    have also been experiencing abnormal hv battery fluctuations since the warning lights came on. before that i hardly noticed it.

    i assume this is a hybrid battery issue? it seems about time for it to go out all things considered. but i want to consult the experts (the priuschat minds) before spending a paycheck or two on a new battery.

    thank you!!
     

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  3. JC91006

    JC91006 Senior Member

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    The symptoms does point to a failing hybrid battery. If the mechanic is a trusted mechanic and suggests the codes point to the hv battery failure, then you probably have that issue.

    Where in SoCal do you live? You can get a second opinion but you should prepare yourself for the battery replacement and possibly other maintenance items (like replacing seeping water pump)
     
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  4. ChapmanF

    ChapmanF Senior Member

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    Sadly, you can tell very little about an issue from the cocktail of warning lights coming up, because there are only a handful of warning lights, and they come on in a small number of typical combinations, and those are standing in for literally hundreds of possible issues the car's computers can be trying to tell you about.

    As a way of getting the information needed to proceed on solving your issues, you simply cannot beat asking the car's computers to tell you why they put those lights on.

    Although a Prius-capable scan tool is needed to get all of the trouble codes from all of the computers in the car, there are useful subsets of the codes that you can get just by connecting two pins with a short wire at the diagnostic connector and counting blinks of lights on the dash. A lot of posts here on PriusChat (search for something like blink codes tc cg) explain how to do that.

    Even having just those codes will make it much easier to give suggestions relevant to your issues.
     
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  5. AndyFromWI

    AndyFromWI Junior Member

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    I'm going through a similar issue, I just swapped two cells from my 2008 traction battery....

    Suggestions:
    A: 12 battery issue.....
    1: Best case it is the 12V battery (I have had this happen to 3 different Prius's).
    From the rear, disconnect the Negative lead of the 12V battery on the frame of the car (it is a 10mm bolt, pointing to the rear).
    By unhooking the 12V battery terminal, you will clear the Red Triangle, and I just prefer to have it disconnected when charging.

    2: Charge the 12V battery with no more than 2 amps, if you have a trickle charger or battery tender.. even better.

    3: After the battery has charged, hook it back up.
    Turn the car on (you will see lots of lights). Turn it off, Turn in back on and all the lights will go out.
    Take it for a test ride 5-10 miles, if no red triangle, that might be the issue. And eventually you might need a new 12V battery.



    B: Traction battery Issue.....
    There are a couple good apps: Dr. Prius, or Torque. You need a blue tooth OBDI module (the apps will give recommendations, the module should be less than $40). Use that to test and verify the traction battery condition.

    This will also let you read and clear battery and engine codes.

    -andy
     
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  6. unluckyduck

    unluckyduck New Member

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    ah, you guys are the best. thank you for your helpful replies!

    so the more tests i do the more it seems obvious that it’s the traction battery. per andy’s suggestion and suggestions from other threads, i got a reliable bluetooth OBD scanner and the Dr. Prius app. you can see the results of the tests i ran tonight - the first is a photo of my battery status while running off the battery only, while the second photo was when i was braking.

    as for the battery life test, dr. prius seems to think my hv battery is toast. i did buy the car used at 132k miles, so this is to be expected. the more i read about what a healthy prius should be like, the more i realize that maybe what i thought was “normal” was actually a dying battery. i wish i had read these threads sooner!

    my plan is to have the error codes read one more time this weekend at an auto shop, and then have the battery completely replaced on tuesday.

    i’ve hired a mobile hybrid battery replacement service hybrid2go - they have abnormally good reviews, but they seem legit. i gave them a call just to be sure and felt good about it. their batteries are refurbished but come with a lifetime warranty, which is great in case it fails again down the line.

    based on this info and the attached data, do y’all think that completely replacing the hv battery is the way to go? if so, what is your opinion on hybrid battery services that AREN’T the dealership?

    i’m not really in a place where shelling out 3 grand is an option, but I’m open to other recommendations if you have them.

    thank you!
     

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  7. unluckyduck

    unluckyduck New Member

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    replying again - i am no expert at reading the battery bars there in my attached photos (i’ll attach them again here for reference) but it seems like only one of my cells is out. is that correct? should i replace just the one cell or the whole dang thing?
     

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  8. mr_guy_mann

    mr_guy_mann Senior Member

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    The screen captures you have certainly suggest that you likely have a faulty battery module. (FYI, the HV pack is made up of 28 Ni-Mh modules in series. The ecu reads the voltage of 14 blocks- so each block is 2 modules. Each sealed module is made of 6 x 1.2V cells = 7.2V nominal. So 28 x 7.2V = 201.6V , roughly. The actual voltage varies a bunch)

    Now what to do. Just locating and replacing one module has a very low chance of working, as these modules deteriorate with age and use. If the replacement module doesn't match the present capacity and state of charge of the others, then the ecu will likely set codes very soon if not immediately. From reading posts here, I might give it a 10% chance of working.

    Next is a "rebuilt or refurbished" pack. Some are close to the cost of a new one, others might be less. Quality can vary wildly These are used modules that are (hopefully) discharge and charge cycled to improve capacity and matched to each other. You should completely understand ALL the terms of the warranty as you will likely need it. At best you can expect 2-3 years IF the rebuilder did a good job AND none of theses (used) modules decides to die anyway.

    There are DIY approaches to refurbishing a pack but that requires some skill, knowledge (or at least the ability to learn), tooling, time, and space to accomplish this. And a tolerance for risk of failure. Again, best case you might get a couple - three years. Worst case is something gets damaged during a "learning experience" and/or the car won't run at all.

    Last is to get new modules, from Toyota or aftermarket from Newpriusbatteries.com. Costs more but either should give 10+ years reliability. There's also a new Lithium ion pack option out there.

    Posted via the PriusChat mobile app.
     
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  9. Eddiebrid

    Eddiebrid New Member

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    hey everyone -
    i as well am having battery issues and are learning little by little about the prius world .
    so far i know ive gotten code p0a80 then i saw two cells read 6.7 volts.....then i started the testing..
    i got some modules from ebay from seller hybrid.sell ....he owns HYBRIDBATTERYSOURCE website but is nice enough to give you the option to just buy modules if you don't want to dish out the hundreds or bucks .

    now can anyone explain how to make my copper plates - nickel - is it worth it to protect against corrosion ??
     
  10. mr_guy_mann

    mr_guy_mann Senior Member

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    If you are talking about the copper busbars, you just buy a set of nickel plated busbars from amazon or someplace.

    Posted via the PriusChat mobile app.
     
  11. unluckyduck

    unluckyduck New Member

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    hi y'all, i figured i'd update here -

    it was, in fact, blocks 11 and 12 that were weak. thankfully, the battery replacement went very smoothly. the car runs much more efficiently now and i saved a lot of money by hiring hybrid2go instead of going to the dealership. my average mpg is way up, yay!

    perhaps this is a question for another thread, but maybe you guys would know - since I've replaced the hybrid battery, i expected my car to depend on the electric motor more. however, the gas engine turns on after like, 2 seconds of acceleration (at reasonable speeds, too, like 0-35).

    Even driving on the freeway at 65 miles per hour (a reasonable speed for a car like the Prius), my car tends to run on only the gas engine, and never the electric motor for more than a few seconds. it only makes heavy use of the electric motor when i stop and when i go up hills.

    I'm wondering if it's because the computer is used to running with a weak battery. However, the guy who installed my new traction battery had to unplug the 12v battery for 30 minutes or so, so that would have reset it, right? I'm not sure why it uses the traction battery so lightly still. would any of you have any advice?
     
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