Influences and false P0A80 positives

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Andres V, Oct 30, 2018.

  1. Andres V

    Andres V Junior Member

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    Hi all.
    Some of you may have helped me troubleshoot my situation, for those who don't know I recently had a "replace hybrid battery" code P0A80 on my lovely 2010 Prius with 150000Km. I have looked for many alternative replacements and I'm hoping to buy a new battery from our friendly neighbor 2k1Toaster who sells brand new cells, just gathering some founds.
    Then came a big doubt. Can this code be thrown by mistake or as a false positive, if it is influenced by some other condition? I have read that a dead 12V battery could start this code and by my Toyota dealer, even a clogged hybrid battery fan can cause this too, as it has happened to me over 2 months ago.
    The condition I'm talking right now is a recall maintanance from Toyota that I lately discovered for my serial number. They are actually 2 concerning a malfunction on the ECU not allowing a correct activation of a security mode when the inverter malfunctions or something like that. Tomorrow I'm expecting a call from Toyota explaining the specifics and I'll share the detailed with you.
    Could a situation like this be causing my dead battery code?
    I haven't tested the 12V battery yet, the fan of the hybrid battery has been cleaned 2 months ago and I have tried a quick test on my hybrid system that I have found on youtube. I get the battery half charged and then I push the car from 0 to 60mph to see if it mantain the charge or discharges very quickly and it does hold the charge correctly discharging only 1 line.

    Posted via the PriusChat mobile app.
     
    #1 Andres V, Oct 30, 2018
    Last edited: Oct 30, 2018
  2. davecook89t

    davecook89t Active Member

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    A dead 12V can certainly cause some strange occurrences in the way of false codes, but I believe I've seen some of the experts on here state that it would not usually cause the P0A80 code. On the other hand, if your HV battery is holding its charge fairly well, that would indicate it could still be in reasonably good health. Are you still driving the car regularly and does it continue to throw that code soon after you have cleared it? (If you don't have a scan tool, you can clear all the car's codes by momentarily disconnecting the 12V). I don't think the recall requiring the inverter reprogramming would have anything to do with a premature failure of your HV battery, but while the car is at the dealer you should probably have that issue addressed anyway.
     
  3. Andres V

    Andres V Junior Member

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    I am not using the car at the moment. The hybrid system has been disabled twice till now on it's own and the codes have been reseted twice by disconnecting the battery as you say just to move the car from the shop to home. The reason why I'm not moving it, it's because they told me from the Toyota dealer that depending on the battery condition, sooner or later the hybrid system will shut off completely the system to avoid further damage to the battery, so, sooner or later it may leave me stranded on the road. It's in my garage up untill I get the new cells and this recall issue taken care of for sure.

    Posted via the PriusChat mobile app.
     
  4. Grit

    Grit Senior Member

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    It’s going to be a workout to push a car that’s a little over 3,000 lbs on a road.
     
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  5. davecook89t

    davecook89t Active Member

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    If it keeps coming up, it probably is legit. I don't know if anyone recommended getting a proper scan tool when you first reported this, perhaps you already have one but if you don't, it might be worthwhile getting one just to get a better handle on what's going on with your battery. I am using this one,
    , along with Torque Pro for Android. There are other OBD2 scan tools that will work, along with other apps (Dr. Prius and Hybrid Assistant come to mind) none of which are very expensive. They all allow you to monitor the State of Charge of the individual modules as you are driving, to determine which ones (if any) are causing problems. I (and most others on this forum) would still recommend that you replace the entire battery (if need be) rather than get into the game of replacing individual modules, but at least you wouldn't be in the dark about the battery's true condition.
     
  6. Andres V

    Andres V Junior Member

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    I get it. I'll check out how much is for the ODB2, that's the one I've seen use the most. The cheapest and most affordable way I found to change the battery is by using 2k1Toaster's kit with new cells, actually new cells, not used ones I think it's worth it if I'm importing those from the US.

    Posted via the PriusChat mobile app.
     
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  7. Luckykat32

    Luckykat32 Junior Member

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    I'm following this thread.

    Something similar happened to me about 2 months ago... the CHECK HYBRID BATTERY came up so a friend checked it out....he owns a shop. But the funny thing is that all of the batteries were in the high 15's and low 16's volt wise, which I believe is correct. Because I have a 2010 with 234k miles I assumed the battery was dead after driving around for a few weeks with only the ICE and no hybrid system, i did the check, then I decided to reset it by disconnecting the battery....that was 700 miles ago now and the light hasn't come back on and its driven at least a little every day. *crossing fingers*

    I've done all the suggested maintenance from this site in the past 6 months except changing the ATF and cleaning the HV fan, which I plan to do next week, along with an oil change....hopefully she keeps on running since the HV battery didn't test bad
     
  8. davecook89t

    davecook89t Active Member

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    Driving the car every day helps to keep the modules charged and to a degree helps to prevent them from getting out of balance, since when they are resting they will discharge at different rates, but I should point out that one "snapshot" of the modules voltages at a particular point in time is not a good measure of how strong the battery is. To get a true idea of the modules' relative state of balance and capacity you should monitor them as they charge and discharge using one of the tools I recommended to Andres. The weakest ones will be the first to reach a high voltage when charging, and will be the first to reach a low voltage when discharging. If the difference between the highest module voltage and the lowest is consistently more than about .3 Volts, you will get the P0A80 code. Once they reach that point, the charge and discharge cycles will exacerbate the out of balance problem because the weak ones will keep getting a greater charge than they can safely handle and under load will become discharged to the point that they will be further damaged.

    Cleaning the HV fan is certainly a step that will promote longer battery life, and while changing the transaxle fluid will not affect the life of the HV battery, it is recommended to preserve the transaxle.
     
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  9. Andres V

    Andres V Junior Member

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    I checked the ODB2, it's dirt cheap I'll buy it as soon as possible, I thought it was something rare to find or for mechanics only.
    Going back to Luckykat32 I agree, my story is the same:
    1. 2 months ago the "CHECK HYBRID SYSTEM" message showed up on the screen and the electric motor deactivated on it's own, only the ICE was running.
    2. At the Toyota they said that they got a Change Battery Error code, they didn't tell me what code in particular, at that moment in time I wasn't as much informed as of right now, but they told me that since they found the battery filter clogged it could be the cause of that message. Cleaned it and reseted the codes. On a side note they returned the car to me with the CHECK ENGINE yellow light still on saying there's still some problem that they didn't even look for and that I had to go back to have it checked again. You can immagine I was very frustrated for the paid half assed maintenance they did but they told me I would't be charged the next time. I had no choice I needed the car, it's the only one I have, I'd be back.
    3. After a month of running smoothly "CHECK HYBRID SYSTEM" message is back with all the same symptoms.
    4. At Toyota this time I forced them to give me the codes that they get in the diagnostic since they weren't willing at the beginning. P0A80 it is.
    5. Codes have been reseted and the car is still in the garage since last month.
    Going back to davecook89t now, I get what you say and it makes perfect sense, a still battery could discharge and loose its balance even worse, that's why every time I have to go to the local grocery shop in my neighborhood I take the Prius for a short drive so it doesn't stay still all the time but I don't feel safe driving around the city everyday. I mean I could always call my insurance to pick me up if everything goes wrong but I'll wait for the ODB2 first, I'd feel safer to know the HV battery real time health before risking to drive even further away.
    Man this last month has been tough, I've been driving with a 2.5L engine VW I could borrow that is consuming double what my Prius does.
     
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  10. davecook89t

    davecook89t Active Member

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    They are cheap, but be aware that many of them have a high defect rate. Many of the members on this board have reported having to return multiple OBD2 readers before they finally got one that worked. The one I pointed you to has a fairly high rating, 4 1/2 stars on Amazon and 10,695 User reviews, but it is not the cheapest one out there. If you can find a cheap one in a local auto parts store that will take it back without charging you much if it's defective, that might be your best bet.
     
  11. wjtracy

    wjtracy Senior Member

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    As far as "false" P0A80 in some rare cases I believe clogged batt cooling fan can cause the code.
     
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  12. TMR-JWAP

    TMR-JWAP Senior Member

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    P0A80 should have freeze frame data. Look at it. It could potentially tell you MUCH information about what was occurring at the exact time the code locked in.
     
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  13. Andres V

    Andres V Junior Member

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    Sorry I don't get it when you talk about "freeze frame data". Should I find this with an ODB o similar accessory?
    Correct me if I'm wrong. What I understood is that the last time Toyota had my car checked out all the data from that error code should remain in the car's computer?
     
    #13 Andres V, Oct 30, 2018
    Last edited: Oct 30, 2018
  14. Andres V

    Andres V Junior Member

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    Hi. I've been looking for similar device, I didn't know they were that common at all. I thought they were special mechanic tools.
    I looked for the one you are recommending and yea it's kind of expensive. I found some a lot cheaper but at the end turns out I found this one at my local Autozone, OBD Reader ODB-1001 from Pilot Automotive (sorry cannot post links yet because of forum regulations).
    It's priced halfway and I get local warranty.
    Before buying, how can I know if this will be compatible with my car. At first I thought OBD2 was a brand but it is really a protocol right? On Board Diagnostics? Looking it up it says it's really on every car, from 1996 to today, so can I rest assured it will work with my 2010 Prius. From then on I can use all the apps I want right? or do I have to use the one that comes with it.
    Thanks.
     
  15. davecook89t

    davecook89t Active Member

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    I know the type that most people use here has an ELM327 chip. I'm not sure if there are any other types or if it is absolutely essential that the one you buy has that chip, but I would say if the one you are looking at has it, you can be pretty confident it will work with the Prius apps I mentioned.
     
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