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Need advice '02 battery issue 144K miles

Discussion in 'Generation 1 Prius Discussion' started by kirbinster, Oct 3, 2014.

  1. kirbinster

    kirbinster Member

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    My '02 Prius with 144,000 miles has been acting a little strange in the morning. When I start it up the battery is typically around 3/4 full but within 30 seconds it drops to 1/2 and then sometimes drops to 1/4. After a couple of miles it is typically back at 3/4 and everything operates normally....until yesterday.

    Yesterday it did the same thing, but then went to 100% while driving on mostly flat roads (some ups and downs but not that much). I then noticed that it kept dumping power to the battery and I was not able to force it to take juice from the battery except maybe for about 5 seconds at a time. After about 10 miles I parked at a store and did some shopping. When I came out she started up fine but the turtle light came on, no triangle of death or anything else. I drove about 1/4 and turned the car off to fill the tank with gasoline. After the fill-up I restarted it and no more turtle. The battery was still full and still accepting more power for about a miles, then everything went back to normal and it went to 3/4 and started giving power to the motor and taking as warranted. When I got home everything seemed fine except that the fan that pulls air through the external vent was running.

    So, what should I do or look for now? I put the scan tool on her and she showed no codes of any sort. BTW I am in Morris County NJ in case anyone knows a good person that might be local to look at this for me. Thanks.
     
  2. kutcht1

    kutcht1 Member

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    Check the voltage on your 12V battery. This has been know to cause all kinds of electrical things to happen when it gets weak.
    TomK
     
  3. ChapmanF

    ChapmanF Senior Member

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    That sounds like the rebalancing cycle that the computer occasionally runs in order to keep the battery in the best condition possible. I've noticed it in my car a few times (I've had the car about 6 years). Basically, instead of aiming to keep the battery around 60% as it normally does, it will go into a mode where it steadily charges all the way up to 100%, stays there for some minutes, and then returns to usual behavior and lets the state of charge return to around the usual 60%. The first time it happened in my car I sort of panicked, turned it off and on and such, trying to intervene, and the time after that I just thought "I'll watch this and see what it does," and that's what it does.

    The fact that it ran the cycle at all means your battery is not brand new and perfect. But you weren't expecting a 12 year old, 144k mile battery to be brand new and perfect. By running this cycle on it now and then, the computer is working to stretch its life out as long as it can.

    -Chap
     
  4. kirbinster

    kirbinster Member

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    Thanks Tom, I will do that. I have replace the 12V battery twice over the years so I am aware of some of those issues. I don't think that is it this time as the car starts fine, even with headlights, radio, A/C fan all on without dimming lights. I will check it though.

    Chap, that is very interesting. I have never seen this before and hope that is what was going on. I will keep an eye on that.
     
  5. dolj

    dolj Senior Member

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    Chap,

    Do you know if the Gen II and Gen III do this as well?
     
  6. kutcht1

    kutcht1 Member

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    Chap that is so cool if the computer actually does this. I want mine to do this as I have almost had it a year and know nothing of it's history but I have to assume it is an all original battery.
    TomK
     
  7. kirbinster

    kirbinster Member

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    I find this as an odd feature. I say that as I have never seen it happen and I have a pair of '02 cars that I have had since 2005 and have never observed this before in either one.
     
  8. usnavystgc

    usnavystgc Die Hard DIYer and Ebike enthusiast.

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    I concur with Chap. I have observed this in my 01 at least 3 times before it got runned over by a reindeer. :)
     
  9. bwilson4web

    bwilson4web BMW i3 and Model 3

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    You might consider getting a Prius-aware scanner and taking a look at your 19 module-pairs. Also, take a look at the four temperature values to see if there is a pattern.

    Right now, I wouldn't set my hair on fire.

    Bob Wilson
     
  10. kirbinster

    kirbinster Member

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    What is a Prius-Aware scanner? How much are they and where do I get one? Thanks
     
  11. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Mini VCI from Amazon.com will set you back around $25. This will provide you with almost the same diagnostic capability as the Toyota dealer techs.

    You need a Windows XP or Windows 7, 32 bit OS laptop to run that.
     
  12. kirbinster

    kirbinster Member

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    Thanks, just ordered one.
     
  13. kirbinster

    kirbinster Member

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    Ok, I just got the scanner from Amazon and hooked it up and saw lots of data. Now I need a clue as to what I am looking for and what ranges I want to see. Thanks.
     
  14. kirbinster

    kirbinster Member

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    Here are two snap shots of the state of the battery. The first was when I just plugged the unit in after the car had been sitting for 24 hours. I then played with this scanner for about an hour with the car cycling on and off for a while. The battery had dropped from showing 3/4th to 1/2, I then drove around the block twice and the dash was showing the battery at 3/4th which is not exactly true as the second image shows it at 58%. It was showing 1/2 when the scanner showed it at 52%. I am kind of surprised that the voltages are higher in the second image even though the state of charge was 58% versus the initial 63%

    Bottom line, I am very confused as to what I am seeing and what if anything it is telling me.
     

    Attached Files:

  15. LEVE

    LEVE Member

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    To my untrained eye, the battery voltages after start and running look pretty good and are relatively consistent. I don't think there's much of an issue at this time unless a discharge test would reveal a low module. I'll let someone better equipped answer that question.
     
  16. bwilson4web

    bwilson4web BMW i3 and Model 3

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    First Snapshot
    • 14.85V Min Voltage
    • 15.34V Max Voltage
    • 15.34 - 14.85 = 0.49V > 0.3V threshold to set unbalanced code
    • #11 Min voltage block
    Second Snapshot
    • 16.07V Min Voltage
    • 16.34V Max Voltage
    • 16.34 - 16.07 = 0.27V ~= 0.3V threshold to set unbalanced code
    • #9 Min voltage block
    This is a marginal battery pack because the lowest module pair and highest module pair differ by 0.27-0.49V which is close and above the 0.3V threshold needed to throw a code from an unbalanced pack. The weakest modules are in the middle which matches past experience. But the pack temperature also shows a problem:
    1. 61F, 57F, 57F, 61F - starts
    2. 70F, 64F, 64F, 66F - ending, #1 probe is significantly hotter! Smoking gun.
    A failing module runs hot and the first clue is excessive heat. It is getting hot in one area, group #1.

    Mitigations:
    • Manually restack or balance the pack - Autoline Daily reports someone does this commercially. However, I would do it manually by ordering 38 module voltages, parallel wiring and charging to 8V, and restack pairing strongest and weakest modules with weakest module pairs on the coolest ends and no weak modules adjacent to each other. Start your battery replacement fund.
    • Buy a rebuilt pack from a quality rebuilder - they have the tools, inventory, and knowledge to build a quality pack and comes with a guarantee. It will have better modules.
    • Buy a pack from Toyota - a known quantity, it will have the same version of modules that just ran a decade. Bring a little more money but easier and faster.
    Bob Wilson
     
  17. kirbinster

    kirbinster Member

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    Is that enough data to really make a determination. I only drove it for about 5 minutes. Is there a better test procedure to make sure this is the right diagnosis?

    Not sure I understand what you are talking about when you say " Manually restack or balance the pack - Autoline Daily reports someone does this commercially. However, I would do it manually by ordering 38 module voltages, parallel wiring and charging to 8V, and restack pairing strongest and weakest modules with weakest module pairs on the coolest ends and no weak modules adjacent to each other. Start your battery replacement fund."

    I've never messed with these but have done electrical work and can follow directions fairly well. How big a job is this and what has to be done?

    Also if it above the limit to throw codes why are no codes being shown and why are there no codes in the history?
     
  18. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Volume 1, the diagnostic manual, describes a controlled test that does a controlled discharge using "R" and a curb and then uses "P" or "D" to put a charge back on while monitoring the traction battery. The tech service can provide the specifics. You might look for a used manual set on eBay.

    Rebalancing a 38 module battery pack means equal charge them and using a controlled load on each to rank them. Then parallel charge them and restock the pairs. But this is just buying time. Battery modules age, some faster than others.

    The diagnostic codes are set but the full specifications are not documented. So time and temperatures may be involved but not documented in the manual. I could speculate if I were in a bar about why there is no code but the diagnostic manual has a definitive test.

    Bob Wilson
     
  19. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Ok, I'm posting from a bar so I can speculate.

    Measuring module-pair voltages in a running Prius has some challenges:
    • Current range: -50A to +70A
    • Voltage measured by sequential sample held in a cap and read
    • Noisy MG1 and MG2
    In an environment like this, I would toss out readings where the current changed too much . . . If the current sign changed, useless. Now there algorithms that could smooth the data but I am at a bar.

    So let me once again endorse the diagnostic manual test.

    Bob Wilson
     
  20. kirbinster

    kirbinster Member

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    Is there a pdf file of the manual available that I can download?