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Prius 250K miles and replaced hybrid battery

Discussion in 'Gen 2 Prius Technical Discussion' started by 2GenPrius, May 30, 2020.

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  1. 2GenPrius

    2GenPrius Member

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    My Prius ended up with the Triangle of Death, so a local Prius servicer came and replaced the battery for me (about $600). I check the voltages and they all seem to be within the same voltage range.

    I used to commute about 75 miles roundtrip every day, and it seemed to be working ok. However, with COVID19, I started teleworking and rarely travel.

    I notice when I do local driving, the battery levels fluctuate a lot more. I'll look over and see the level indicated at two bars, then will jump up to full green after few minutes of the regular engine running. The car seems to hesitate to go, even when the battery is full. My fuel economy used to be about 43mpg (highway) and about 36 (local).

    It has shrunk down to about 23mpgs. Tried calling the Prius servicer (as I had a warranty) yet with the COVID19 ongoing I think they went out of business. Is it possible that the voltages can be reported as balanced but still have a bad cell in the battery pack? There are no codes, no warning lights, nada.

    Please Prius Gods, help advise me on what I could do on my own to troubleshoot.
     
    #1 2GenPrius, May 30, 2020
  2. SFO

    SFO Senior Member

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    Many like to maintain their HV batteries by balancing or reconditioning them before they fail, you could be on to something.

    If needed, start be grabbing a higher quality OBD2 code (DTCs) reader : https://priusapp.com/obd.html

    Then you can test/graph the HV battery with either Dr Prius or Hybrid Assistant and the sister app Hybrid Reported.

    Which metroplex are you nearest, as California is a decent sized state.
     
    #2 SFO, May 30, 2020
    Raytheeagle likes this.
  3. ttou68

    ttou68 Active Member

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    Here's a thought, might help.. I did this for my mother and son's Prius and helped with fuel economy when they haven't been driving for a while now with COVID-19...

    Traction battery maintenance is an important task and 12V battery could be just as important. We don't drive our vehicles with COVID-19, And fuel economy could be impacted greatly, with older traction battery and low charge on 12V battery...

    Try to charge your 12V battery with a battery charger and see if that improve your fuel economy..

    Posted via the PriusChat mobile app.
     
    #3 ttou68, May 30, 2020
    Last edited: May 30, 2020
  4. TMR-JWAP

    TMR-JWAP Senior Member

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    The "service" that replaced your battery installed a battery that has some modules with excessive self-discharge or low capacity. A good battery should be able to sit for a month or more without significant self discharge. A battery on the brink of failure will typically be parked in the evening (after driving home) with several blue bars, only to have 2 purple bars in the morning. This is due to the ecu detecting some blocks voltages that have dropped significantly overnight from self discharge/low capacity.

    Imagine having (28) 55 gallon drums of water and 28 drill bits ranging in size from 1/28th of an inch up to one inch (28/28ths) in diameter. Now take each drill bit and use it to drill a hole in a drum, so each drum has a single hole in it making water leak out. Those are your modules self discharging. The "service" gave you some drums with 1" holes.
     
    #4 TMR-JWAP, May 30, 2020
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  5. 2GenPrius

    2GenPrius Member

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    Thank you all for your replies, I greatly appreciate it.

    I'm in Southern California, Orange County area.

    I tried contacting the service person, yet they never contacted me back and its been a month. I want to believe that it's the COVID thing, but they just might be choosing not to return my call.

    I do have an OBDII sensor and can download the Dr. Prius/Hybrid Assistant app. How do I prove that the replacement pack is complete crap. It supposedly has a 12K/1year written warranty.
     
    #5 2GenPrius, May 31, 2020
  6. bisco

    bisco cookie crumbler

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    the 600 bucks is proof. what are you trying to accomplish?
     
    #6 bisco, May 31, 2020
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  7. 2GenPrius

    2GenPrius Member

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    I just want them to fix it. I found them on my Yelp app.
     
    #7 2GenPrius, May 31, 2020
  8. TMR-JWAP

    TMR-JWAP Senior Member

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    The problem is that, although the HV battery is sketchy, there are no codes. It's going to be really hard to convince anyone to provide warranty work for a HV battery that isn't coding out. Also, most rebuilders, even the big ones, will void the warranty if the car is not driven for 30 days. Because they KNOW many modules will have self discharge issues that won't show up if the car is a daily driver, but will cause the battery to fail if undriven for extended periods. When I build a battery using modules from late model wrecks, they can sit for 6 months or more without even blinking. Probably even a year or more.

    Your other option is to drive it more often.

    In a Gen 2, even a very good 12v battery will die after about 5-6 weeks of the car being unused due to the electronics load.
     
    #8 TMR-JWAP, May 31, 2020
  9. bisco

    bisco cookie crumbler

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    how can they fix it if they are out of business?
     
    #9 bisco, May 31, 2020
  10. 2GenPrius

    2GenPrius Member

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    Thanks. I haven't been driving it long-distance (highway), yet have been driving daily short-distance (locally, about 20-30 minutes of street driving collectively). I did need to drive up to work recently (45 minute one way drive) to get something and mileage improved slightly. During street driving, the discharge and subsequent recharge is really bad. It seems the car really struggles, it doesn't glide as it used to. This is the same signs I experienced right before I experienced the TOD on my original battery pack.

    I think you're onto something with the discharge rates begin different for each module...is there a way I can test this via the OBDII and aforementioned apps, or is this something only a specialist can pinpoint? Like I said, the battery levels are all over the place, and not consistent when they first replaced it. My car is stock, so there should be nothing draining the battery other than self-discharge.
     
    #10 2GenPrius, May 31, 2020
  11. TMR-JWAP

    TMR-JWAP Senior Member

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    If you have an android phone and a wireless OBD device (I have an OBD LINK LX), you can get an app called Hybrid Assistant and Hybrid Reporter. There is a test you can perform using the AC system to load the HV battery. It has to be done after the car is warmed up, so the engine will not run. Then the Hybrid Reporter app can be used to graph the data. It will show 14 lines on the graph plotting voltage vs time. It makes it very easy to see weak modules, as their voltage will drop faster. Give me a couple minutes and I'll throw a link on here to show some tests I've posted previously.

    Just Another HV Battery Thread and Experiments | PriusChat
     
    #11 TMR-JWAP, May 31, 2020
  12. AzusaPrius

    AzusaPrius Senior Member

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    The price alone should tell you that you got a battery that wont last long.

    Posted via the PriusChat mobile app.
     
    #12 AzusaPrius, Jun 1, 2020
  13. 2GenPrius

    2GenPrius Member

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    Thank you so much for the link. It is very detailed. I will try and replicate some of your troubleshooting this coming weekend. I finally was able to get a hold of the other repair guy today. Apparently the other guy has been out for a while.

    Anyways, he was able to reset the entire system after plugging it into the OBDII scan tool he had. Car seemed to work better for a bit, even the battery/mpgs are improving just after a short-drive. Gonna try it daily for a week to see what happens, then run your test by the time I hit the weekend.
     
    #13 2GenPrius, Jun 1, 2020
  14. 2GenPrius

    2GenPrius Member

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    So I ran the test and these are the results I got. I don't understand because even with the car not moving and the AC on full blast, it has never switched on the gasoline engine right away to keep the car running. The battery drops quickly. When I look at the report, it says total estimated capacity is 2.06Ah. Is that right?
     
    #14 2GenPrius, Jun 10, 2020
    Last edited: Jun 10, 2020
  15. 2GenPrius

    2GenPrius Member

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    So looking over my posted images more carefully, does this mean that Battery module 4 & 8 are bad or on their way out? Or does the HV battery need better balancing?
     
    #15 2GenPrius, Jun 12, 2020
  16. TMR-JWAP

    TMR-JWAP Senior Member

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    Unfortunately, the forum posted my previous entry 3 times. I edited two of them to show 'duplicate post' and now it looks like even the original post is gone. That sucks, because it was a lot of writing.

    You have too much 'busy' in the test. It needs to be done with the engine not running, so you can see how the battery performs, not how the entire HV system performs. Essentially, you need only the first three minutes of your test, but the additional 15 minutes of data clutters it up to the point you can't really 'see' the battery performance.

    Get the Hybrid Assistant app up and running. Take the car for a drive to get it fully warmed up. Park somewhere, put the car in 'Park'. The SOC should be around 60% give or take a bit. The engine should stay off (until SOC hits around 42-43%.)

    Open all the windows or doors and crank the AC to max and immediately start the battery test. Stop the test when SOC is about 43-44%. You want to stop the test before the engine starts so it doesn't skew the numbers. Then use Hybrid Reporter on that data and show us the screen captures.
     
    #16 TMR-JWAP, Jun 12, 2020
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  17. 2GenPrius

    2GenPrius Member

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    Ok will do. What was weird as I was trying to get it up to over 60% SOC, it seemed as if the engine wanted to stay on until it hit 70% SOC (then turned off). I did run the Hybrid Assistant app to monitor the charging and even with the AC running in the cabin, it seems as though the battery is overheating. The fan was kicking on full blast. I did a screenshot.

    [​IMG]

    I noted that Module #1 has the highest resistance rating than the rest of the pack...and correct me if I'm wrong, doesn't electrical flow resistance generate much more heat? I did clean the fan, and it does flow from the vented area (double-checked).
     
    #17 2GenPrius, Jun 13, 2020
  18. 2GenPrius

    2GenPrius Member

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    So I re-did the test after manually charging up the battery SOC to over 60%. I noticed that the battery doesn't last long, yet the rate of discharge jumps substantially. It's almost as if the system is bogging to charge/catch-up. In light of what the other poster said, I stopped by an Autozone and had them run a battery check on the 12V. Turns out it failed the battery test (I'm assuming it has a bad cell).

    The onboard diagnostics for voltage reads 12V, and 14V~ while the car is running. I'm assuming the battery level fluctuates all over the place because it is being zapped by the weak 12V battery. I plan to stop by the stealership tomorrow morning to get a True2 AGM Toyota Battery (they have a sale right now) and gonna see if that solves the ills. If not, going back to the hybrid folk and let them tinker with it a bit.
     
    #18 2GenPrius, Jun 15, 2020
  19. TMR-JWAP

    TMR-JWAP Senior Member

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    It's interesting to see that your battery started at ~63% SOC and looks like it was about 50% when the engine kicked on. That's unusual. The good news is it doesn't look as if you have any 'stand out' weak blocks. If anything, you have one block that is performing a bit better than the others. Sometimes this can lead to problems, but I don't think it will in your case. You're only sitting around a ~0.2 volt difference between your highest and lowest block voltages. Overall though, the HV battery itself does appear to be a bit on the weak end.
     
    #19 TMR-JWAP, Jun 15, 2020
  20. 2GenPrius

    2GenPrius Member

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    Thanks. So I've been testing it by myself, I actually bought the full version of Dr. Prius and been running the acceleration/deceleration tests. Wondering if those are accurate at all. The first two tests noted problems in Block #1 (one test) and #11 (the other test) for being out of balance. The third test said no problems. Did a battery life test and got 54.3% fair battery life, and that really sucks.

    I did notice when things get hot out and I need to run the AC, it zaps the battery a lot. If I don't use the battery, it's slowly reflecting old mpgs but nowhere near what I was getting before my original pack went toast. The middle battery temp always seems warmest, yet the highest resistance readings seem to be at the beginning and end of the pack.
     
    #20 2GenPrius, Jun 20, 2020
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