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2005 Prius with 193K miles and exploded battery module

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by rbdigital, Jul 22, 2015.

  1. rbdigital

    rbdigital Hybrid Family Father

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    I've a 2005 Prius with ~193,000 miles. It recently started throwing codes P3019 (Battery Block 9 becomes weak) and P0A80 (Replace Hybrid Battery). Codes were pulled with a laptop running Techstream and a mini-VCI cable.

    Figuring I had some time, cleared the codes and only drove the Prius for short trips. At first things were OK, but of course the codes re-set after a few days, and pretty soon they were permanent. And the car had very little power, battery fan running on high.

    Then when slowly accelerating from a traffic light (there is no rapid acceleration in a gimpy Prius), there was a "BANG" noise, really loud. It sounded like someone tossed an M-80 at the car. Pulled over, didn't see any damage, though there was a strong "fireworks" smell like gunpowder outside the car. Started the car, it fired up fine, drove it home.

    After a couple more weeks the car refused to start, wouldn't go into "Ready" mode. So finally I took the interior apart and opened up the battery case. Here is what I found (pic attached).

    Moral of story - don't drive too far when you get the P0A80.

    Did measure the module voltages:

    1 7.53 - low
    2 7.64
    3 7.63
    4 7.65
    5 7.63
    6 7.62
    7 7.63
    8 7.63
    9 7.62
    10 7.64
    11 7.60
    12 7.60
    13 7.62
    14 7.65
    15 7.64
    16 7.64
    17 7.64
    18 0.60 - damaged module
    19 7.61
    20 7.65
    21 7.63
    22 7.63
    23 7.63
    24 7.63
    25 7.61
    26 7.65
    27 7.63
    28 7.56 - low

    The plan is to discharge / recharge the two lowest (1 and 28) modules, and replace module 18. I realize it would be best to rebalance the entire pack, but that will take a lot of time. But maybe I'll be forced into that......

    Has anyone ever blown up a module before?
     

    Attached Files:

  2. SageBrush

    SageBrush Senior Member

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    Wow. Amazing that the car ran at all after the boom
    I wonder how a Li-x battery would have "performed."
     
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I think you should replace modules 17 and 19 as well, because they were very likely stressed by being next to module 18 which overheated prior to blowing up.

    The Prius and its passengers would probably have become a well-done barbecue.
     
    #3 Patrick Wong, Jul 23, 2015
    Last edited: Jul 23, 2015
  4. SeanForReal

    SeanForReal Junior Member

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    never blown up but my brother has a 2005 and at about 175,000 miles ( about a month ago) through some codes regarding the battery pack. Ended up having to replace one cell and re balancing the pack. This took a few days but runs fine now. I would bite the bullet and just re balance the pack. Might as well if your going to have it dismantled
     
  5. gdanner

    gdanner Member

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    Wow! That really ****POPPED****

    I drove my 2005 Prius for about 1 week after the first POA80 appeared, resetting DTC codes many times. Then I removed my HV battery. One module was at 6.62V. I replaced it with a "used/tested" module from eBay.

    The bad module I took out of my HV battery showed no physical signs of damage, leaking, or overheating. I've got it on my workbench now and I plan to run some tests on it.

    I also replaced 1 other module that was about 0.1V lower than the others. Since then my car has been running perfectly. No more DTC codes, and mpg improved by nearly 10 mpg (mpg for tank is currently 42.5).
     
    rbdigital likes this.
  6. rbdigital

    rbdigital Hybrid Family Father

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    I've been cycling my modules and have learned some things.

    First, I'm using a Hitec X4 80 hobby charger. It doesn't support turning off "delta peak" detection, but you can set the limit to 20mv/cell (max), which is what I've done. My settings are: charge current 3.0amps, delta peak detection 20mv/cell, waste timer setting 1min, safety timer off, capacity cutoff 7600mah.

    I'm limiting the charge current to 3.0amps for safety, and because I only have a 6amp trickle charger hooked up to my old Prius 2001 battery. So far I've burned up one trickle charger, but Harbour Freight is a short drive away and accepts returns for 90 days. Think I will be visiting them often.......

    When my X4 charger arrived I found it only had 1 set of charger leads, so I foolishly "cheaped out" and bought a set of inexpensive charger leads on Amazon. I think these caused most of my initial problems. While charging at 3amps, I measured 0.3 volts across each lead (battery to charger), so the voltages being sensed by the charger were off by 0.6 volts, maybe more. I ended up making charging leads from a spare heavy duty extension cord.

    You can view my progress tracking spreadsheet at this link.

    A picture of my charging setup is attached.

    Any module that accepted less than 3000mah of discharge will be cycled again since I've no faith in the early charging numbers before the better leads were put into use.

    Charging forward.....
     

    Attached Files:

    #6 rbdigital, Jul 29, 2015
    Last edited: Jul 29, 2015
  7. rbdigital

    rbdigital Hybrid Family Father

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    I am unable to post links until I have four posts. So here is my 4th post.....
     
  8. gdanner

    gdanner Member

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    I'd be skeptical about modules that still have < 3000 mAh capacity after cycling.
     
  9. rbdigital

    rbdigital Hybrid Family Father

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    OK, finished cycling my modules. They all look pretty good, except the one that "blew its stack" (module 18).

    Patrick: Modules 17 and 19 measure in at 4390mah and 5078mah, so I think they are OK. However, I haven't done a load test yet.

    Here are a couple of videos if anyone's interested:

    • - front side bus bars showing corrosion
    • - rear side bus bars also showing corrosion
    • - closeup of failed module 18
    I tried rehydrating module 18 with distilled water. When I started, it measured 0.60 volts with my DMM. I tried charging it at 3.0ah but I quickly stopped, because (1) the cells began gassing/fizzing/boiling, and (2) I realized the cell closest to the top (+ end) was leaking water/electrolyte through a crack in the case. The module quickly rose to ~6 volts, and quickly dropped back to 0.7 volts several hours later.

    So now I get to dismantle the pack and clean all the modules.....
     
  10. gdanner

    gdanner Member

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    Your bus bars and connection nuts have a whole lot more corrosion on them than mine did.

    I wonder if your corrosion resulted from the electrolyte which sprayed out of the exploded module?

    My recommendation is to totally clean the busbars, the nuts, and the studs on your modules. The electrolyte inside NiMH cells is chemically "basic" (e.g., it's similar to lye). So you need to use something slightly acidic to neutralize it (a weak vinegar solution perhaps?). Or simply wash all these parts very well with soap and water, rinse them several times with clean water, and then dry them thoroughly. I've seen folks selling Prius HV busbar assemblies on eBay in case some of yours don't clean up very well.

    I used the following spray-on antioxidant when I reassembled my HV pack. I've used this stuff for many years to clean contacts and controls inside electronic devices (stereos, guitar amps, etc.). IMHO it's the world's best electrical contact cleaner and preservative

    Its'available here:


    Caig Laboratories DeoxIT D5 Spray Contact Cleaner, 5% solution, 5 oz. | D5S-6 (D5S6) | Caig Laboratories


    One can of Caig DeOxit will last for years. This stuff works best when it's sprayed on as a very thin coating.

    My rebuilt HV pack is still working great after 5 weeks of normal driving. I haven't done any "extreme" tests on my rebuilt pack yet. For example, I haven't deliberately tried to discharge it. It did get down to 2 purple bars one time when I was in a McDonald's drive-up lane for 10-15 minutes with the AC running. The ICE would start up periodically to keep the SOC at a minimum of 2 bars. That seems like normal behavior to me. My HV battery regained its "normal" SOC of 6 blue bars within about 30 minutes of normal driving after I left the McDonalds. I occasionally get 7 green bars when driving with the AC turned off. But most of the time the MFD display SOC stays at 6 bars. I haven't observed any "wild" up and down variation on the MFD SOC display. So I think I'm OK at the moment.

    Best of luck getting your HV battery finished and back into the car!

    -EB
     
    rbdigital likes this.
  11. jyoost

    jyoost Junior Member

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    Recently happened to me. Drove and acted better after explosion did yours? I figured module went from marginal open to short thus eliminating itself from pack.

    Posted via the PriusChat mobile app.
     
  12. ericbecky

    ericbecky Hybrid Battery Hero

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    Forcing the car to drive with a shorted/exploded module is a bad idea.

    The system will be a fire hazard.

    It won't be operating in the correct voltage range and could easily damage other electronic components.
     
  13. edthefox5

    edthefox5 Senior Member

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    D5 is a great contact cleaner but a lousy product for anti corrosion on a buss bar.
    Use NO OX it's designed for anti corrosion on battery terminals.
    It's a heavy grease that stays where you put it.
    Works good in an ac panel too. If you clean oxidation off a pure copper buss bar it will quickly oxidize again like crazy with current going thru it and presence of electrolyte gas. Apply NO OX to all surfaces of the cleaned buss bar and battery studs.