Replaced bad HV module. Left with P3024.

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Jake.T.Mathern, Oct 28, 2019.

  1. Jake.T.Mathern

    Jake.T.Mathern New Member

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    Hi forum,

    I had the dreaded P0A80 after 131k mi and decided to take some of my spare time to DIY the repair. I removed the battery and measured voltage (not under load) to find the problem module.
    Here were my voltage readings on the battery taken about a day after driving it (list is in reverse, so module 28 is the 1st):
    [​IMG]
    I decided to replace only the module reading 6.61v and see if the problems would be alleviated temporarily.
    I bought the part online and swapped the cell out. It read 7.93. I (perhaps erroneously) did NOT do anything else, such as re-balancing the battery.
    The car drove fine for a day, but then the fan kicked into gear and I got hit with another red triangle. Halfway home the car began accelerating sluggishly as though the hybrid battery was completely offline. I got the code P3024 (according to this forum, abnormally high resistance in battery block 14).

    I've taken the battery back out and am not sure what to do with it.
    There are a few options for me here:
    1. Get a new battery
    2. Try replacing the other 27 modules
    3. Try again with the 1 cell replacement

    Ultimately I am not sure if I just did something wrong... The module replacement videos I watched did not mention anything about charging/balancing the pack. It is probably worth mentioning that I screwed the plastic end piece of the pack on backwards, which I realized when I took it back out... (Stupid, I know. If this is a probable cause for p3024 then I'll be damned. This is the only mistake I know for a fact I made in reassembly.)

    I'm looking for some suggestions on what to do next, and ideas on what would have caused p3024.
     
  2. SFO

    SFO Senior Member

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    Welcome to PriusChat!!
    Finding the questionable modules is best done under load, or by letting the pack sit for many days, the weak modules will start to voltage sag a bit faster when compared to the rest of the pack.
    Given that you only had a P0A80 to work with, not a bad call at all.
    Rebalancing is always best, especially at your mileage or when swapping modules.

    Prior to the P0A80 and this repair, did you notice any of the telltale signs of battery degradation?
    Sounds like you've found another bad module, have you measured the voltages for that block already?

    Was the HV battery fan cleaned recently?

    Did you clean up the wiring harness and bus bars during the swap?
    Could be worth the investment, and should last quite some time.
    Could get expensive quickly if buying online individually. Might look for a decent pack at a local junk yard
    This sounds like the most bang for the buck, especially since you've removed the pack and are familiar with the process.
    Doesn't sound you did anything wrong, beyond the stated. Quite possible that was the cause though.
    If the P3024 was the end module closest to the reversed compression plate, that could be one answer for the current P3024. Both end modules will swell on the side closest to the plates (opposite ends of the pack), as the plastic plate doesn't offer much physical resistance. Reversing the plate gave the module even more room to bloat, and fail.

    Personally, I would just swap another decent module into the mix. But your spare time situation might be different now.

    Pinging @PriusCamper who is always helpful and has a wealth of knowledge on the local available battery options (junk yards, rebuilt packs, etc). And if not already in use, has the proper balancing gear nearby to you..
     
    #2 SFO, Oct 29, 2019
    Last edited: Oct 29, 2019
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  3. PriusCamper

    PriusCamper Senior Member

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    HI Jake, I'm an hour south of you in Olympia... Congratulations on getting this far... Even that much is a challenge... You succeeded in finding the bad module, just not finding the next module to go bad. You're getting close to it being fixed though. And if you can clear the codes and get some miles on the pack, things might settle down for a while.

    There's several way to find bad modules before they go bad. Creating a spread sheet of all numbers from load testing is key... Also if you recondition individual modules simultaneously by discharging the same way you do load testing you can watch the voltage drop and a module soon to go bad will lose all it's voltage before the other modules.

    Also charging and balancing with a Prolong charger is a great way to wrap up the work once the pack is back in the car... Anyways, let me know how I can help? Currently all my loaner packs are out right now, but if I get one back maybe I could help you out.

    Or if you've had enough, there's a Seattle Toyota dealer selling a replacement pack for $1650 and takes a couple hours to install....
     
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  4. Jake.T.Mathern

    Jake.T.Mathern New Member

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    Thanks for the reply SFO

    Do you have a link to a good resource on how to do this? I don't really have any fancy equipment right now, but if it's tangibly good for the battery, I'd give it a shot.

    No, but I wasn't keeping an eye out for it.
    I do have those voltages measured in the post. If blocks are in groups of 2, I had 7.77/7.83 for modules 27 and 28 respectively. I did a quick test on the last 2 modules and they seemed fine, despite the code.

    No and no. Both sound like a good idea.

    Do you think replacing only a few cells will last me long enough that I should wait on doing a complete replacement? I've read on here these cells have small deviation on lifetime, though 130k feels a little low compared to what I've seen (though it is 12 years old).

    That makes a lot of sense in hindsight.
     
  5. Jake.T.Mathern

    Jake.T.Mathern New Member

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    Hello! Thank you for the reply. I'm not giving up quite yet!

    I'd definitely be interested in finding the other modules soon to go bad, since I have the battery out anyways. Do you think replacing the modules that are <7.8v in my above list (not under load) would be mostly accurate, or is load testing a must? I'm just a little hesitant because I feel like this part would be the most dangerous (and time consuming), so I'd be ok with 80% accuracy. Otherwise, the way it sounds, I might as well recondition the whole battery while I do a load test. We're probably going to say goodbye to this car before it hits 150k so I don't know if that's worth it. What do you think?

    The prolong charger seems like a no-brainer, so I thank you for that input. I'll see if I can get my hands on one.
    Is it a potential problem that I did not charge the new module at all? I assume the battery was at about half capacity when I put in the new, empty module.
     
    #5 Jake.T.Mathern, Oct 29, 2019
    Last edited: Oct 29, 2019
  6. TMR-JWAP

    TMR-JWAP Senior Member

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    Jake,

    The DTC P3024 is actually "battery block 14 becomes weak". Block 14 is the 2 modules closest to the ECU end. The ECU is merely looking for a certain voltage difference between the highest block voltage and lowest block voltage. Once it sees that threshold is exceeded, it triggers the P0A80 code. It doesn't necessarily mean you have a "bad" module, just that you have exceeded the threshold between strongest and weakest. If the module you previously installed was a "superman" module, it may be causing its block to read very high, which would make it that much easier for the "weakest" block to trigger the threshold. This is why it's more important to have 28 well balanced modules than 27 decent modules and one great module. That great module will screw you, since it may make even a decent module trigger the code. The absolute worst thing you could do for a OEM Gen 2 HV battery would be to install a single brand new module. You need one that's matched to the average of the other 27. Newer/higher capacity is not actually better.

    The P0A80 code will illuminate the RTOD but still allow you to go ready and drive the car normally. Any individual block code (like P3014) will allow you to drive the car, but only in fail-safe mode.

    The plastic end caps and steel tubes are designed so that when properly assembled, all you need to do is tighten the 8 fastener bolts and they'll pull tight on the tubes providing the correct clamp force on the modules. If you install one backwards, all you'll see is that some threads on the fasteners are still exposed. The worse that would happen is that they clamp even tighter, unless you left it loose in order the get the end caps to fit on the floor plate studs.
     
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  7. PriusCamper

    PriusCamper Senior Member

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    Well, at the very least, you're going to want to charge or discharge each module so they all have roughly the same voltage before you put it back in the car..

    And then to do reconditioning of individual modules you're going to need to charge the modules up with NiMH rc hobby chargers. You're also gonna want to watch multiple voltmeters reading voltage as the modules discharge so you can compare how fast or slow. Of course before you get to that you're going to need to build a spreadsheet and load test the modules. Did you find the load test instructions yet?

    Your main challenge is gathering up all the equipment... Enclosed is a photo of what a system that's going to not take an eternity to do all this work. It can discharge 5 modules and charge 5 modules at the same time. I hope to upgrade to a new system soon tha tcan do more than that. My buddy in Oregon can do as many as 80 modules at once with lab-grade equipment, but that costs tens of thousands.

    Buying a Prolong Charger used can be had for $200 in rare circumstances, but I've only seen that a few times. In general they're expensive and there's few easy ways around the $150 wiring harness, which has a box that controls fan speed that can't be replicated on the cheap.

    Another way to look at it if you're planning to sell the car at 150K and are interested in your next car being a 2015 or earlier Prius, you could buy a pack that doesn't require a core return/deposit like one of these: http://newpriusbatteries.com/ and plan to use that pack in your next car and take your time rebuilding failed pack and put it back in when you're ready to sell.

    Or alternatively, buy a new pack at Toyota dealer, ditch your old pack with them to get your core deposit covered, then buy a newer used Prius when your current one hits 150K and put the pack from that newer used Prius in the one you're going to sell, then put your brand new pack in your new used Prius and have no worries for a long time.
     

    Attached Files:

  8. Jake.T.Mathern

    Jake.T.Mathern New Member

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    I see. This is really useful information, thanks. So the answer is to balance the modules out, then? Or am I screwed because this new module is just in better condition?
     
    #8 Jake.T.Mathern, Oct 30, 2019
    Last edited: Oct 30, 2019
  9. Jake.T.Mathern

    Jake.T.Mathern New Member

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    Thanks for taking the time to help. We were looking at upgrading to a new prius model most likely. In a few years, I mean. The 2015 ones use the same battery pack? that's good to hear.
    Is there a good reason to buy a new pack instead of buying 27 (more) new modules and swapping them into the existing pack? Seems like that would be the cheaper option for me, if possible. BONUS points if it means not having to put all of this effort into rebalancing.

    I'll have to get on that, but I want to do some cost benefit analysis first

    You're saying I will want this whole setup to do that? Looks like a blast haha. Well, if you have any exact recommendations on components, now is the time to tell me!
     
    #9 Jake.T.Mathern, Oct 30, 2019
    Last edited: Oct 30, 2019
  10. PriusCamper

    PriusCamper Senior Member

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    I got started with just two chargers and it was much slower compared to five...

    The chargers are the SKYRC IMAX B6AC V2 for about $50 each... The free multi testers with coupon at Harbor Freight were a fail. So I bought those black ones on Ebay for about $5 each... The light bubs area cheap ($2) 12v 50w and 12v 20w to get most of the charge out of the pack and then the 10W discharge resisters for final stage of three successively deeper rounds of discharge. Hybrid Automotive has good discharge numbers in their online owners' manuals.

    When I upgrade I'm switching to these chargers: HTRC T240 DUO Touch Screen Dual Channel RC car lipo battery Balance Charger
     
  11. Jake.T.Mathern

    Jake.T.Mathern New Member

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    So this work will recondition the individual modules, but going off of @TMR-JWAP's reply, the problem may be that the brand new cell is too good. I don't imagine doing this work will fix that problem, since this difference is caused by wear on the module, right?
    I figure the band-aid for that case would be to get a module that has a bit of wear on it, matching the others. Correct me if I'm wrong.
     
  12. PriusCamper

    PriusCamper Senior Member

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    Yes... But given the labor involved buying just any old spare module online will be problematic. I did that once and got 3 miles out of the module I bought before it failed. Finding a good person to buy healthy modules from is essential. And in general those modules I buy are healthier than the pack, because they've been reconditioned. So I match the pack to the module by reconditioning it.
     
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  13. Jake.T.Mathern

    Jake.T.Mathern New Member

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    Sorry to bump an old thread, but I figure I should post an update in case anyone finds this through google or something.
    We just let the battery sit for a while and measured voltage drop over time. Unsurprisingly, the modules above that read 7.6 (m16) and 7.54 (m1) seemed to lose voltage faster. We probably didn't need to wait to know this, though, and should have just replaced these initially. We were probably trying to be cheap about it.

    Anyways, we ordered 2 more refurbished modules. We would have ordered some with matching mileage from hybridautomotive.com but they were out so we just went with eBay and prayed. We tested our new modules, replaced the old ones, cleaned corrosion, and added some dielectric grease. The prius has been working fine now for 2 weeks. We've been checking voltages from time to time using the Torque app and a bluetooth OBD reader and there doesn't seem to be much deviation between blocks.

    I assume the initial p0A80 was caused by the very bad module, and after replacing that with a refurbed module, the voltage difference under load between the worse-but-not-quite-dead module(s) and the refurbed module was too much, causing the p3024. That's my novice take on it, using what I've learned from this thread.

    Overall I would say our biggest mistake when working on this was, following our first module swap, putting the car completely back together instead of just testing it out for a few days first. I think we were just a bit too excited. Happy (and probably a little lucky) that it seems to be working for us at least for now though, so... thank you everybody for your guidance!
     
    #13 Jake.T.Mathern, Nov 18, 2019
    Last edited: Nov 18, 2019
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