1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Bad hybrid battery problems

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Michael K, Jul 25, 2014.

  1. ericbecky

    ericbecky Hybrid Battery Hero

    Joined:
    Mar 12, 2004
    4,365
    3,209
    1
    Location:
    Madison, Wisconsin
    Vehicle:
    2005 Prius
    Model:
    Two
    There will be no guarantee. Voltage is somewhat useful, but not definitive at all.
    What you really need is a handy way to load test each module quickly.
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,198
    6,461
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    It's not likely that the battery which has been sitting for 4 years without being recharged will be good. Toyota's vehicle storage recommendations include making the car READY to charge the traction battery for 30 minutes, every two months.

    You can measure module voltage but a real test would involve putting a good load on the battery to see what happens to the voltage on the 28 modules. Its not easy to do that without installing the battery in the car.
     
  3. vvillovv

    vvillovv Senior Member

    Joined:
    Mar 19, 2013
    3,492
    1,231
    1
    Location:
    NY
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    Be careful on the disassemble process and take pictures, lots of pictures.
    Disassemble one pack at a time. So you have the other assembled pack to look at as your reassemble.
    It may not be rocket science, but getting the pack back together the way it's supposed to be will be challenging,
    especially the first few times you do it.

    Two more posts show up as I was writing the above and I'd like to address the issue of testing the pack.

    I believe and I think EricBecky can probably explain this clearer than I,
    that the best way to get a general idea of the packs health is to run a charge / discharge cycle on the pack using a charger with monitoring software built specifically for rebalancing hybrid packs. From my experience it's possible to see small differences between any packs you run though this process, and many times not even have to disassemble the pack to rebalanced it.

    Patrick Wong, You may be correct in your observation about packs sitting for several months without charging.
    My battery mentor reports prius NiMH modules to be extremely resilient even after overcharging without being in compression so that the cell expands 2 times it's normal size and even cell reversal if the time the cell is in reverse is short enough.. Geeez, let me try explaining that last sentence again.
    Some Gen 2 prius cells have been brought back from a reversed polarity state, but only if that that reversed polarity state was measured for a short ( sevreal minutes ) duration.

    And not all cells that have shown reversed no matter what lenght of time they show reversed polarity will be recoverable.

    Some of what I've written above is from my oen experience and some is what I've been told about.
    As always YMMV as you go through your own process of figuring out this re balancing / rebuilding the pack thing. .
     
    #23 vvillovv, Jul 26, 2014
    Last edited: Jul 26, 2014
  4. Michael K

    Michael K Junior Member

    Joined:
    Jul 25, 2014
    31
    1
    0
    Location:
    Orlando, FL
    Vehicle:
    2007 Prius
    Model:
    N/A
    Well, disassembled the pack while keeping it in the car (I know, I know... bad idea) and have found Cell #14 to be the problem. Every other cell tested at between 8.09 and 8.11 Volts. This wasn't under load though.

    I'm building a tester with the 55w halogen that I saw people talking about and then take another measurement to see the drop over 15 seconds and make sure they all drop at the about the same rate. Is that the right way to do this?

    I'm gonna partially put it back together and pull the pack from the car. This leaves my wife and I down to one car. I guess we will have to beg and borrow cars for the next week or so while I get this thing fixed and balanced.

    I have a question though: I keep hearing about how you want to match the batteries based on similar characteristics. What exactly should I be looking for? I had planning on taking someone on heres advice and put the center batteries to the outside and the outside batteries to the inside since the inside batteries have had 256,000 miles of being hot all the time. What else should I be looking for with the matching?

    Does anyone have any good cells that they wanna sell me? Or the balancers?
     
  5. ericbecky

    ericbecky Hybrid Battery Hero

    Joined:
    Mar 12, 2004
    4,365
    3,209
    1
    Location:
    Madison, Wisconsin
    Vehicle:
    2005 Prius
    Model:
    Two
    You'll never get it "perfect". The charging/discharging/monitoring/load test equipment you own will have limits to it.
    I can sell you some good modules but there is not really a way for you to get replacement cells that are going to exactly match all the characteristics of the existing ones. And no matter what you do, at some point it is diminishing returns.
    So even with all your days or weeks of effort, you sort of end up with "good enough" anyway.

    Think about it. Let's say you test them all with your 55w halogen, and they droop from 8.09v to 8.00v.
    How are you going to find another module that exactly matches that profile?
    Maybe I use a different load test than you do. Maybe your equipment is calibrated differently than mine. Maybe you load test for 15 seconds, but I load test for 20 seconds. So no matter what you buy, it won't match.

    So, can you mix and match them to try to get things better? Yes. But will it be significantly better than simply replacing the most obvious problem and moving on? Hard to say.

    Going forward you should invest in tools that will let you monitor the pack while driving. This way, if there is a problem in the future you will be able to hook up your equipment and pinpoint it before you even remove the pack. And the second or third time around, it will take you much less time to make the replacement.

    With a car/battery this old, I would get a grid charger to help keep things balanced and to do some preventive charging/discharging on the entire pack the pack once in a while. You could install it before you reinstall the pack this time. Feel free to call if you have questions.
     
  6. vvillovv

    vvillovv Senior Member

    Joined:
    Mar 19, 2013
    3,492
    1,231
    1
    Location:
    NY
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    No exactly, but the concept is correct.
    This is the tricky part,
    Generally, you want to find cells that reach their top charge and bottom charge limits at the same time as compared to other cells that take longer to reach their top voltage during charging and their lowest voltage while discharging.

    ie: the strongest cells will take the longest time to discharge fully and the shortest time to charge fully,
    no matter what position in the pack they came from.

    I'm still not experienced enough comment on which order to reassemble the matched cells in. I believe I've read a reference to which order works best, but I'd have to search the archive to refresh my memory on that.

    Eric Becky posted above to contact him.
     
    #26 vvillovv, Jul 26, 2014
    Last edited: Jul 26, 2014
  7. Michael K

    Michael K Junior Member

    Joined:
    Jul 25, 2014
    31
    1
    0
    Location:
    Orlando, FL
    Vehicle:
    2007 Prius
    Model:
    N/A
    Ya, I understand that I can't make it perfect but if I can get 24 months by matching them compared to 18 months, that is 6 months more of not having to worry about my wife being upset that we purchased a car with a known problem (She is the one that test drove it and signed the paperwork).

    I just purchased the 7 imax b6 balancers from Amazon (Gotta love Amazon Prime). Should be here Tuesday... I'll start balancing the batteries while I await the cells.

    How much would you want for 3 good cells shipped to 33837? (Getting 2 extras just in case)
     
  8. ericbecky

    ericbecky Hybrid Battery Hero

    Joined:
    Mar 12, 2004
    4,365
    3,209
    1
    Location:
    Madison, Wisconsin
    Vehicle:
    2005 Prius
    Model:
    Two
    Option 1) Putting a replacement battery module in it involves less than a day's work.
    Option 2) Babysitting battery chargers, writing down measurements, comparing data, getting back on the forum to solicit more opinions, etc, etc will take several days, and more likely, weeks.

    I know my wife would opt for option 1, even if I had to do it again in a year.
     
  9. Michael K

    Michael K Junior Member

    Joined:
    Jul 25, 2014
    31
    1
    0
    Location:
    Orlando, FL
    Vehicle:
    2007 Prius
    Model:
    N/A

    From what I have read, just replacing a cell will not fix the issue and it will throw a code within the first 30 miles. The car is already out of commission and due to driving it with a bad battery, we have have messed up the inverter (mechanic said it would be ok to drive, he also said the battery he was putting in was good...)
     
  10. vvillovv

    vvillovv Senior Member

    Joined:
    Mar 19, 2013
    3,492
    1,231
    1
    Location:
    NY
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    None of us can tell you what to do about what your mechanic told your wife who told you about the car.
    You have to do your homework and get fault codes before and after, or take the word of a mechanic you trust.
    Fault codes before, coincidentally ( at least in my mind ) is one of the main reasons there are no guarantees with rebalancing a pack. There 's lots of other stuff going on in the car at the same time and even dealer shops have their own ways of interpreting the cars general health.
     
    #30 vvillovv, Jul 26, 2014
    Last edited: Jul 26, 2014
  11. ericbecky

    ericbecky Hybrid Battery Hero

    Joined:
    Mar 12, 2004
    4,365
    3,209
    1
    Location:
    Madison, Wisconsin
    Vehicle:
    2005 Prius
    Model:
    Two
    Not sure how the mechanic can get a junkyard battery and know it is good. Most mechanics would buy it from the yard, and install it to confirm whether or not it is good. Only takes a few minutes to put it in the car. And most yards have a return guarantee.

    A bad battery will not generally mess up the inverter. The car has protection in place. A messed up inverter has other causes.

    What were the voltages of the modules that were outliers? Or can you post a list of all the modules voltages. (numbered 1-28) See what vanionbb did in his post New Prius Owner 2002, battery issues (shocking!) | PriusChat

    To best balance the pack at the top you will want a high voltage dc charger that can gently charge the entire pack as one unit. Start at empty, then fill with 6.5 ah. Alternately you could have a series of lower voltage chargers that can charge all 28 modules simultaneously.
     
  12. vvillovv

    vvillovv Senior Member

    Joined:
    Mar 19, 2013
    3,492
    1,231
    1
    Location:
    NY
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    I wish I had electical engineering degree.
    Just thinking of all the toys I could build with it. :)
     
  13. Michael K

    Michael K Junior Member

    Joined:
    Jul 25, 2014
    31
    1
    0
    Location:
    Orlando, FL
    Vehicle:
    2007 Prius
    Model:
    N/A
    Ok, so I took voltage readings prior to the 55w halogen for 20 seconds and then again after. I have also put the difference to see if there is any noticeable losses on any cell. Cell # 4, 24 and 27 all had a 0.16 drop. Of course due to the lack of scientific method used with the halogen (used a 20 second timer on my phone that i hit almost always right when I clamped the alligator clip on but maybe a second or 2 off)
    01 8.11 7.97 0.14
    02 8.11 7.97 0.14
    03 8.11 7.97 0.14
    04 8.11 7.95 0.16
    05 8.11 7.96 0.15
    06 8.10 7.96 0.14
    07 8.10 7.96 0.14
    08 8.09 7.95 0.14
    09 8.11 7.96 0.15
    10 8.09 7.95 0.14
    11 8.09 7.95 0.14
    12 8.08 7.95 0.13
    13 8.08 7.94 0.14
    14 6.81 6.61 0.20
    15 8.08 7.94 0.14
    16 8.08 7.94 0.14
    17 8.08 7.94 0.14
    18 8.09 7.95 0.14
    19 8.08 7.95 0.13
    20 8.09 7.95 0.14
    21 8.08 7.94 0.14
    22 8.09 7.95 0.14
    23 8.10 7.95 0.15
    24 8.09 7.93 0.16
    25 8.10 7.96 0.14
    26 8.10 7.96 0.14
    27 8.11 7.95 0.16
    28 8.10 7.95 0.15
     
  14. Michael K

    Michael K Junior Member

    Joined:
    Jul 25, 2014
    31
    1
    0
    Location:
    Orlando, FL
    Vehicle:
    2007 Prius
    Model:
    N/A
    You'd think but it's like being a mechanic... When you get home you don't want to work on your own crap...
     
  15. Michael K

    Michael K Junior Member

    Joined:
    Jul 25, 2014
    31
    1
    0
    Location:
    Orlando, FL
    Vehicle:
    2007 Prius
    Model:
    N/A
    The reason I was thinking that the inverter is going bad is that last night the car died on the road and when I pulled the codes there were 3 relating to the inverter (p0a78, p0a7a and p0a92). The car wouldn't start with these codes so I cleared them and drove the car the 1.2 miles home in limp mode. When we first got the car 4 days ago, you could drive it at interstate speeds with no problems. Now, it will accelerate for about 20 seconds and then go into limp mode. When you shut the car off, it sounds like a jet engine winding down. I'm hoping this is all related to the battery... of course a used inverter is less than $300 and are EVERYWHERE... already found one 15 miles from my house if needed. It looks like they are pretty easy to replace too... Gotta focus on the battery and not worry about anything else yet... once the battery codes clear MAYBE I'll be able to get a few hundred miles before needing MORE work....
     
  16. MTL_hihy

    MTL_hihy Active Member

    Joined:
    Sep 2, 2013
    536
    261
    0
    Location:
    Maritimes, Canada
    Vehicle:
    Other Hybrid
    Model:
    N/A

    Few comments.......

    1) When you do your load test, do it for longer (like 2+ minutes) so that it gives you a better idea of which modules are holding up under load.....adding more load (like 2nd headlight) will also help with more definitive results.
    2) Those codes definitely point to an inverter problem so make sure to inspect all the connections an wiring, then if you don't find anything I would just install another inverter to be sure that's not your issue.
     
  17. Michael K

    Michael K Junior Member

    Joined:
    Jul 25, 2014
    31
    1
    0
    Location:
    Orlando, FL
    Vehicle:
    2007 Prius
    Model:
    N/A
    I was all set to start the process of getting this battery rebuilt and a company called saying they could replace it today for $1000. They seem legit but now I can't get a hold of them... UGH!!!
     
  18. vvillovv

    vvillovv Senior Member

    Joined:
    Mar 19, 2013
    3,492
    1,231
    1
    Location:
    NY
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    Even if you did get a new battery for a grand would it work?
    read
    MTL_hihy
    post above again.
     
  19. Michael K

    Michael K Junior Member

    Joined:
    Jul 25, 2014
    31
    1
    0
    Location:
    Orlando, FL
    Vehicle:
    2007 Prius
    Model:
    N/A
    Ok, so the battery was replaced last night with a company that specializing in replacing them. It came with an 18 month warranty so hopefully that will be good. BIG problem though... The car is now throwing a new code and i think it is due to driving the car with a bad battery. The code was p0a92. It appears to be a transmission code. Should I bring the car to Toyota for diagnosis or just get a used transmission and swap it out?
     
  20. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,198
    6,461
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    DTC P0A92 means that MG1 within the transaxle has failed. Given the fact your car has logged 256K miles I suggest you replace both the engine and the transaxle at the same time. There is no difference in labor effort since they both have to be removed from the car, and you should be able to get a decent used 2G Prius engine with less than 100K miles for <$500.

    And, don't be surprised if you should find other significant subsystems have to be replaced before you are done. For example, the inverter.
     
    #40 Patrick Wong, Jul 31, 2014
    Last edited: Jul 31, 2014