Gen II Prius Individual Battery Module Replacement

Discussion in 'Gen 2 Prius Technical Discussion' started by ryousideways, Apr 24, 2013.

  1. Britprius

    Britprius Senior Member

    Joined:
    Jun 14, 2010
    5,194
    1,874
    0
    Location:
    Herefordshire England
    Vehicle:
    2008 Prius
    You could use the Prius battery but it is not very happy being discharged to far. It would be better to pick up a cheap battery for a lawn mower or some such like, even one from a breakers yard.

    Your connection sequence is correct.

    John (Britprius)
     
    Cyon Kim and ryousideways like this.
  2. Britprius

    Britprius Senior Member

    Joined:
    Jun 14, 2010
    5,194
    1,874
    0
    Location:
    Herefordshire England
    Vehicle:
    2008 Prius
    A way of making sure all the modules are at the same voltage "once they are all balanced, and all at a reasonable level of charge" is to connect them in all in parallel and leave them for a few hours. This will equalise the voltages.

    John (Britprius)
     
    Fostel and j12piprius like this.
  3. ryousideways

    ryousideways Member

    Joined:
    Apr 24, 2013
    35
    91
    0
    Location:
    Merritt Island, Florida
    Vehicle:
    2005 Prius
    Model:
    II
    I picked up those Hitec X4 chargers a few days ago and a car battery. I connected the [email protected] 6amp trickle charger to the car battery with the Hitec chargers.

    1st mistake:
    The first set up I selected was completely incorrect. I have never used chargers like these before and even though I read the manual I still screwed up the first over night charge. I accidently set the modules to drain to .6V instead of 6V. I check the next day and the log says that was what happened. Hopefully that drain does not kill those 8 modules...

    Anyways I set up my new setting which I think are a bit more correct.

    5 amp Charge
    .7 amp Discharge to 6V
    6750 mAhr
    dsch<chg 3 cycles

    So It discharges that module until it hits 6 volts. Then there is a 5 min cool down period before it charges it at 5 amps from 0 to 6750mAhr. Then it repeats the process two more times. (three times total)

    2nd mistake:
    So after getting the correct settings I let it run overnight and checked on it in the morning. When I looked at it all of the chargers were displaying the "low input Voltage" error. Apparently the car battery/trickle charger was not enough to power all 8 chargers at once. It managed to get through 2 cycles and stopped during the discharge phase.

    I went ahead an grabbed a 450watt ATX computer power source that was in my office. I cut off the heads, combined the black wires for the ground and the only only green wire to turn in on. I combined all the yellow wires together for the 12v power source. The power source is suppose to deliver 24 amps at 12 volts.

    And that is the set up I have going right now. Eight of the battery modules are finished so far. The car battery is powering one of the Hitec X4 chargers and my ghetto rigged computer power source is juicing the other.

    I figured I would upload some pictures of the progress.

    My latest set up with the computer power source.
    [​IMG]

    [​IMG]

    This was the original set up with a single car battery and two multichargers
    [​IMG]

    The trickle charger to the battery.
    [​IMG]

    The was how I managed to get the modules to go back in correctly. That was a pain.
    [​IMG]

    [​IMG]

    A view of the temperature sensors below the battery modules.
    [​IMG]

    I believe this was one of the original modules that went bad.
    [​IMG]
     
    MHood, Eddy2014, raffpoz and 4 others like this.
  4. jdenenberg

    jdenenberg EE Professor

    Joined:
    Nov 21, 2005
    3,433
    1,496
    1
    Location:
    Trumbull, CT
    Vehicle:
    2020 Prius
    Model:
    LE AWD-e
    You need to use a charger that can almost keep up with the charging load or the battery will discharge before you finish a charging cycle (as you discovered)
    We all went through a learning curve on these very capable charger/rebalancers.
    Just don't use the computer supply to charge the 12v battery as it will happily overcharge it during the discharge phase of the cycles.
    Let us see a typical data output from the three discharge/charging cycles. You can also measure module series resistance by reading the voltage drop at a 1 amp discharge, but use a digital voltmeter at the module terminals to eliminate the resistance in the connecting cables. Do this after letting the modules rest 24 hours to dissipate the surface charge that remains after a full charge.

    JeffD
     
    flxcon likes this.
  5. YY4U

    YY4U Junior Member

    Joined:
    Apr 6, 2013
    85
    22
    0
    Vehicle:
    2006 Prius
    Model:
    N/A
    I'm doing the same thing right now on another thread. I had my trickle charger charging the 12v battery at 2 amps while trying to run 4 dc6's and got the "low input voltage" error on all 4 chargers. Low voltage cutoff can't be set at less than 10v. Switched to 6 amps and no problems, but I just checked voltage on the 12v batt as all 4 dc6's were discharging and it read over 15v, so I switched back to 2 amps. I'll keep an eye on it and switch back to 6 amps when they start charging.

    Am I missing something that is about to start yet another issue? I've had my share so far with this project.

    YY
     
    Eddy2014 likes this.
  6. ryousideways

    ryousideways Member

    Joined:
    Apr 24, 2013
    35
    91
    0
    Location:
    Merritt Island, Florida
    Vehicle:
    2005 Prius
    Model:
    II
    Here is what I have collected so far. One thing to remember is my power source died during one of the 8 charging times so you will see an a 4th set of charge discharge data. That is where I set up a single discharge/charge. If there is a **** that means the discharge cycle was not written down.

    LET THERE BE DATA!!!

    Battery Module #1
    Discharge: 3921mAh | 5706mAh | 4226mAh | ****mAh
    Charge: 6750mAh | 6750mAh | 0000mAh | 6750mAh

    Battery Module #2
    Discharge: 4710mAh | 5619mAh | 5723mAh
    Charge: 6750mAh | 6750mAh | 6750mAh

    Battery Module #3
    Discharge: 2190mAh | 5737mAh | 5208mAh | ****mAh
    Charge: 6750mAh | 6750mAh | 0000mAh | 6750mAh

    Battery Module #4
    Discharge: 4180mAh | 5314mAh | 5433mAh
    Charge: 6750mAh | 6751mAh | 6750mAh

    Battery Module #5
    Discharge: 1949mAh | 5655mAh | 5554mAh | ****mAh
    Charge: 6750mAh | 6750mAh | 0000mAh | 6750mAh

    Battery Module #6
    Discharge: 2453mAh | 3002mAh | 4072mAh
    Charge: 5056mAh | 6287mAh | 6641mAh

    Battery Module #7
    Discharge: 1758mAh | 5681mAh | 5756mAh | 2920mAh
    Charge: 6750mAh | 6750mAh | 0007mAh | 6750mAh

    Battery Module #8: Cycles are Pending

    Battery Module #9
    Discharge: 2983mAh | 4262mAh | 5096mAh
    Charge: 6028mAh | 6750mAh | 6750mAh

    Battery Module #10 -- #19: Cycles are Pending

    Battery Module #20
    Discharge: 4075mAh | 5164mAh | 5255mAh
    Charge: 6751mAh | 6751mAh | 6750mAh

    Battery Module #21

    Discharge: 4647mAh | 5472mAh | 5585mAh
    Charge: 6750mAh | 6750mAh | 6750mAh

    Battery Module #22

    Discharge: 0680mAh | 5616mAh | 5637mAh | ****mAh
    Charge: 6750mAh | 6750mAh | 6446mAh | 6750mAh

    Battery Module #23

    Discharge: 3392mAh | 4536mAh | 5052mAh
    Charge: 6274mAh | 6750mAh | 6750mAh

    Battery Module #24

    Discharge: 1178mAh | 5567mAh | 5534mAh | ****mAh
    Charge: 6750mAh | 6750mAh | 1527mAh | 6750mAh

    Battery Module #25

    Discharge: 4658mAh | 5241mAh | 5622mAh
    Charge: 6274mAh | 6750mAh | 6751mAh

    Battery Module #26

    Discharge: 1321mAh | 5761mAh | 5777mAh | ****mAh
    Charge: 6750mAh | 6750mAh | 1019mAh | 6750mAh

    Battery Module #27

    Discharge: 2343mAh | 3496mAh | 4182mAh
    Charge: 5046mAh | 6267mAh | 6750mAh

    Battery Module #28

    Discharge: 1401mAh | 5786mAh | 5795mAh | ****mAh
    Charge: 6750mAh | 6750mAh | 1501mAh | 6751mAh

    Whew! At least there is only 28 batteries!
     
  7. YY4U

    YY4U Junior Member

    Joined:
    Apr 6, 2013
    85
    22
    0
    Vehicle:
    2006 Prius
    Model:
    N/A
    #6 and #27 look suspect. Perhaps another cycle would help?

    Two Y's
     
  8. ryousideways

    ryousideways Member

    Joined:
    Apr 24, 2013
    35
    91
    0
    Location:
    Merritt Island, Florida
    Vehicle:
    2005 Prius
    Model:
    II
    Yup. I ran into the same issue. I have actually been monitoring my Hitec X4 chargers once every 4 to 8 hours or so. I have been switching the trickle charger from 12 volts @ 2amps to 12 volts @ 6amps and back again. I use my multimeter to check the voltage of the battery. If I see it starting to spike close to 15 volts, I knock the trickle charger down to 2 amps. If it starts to drop below 12 volts I kick it back up to 6 amps.

    The other Hitec X4 charger is being powered the computer power source I customized so its a constant 12 volts (as long as my power does not go out.)
     
  9. ryousideways

    ryousideways Member

    Joined:
    Apr 24, 2013
    35
    91
    0
    Location:
    Merritt Island, Florida
    Vehicle:
    2005 Prius
    Model:
    II
    I agree but not exactly sure yet. I think one of the prius gurus will pop in some time today for the assist.
     
  10. jdenenberg

    jdenenberg EE Professor

    Joined:
    Nov 21, 2005
    3,433
    1,496
    1
    Location:
    Trumbull, CT
    Vehicle:
    2020 Prius
    Model:
    LE AWD-e
    I agree, but your charging cutoff at 6750 is triggering before charging is complete. I would raise the safety limit to 7250 mAh.

    My modules got to 6.5 Ah by the third cycle with the higher charging safety limit.

    JeffD
     
    gdanner likes this.
  11. ryousideways

    ryousideways Member

    Joined:
    Apr 24, 2013
    35
    91
    0
    Location:
    Merritt Island, Florida
    Vehicle:
    2005 Prius
    Model:
    II
    I decided to use 6750mAh because I saw it on another thread somewhere on prius chat. I have also seen the limit set to 7500 mAh. I figured as long as it was above 6500 mAh it would be ok.

    Does this mean I need to start the 3 cycle process all over again with all of the battery modules at 7250 mAh? Or should I just do another 3 cycle process to modules #6 and #27? Or just a one cycle discharge to charge?
     
  12. jdenenberg

    jdenenberg EE Professor

    Joined:
    Nov 21, 2005
    3,433
    1,496
    1
    Location:
    Trumbull, CT
    Vehicle:
    2020 Prius
    Model:
    LE AWD-e
    One cycle at 7250 should do, but do some more modules at the higher setting to see how it goes. Have you checked the resting voltage of your modules? They should be a bit below 8v after a resting period and then exhibit a very slow self discharge rate for the next few weeks. I would also determine the series resistance of each module by measuring the terminal voltage while doing a 1 amp discharge.

    Matching all 28 rebalanced modules:
    1. Same capacity - within about 0.2 ah
    2. Same terminal voltage - within 0.05 v by controlled discharge of high modules
    3. Same series resistance - within about 10% (you can pair up modules to control this further as the resistances add)
    and all having similar low self discharge rates will result in not having to do the job again for a long time.

    JeffD
     
  13. ryousideways

    ryousideways Member

    Joined:
    Apr 24, 2013
    35
    91
    0
    Location:
    Merritt Island, Florida
    Vehicle:
    2005 Prius
    Model:
    II
    I finally got to the point where I can attach the batteries in parallel. Thank you for the sugesstion. Took almost 2 hours to set up the wiring. Right now it is sitting in the garage equalizing out.

    Another update with photos:

    The crazy wiring you see below is the custom harness I created
    to connect the modules in parallel. All the positive terminals connect to the positive
    and the negative to the negative. It is just speaker cable I found in my garage.
    [​IMG]

    [​IMG]

    [​IMG]

    This is the paper where I recorded all my data from the Hitec x4 chargers.
    [​IMG]

    [​IMG]

    More info in a bit...
     
    maverick1970 and TheDoof like this.
  14. YY4U

    YY4U Junior Member

    Joined:
    Apr 6, 2013
    85
    22
    0
    Vehicle:
    2006 Prius
    Model:
    N/A
    Update?
     
  15. ryousideways

    ryousideways Member

    Joined:
    Apr 24, 2013
    35
    91
    0
    Location:
    Merritt Island, Florida
    Vehicle:
    2005 Prius
    Model:
    II
    Sorry for the delay everyone. After I got it back together I drove it 120 miles with a mix of highway and stop and go traffic. Before I had balanced the battery pack I was only able to make it about 16 miles before the triangle would show and battery vent fan would kick on. Proper battery balancing is must.

    I just got back from taking it for a 3000 mile test drive after putting it back together. Yes, you read correctly. 3000 miles. I drove from Cocoa Beach, FL to Atlanta to Washington DC, to Maryland and back. (Rock climbing trip) I am happy to report that there have been no problems! The trip averaged about 48 mpg.

    That funky code I was throwing U0100 and U01111 was from plugging in the OBD II scanner while the car was running. It would trip the code as soon as I plugged it in. (You must plug it in while the car is off THEN run the scanner)

    I will work on putting together a simple step by step process of exactly how to do this. In the meantime here is a quick overview:

    Tools:
    • Metric sockets
    • Common Sense (This will help prevent you from electrocuting yourself)
    • Electrical Tape
    • 10 feet of stereo wire

    NOTE: Make a post on Facebook to see if any of your friends have these battery chargers. I bought mine only to find out a few friends already owned what I needed. These battery chargers are commonly used to power R/C cars, planes, and helicopters.

    Basically you will need to disassemble the back of your prius in order to get to the battery pack so you can remove it.
    There are quite a few videos out on how to safely remove the battery pack. From there you disassemble the battery pack itself by removing the top casing and both bus bars that are under the plastic covers. Use extreme caution when doing this. The batteries are wired up in series.

    Label your battery modules with a permanent marker. 1 through 28. You use the voltmeter to test the voltage of each individual cell. Record your results on a sheet of paper or excel spread sheet. All of them should be within .05 volts. The modules with abnormally low voltage are usually the cause. In my case I had two modules go bad. It is a good idea to load test the battery as well. I used a 55 watt halogen bulb with some alligator clips. If you are unsure which modules are bad, post your results here on priuschat. The forum is very helpful.

    Once you determine your bad modules
    It helps to mark the culprit module with an "X" or something to help you remember what to replace.You must replace them. You can order used replacement modules from ebay. They are generally $30 to $50 a piece. You will have to remove the battery modules one by one until you get to the bad battery. Each module is held in by one screw at the bottom of the case.

    Balancing the battery pack:
    IMPORTANT NOTE: Leave battery modules compressed in the case when charging. Otherwise they will swell.
    It takes about 1.5 days to balance a single battery module. So 8 NiMh balancers will allow you to balance all 28 of your batteries in about 6 days. I figured 8 chargers was a good time to cost ratio. If you have 14 charger it will take only 3 days. If you have 1 charger it will take 42 days. (1 charger not recommended)
    Because your battery pack is wired in series each module should have almost an identical voltage and charge. This is where your expensive chargers come in handy. You will need to discharge then charge each individual module three times. Set to NiMH.

    Settings:
    Charge at 5 amps up to 7250mAhr
    Discharge at .7 aMhr down to 6 volts
    DSCH<CHG for 3 cycles.
    Other settings: I set the timer limit to 720 minute cut off. I also set the cool down period to 5 minutes.

    As you balance your modules, record the 3 cycles of data the your chargers have given you. If you notice one of the batteries is not charging to full capacity, run another cycle. If it still is not charging to full capacity you may need to order another module from ebay. After all your modules have been balanced by your chargers, check and record the voltage of each one. They all should be within .05 volts of each other.

    Final balancing:
    This is where it is a little tricky and time consuming. You need to create a wiring harness to connect all your modules together in parallel. This means all of the positive terminals are wired together and all the negatives terminals are wired together. Positive to positive, negative to negative. DO NOT TOUCH THE POSITIVE TO THE NEGATIVE!!! You are basically creating one large 7.2 volt battery. Doing this will equalize the voltage difference between the batteries. Leave it like this for about 6 to 24 hours. It took about 6 hours for my batteries voltage to equalize.

    Do a final voltage check to all your battery modules. At this point they should be identical with a .01 to 02 volt difference. Remove your custom harness you made and reassemble your battery casing. Installation is reverse of removal. Before putting all of your interior pieces back together take your Prius for a test drive.


    I literally put my prius back together the day I left for my epic road trip and it has been working ever since. Thank you everyone here for all your help!!!
     
  16. YY4U

    YY4U Junior Member

    Joined:
    Apr 6, 2013
    85
    22
    0
    Vehicle:
    2006 Prius
    Model:
    N/A
    Congratulations on a fine job and write up!

    Things aren't going as well for me.
     
  17. wegortw

    wegortw Junior Member

    Joined:
    May 7, 2013
    38
    24
    0
    Location:
    Austin, TX
    Vehicle:
    2005 Prius
    Model:
    II
    Starting my rebuild next week for the following reasons:

    P0A60 - Voltage difference between battery blocks is higher than standard
    P3019 - BATTERY BLOCK 9 BECOMES WEAK

    I just wanted to say I love you :) (the bro type) for this great write up!
     
  18. ryousideways

    ryousideways Member

    Joined:
    Apr 24, 2013
    35
    91
    0
    Location:
    Merritt Island, Florida
    Vehicle:
    2005 Prius
    Model:
    II
    Haha you are welcome! Just be careful and use common sense. If you have problems/questions create a post. I am working on a detailed write up so hopefully it will be up before you get started. :)
     
    Eddy2014 and Kala like this.
  19. wegortw

    wegortw Junior Member

    Joined:
    May 7, 2013
    38
    24
    0
    Location:
    Austin, TX
    Vehicle:
    2005 Prius
    Model:
    II
    Question about the wiring harness pictures above, it looks like you ran the negatives to every other one on the same side but on the positives you crossed the batteries to the opposite side for all of them; why did you set it up this way?

    I am basically thinking of running the positive and negatives to every other one on the same side, then at the ends running them across to put them in parallel; would this be wrong?

    Separate devils advocate question, I understand re-balancing the whole pack truly puts new life into the pack. But seeing how I am short on time with no backup transportation I am thinking of...

    1. Just replacing the bad cell
    2. Charging it to match the charges of the others (7.81)
    3. Doing the final balance, putting the batteries in parallel and letting them level out

    I have read where others have just replaced and reinstalled without the final balance and had a bad experience, but I didn't see any forum threads where they tried it with the final balance. Would this work?
     
  20. jdenenberg

    jdenenberg EE Professor

    Joined:
    Nov 21, 2005
    3,433
    1,496
    1
    Location:
    Trumbull, CT
    Vehicle:
    2020 Prius
    Model:
    LE AWD-e
    Success will depend on how well the replacement module matches the other 27 modules:
    1. Capacity - How much energy does each module store
    2. Self discharge rate - Usually very slow in a good module; about a tenth of a volt per month (after the surface charge dissipates)
    3. Series resistance - all batteries exhibit a voltage drop while sourcing or sinking current.
    You should at least do a rebalancing run on the replacement module to check that it is in good shape.

    JeffD
     
    Eddy2014 and flxcon like this.
Loading...