Hybrid battery load test and intelligent tester have different results

Discussion in 'Gen 2 Prius Technical Discussion' started by sushiho160418889, Mar 18, 2018.

  1. sushiho160418889

    sushiho160418889 New Member

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    Hi there, the data list live of GTS intelligent tester said my Gen2 (2005) always has a abnormal low voltage on block 1 and block 10 but when i disassembly the battery and performed load test on each module (28 modules) I found out that the voltage drops of block 1 and block 10 are quite normal comparing with other blocks . My questions are:

    1) Which method can accurately identify the modules with bad condition, load test or intelligent tester ? why ?

    2) Is there any possibility that bad connecting wire can cause these problems? (the signal wires and high voltage wire are full of oxidation)

    3) the high voltage wire from service plug is full of oxidation as well and it's connected between two modules in block 10, could it be the reason ?

    4) I have another battery pack of 28 modules from another Gen2, so if i wanna identify the best 28 modules, what should I do?
     
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  2. Dxta

    Dxta Senior Member

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    You would only get good results, when you load test the modules using an automotive headlamp bulb, when you have the pack on your work table.

    You can also discharge/charge the pack while in the car, and observe what voltage readings you get on tech stream.

    The voltage sense wires are a big culprit in this case, since you got NP discrepancies on the modules you tested. Clean the corrosion, and test again.

    PS: Without doing a load test, you'd never get the bad modules.
     
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  3. jadziasman

    jadziasman Prius owner emeritus

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    You need to do capacity test instead of load tests. Discharging a module for 1 to 2 minutes does not drop the voltage enough to find the weak ones. Capacity testing will. Weak modules discharge to 6V from fully charged in 15 minutes. Strong modules discharge to 6V from fully charged in 30 minutes. That is with using a 12V 55w headlight lamp with both filaments connected. Try that.
     
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  4. sushiho160418889

    sushiho160418889 New Member

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    I've performed the load test earlier with an automotive light bulb (sorry I forgot the watts it has, i will check it tomorrow). Here's the result:


    All modules had an initial voltage of approximate 8.16V and then they were discharged in 180 seconds

    Module Voltage drop (V)

    01 0.366
    02 0.38
    03 0.382
    04 0.381
    05 0.388
    06 0.393
    07 0.382
    08 0.38
    09 0.387
    10 0.392
    11 0.387
    12 0.386
    13 0.399
    14 0.387
    15 0.39
    16 0.385
    17 0.407
    18 0.454
    19 0.404
    20 0.382
    21 0.405
    22 0.388
    23 0.39
    24 0.394
    25 0.38
    26 0.383
    27 0.377
    28 0.393


    Is that normal to have the high voltage drop in the middle and low at both ends?
     
    #4 sushiho160418889, Mar 18, 2018
    Last edited: Mar 18, 2018
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  5. sushiho160418889

    sushiho160418889 New Member

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    Discharging the modules until 6V, would it damage the modules?
     
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  6. sushiho160418889

    sushiho160418889 New Member

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    Regarding the high voltage wire, the one connected to the first module (netgative) has so much corrosion but the one connected to the last module (positive) is perfectly fine. Can anyone explain this?
     
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  7. jadziasman

    jadziasman Prius owner emeritus

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    No.
     
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  8. jadziasman

    jadziasman Prius owner emeritus

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    This is not the typical experience of most who have opened the HV pack and inspected it. Most of the copper plates and fasteners linking the modules to create the 200+ volt battery have corrosion on them after several years of use due to condensed moisture inside the battery pack which is inevitable except in arid regions. Localized corrosion such as yours could mean that the first module is venting gas ever so slightly. The modules are vented to reduce the possibility that they will explode.
     
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  9. sushiho160418889

    sushiho160418889 New Member

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    but why the negative terminal instead of positive?
     
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  10. jadziasman

    jadziasman Prius owner emeritus

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    While corrosion is much more prevalent with the anode than the cathode, cathodic corrosion does occur in some circumstances. Personally, I don't know what conditions promote it.
     
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  11. Dxta

    Dxta Senior Member

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    It won't damage the modules. That would be like 1.0V per cell. Going beyond that, would be damaging to them.
     
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  12. Dxta

    Dxta Senior Member

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    I seems not to get what these values mean. Y are they in the 0.3....? Aren't they supposed to be in their 7...or 8..?
     
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  13. fotomoto

    fotomoto Senior Member

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    Yes. The inner pack modules run hotter over their lifetime and numerous failures are reported there but there are exceptions so it's not a hard and fast rule. During my (wack-a-mole) repairs, I reshuffled the whole pack to move the middle modules to the ends.
     
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  14. dolj

    dolj Senior Member

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    It is the delta voltage –> starting voltage - ending voltage
     
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  15. Dxta

    Dxta Senior Member

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    Alright, thanks a lot.
     
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  16. sushiho160418889

    sushiho160418889 New Member

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    The values are calculated by initial voltage minus the end voltage after 180 seconds
     
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  17. Rohana Mallawa

    Rohana Mallawa New Member

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    Please explain what is the Value used as "fully charged" condition in this test.
    Thanks
     
    #17 Rohana Mallawa, Jun 21, 2020
    Last edited by a moderator: Jun 22, 2020
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  18. RickyV12

    RickyV12 Junior Member

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    Thanks for your info, you must know those battery module very well, It is cheap way testing capacity of battery, I fully charge 3 module using 24V smart car charger with timer, Then I did 12V 55W car light test, Good modules last for 30+min discharge to 6V, while weak battery last less than 15 min.
    It is also a cheap way to recondition batteries as well, I used this cheap methods to charge and discharge battery to recondition batteries, After 2 times. all batteries can keep car light bulks for more than 40 to 50 min. I used 3 car light bulbs with 24V smart car battery charger, I recondition 28 modules in less than 1 day.
     
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  19. C Wagner

    C Wagner Member

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    This looks a risky way to charge, although discharge to 6V (if you catch the cutoff correctly) seems pretty good. The problem with charging with a charger not made for NIMH is that you have to turn down the charging current as you get above 8.4 or so volts. If you don't, the modules will expand and more importantly will outgas -- and you'll never get that electrolyte back in there, so you don't want a lot of outgassing for module long life. I wrote up a Wiki on my experiences repairing the HV pack and its modules including the charge cycling and the rebalance, if anyone is interested to go through the process.
     
  20. Dxta

    Dxta Senior Member

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    Alot of interest. Drop the link here
     
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