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Do older hybrid battery packs heat up more than newer ones?

Discussion in 'Gen 2 Prius Main Forum' started by Brando714, Jun 14, 2020.

  1. Brando714

    Brando714 Member

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    So I just want to know the answer to that question because I tried everything to see why my hybrid battery is heating up according to Dr.Prius' temperature chart. So I tried everything at least I know of to see why this can be. I cleaned the fan, I cleaned the harness, and at high 120s fan speed is at 5 out of 6 and I even got out of the car and can hear and feel the fan operating. I even took off the cover, undid the dent on the battery cover where technicians may have leaned their knees or sat on and now it is flat and even so unusual air flow when it was caved in. I made sure the 2 vents on the right side of the battery were fully inside the battery pack and installed properly. Also made sure the other ends were properly installed into the fan and duct. I checked the surrounding harness to make sure no other harness had water corrosion. Only one of the harness, the bigger one, had green water corrosion that gave out some codes but since then I sprayed DeOxyIT and cleaned it with toothbrush and plugged/unplugged few times and code has not popped up in few days. I'm pretty sure harness contact is fine now since fan speed does reach 5 out of 6 like I said, but wonder when it will reach full speed of 6? Did I do everything to try to see why my fan isn't keeping my battery at normal temperatures? Also I know on the left top side of the battery, there is a black strip or blockage so air flow coming in wont just escape to the other end, but rather distribute the air down each of the blocks. I'm puzzled what's going on. No error codes. California weather is 90F and AC is not on full blast but cool enough for comfort. 12.6V is the battery when engine not on
     
  2. sam spade 2

    sam spade 2 Senior Member

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    What exactly makes you think that the temps you are seeing is NOT "normal" ?
    Charging and discharging creates heat. The faster the current flows, the more the temp goes up.
    The ventilation is there not to keep it "cool" necessarily but to keep it from OVERheating.
     
  3. Brando714

    Brando714 Member

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    Because Dr. Prius app shows 130F for a 25 mile drive and is in RED with the warning "Abnormal Temperature" on it
     
  4. PriusCamper

    PriusCamper Senior Member

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    A thermal camera will help with a problem like this... Are all temp numbers the same on Dr. Prius app? Usually if it's not a ventilation failure, the heat is from one of the 168 cells wired up in a series. When big amps move through a failing cell it creates a lot of heat. Once you get it up to 130' again use a thermal cam to find the source of the problem.
     
  5. Rmay635703

    Rmay635703 Senior Member

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    Since others can’t answer

    Yes a aging pack can have an increase in internal resistance and thus heat but in your case you would do well to figure out if a cell or two has failed or if the ventilation fan is plugged

    that is all
     
  6. PriusCamper

    PriusCamper Senior Member

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    It's not that we can't answer that question, it's that the question is not relevant to this particular problem.
     
  7. Brando714

    Brando714 Member

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    damn, I dont have a thermal cam.
     
  8. Brando714

    Brando714 Member

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    YES the fan works. I hear it clearly when I put my ear to the passenger side and feel the air. The harness not only is firmly connected but before it I cleaned it with DeOxyIt and lightly brushed it with toothbrush and NO it did not mess it up in the process because once again, not only do I see the fan speed on TorquePro app but also I hear it and feel it. If it was a fan issue, I would've figured it out long time ago because it was the first source I went to
     
    #8 Brando714, Jun 14, 2020
    Last edited by a moderator: Jun 15, 2020
  9. 2GenPrius

    2GenPrius Member

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    Hey I've been tinkering with my Prius because it seems to have an heat issue with the battery as well. Did you look at the resistance rates also for each module?

    This is the crap I've been dealing with, and I'm not too far from you in the OC with my own woes. I'm using Hybrid Assistant.

    I think I've narrowed my problem down to a bad 12V, will find out tomorrow (discharge/charge rates all over the place on the screen, bad fuel economy). The fan on Hybrid Assistant will spin down on Level 6 and it sounds like an aircraft landing in the cabin when it gets that hot.

    [​IMG]
     
  10. Brando714

    Brando714 Member

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    thanks for your response. Here is my screenshot of when I took it right before it reached 130. Amp discharge seems crazy but it kept fluctuating so hard to see what the average was. I have another screen shot when temperatures were still in the mid 110s and amp discharge saids 2.5. Also I checked the 12V battery with multimeter which saids 12.6V as well from the display inside the car using the Secret Display screen AKA 12V battery check:

    Without brake pedal, press the Power button once and release to enter ACC mode
    - Press and hold the MFD Info button, then turn the headlights on and off three times to enter Maintenance mode; release Info button
    - Press “Menu” (on screen)
    - Press “Display Check”
    - Press “Vehicle Signal Check” - the battery voltage is shown and should be about 12.4 to 12.8 Volts (normal for an unloaded battery)
    - Again without brake pedal, press Power button and release to put a current load on the battery - the voltage should stay above 12.0V (if less than 12.0V the battery is not well, or there is a fault or unusual load somewhere)
    - Press brake pedal and press Power button once to enter "Ready" mode - the battery is now charging at about 14V (if less than 13.6V or more than 14.4 there may be a problem with the charging circuit)
    - Turn car OFF to leave Maintenance mode
     

    Attached Files:

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  11. PriusCamper

    PriusCamper Senior Member

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    If you know anyone who's a home inspector, they have 'em...
     
  12. fmerkel

    fmerkel Member

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    Ignoring al the other variables. yes....absolutely..... an older battery heats up more with use than a newer equivalent battery.
    As batteries age, their internal resistance goes up. This is true for ALL rechargeable batteries. It's not quite accurate but think of it like 'friction'. As electrons go in and out during use on an an older battery they have more 'friction' to overcome and this translates as heat. Ultimately this manifests itself as a battery that is failing to do the work that is required. Doesn't matter if this is a NiMh AA cell in a flashlight. or a whole pack of them trying to move a car down the road.
    Cells get old and fail. How and when can be quite variable depending on the hugely variable issue of use.
     
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  13. Brando714

    Brando714 Member

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    thank you for your response and input. Would a reconditioned battery solve this problem?
     
  14. 2GenPrius

    2GenPrius Member

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    I had already tested the 12V battery (followed the procedure above as well) and assumed it was good as it passed the signal tests above with NO codes. I'm used to seeing a battery fails and the dash lights up like Xmas, but I guess with hybrids it doesn't happen. I happened to take the 12V battery Autozone for a test. It tested at 99% capacity, yet the screen stated that the battery still failed load test (I'm thinking a cell in it probably died).

    This kinda makes sense, because as my hybrid battery is charging/discharging, I'm noticing the levels fluctuate everywhere.

    The resistance range for my first module set is really high compared to the rest.
    [​IMG]

    The local Toyota dealership has a sale on them this month (wonder why, summer all batteries dying) so gonna get me a True2 AGM Toyota. I've been driving the car for about two years, and my gf three years before then so maybe its the 12V battery.
     
  15. Brando714

    Brando714 Member

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    Your amp/current has a huge difference compared to mine, which is pretty much all in unison except for one block (occassionally). also I'd like to mention that I watched a ChrisFix video and he mentions that the battery pack gets hot the most in the middle, so to put the thermometer (green wires on top of the battery pack) more closer to the center so the fan can kick on sooner and stronger.
     
  16. 2GenPrius

    2GenPrius Member

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    The levels fluctuate as the car runs and the battery charges/discharges. When I replace the 12V battery tomorrow, I'm assuming it will stabilize the gap.
     
  17. Brando714

    Brando714 Member

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    I'm finally out of furlough starting tomorrow so I will be driving 40 miles one way for the first time on the Prius so I will post an update on how hot the battery temperatures get. Also I'd like to clarify that ChrisFix did not say to put the temp. gauge all in the center, but rather just a couple rows closer towards the center on the sensors that are on the left and right side
     
  18. Brando714

    Brando714 Member

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    Ya hopefully it's a cheap 12V battery fix compared to replacing the whole hybrid battery pack
     
  19. dolj

    dolj Senior Member

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    @2GenPrius, the 12 V battery has nothing to do with what you are seeing in the HV battery. You are wasting $200-$250 chasing that.

    @Brando714 and @2GenPrius, The value of the charge/discharge Amps is not high. The voltage levels of the green bars will always be moving up and down while the HV battery is in use. The way the app displays the bars exaggerates the difference. Your screenshots show 0.13/0.14/01.7 V which is well within specs.

    @Brando714, I'd be wanting to verify that the temperature is actually in the region of what is reported by the temperature sensors. I think somebody has already suggested using an IR thermometer? That's what I'd be doing.

    Is it possible for you to get a photo of how the three temp sensors are mounted inside the battery?
     
    #19 dolj, Jun 15, 2020
    Last edited: Jun 15, 2020
  20. sam spade 2

    sam spade 2 Senior Member

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    BUT a higher internal resistance likely means a LOWER maximum current flow, both charging and discharging, which will mean less available stored energy but not necessarily higher temperatures. Might actually be a bit lower.

    HOWEVER...... if some of the cells or modules fail in such a way that their resistance actually is LOWER, then overall current may go UP and that cell might overheat.

    I don't think that a thermal "camera" is necessary to detect hot spots.
    A hand held IR thermometer should do the job. Even the ones from Harbor Freight seem to be reasonably good.