HV Battery Question

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by cnc97, Feb 19, 2021.

  1. cnc97

    cnc97 Senior Member

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    For the battery experts, I am noticing the following things occurring.

    1. HV Pack voltage drops below 180v under hard acceleration. It quickly recovers to over 200v during normal driving

    2. HV Pack voltage goes to 265v under regen, quickly dropping to 200v on normal driving.

    Internal resistance shows to be 21-24 milliohms.

    Am I in the early stages of a battery failing?
     
  2. sam spade 2

    sam spade 2 Senior Member

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    Maybe. But those measurements alone don't prove it.

    Exactly how are you determining that internal resistance ?
     
  3. cnc97

    cnc97 Senior Member

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    These are readings on either the Dr Prius app, or thru my OBD scanner.
     
  4. cnc97

    cnc97 Senior Member

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    And the voltage readings, the extreme high and low show in red on the Dr Prius app.
     
  5. cnc97

    cnc97 Senior Member

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    I got out for an extended drive this evening. About 30 minutes. Other then the wild voltage fluctuation, the car is driving fine.

    Should I start battery shopping, or is this just a product of the outside temps hanging out in the 20’s or below?
     
  6. cnc97

    cnc97 Senior Member

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    Deleted, double post
     
  7. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    The numbers don't say much of anything of value. Many of the tests and apps out there are just above useless or are there to peddle something to you.

    For prismatic cells, your internal resistance is high. But it doesn't matter. It just has to be closely equal to the rest of the pack, which it appears to be. Large voltage swings are also normal. Your capacity is obviously degraded, but the car is taking care of it just fine.
     
  8. cnc97

    cnc97 Senior Member

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    In other words, unless codes come up, I’m not really going to know that it’s time to replace it?
     
  9. vvillovv

    vvillovv Senior Member

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    If DrPrius graph is turing RED during regen, I'd suspect pack degradation. How much is not easy to determine and often has a lot to do with your driving style.
    My Prime is also showing higher internal resistance during this cold snap.
    I believe going easy on charge and regen (trying to keep it out of the RED zone and reducing the voltage swing and much as you can manually by Amps gauge in DrPrius) can help the car and you take better care of the pack.
    Keep your finger crossed the pack recovers nicely as the temps warm up. I know I am....
     
  10. cnc97

    cnc97 Senior Member

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    I have got a “too good to pass up” deal on a pack from a wrecked, low mile 2014 Prius. Someone knocked the bumper cover off it, but it popped all the bags, so it got totaled. The yard is pulling it today, and I’ll get it late tonight or lunch time tomorrow. I have a hobby 4 bank charger that I will use to make sure the battery is up to snuff before I install it.
     
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  11. cnc97

    cnc97 Senior Member

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    Picked up the pack this morning. Showing 221v at the leads when removed from car. They took the cooling fan and everything else off of it. I’m off this weekend, so I think I’m just going to go for it. I personally know who took the battery out, and he yard drove it to the dismantle shop.
     
  12. cnc97

    cnc97 Senior Member

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    Swapped the newer pack in this evening. Took about 90 minutes. My heart sank as I hit the power button and was graced with a Check Hybrid System message. P0B47. I was set to swap the pack back over and it dawned on me, recheck all my plugs that I messed with. The voltage sense connector to the battery ECU wasn’t secure. It clicked a second time and all is well. I’ve been too busy hotdogging to see if the mileage is going to come up.

    The charge percent is a lot less “fluid” then it was, so we will see.
     
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  13. vvillovv

    vvillovv Senior Member

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    Great work and 90 min. awesome...

    I know feelings both of a loose connection and wanting to see just how much juice another pack gives the car.

    I hope your spare has as much or more juice than the original.
     
  14. cnc97

    cnc97 Senior Member

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    Home to gas station to work this morning. Almost 2 miles from indicated 60% charge until ICE kicked in.
     

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  15. vvillovv

    vvillovv Senior Member

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    That looks OK to me 1000 miles away and about 10 degrees colder here today. Nothing earth shattering, although if I comprehended the meaning of hotdogging correctly, I think it may take the computers a while to adjust to less hotdoggin type drivin.
    Do you have techstream or an app and elm327 bluetooth?
     
  16. cnc97

    cnc97 Senior Member

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    Top One Bluetooth OBD and Car Scanner/Dr Prius apps. Internal Resistance on newer pack is 17 milliohms. State of charge drops by decimals of a percent instead of whole digits of a percent during driving.
     
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  17. vvillovv

    vvillovv Senior Member

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    I think I get your meaning now.......;)

    edit: I must have crossed some of my own wires. I'm also following a similar thread with a 2014 Plugin spare traction pack in the PiP section. And the dash pic above reminded me of my 14 PIP gauges.

    2 EV miles in a 10? are you serious? :whistle:
     
    #17 vvillovv, Feb 26, 2021
    Last edited: Feb 26, 2021
  18. cnc97

    cnc97 Senior Member

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    Five days and five commutes later. Economy has settled into 48ish MPG with warmup penalty for lows in the mid 30’s here. That’s a huge gain from the indicated 33 mpg that I was getting.

    And the EV is 1.5-1.6 miles. I mapped it out today on one of my trips. If I could survive without needing the heat on, I could probably get another few tenths of a mile, as that’s about how long it takes for the ICE to kick back on due to coolant temp falling. This spring/summer I’m going to try and gain entry to the 700 mile club. I made it to the 600 mile club in 2018.
     
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  19. vvillovv

    vvillovv Senior Member

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    My 06 other hybrid is getting unbalanced again in the cold weather, even with all the tricks I can think up to go easy on the charge and regen and keepin the batteries warm, but not too warm. I even commented in a email a month ago that I was sure my strongest ole pack was not strong enough to make it through the winter.

    It's always a kick for me when I read about a successful pack install and how much of an improvement it can make in our hybrids performance.

    I'll keep my fingers crossed for ya makin it into the big 700 club this year too.
     
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