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What is the lower limit of SOC to start the ICE?

Discussion in 'Gen 2 Prius Technical Discussion' started by y_one2002, Oct 11, 2015.

  1. y_one2002

    y_one2002 Junior Member

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    I am planning to deep drain the HV battery by putting my 2006 Prius in neutral and keep some current draw from the HV battery. I don't have a grid charger installed.
    I wonder what is the safe SOC that I can still start the ICE?
    Thanks.
     
    #1 y_one2002, Oct 11, 2015
  2. bisco

    bisco cookie crumbler

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    welcome! two purple bars. if you leave it in park, it will do it automatically.
     
    #2 bisco, Oct 11, 2015
  3. y_one2002

    y_one2002 Junior Member

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    I wonder if the battery can go further down below 40% SOC and still can start the engine.
    If so, what is the safe and lowest point?
    Thanks.
     
    #3 y_one2002, Oct 11, 2015
  4. bisco

    bisco cookie crumbler

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    hmmm, good question. it's probably more of a computer cutoff limit. i wonder if it's in the service manual.
     
    #4 bisco, Oct 11, 2015
  5. dorunron

    dorunron Senior Member

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    Just have to ask this question. Why are you wanting to discharge the traction battery?
     
    #5 dorunron, Oct 11, 2015
  6. y_one2002

    y_one2002 Junior Member

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    My 10 year old Prius just passed 150k miles. I am planning to perform a battery recondition even though everything is working fine.
    Deep draining the battery is part of my experiment. I want to test it before the battery recondition. I want to find out if deep draining can actually bring back some lost performance.
     
    #6 y_one2002, Oct 12, 2015
  7. jeff652

    jeff652 Senior Member

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    It certainly can, if done right. We have scores of customers who have already done this with their Prius and had great results. The car will prevent the battery from being drained anywhere near enough for a deep discharge to benefit the cells. You won't be able to do it with just the car. You need an external load, and an external charge source to bring it back after discharging.
     
    #7 jeff652, Oct 12, 2015
  8. y_one2002

    y_one2002 Junior Member

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    I have seen charging/discharging individual battery cells could help. I am uncertain doing that on the whole pack could help . That is why I want to do the experiment. Right now I am still looking for the answer to my original question. Anyone know? Thanks.
     
    #8 y_one2002, Oct 12, 2015
  9. CooCooCaChoo

    CooCooCaChoo Senior Member

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    One time I went through a car wash and came out the other side with 1 red bar and the Red Triangle with the warning to switch to D or P to recharge the battery.

    This was one of those where you have to put the transmission into neutral and get pulled along through the wash. I went in with 4 bars I think and came out with 1 red and was still able to have the ICE engage and charge the battery.
     
    #9 CooCooCaChoo, Oct 12, 2015
  10. HGS

    HGS Member

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    I suppose if money is not an issue, experimenting would be fun. But, if the car is running well, I wouldn't touch mine. The traction battery should go many more miles and years on average. There are some very high mileage cars with the original untouched battery. The failure rate is sub-3% I hear on PC.

    There is a small chance the experiment will cost, not, save money. But, all in all, good luck with your adventure.

    Cheers!
     
    #10 HGS, Oct 12, 2015
    dorunron likes this.
  11. y_one2002

    y_one2002 Junior Member

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    You have a very good point. I am still debating if i should perform the task. I ordered the Techstream cable and software. I will find out the delta V under load and determine if I will do it.

    Hey guys,
    What is HV battery terminal stud size?
    What connection should be used to charge individual battery module for 3A current? alligator clip or fork terminal?
    thanks.
     
    #11 y_one2002, Oct 12, 2015
  12. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    As others have said the car will not let you drain the battery to a point of too low to start. If you really want to drain your battery down use reverse, not neutral. To do a charge and discharge test.

    With a Mini VCI and Techstream you can look at live battery data while doing the charge and discharge test.

    Brad
     
    #12 strawbrad, Oct 22, 2015
  13. j12

    j12 Junior Member

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    Or with the torque app and the custom PIDs you can also see the NiMH volt delta under load. But at 150k miles I wouldn't touch it. I bought my prius at 150k miles and now has 220k miles on the original battery. Just drove to tahoe and yosemite from san francisco the last two weekends without a hitch.
    Right now I have to add just over half a quart of oil 2500 miles into my 5000 mile oil change interval but other than that my prius has been stupid reliable.
     
    #13 j12, Oct 29, 2015
  14. y_one2002

    y_one2002 Junior Member

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    I did the load test (charge and discharge) while the whole battery pack inside the car. Using the Mini VCI cable, I recorded the Delta V. They are within 0.2 V 99% of time. I believe the battery pack is still very healthy, and I decided not to do anything to the battery now. Thanks guys for the useful info on the forum.
     
    #14 y_one2002, Nov 1, 2015
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