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New Battery Break-in ??

Discussion in 'Roadster' started by Strib, Sep 30, 2015.

  1. Strib

    Strib Member

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    Is there a preferred method to break in a new battery pack? I just had my battery pack replaced. The service manager passed on that, in order to successfully balance the battery, what I needed to do is drive the car until depleted to about 10 miles remaining (without charging in the interim), then fully charge it. Do this repeatedly for several weeks. Does this make sense? It sounds unneccessarily stressful on the battery, and I don't see how it aids balancing. I haven't charged since I got the new battery pack home, but looking at the ESS grid, it's all zeros - seems well balanced already. The CAC seems higher than previously but I don't know if the calculation has any carry over from the prior battery pack.
     
  2. Doug_G

    Doug_G Lead Moderator

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    The car balances more aggressively when you 100% (Range) charge it. But it still balances after each Standard-mode charge. It will gradually balance on its own if you just plug it in every night.

    What the procedure he suggested does is show the car's computer the full range of almost-empty to completely-full. It basically calibrates the "fuel gauge". It's not a bad thing to do - once - after you balance the pack.
     
  3. supersnoop

    supersnoop Tesla Roadster #334

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    The car has to learn the capacity of the new battery. It get's the best measurement when you go from a completely full charge to an almost empty charge in a single event without turning off the key.

    My CAC had dropped to 141 when my battery was replaced. The new battery started there and slowly climbed. Most people said it would take a month or two, but it took me eight months to reach 154 CAC. And it still seems to be climbing.
     
  4. apacheguy

    apacheguy Sig 255, VIN 320

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    Does balancing work differently in the Roadster? I saw a claim once that, if left plugged in after charging completes, a balancing program is automatically started. In my Model S, even if I charge to 90% the car immediately sleeps after completing charging at 40 amps. The only time I've seen something remotely similar to balancing occur is at 100% where it trickle charges for an hour or so. But even this may not be balancing, but rather slowing down the taper so as to avoid overcharging or damaging the cells.
     
  5. wiztecy

    wiztecy Active Member

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    I had my ESS replaced twice. I did the Range Mode balance on the 1st one, the second one I just fully charged it in Std. Mode. Takes longer but the pack will balance. Also after it balances the CAC can still climb for months. I didn't pull it down to the 30% area until I needed to do a range charge for regular driving purposes or if I saw the pack wasn't climbing where I should be in terms of health.. Once I see my CAC matches my previous pack, then I'm happy. But if it fails to reach the same CAC then I'd do all those tricks, which I did with the 1st replacement pack. And all those tricks didn't work on the 1st replacement pack, the CAC never reached my original one. Most it went up to was 146CAC where I was looking for around 152CAC. Hence my 2nd replacement ESS. That one, as I mentioned, did match my original 152 CAC and then some where it peaked all the way up to 160 CAC. I did the std. mode balancing with that one and only rand it down to the low SOC when I needed to do planned road trip.
     
  6. hcsharp

    hcsharp Active Member

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    The balancing program in the S is almost identical to the Roadster. It doesn't balance at all while charging. You don't have to leave it plugged in. Even if it goes to sleep it will still balance at the end of a charge.
     
  7. spaceballs

    spaceballs Member

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    Grab logs via USB stick, compare voltages across each brick. If they are unbalanced, do a charge and when it finishes just let it sit for a long time. If you can see the service menu look when it's balancing and if it stops, re-start the charge. Keep grabbing USB logs until it's done balancing the bricks.
     
  8. Doug_G

    Doug_G Lead Moderator

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    Or just drive it daily and don't worry about it. In a few weeks it will balance.
     
  9. Zak

    Zak Member

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    I agree Doug_G. Just make sure you are charging at a high enough rate that the car has time to sit at full charge and balance. When people use the 110V connector for primary charge the battery will often go out of balance because the car never quite makes it to full charge.
     
  10. MLAUTO

    MLAUTO Member

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    Not true. Using 110V actually ends with a higher state of charge. One charge is enough to balance the pack if the lowest brick stays above 79% SOC. You just have to keep the car awake.
     
  11. hcsharp

    hcsharp Active Member

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    You misunderstood him. He was saying that 120v is often too slow to have the car fully charged and then take time to balance before they have to drive it.
     
  12. wiztecy

    wiztecy Active Member

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    #12 wiztecy, Oct 3, 2015
    Last edited: Oct 4, 2015
    That's exactly what the Tesla technicians said to me regards to the 120V balancing issue. They indicated they see it all the time.
     
  13. MLAUTO

    MLAUTO Member

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    I guess I don't drive enough. Overnight on 110V always seems to be enough time to fully charge for me.
     
  14. Doug_G

    Doug_G Lead Moderator

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    Depends on your daily mileage. You are way more likely to be able to do this with a Roadster than a Model S; but still, most people can't.
     
  15. Strib

    Strib Member

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    What is the definition of 'Balance'?

    Electrically, how is it brought about?
     
  16. Ampster

    Ampster Member

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    #16 Ampster, Oct 10, 2015
    Last edited: Oct 10, 2015
    Equal cell (brick) voltages accross the entire pack. It is brought about by shunting current from high cells so low cells can catch up or equalize. It is usually done near the top of a charge cycle, often when voltage is not increasing and current is decreasing.
     
  17. spaceballs

    spaceballs Member

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    I think it only does it after the charge is complete.
     
  18. Ampster

    Ampster Member

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    #18 Ampster, Oct 10, 2015
    Last edited: Oct 10, 2015
    I don't know the specifics of the Tesla battery management algorithm. Some hobby RC balancers are passive and work only after charging by bringing down high cells. Most start working when constant current (CC) portion of charge cycle shifts to constant voltage (CV) so technically if current is flowing some cells are charging. But one could easily say it is done at the end or at the top.
     
  19. spaceballs

    spaceballs Member

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    I see, I'm just going off what I see with my flir camera on the BMB board looking at the bleed resistors on my roadster.
     
  20. Ampster

    Ampster Member

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    That sounds right. You don't see the bleed resistors getting hot until the end, correct?
     

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