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Regenerative Braking with 100% Charged Software-Limited 60 kWh Battery

Discussion in 'Model S: Battery & Charging' started by Tesl@ Bargain, Oct 12, 2016.

  1. Tesl@ Bargain

    Tesl@ Bargain Member

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    In this video I am demonstrating regenerative braking with a 100% charged battery in our new Tesla Model S 60 (applies to a Tesla Model X 60D as well), which is one of the advantages of having a 75 kWh battery software-limited to 60 kWh.

    This clearly confirms that regular charging and regenerative braking is not using the same logic. It's charging limited by software vs. BMS using real SoC.

    If starting like this on a really high hill, will it charge till ~120% (~ 72 kWh)? What do you think?
     
    • Informative x 3
  2. habanero69

    habanero69 I Dont Need Cialis. I Drive an EV.

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    I have a S60. With a full charge, I have noticed that at the very beginning of a drive immediately after, the regenerative braking was practically nil. I about ran into the car in front at my first red light waiting on regen to start. Within a mile or 2 I was able to detect some regen braking, and after a few more miles it was normal. Is this normal? I have no idea. I haven't done a full charge since that to retest. It was just plain weird... :confused:
     
  3. Tesl@ Bargain

    Tesl@ Bargain Member

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    That would be really strange, I did my test directly after unplugging. Fact is, if there is no dotted line below the 0 in the energy meter, regenerative braking is available. I have seen part of that area being dotted in the morning lately, but that was because of low outside temperature. Have a look what your energy meter is telling you after charging to 100%.
     
  4. habanero69

    habanero69 I Dont Need Cialis. I Drive an EV.

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    I actually did have the dotted line briefly and wasn't sure if that meant regen was not active or what. I've read a lot on the car, but for some reason had not seen anything about the dotted line, but assumed it probably was regen related. In fact, I'd forgot if you hadn't brought it up... Whether it will charge beyond 100%/60kWH I don't know. I assume that the software won't charge beyond the 100%, but how do they dump the excess? Little or no regen like I had wouldn't make sense or be safe I would think. Where else could it be dumped? Maybe it does go to battery but the car won't show/tell us. Hmmmmmmmmm...
     
  5. stopcrazypp

    stopcrazypp Well-Known Member

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    I remember in the 40kWh, the limiter was simply done by the same method as when you set the max percentage you want to charge the battery. It's not a global limiter on the capacity, so I would not be surprised if regen is unaffected.
     
  6. No2DinosaurFuel

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    This got me wondering if someone can build a treadmill for the S60/D and this is one way to charge your S60/D up to the 75KWh before any drive. Just put the car on the treadmill for car contraption once you fully charge to 100%. This way you save $6k or $9K or whatever it cost to upgrade to the 75KWh.
     
  7. Jlwine

    Jlwine Member

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    With my software limited 60D on a100% charge, as I coast down my long drive regen works immediately as I exit my garage.
     
  8. Tesl@ Bargain

    Tesl@ Bargain Member

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    Yes, that's what this is all about. If you charge a 60(D) to 100%, it's the same as charging a 75(D) to 80%, so for daily commute the outcome and available range is exactly the same. The only thing that's missing is the start-charge if you want or need the extra 15 kWh-ish on the first leg of a road trip, but with the current and increasing SuC availability that should never be an issue.

    I really love our (software-limited) S 60, the 15 kWh buffer just seems right to get the most out of battery life, and that capacity is just perfect for all of our usage cases. I nevertheless make the nightly charge for our daily urban commute only to 80% (which is 64% true SoC), because moving around the 50% mark (true SoC) is what's best for the battery pack.

    The availability of regenerative braking in any conditions is very important for us, living on a hill and with hilly surroundings.
     
  9. cwerdna

    cwerdna Active Member

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    Using Helpful links to TM-Spy threads. on software capacity limited cars would likely give better insight as to what's going on and how high the battery's being charged at 100% on those.
     
  10. Tesl@ Bargain

    Tesl@ Bargain Member

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    If it wasn't for the need of a TDC to ODB adapter, I'd be playing around with it, since I already have the proper ODB BT dongle from using LeafSpy in our Nissan LEAF. Have to read up the the TM-Spy development for Android.
     
  11. gordon727200

    gordon727200 New Member

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    Why won't Tesla tell us if in fact it's OK to charge to 100% at all times?
     
  12. outie

    outie Member

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    Because they don't want to open a can of worms. There are so many battery configurations and they will have a lot of explanation to do to every single owner. All the owners will get confused.

    "Why can this guy charge to 100% all the time but I can't?"

    "I have a 85kwh battery does that mean I can charge to 100% because the underlying battery could be a 90 or 100??? What do you mean it's not? But the 60 guys say theirs are actually larger!"
     
  13. No2DinosaurFuel

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    They want to upsell. Also it keeps the message consistent so easier for the representative to remember vs saying "wait what model S do you have?"
     
  14. The_Mike

    The_Mike Member

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    Dotted line means limited regeneration either because of low battery pack temperature or maximum charge. In this situation you would have little to no regenerative braking and you would have to rely on the friction of brake pads like every other car on the road. This is expected behavior and is especially notable if you park the car outside in winter, unplugged.

    What the OP is demonstrating is that the new 60 is a software-limited 75 kWh pack, and can be charged above its "100%" limit by regeneration, which is a nifty feature if you regularly charge to 100% and live on top of a hill. If he had a 75 kWh, no energy would be generated. It would be interesting to see if the control software ever reads a state of charge of over 100%, or if it just interprets any additional kWhs as 100%. The OP should be able to drive some slight extra distance before the battery drops from 100% to 99%. It would be interesting to see how far.

    I personally have a 60D just like the OP, and find it to be the best balance of practicality and cost. The only use-case where the 75 kWh has an advantage is while range charging for a trip. In all other cases, the 60 is just as good.
     
    • Like x 1
  15. abasile

    abasile Independent Software Eng.

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    Allowing regen at "100%" charge on a new 60 is a nice "freebie". The last time we took the direct route down the mountain we live on, the charge in our S-85 went from 80% to 87%, so that could be a rather significant benefit for some. Still, I'd be concerned that this might be disabled in a future firmware release; Tesla might choose to close this "loophole".
     
  16. Tesl@ Bargain

    Tesl@ Bargain Member

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    Would not make any sense, because it is of practical use without downside, but clearly not something Tesla might disable on purpose for no reasons. It may not even be part of the firmware but a sole matter of the BMS instead.
     
  17. abasile

    abasile Independent Software Eng.

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    The downside for Tesla is that you're able to use more than the "60 kWh" and thus have one less incentive to pay for the 75 kWh upgrade.
     
  18. wes07

    wes07 New Member

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    I've had my s60 for about a month and have never charged it 100% but then when I heard of the upgrade I started looking things up because it sounded fishy and sure enough there's a post like this. How many of you guys with batteries that are "upgradable" are consistently charging to 100% on a regular basis?
     
  19. Tesl@ Bargain

    Tesl@ Bargain Member

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    Not really, because though it clearly is an advantage, you can barely use it to charge more than the 60 kWh unless you try some (unpractical) trickery. How many people live on a hill? How many people live on a really high mountain? Our way goes downhill for about 1 km ~ 0.62 miles, but the recuperated energy is just between 200 and 270 Wh. That certainly has no influence on a decision to purchase the 75 kWh upgrade or not.

    It does not matter, you can do as you like without harming the battery. With the 75 kWh battery software-limited to 60 kWh it is a fact, that the displayed 100% charge is 80% real SoC. Tesla recommends charging between 50 and 90% for daily commute, and 100% only for starting a road-trip, but that advice is for an unlimited battery. Charge the software-limited battery to 100% and you really only have a true charge of 80%, so well in the advised zone for daily use. There is absolutely no doubt about the correctness of that statement, even if less informed Tesla employees should tell you otherwise.

    If you still do not trust that information, just keep the same procedure as you would do with an unlimited battery, and you will do your battery life even more good, because 80% on the limited battery really is 64% SoC, and moving around 50% SoC is best for battery life. That's what I do, only charging to 80% for the daily commute, not because I have doubts, but because I can. :)
     
  20. The_Mike

    The_Mike Member

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    With my 60D, I regularly charge to 90%. But during any kind of trip I charge to 100%, and in fact supercharge to 100% as well when we stop for a meal. (Supercharging the 60D to 100% is impressively fast, due to it really being only 80%)
     

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