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Suggestion for battery pre-heating and charge-end scheduling sent to Tesla

Discussion in 'Model S: Battery & Charging' started by Andyw2100, Feb 7, 2015.

  1. Andyw2100

    Andyw2100 Well-Known Member

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    #1 Andyw2100, Feb 7, 2015
    Last edited: Oct 18, 2015
    Edit: I am updating this thread on October 18, 2015. I am hoping that if we make a concerted effort, we may be able to get Tesla to add some sort of traction pack pre-heating to version 7.1 or a later version, since they have added battery heating for performance reasons to version 7 with the "Max Battery Power" option.

    My plan is to write them again, mentioning this letter, this thread, the fact that they now have an option to heat the pack anyway, and also directing them to this poll:

    Would you use battery heating if it were available?

    (If you haven't yet voted in the poll, please consider doing so.)


    The letter below was written on February 7, 2015. This ends the October 18, 2015 edit.
    ---


    I just sent the following e-mail message to [email protected].

    --
    To whom this may concern at the [email protected] email address:

    I’d appreciate it if you would please pass this along to the appropriate people in the engineering department. Thanks very much. –AW



    I understand that while the new torque sleep efficiency improvements to the P85Ds function with range mode both on and off, that these improved efficiencies are significantly enhanced with range mode on. That being the case, I’d like to suggest an improvement that would help make it easier for many of us to leave range mode on all the time. This improvement would also have many other benefits.

    I’d like to suggest that you add an option to the mobile applications to allow for battery pack pre-heating as a function independent of cabin pre-heating, and also not tied to whether or not the car is in range mode. This would allow us to pre-heat the battery while on shore power, so that we don’t lose regenerative braking at the start of our trips, and also don’t have to use battery power to warm the pack once the trip has started.

    Right now, I am often pre-heating the cabin much longer than I need to, and to a much higher temperature than I want to, wasting electricity in the process, just to heat the battery pack, because the only way that I can heat the pack is to heat the cabin. Also, if I forget to toggle range mode off when I exit the vehicle I can’t preheat the battery pack at all, which has me starting my next trip with no regenerative braking.

    If you do find a way to add the ability to pre-heat the battery pack via the app, it would be even better if this could be scheduled, such that we could set a time that we would like the pack heated by, and have the car ready to go by that time.

    Since I’ve brought up scheduling anyway, I may as well put in a plug for being able to schedule the time for charging to end, instead of just the time for charging to start. (I know this has been suggested before.) I’ve given this a lot of thought, as I’m sure your software engineers have as well. I realize that there are many issues with this, including the fact that available current can change, the temperature of the pack can change, etc. I thought one way this could be implemented would be that the scheduling screen could have a disclaimer on it, indicating that the time for charging to end is an estimate, and that the estimate will be more accurate, based on the flexibility given in the parameters the user selects. The user would then select the approximate end time, along with the time at which charging may not start before. The user would also select the preferred charging amperage, along with the range of possible amperages at which to charge. So, as an example, I charge with an HPWC capable of 80 Amp charging. But I generally charge at 56 Amps, as I don’t need to stress any of the components of the system by charging at 80 amps most of the time. So I might select 6:30 AM as the approximate end time, 1:00 AM as the “do not start before” time, 56 amps as my preferred charging amperage, and 0-72 amps as the range of amperages to allow for charging. The software would then compute a start time based on those parameters. As long as the software is given a range of amperages to be able to charge at, and is not committing to an exact time to complete the charging, this should be workable, and extremely useful to Tesla owners. It has the added benefit of packs not sitting at high states of charge for hours unnecessarily.

    This would also work really well in conjunction with the scheduling of the battery heating, because if someone was going to schedule the battery to be heated and ready at the same time they wanted the car charged and ready, these two systems would work together, and the battery likely would not need to be incrementally heated at all, since the charging would be completing at the correct time.

    The energy savings and added convenience these features would bring to Tesla owners is significant. I realize that implementing these things would not be easy, but I trust that the Tesla software engineers are up to the task. I hope Tesla will decide to move forward on these suggestions. The sooner the better!

    Thanks very much!
     
    • Like x 1
  2. liuping

    liuping Active Member

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    +1

    Excellent suggestions. I hope they can implement range mode pack warming and scheduled charge end timing.
     
  3. BerTX

    BerTX Member

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    Great suggestions.

    Maybe they can do most of the charge immediately, then re-start at an estimated time before the desired end time? That way they would have a more accurate measurement of start time with less room for error, the pack would have a usable charge for an unexpected 2 am ice cream run, and if the charge did not completely reach your desired charge level, it would probably still have a usable charge.
     
  4. Andyw2100

    Andyw2100 Well-Known Member

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    Well, my understanding is that it takes a while for the pack to get up to temperature. Charging the pack for just a little while--say 30 minutes to "top it off" isn't going to do it. So personally I'd like to see it be one continuous charging period, so the pack is both charged and warm.
     
  5. Jgdixon

    Jgdixon Member

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    Awesome, we just had a local owners club meet up and some of us were discussing these exact discussions.
    The battery heating suggestion would help everyone as we'll not just those of us with Ds.
     
  6. Andyw2100

    Andyw2100 Well-Known Member

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    Yes, exactly. And actually all the suggestions I made would be good for all owners, not just P85D owners.

    Everyone could benefit from being able to heat the battery pack when not on range mode, and without it being connected to cabin heating, and everyone could benefit from being able to schedule an estimated time for charges to end. It's just that the battery heating in particular will make it easier to leave range mode enabled all the time, and P85D users may have even more interest in that one aspect of this now, since we're going to get the best efficiency in range mode.

    If you and your owners club members like the ideas, feel free to draft something at your next meeting and send it in. I would have to think that the more support ideas get, the more likely they are to be implemented, provided, of course, that they are reasonable.
     
  7. TES-E

    TES-E Member

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    Excellent suggestions! I hope they listen.
     
  8. Xenoilphobe

    Xenoilphobe Active Member

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    Very good suggestion.
     
  9. Freeride

    Freeride Member

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    I second this. For me, heating the cabin is just complete waste of energy. I want to choose.
     
  10. Siggy

    Siggy Member

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    Exzellent. I wanz this too.
    Siggy
     
  11. gpetti

    gpetti Active Member

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    Nicely written and explained. I'm guessing that this may not be the first time they have heard this, but the topic is more important than ever, given the increased value of Range mode. Definitely doesn't hurt to raise it either way.
     
  12. SeminoleFSU

    SeminoleFSU Member

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    +1 for starters, at the minimum make it where range mode doesn't stop or reduce pack heating.. That alone would be nice. I rarely use range mode but when I do I would like the pack to heat when charging
     
  13. Andyw2100

    Andyw2100 Well-Known Member

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    I just created a poll on the battery heating option here:

    Would you use battery heating if it were available?

    My hope is that if Tesla see that enough people are interested in this, they will be more likely to make it happen. If you like the idea, please go vote in the poll. If you really, really like the idea, also take a moment and write to Tesla. (But definitely go vote in the poll.)

    Thanks!
     
  14. Jgdixon

    Jgdixon Member

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    In addition it is silly that when it is really cold we have to cycle the heat on at least twice through the app to get the pack warmed up so we have regen. Then you go out to a really hot cabin which is the waste. Many times I've opened the windows to cool the stifling hot interior on a cold winter day!
     
  15. Jaff

    Jaff Active Member

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    Agree John...I would like to be able to choose (for example) to be able to preheat the battery for an hour, with the cabin heat (including seat heater & steering wheel heater) only coming on to the thermostat temp for the last 10 minutes...be nice to be able to program this for the regular work week just like an entry in the calendar...

     
  16. Andyw2100

    Andyw2100 Well-Known Member

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    I'm bumping this thread because I think that the time may be right for us to convince Tesla to act on this. With version 7, Tesla has provided the ability to heat the traction pack with the "Max Battery Power" option, for performance reasons. So perhaps it wouldn't be too difficult for Tesla to work in another mode that heats the traction pack for the more practical reason of eliminating the regenerative braking limit for version 7.1 or later.

    There is also a poll on pack heating that I started here:

    Would you use battery heating if it were available?
     
  17. AWDtsla

    AWDtsla Active Member

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    +1. Can't believe charge-end scheduling isn't already implemented. Maybe charge ready-by would be a better term.
     
  18. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    A direct pre-heat option would be nice for winter ops, but from my experience, there is a reasonable work-around that currently works. I do this procedure before any range challenged winter drive.

    1. Turn off "range mode."
    2. Start charging so that it will end shortly (0-60 minutes) before departure.
    3. At 60-90 minutes before departure, use the App to turn on cabin heating and set the temperature to much higher than your comfort level. I chose around 80˚ F., 26˚ C.
    4. App initiated interior heating turns off after 30 minutes, so every 30 minutes, turn it back on.
    5. Turn on "range mode" before departure.

    Notes:
    • Turning range mode allows for full battery heating during charging.
    • Charging will heat the battery to reasonable tempertures both through the explicit battery heater and waste heat of the charging process.
    • The battery has a lot of thermal mass, so even if you finish charging an hour before departure, it will be pretty warm when you leave.
    • Preheating the interior stores thermal energy in the interior and avoids wasting battery energy on heat at the start of the trip. Often, I can drive for 30 minutes without any climate control when I start with a nice, warm cabin.
    • Range mode on during the drive conserves on the battery heater during your drive.

    Happy winter hypermiling!
     
  19. Evbwcaer

    Evbwcaer Member

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    I add the suggestion that the current charge start time scheduler, and any future end time schedulers, have the ability to schedule for whatever day you want, not just the time in the next 24 hour period. I know I am a minority in needing this function, but I will be on camping trips with no cell service, plugged into a 110. I'd like to have a range charge finish just as I schedule, a few days in the future.

    A battery heat function would also be good if you are approaching a Supercharger with a cold battery.
     
  20. Andyw2100

    Andyw2100 Well-Known Member

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    That work-around works, but only to a point, and it does require quite a bit of work. The process could be simplified to such a great extent if Tesla got involved and helped.

    Here are some of the limitations, as I see them, of your system, which I already use:

    --this won't heat the pack beyond the point where it is still somewhat regen limited. I don't recall the exact limit, but I believe it is 30 kW. (At least that has been my experience, in a pretty cold climate.)
    --If you don't like your cabin particularly warm, you are completely wasting energy by heating the cabin just to heat the pack. I wind up having to cool the cabin once I start driving if I've heated it this way.
    --If you (or your spouse, or someone else who last drove the car) forgot to turn off range mode when they left the car, you'll have to physically go to the car to turn range mode off before charging the battery.

    It just seems kind of crazy how many hoops we are jumping through to get a partial solution, when Tesla could easily give us a complete solution with no hoop-jumping required.
     

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