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regen in cold climate first miles as a software update ?

Discussion in 'Model S: Battery & Charging' started by NielsChr, Feb 3, 2013.

  1. NielsChr

    NielsChr Member

    Oct 18, 2011
    #1 NielsChr, Feb 3, 2013
    Last edited: Feb 3, 2013
    I have read reports about model S regen is disabled the first 10-15 miles if batteries are to cold.

    I can understand that the batteries might not like to be charged hard when temp is to low, but what I don't get is why disable electric breaking all together. ? they should dynamically lower the regen effect depening on the NET current flow from batteries.

    let me explain:
    First miles while the car is cold, a lot of energy is at same time used to heat the cabin and battery (e.g. 5 or 10 kw) - this energy is taken from the battery - why not using the regen to supply this energy instead of disable electric breaking it all together.

    Depending on the design of the car (asuming there is a electric heat element build into the cars battery/cabin) it might just be a matter of software update or it would require a larger heater to consume all the energy from the electric breaking....

    the total sum of the battery current is the net current consumption
    10 kw regen from electric breaking + 10 kw heat to cabin/battery self = 0 current to/from battery

    if Tesla was to build this as a software update, they should "just" messure the net current going out/into the battery (asuming they already doing this) and asure this never gets higher(lower) than a certen value while regenerating.
    When lifting the "gas" the heater should go to "max", consuming as mutch electric breaking energy as posible...only if the battery current gets negatively higher(lower) than allowed they should warn driver in display and stop increase regen power (electric breake) - still allowing regen, but only to a level witch is accepted by the battery.

    see this:

    this way regen is not disabled and cars is heated faster (while it is cold) and further less energy is wasted into heating the cabin as regen is doing this.

    extra HW is only needed if the already build in heaters can not use the regen energy
    What do you think, will this come as a SW, HW or not at all update ?
  2. Doug_G

    Doug_G Lead Moderator

    Apr 2, 2010
    Ottawa, Canada
    When regen is not fully disabled, you get some energy going into running the pack heater and cabin heater. You can sometimes see it balancing around zero while decelerating, if the regen limit is low.

    I suspect the system is trying to charge the batteries but the draw is balancing it. I doubt any special measures were taken.

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