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Model S Battery Pack Charging Protocols

Discussion in 'Charging Standards and Infrastructure' started by gkalexdc, Jun 13, 2012.

  1. gkalexdc

    gkalexdc Member

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    I started this thread to educate newer EV owners about charging protocols. ... Like me !!
    Since I owned a LEAF, I know "some" of the rules, such as "Rapid charging" with the CHAdeMO is alright about once a day, it is not good for the pack longevity if you utilize this method frequently., like chargin with it everyday.
    So The Question for the Group IS; If I have equipped my Model S 85kWh car with Twin Chargers, and I am charging at home with a HPC, what is the best way to set that charger up? Is it bad for me to have a 90Amp breaker on this HPC and rapid charge the battery pack every single night? Should I set the HPC up with a 40 amp only breaker.
    I am thinking that a lot of people are going to set up a 100 AMP breaker on their HPC circuits and rapid charge the LONGEVITY right out of their packs. Opinions ???? (please!):smile:
     
  2. Sparrow

    Sparrow S105/ Roadster 189

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    I could easily be wrong, but first of all CHAdeMO charging is done at 50KW whereas our Tesla HPCs are 20KW. Second the 85kWh pack is more than 3 times larger than the Leaf's 24kWh pack so the effective charge rate per kWh is something like 8 times less. Third, the Tesla has active cooling.
     
  3. efusco

    efusco Moderator - Model S & X forums

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    Looking forward to the replies to this thread.
    My impression was you could use the 80amp HPC, but you set the charge rate/energy through the car itself and can tell it you don't want to trash your longevity. But that if you need the rapid full 80 amp charge you have that option.
     
  4. ChadS

    ChadS Petroleum is for sissies

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    I don't think home charging is going to hurt a pack that big. The fastest you can get at home is 20kW; an 85kWh pack should not mind that at all. That said, I wouldn't bother with 20kW at home unless you happen to have a 90A slot sitting open in your breaker box. 10kW (240V 40A) is more grid friendly, and will still get the car charged overnight even on the few days you happen to run it all the way down. Most Roadster owners charge even lower than that.

    As Sparrow notes, 50Kw CHAdeMO into a 24kWh pack is a different story. But even there, Mitsubishi says doing it daily is fine, and Nissan is removing their warning about it. You won't want to do 90kW Supercharging every day, though, even if you happen to live near one.
     
  5. strider

    strider Active Member

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    In theory there will be more degradation if you charge at higher amperage. However, even with the smaller packs this additional loss will be unnoticeable. The bulk of Tesla's IP is in taking care of the battery - the car and HPC/UMC communicate so if the battery is getting too hot at a fast charge rate it will tell the HPC/UMC to slow down. So you should feel free to charge at 90A all you want. That being said, I believe it was Tomsax who did some calculations and for the Roadster, the sweet spot for charing efficiency was 40A (above or below that you're using extra power to cool the battery so you have a lower % of wall power moving into the battery). Though unless you're on 120V the difference is slight. But if you want to squeeze every last electron, set the HPC for 40A unless you need to charge more quickly. Again, the above was for the Roadster, with a larger pack in Model S the sweet spot may be different. I'll leave it to the smart people to figure it out.

    The only thing you have to mind yourself on is Range Mode charging and supercharging. Range Mode charging to 100% often will degrade the battery (likewise using the bottom 10% of the battery driving in Range mode will also degrade the battery). If you stay with standard mode most of the time you'll be fine.

    No data yet on Supercharging so we'll have to wait and see with that.
     
  6. Lloyd

    Lloyd Active Member

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    Have we been told yet that there will be different charging or driving modes?
     
  7. stopcrazypp

    stopcrazypp Well-Known Member

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    First of all the 20kW HPC as used in any Tesla vehicle is not "rapid charging". Rapid/Quick charging is defined as a charge from 0% to 100% in under 1 hour (or a charge at a rate equivalent to that like from 0-50% under 30 minutes). A Leaf charge is 24kWh/50kW = 0.48 hours.

    The 85kWh pack will take about 4.25 hours (85kWh/20kW) to charge on 20kW, so it's definitely not rapid charging and shouldn't be too stressful on the battery pack.
     
  8. gkalexdc

    gkalexdc Member

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    My major question is, then, What is the definition of Effective Charge Rate per kWh? Is it that a larger pack doesnt get as "hot" during charge vs. a 3 times less capacity battery pack?

     
  9. strider

    strider Active Member

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    Yes, Standard and Range modes. Not 4 like the Roadster.
     
  10. strider

    strider Active Member

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    Well most people view anything >7.6kW (240V @32A) as "quick" charging since it needs dedicated equipment (permanently installed EVSE) and are also not very common. But we agree that using an HPC will not harm your battery.
     
  11. artsci

    artsci Sponsor

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    #11 artsci, Jun 15, 2012
    Last edited: Jun 17, 2012
    If you set the HPC for 40 amps and you have a breaker that can handle the load, why even bother with the HPC? Doesn't the universal charger charge at 40 amps?
     
  12. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    1. Sometimes you might need a rapid charge just like sometimes you need a range charge.

    2. You might want to charge your friend's (or forum friend's) Tesla.
     
  13. Todd Burch

    Todd Burch Electron Pilot

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    #13 Todd Burch, Jun 15, 2012
    Last edited: Jun 16, 2012
    If you look at the various screenshots of the touchscreen on TMC they show 2 modes: standard and range. I'm not sure anyone knows whether a storage mode explicitly exists, or how it's entered.

    Edit: Here it is
    http://www.teslamotorsclub.com/attachment.php?attachmentid=6291&d=1338043600
     
  14. Lloyd

    Lloyd Active Member

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    very cool,

    Thanks!
     
  15. dhrivnak

    dhrivnak Active Member

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    Since the wire and breaker likely add a modest amount of extra cost i would install 100amp if you can but set the car to charge at 40 amps. This is what i do. For the Roadster 40 amp is the most efficient as higher rates tend to kick on the ac for battery cooling. Then on those few occasions i can rapid charge or help out a fellow roadster charge on a trip.

    The charger makes this easy as the GPS tracks the location so it knows home is 40 amps. The lower current is also easier on the utility. Again two taps and i can override.
     
  16. xhawk101

    xhawk101 Active Member

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    Nema 6-50 vs 14- Today I had an electrician look at my outlet today and I can easily have my correct outlet converted to the 6-50 for about 100 bucks otherwise what is the reason to convert to a 'recomended' 14-50, 4 prong as opposed to my current 3 prong outlet? Both have identical 31 amp charge rates...
     
  17. doug

    doug Administrator / Head Moderator

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    The only reason NEMA 14-50 is recommended is because that's what you find in the wild (at RV parks, campgrounds, etc) in North America. The fourth pin adds the neutral line so you can 120V or 240V, since a RV might have 120V appliances. The Model S doesn't actually use this neutral pin, so you could use NEMA 6-50 (and that plug is available with the UMC), but you'd also want the 14-50 to charge in the wild.

    Both are actually good for 40 amps continuous, 50 peak (where the "-50" comes from).
     
  18. xhawk101

    xhawk101 Active Member

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    Excellent ...thanks!
     

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