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How do the battery cells charge when charging?

Discussion in 'Model S: Battery & Charging' started by aus, Jan 31, 2016.

  1. aus

    aus Member

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    Just curious if all the cells charge evenly across the pack or do some charge first and then others charge full, and so on and so on?

    Just wondering if I supercharge to about 60% and then finish up overnight is that better for the cells/pack?

    .
     
  2. Drewflux

    Drewflux Member

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    If i remember correctly, when this came up on the roadster.Tesla had been fairly tight lipped on how the battery balance system works and when it operates. Most of what I read about this type of battery construction says keeping the SOC between 30-90% is best for long term durability. I dont think there is any advantage in supercharging then top off later, other than possibly reseting the calculation the BMS uses to give estimated range distance.
     
  3. jerry33

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

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    In general, the slower you charge (down to a point) the better it is for the battery. However, with Tesla's liquid cooling and BMS, the difference is negligible. Pack balancing turns on when you get to 93% (discovered by WK57), so occasionally charge to that level to make sure that balancing occurs. Once it starts, it balances the pack at every charge level until the balancing is finished.

    it's kind of inconvenient to partially charge at an SC and then charge again at home. Just charge at home unless you're on a trip or need additional charge.
     
  4. scaesare

    scaesare Active Member

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    To answer your one specific question: the former. The cells all receive the same charge[1], there is no "staging" where some cells are charged to 100% ahead of others.

    [1] Although imbalance can prevent them from having the EXACT same charge, that is the goal, and mechanisms (balancing) exist to attempt to attain that.
     
  5. aus

    aus Member

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    Thanks for the input.
    We have two superchargers about 20 miles away in opposite directions, so we tend to charge for 15-20 minutes if we drive by and have the time, and if SC stalls are available.
    I don't usually charge every night, and was wondering if I should top it off when I get home or just wait until I need a charge like I usually do.

    jerry33, thanks for the info on pack balancing at 93%. I'm set at 90% max charge now, so I'll be sure to set it to 95% once in a while.
    Is once a month enough to balance the pack?
    .
     
  6. Muzzman1

    Muzzman1 Member

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    Thanks for that info Jerry, can you possibly reference that thread/post. I'd love to read up about that.
     

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