Battery Usage

[wdluhn]

I am curious as to how Tesla uses the batteries.

When my car says 50% does that mean that all battery cells are 50% charged, or does it mean that half the cells are 100% charged?

The questions comes from my wondering if when I only charge to 80% the battery pack is keeping some cells offline on a rotation, or if it always uses every cell and charges them all to the set limit.

 

[Sophias_dad]

It means all the battery cells are 50% charged, or at least the car thinks they are all 50% charged. There are like a zillion cells, they wouldn't have individual drive circuits for each.

There are (I think) 11 modules made up of a (zillion/11) cells each. It >might< be possible for Tesla to disconnect some modules for rotation, but to what end? Lithium batteries don't seem to enjoy being either very fully charged or very fully discharged, so it would be silly to disconnect a module unless it was misbehaving.

 

[GtiMart]

~4V batteries are put in series in bricks of 96 to come up to ~400V. Multiple such bricks are used in parallel to augment the capacity to ~55kWh, ~78kWh etc. The whole thing is used at the same time. Technically voltage would stay exactly the same across but small variances occur over time. There is provision to rebalance that difference.