So I'm really in to figuring out Tesla's battery architecture and I love reading stuff about it. Now we know that the new 100kWh pack is a completely new architecture, including cell count and cooling system. There will definitely be people with more knowledge on batteries and will be able to make better guesses here on this forum, all in all whatever I learnt I read it online and I'm no engineer, not an authority by any means.
But here goes nothing.
Here's what we know;
So same chemistry cells, 3.3 * 3.7 = 12,21Wh. 96370/12,21 = 7892 cells for the new pack. 788 new cells, that's an addition of 78lbs just cell weight assuming ~45 grams per cell.
We also know that the drivetrain is the same. So 96 cells in series is 3,7 * 96 = 355 nominal volts for the pack. That should be the same. So for a 96.370Wh pack, you need 96370/355 = 271Ah pack. Compared to 244Ah of 90D. To achieve that you need to connect 82 cells parallel. And we assumed ~7892 cell count for the new pack, ~7892/82 = 96 cells needed in series. Same as before.
So Tesla somehow managed to put 8 more cells per group of 74 and group, module count didn't change. Elon said they were at the theorotical limit and that they've changed the entire cooling system. So my money's on them making cooling ducts thinner and overall packaging much tighter, allowing them to put somehow 788 new cells into the pack.
Another logic supporting my theory which would make thinks simpler for Tesla since not changing the entire layout is probably easier to do is;
We know that P90D's reach around 450kW peak power with a full charge in Ludicrous mode. Full charge is 403V. 450000/403 is 1116 Amps current. For the 244Ah 90D pack that's 4.5C. Assuming the same C rate for the new pack wouldn't be nonsense since chemistry didn't change. That would put it on 1220Amps. 1220* 403 = ~492kW.
However this logic fades away after the fact that recently delivered 90D packs achieved these power outputs and we found out that they are not software limited 100 packs.
What do you guys think? It could also be that they've changed it entirely so there's no way we can figure it out. Decreased the amount of cells in a group, decreased group count, increased module count... Who knows? We can't know before a teardown probably. Maybe I'm completely wrong about this but I just love speculating about Tesla's engineering feats.
But here goes nothing.
Here's what we know;
- Cell chemistry is the same.
- Pack is 74 cells in parallel. That is a group. 6 groups connected in series is a module and 16 modules make the pack. 7104 cells in total.
- We know that original 85 pack had 3.1Ah cells and their nominal voltage is 3.7V. 4.2V fully charged, 3.2V cutoff.
- 90 pack is a 6% increase thanks to silicon on the cathode. That puts it in ~3.3Ah. So 3,3Ah * 3,7V * 7104 = 86740Wh --> 90 pack. With a 97% allowed DoD we end up with 84kWh usable energy. I think that would be in line with people's experience thus far with 90 packs.
So same chemistry cells, 3.3 * 3.7 = 12,21Wh. 96370/12,21 = 7892 cells for the new pack. 788 new cells, that's an addition of 78lbs just cell weight assuming ~45 grams per cell.
We also know that the drivetrain is the same. So 96 cells in series is 3,7 * 96 = 355 nominal volts for the pack. That should be the same. So for a 96.370Wh pack, you need 96370/355 = 271Ah pack. Compared to 244Ah of 90D. To achieve that you need to connect 82 cells parallel. And we assumed ~7892 cell count for the new pack, ~7892/82 = 96 cells needed in series. Same as before.
So Tesla somehow managed to put 8 more cells per group of 74 and group, module count didn't change. Elon said they were at the theorotical limit and that they've changed the entire cooling system. So my money's on them making cooling ducts thinner and overall packaging much tighter, allowing them to put somehow 788 new cells into the pack.
Another logic supporting my theory which would make thinks simpler for Tesla since not changing the entire layout is probably easier to do is;
We know that P90D's reach around 450kW peak power with a full charge in Ludicrous mode. Full charge is 403V. 450000/403 is 1116 Amps current. For the 244Ah 90D pack that's 4.5C. Assuming the same C rate for the new pack wouldn't be nonsense since chemistry didn't change. That would put it on 1220Amps. 1220* 403 = ~492kW.
However this logic fades away after the fact that recently delivered 90D packs achieved these power outputs and we found out that they are not software limited 100 packs.
What do you guys think? It could also be that they've changed it entirely so there's no way we can figure it out. Decreased the amount of cells in a group, decreased group count, increased module count... Who knows? We can't know before a teardown probably. Maybe I'm completely wrong about this but I just love speculating about Tesla's engineering feats.