P100D in the works!!! :)

[glhs272]

I guess I didn't make myself clear enough, but you still answered some of my questions. But first I have to disagree on some things. If the modules are in series, they don't have to be the same. If they were parallel, they would, because then there could be a voltage difference, but if they are in series, the voltage is just added.

Another thing would be the amount of different modules you are describing. How could having two different chemistries be efficient? Or some with less cells and some with more. And 85* 14/16 would be 75kWh. Are you sure thats the way it is, or are you just guessing. And that would mean that a upgraded pack, with only the cells used in the 100, would give us a 87.5...
I just came up with 12 modules, because thats about whats needed to get from 85 to 60 and 90 to 70, but because I have heard somewhere that they had 14 modules, that 4 might be half empty.

And I don't know where you are reading an auxiliary pack into my post.

But I get the balancing issues, that might really be quite tricky. I just thought that it might be more efficient, if they used one cell and one module for their whole lineup, not 3 cells and 4 different module configurations (assuming that the M3 might also need 2 different packs). Because, to me, thats sounds very inefficient.

Edit: Sorry the modules might still have to be the same, because the internal resistance would be twice as high in half empty modules... Its late over here in Germany....

1) With half filled modules you would also reduce the ampacity of that module in half and because they are all in series that would cut the max current output of the pack in half. Otherwise you would stress out the half empty module. In theory it would work, kinda sorta... but asking for trouble.

2) Agreed, having 2 chemistries isn't efficient. It's just that it's what Tesla has available to them at the moment. I am sure they are winding down their production of the carbon only cells. Once that's complete, they could go onto just having mild silicon cells (type 90) which would therefore force an upgrade to the 70 pack. However, with the rumored P100D pack, they may have a new module type on the way, might be a good time to drop that type 85 module. So I guess what I am saying is the fact that there are two types of modules probably has to do with production capacity and being unable to whole sale change their entire production of vehicles from one type of module to another. Instead ramping up the new one and ramping down older ones, therefore needing two types during the transition. I don't know really, just a guess.

3) The 70kwh pack is in fact just an 85kwh pack without 2 of the modules, as verified elsewhere on this forum by folks tearing the pack apart. I know that makes it SEEM like more than a 70kwh pack if you use the simple math of 85*(14/16)=74.375. However, the 85 pack is really an 81kwh, so in fact 81*(14/16)=70.875. But that issue (85pack=81kwh) is widely discussed on a different thread.

4) I re-read your prior post, and I don't know where I got the auxiliary pack idea, sorry.

 

[R.S]

Thanks for the nice input. So if the 70 is a 14 module 85, then we skipped the 90 cells, if the 100 cells come soon, or at least we won't see them for very long. I always thought that the 90 was an intermediate solution, probably because the 100 wasn't ready in time, so they went for less silicon. Straubel and Musk both commented on suppliers not taking enough risk, that might have been a hint at Panasonic. It was probably also the reason why they just slipped it in, without a big Teslaesque entrance. But with the 100kWh pack coming, the small pack might actually end up to be a 85-90. We will see. But there is still the issue of having to use two different modules for the S/X and the 3, but there are great guys working at Tesla, if its possible, they will figure it out.