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How come no (p)105d yet?
- Thread starter Zooomer
- Start date
It's just a different cell size. Model S/X used 18650 cells and for the Model 3 (and future models) Tesla decided to produce 2170 cells. It really is just a different packaging size. Tesla's explanation was that this form factor allows better packaging of the battery packs. Ultimately what is inside the cells is what counts most.
When Elon and JB talk about how battery energy density improves by X%/year what they mean is “on average”. They don’t mean that every year there are new cells that have X% more than a year earlier.
We know that the 2170 cells produced at the Reno Gigafactory have a higher energy density than the 18650 cells (which Panasonic produces in Japan and sells to Tesla) that have always been used in the S/X.
WIth the tweet from Elon last Friday announcing that Tesla is dropping the 75kWh pack, there is a lot of speculation in other threads on TMC that very soon Tesla will switch to 2170 cells for the S/X and there will be new higher capacity pack size choices.At this point, it is only speculation. I expect we will know for sure very soon...
It’s likely more than just different cell dimensions. 2170 cells have a higher energy density than 18650 cells, according to Elon. See
Elon Musk on Tesla/Panasonic’s new 2170 battery cell: ‘highest energy density cell in the world…that is also the cheapest’
Tesla can use the same chemistry in their 18650s as the 2170s, so they can both have the highest energy density for their form factor. Where 2170 has an additional advantage is that the additional size is all active area. The 70 mm height gives 5 mm extra active height, but the 65mm isn't all active (can, cap, separator, terminals), so the energy goes up by a higher fraction than the size, thus higher energy density. Same with the width increase, 3mm of more layers, all of which are larger than the largest wrap in a 18650.
Whilst I would love a bigger battery, it is unlikely that ANY car will be viable for EVERYONE, it needs rather to reach a critical mass overall and be available in different forms for different groups of people. Asking for such viability is inconsistent with wanting the S to have more range than the 3- they are both electric cars, so either they need both to be viable for EVERYONE or it must be acknowledged that different people's needs and resources are different.
MarkS22
Member
Great point. This reminds me of Elon noting how stacking batteries two high (eg Roadster 2020) doesn’t double the height of the pack, since you don’t need to double the support materials, like the outer shell.
I always liked the analogy that adding a second 1 GW power plant doesn't double your available power, it adds 1GW.
Really like this when applied to Tesla vehicle production. Boosting production 20% at this point doesn't post profit 20% since baseload (fixed expenses) are already covered, it boosts it way more.
(But I digress while waiting for the Q4/ FY18 report date)
I think you're prob right.
I didn't know Tesla was importing 18650 cells either. Would make sense to switch to 2170 but from what I understand they are already capacity limited and buying energy storage cells from other suppliers.
It's interesting that the LR 3 charges much faster than the 75KW S. Same battery size but the 2170s can handle more charge (or the cooling system is better). This would make a LR S of 100 or higher KW able to charge at full supercharger speed 144KW.
Cooling system is better on the 3. It has multiple parallel cooling paths versus the single path of the S/X, that reduces the inlet to outlet differential. 2170s could also be better at cooling due to more active area with less layers (not proven to be that way, but reasonable).
A single layer 2170 S/X pack would probably be in the 105 kWh range. Uber simple calc: 15/16 module area (no double stacked penthouse) * 55/50 (assuming 15mm of dead space in both cells) = 3% capacity increase (from current 102.4).
Could get even better by reducing module count and wall dead space, but some of that may be needed to get the largest number of cells to fit width wise.
Could you explain this better? Seems like a single stack of 2170 would be a lot more than 3% increase...
The 18650 100 pack uses 16 modules with one on a second layer in front. A new pack would likely drop that module so you lose 6% of the area for cells. The extra height of the 2170 gains active area back, so you end up with a net gain, but not as much as if you directly replaced all 16 modules worth of cells with 2170s.
(Assuming 15mm of non active space, the 2170 gives a 10% active cell area volume boost for the same cell footprint area.)
To help imagine it in S terms, a Model 3 LR pack has about the same capacity as an 85 S pack. It has 2000 fewer cells and weight several hundred pounds less for that capacity. 2170 packs more storage into the same space and weight. With cooling etc, about 20% more.
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