Model Y - Gigafactory Texas Production

[SigNC]

Huh? If the free market doesn’t care how much something costs to make, then manufacturers’ cost savings ONLY benefits the manufacturers, NOT the customers.

Not exactly. The point of the free market not caring is that the consumer will buy the best product at a given price. They don't care if they are buying at 50k and it cost you 49k or they are buying at 50k and it cost you 20k if it's the best option. The free market will in theory drive prices down as there is competition at that price point but right now, tesla pretty much has none.

 

[pepperoni]

Not exactly. The point of the free market not caring is that the consumer will buy the best product at a given price. They don't care if they are buying at 50k and it cost you 49k or they are buying at 50k and it cost you 20k if it's the best option. The free market will in theory drive prices down as there is competition at that price point but right now, tesla pretty much has none.

Not disagreeing with your post. I was simply bemused by the previous self-contradicting post, with apologies to @CyberGus. Either the free market cares about manufacturing costs or it doesn’t.

 

[MontyFloyd]

Actually 6000-odd small thin 18650 cells are -great- for power output and cooling. They're just not fun for cost of manufacturing and assembly which is what the 4680 is really all about.

The continuous-tab of the 4680 presents potential for lower resistance and thermal losses, which partially compensate for the inherently harder to cool thick chunky cylinder package. But the real deal is all about needing to make 8x fewer cells per car, and maybe getting rid of some redundant structural material around the pack.

MY has 4,416 of 2170 cells.
Little less than 1/5 needed in 4680 version.

 

[Mrbrock]

MY has 4,416 of 2170 cells.
Little less than 1/5 needed in 4680 version.

Just because there are less cells doesn’t mean there’s less material needed. About the only material saved is the cell walls. It takes longer to make a bigger cell. How much is the question. If it takes 5 times as long then there’s only savings in assembly time. But if it’s only 3 or 4 times, then you make more cells on an energy equivalent basis so you will be able to produce full packs faster and therefore more cars.

 

[ZenRockGarden]

Just because there are less cells doesn’t mean there’s less material needed. About the only material saved is the cell walls. It takes longer to make a bigger cell. How much is the question. If it takes 5 times as long then there’s only savings in assembly time. But if it’s only 3 or 4 times, then you make more cells on an energy equivalent basis so you will be able to produce full packs faster and therefore more cars.

There is a ton of labor in assembling, connecting and assuring that every single one of the many-thousand cells is working perfectly.

It's literally the fewer-moving-parts concept. If you replace thousands of parts with hundreds, it's simpler, cheaper to make, cheaper to assemble, cheaper to test, and less likely to fail.

 

[SigNC]

There is a ton of labor in assembling, connecting and assuring that every single one of the many-thousand cells is working perfectly.

It's literally the fewer-moving-parts concept. If you replace thousands of parts with hundreds, it's simpler, cheaper to make, cheaper to assemble, cheaper to test, and less likely to fail.

But also a much bigger hit if a cell does in fact go bad.

 

[MP3Mike]

But also a much bigger hit if a cell does in fact go bad.

Not really. If a cell goes bad your pack needs replaced regardless... (A single cell going bad makes it impossible to keep the pack in balance.)

 

[MontyFloyd]

If it takes 5 times as long then there’s only savings in assembly time.

5 time as long to make 1/5 the number of cells = no change.

I did not say less materials needed (except for said battery container), just the mfg time.

So yes, as you point out, excluding the other trivial differences, what is the per-cell mfg time? That is big (biggest?) Q.

 

[SigNC]

Not really. If a cell goes bad your pack needs replaced regardless... (A single cell going bad makes it impossible to keep the pack in balance.)

As I understand it it depends on how the cell is faulty. A hard short and it basically will disconnect itself from the pack via a fusible link.

 

[MP3Mike]

As I understand it it depends on how the cell is faulty. A hard short and it basically will disconnect itself from the pack via a fusible link.

And at that point the pack can never be balanced again, because the brick that contains the failed cell has significantly less energy storage than the other bricks. Any cell failure = pack replacement.

 

[ZenRockGarden]

But also a much bigger hit if a cell does in fact go bad.

Size don't matter - a failed cell wrecks the voltage balance on the pack regardless of cell format. Fewer cells is simply fewer points of failure, fewer cells which could die, fewer connections which could break, fewer cooling pipes to leak...

The only reason to not use much bigger cells has been the increased resistive losses and lower surface area for cooling - those are compensated for by the 4680 continuous tab design.

 

[CRIMSON_DATE]

Size don't matter - a failed cell wrecks the voltage balance on the pack regardless of cell format. Fewer cells is simply fewer points of failure, fewer cells which could die, fewer connections which could break, fewer cooling pipes to leak...

The only reason to not use much bigger cells has been the increased resistive losses and lower surface area for cooling - those are compensated for by the 4680 continuous tab design.

That was true for the 2170's because the battery pack is comprised of several smaller packs and a failed battery in one threw it out of balance but I believe the 4680 is actually a single pack so a bad battery may not result in anything more then lower capacity.

 

[MP3Mike]

That was true for the 2170's because the battery pack is comprised of several smaller packs and a failed battery in one threw it out of balance but I believe the 4680 is actually a single pack so a bad battery may not result in anything more then lower capacity.

While it is physically different, the electrical wiring is essentially the same, it is still a combination of cells in series and parallel. Any single cell failure means you need a new pack.

 

[ZenRockGarden]

That was true for the 2170's because the battery pack is comprised of several smaller packs and a failed battery in one threw it out of balance but I believe the 4680 is actually a single pack so a bad battery may not result in anything more then lower capacity.

4680's are arranged in racks of cells, 6 wide. They are not all ganged together.

 

[MontyFloyd]

And at that point the pack can never be balanced again, because the brick that contains the failed cell has significantly less energy storage than the other bricks. Any cell failure = pack replacement.

Can the bricks be individually be controlled, balance out variations and failures?

 

[MP3Mike]

Can the bricks be individually be controlled, balance out variations and failures?

They are individually balanced, but you can't balance out a failed/missing cell. (The only thing that might work would be to open the pack and remove one cell from all of the other bricks, so that every brick still has the same number of cells. But that would result in significant capacity loss.)

 

[voip-ninja]

My possibly wrong understanding is that if a cell fails in a 2170 car that individual battery module can be swapped out, whereas the expectation with the 4680 cars is that if there is a failure the entire battery will have to be swapped. Since the battery is part of the car's structure this will be messy and expensive.

The good news is that nobody is better at this stuff than Tesla. I would expect battery failures to be quite rare and in most cases they would be covered under warranty.

 

[MontyFloyd]

They are individually balanced, but you can't balance out a failed/missing cell. (The only thing that might work would be to open the pack and remove one cell from all of the other bricks, so that every brick still has the same number of cells. But that would result in significant capacity loss.)

What I am saying is put a DC-DC with each block to output same as other blocks.
Well, more like having more than 1 pack, several smaller packs.
More complexity, better reliability.

 

[MP3Mike]

My possibly wrong understanding is that if a cell fails in a 2170 car that individual battery module can be swapped out,

Not really. The modules have the be very closely balanced to each other, or the pack will just fail in a short period of time by falling out of balance. And in the 2170 packs there are only 4 modules. (The 18650 packs have 14-16 modules.) If you have enough bad packs you might be able to find a perfect match, but from everything we have seen not even Tesla replaces failed modules. (What they will do is take a failed 16 module pack and remove 2 bad modules to make a refurbished 14 module pack.)

 

[CRIMSON_DATE]

My possibly wrong understanding is that if a cell fails in a 2170 car that individual battery module can be swapped out, whereas the expectation with the 4680 cars is that if there is a failure the entire battery will have to be swapped. Since the battery is part of the car's structure this will be messy and expensive.

The good news is that nobody is better at this stuff than Tesla. I would expect battery failures to be quite rare and in most cases they would be covered under warranty.

Well, Tesla does not replace battery modules. they will onky replace the whole pack. you wil need to go to a third party to get a modual replaced