Pics/Info: Inside the Tesla 100 kWh Battery Pack

[Electric700]

I originally posted this on my projects site, but will also post here.

All rights reserved. Images may not be copied or used without my express permission.

Pics and Info: Inside the Tesla 100kWh Battery Pack | wk057's SkieNET

Jason Hughes on Twitter

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So I recently purchased the first known salvage auction Tesla with the new 100kWh battery pack, a P100D VIN 159k.

There have been tons of rumors flying around how what changes Tesla had made to increase the capacity so drastically. Rumors of new cooling patents, increased voltage, new cell double bond wiring, incompatible with older cars, and all sorts of things.



Personally, I figured Tesla wouldn't reinvent the wheel just yet and go with a whole new pack design, but who knows. Not me, so that had to be corrected.

Without further ado, here is a shot of a module from the 100 kWh pack.







So, immediately with one picture we have a lot of answers.

• They're 18650s
• There are more of them (12 more per group to be exact)
• Single cell fuse/bond wires
• Still six cell groups (no voltage change)

Awesome. 516 cells per module. That's 8,256 cells per pack, a ~16% increase vs the 85/90 packs.

A comparison with an older module makes the added cells more clear:



Basically they crammed a couple more rows of cells into the module.



But what about the rumors around cooling? Well, they did modify the cooling, but not in any exotic way. The new modules simply have two shorter and thinner cooling loops per module. This way the coolant doesnt have to run past so many cells before exiting.







What about compatibility with other/older cars? Well, the pack itself has the same high-voltage connection, the same low voltages connectors, and the same cooling connector. However, the pack has the newer ring around the high-voltage connector. So, it's plug-and-play (for the most part, firmware and config changes needed) on the Model X and refreshed Model S, however it would require a different spacer ring on the high voltage connector. Tesla even has a part number for it, so it should be pretty simple to put into any Model S/X.

The six screws on the orange HV connector can be removed to replace the ring with one compatible with older Model S.

As for real capacity, the BMS reports usable capacity at a whopping 98.4 kWh. It also reports a 4 kWh unusable bottom charge, so that's 102.4 kWh total pack capacity! Congratulations, Tesla. A high capacity pack that meets its nameplate rating!



Also, the BMS reports a max discharge current of 1,760A for the P100D Ludicrous pack. The normal Ludicrous P90D/P85D packs report 1,520A. This makes perfect sense with scaling, since it's 74 vs 86 cells per group.



Additionally, the pyro fuse in the 100 kWh is labeled differently. I couldn't find any physical differences between the normal ones, but it is labeled "DISCONNECT,PYROTECHNIC,HYBRID,100kWh", which suggests it has a different setting for the higher current. It also still has the two non-rechargeable lithium ion cells in the case, suggesting it will need replacement at some point like the rest of them.



It's great to put rumors about this pack to rest. No exotic cooling, is compatible with older cars (physically), no new cell type, etc. Just a new module design that packs more cells into each one.



Enjoy.

-wk

Great job Wk057! Thanks for that.

 

[supratachophobia]

Tesla had considered a battery resale program, but they found it would not make sense given the dropping cost of new battery cells. Keep in mind the target is below $100/kWh, Tesla's current pack costs were quoted at below $190/kWh early last year.

Right now it makes sense to reuse packs by refurbishing them (since they have no choice but to take the back pack under warranty), but trying to assign a significant core value to them would be difficult.

Your cell degradation percentage calculation for value is also way too optimistic. Rather there will first be a huge cut because of used part depreciation, then a cut from newer packs being more competitive. Going with some more realistic assumptions, say the pack has been used 50k miles (I'm using this because the following values are available at this mileage): the car will lose 28% in value by this time, pack degrades around 5%. So core value will be at most $190/kWh * 72% = $137/kWh. The pack most likely would be an 85kWh, so valued at 80kWh with 5% loss, for a core value of ~$11k.

In case you think that core value is low, Nissan offers only a $1000 core value for their 24kWh pack. Even at half capacity, that is only $83/kWh.

The marginal retail price of a Tesla pack is $300/kWh ($3000 for the 10kWh upgrade), so 100kWh would be $30000. Add in the other costs around $2000 (the destination, installation, certification, etc) and that works out to $32k. $32-11k = $21k to do the upgrade. That's high enough that it will make people seriously consider putting that $21k toward a new Tesla and selling their old one.

The other driving force is that service centers are already swamped handling regular service issues, plus the battery packs are worth far more money installed in a new car than upgrading an older car (which also discourages the owner from buying a new one).

You've essentially just framed the need for an entire battery upgrade industry for out of warranty cars.

 

[SomeJoe7777]

You've essentially just framed the need for an entire battery upgrade industry for out of warranty cars.

I think you're right that out-of-warranty cars will indeed be swapping batteries around. Extra batteries will be on the market from wrecked vehicles, and out-of-warranty vehicle owners may want to upgrade or replace a heavily degraded pack. So there will be a market.

The question is, what will Tesla do when those cars come in for non-warranty service? If the pack has been changed, even to an identical part number thus requiring no firmware modifications, do they turn it away and refuse to work on it? And if so, who will work on it, given that Tesla will (currently) only allow 3rd-party body shops, not 3rd-party drive system and battery work?

 

[JRP3]

If it's out of warranty Tesla has no say about who can work on the vehicle.

 

[strider]

I think you're right that out-of-warranty cars will indeed be swapping batteries around. Extra batteries will be on the market from wrecked vehicles, and out-of-warranty vehicle owners may want to upgrade or replace a heavily degraded pack. So there will be a market.

The question is, what will Tesla do when those cars come in for non-warranty service? If the pack has been changed, even to an identical part number thus requiring no firmware modifications, do they turn it away and refuse to work on it? And if so, who will work on it, given that Tesla will (currently) only allow 3rd-party body shops, not 3rd-party drive system and battery work?

I think for the next few years while M3 is rolling out the answer is they won't touch it. SCs are hammered now before they start building tons of M3's. But a few years down the line when they have the new car servicing down pat I can see them doing this themselves or billing shop rates to help people do swaps. If you have idle techs, why not put them to work and make some money?

 

[msnow]

If it's out of warranty Tesla has no say about who can work on the vehicle.

As long as they provide parts.

 

[GSP]

As long as they provide parts.

And service information, and special tools required.

GSP

 

[smac]

And service information, and special tools required.

And firmware unlocks.

 

[AWDtsla]

ok, let me try this again.
Selling a 100kwh pack for 25k new. 25% profit gives a cost of $18,750.

Now if a brand new 100 pack is worth that to Tesla, what is a used 90 degraded to 80 worth? Even at100% value it's worth a 'cost' of 15k. But it's not worth new value because it's used. So 10-12k. Add labor and risk and cost of business... you'd have to charge a guy upgrading 15k+

Any time we get customers asking to trade in used we deal w this. They forget our cost of new is half retail so used has to be worth like 25% of new. People get so mad and we don't want the rep of selling used. We just say we don't take trade ins.

If it was 25k new, I'd rather pay for a new pack, and keep my old one. I could get a good fraction of that pack in the used market, if not just finding another use for the cells. Everyone that has ever tried has apparently been told they cannot keep their old pack.

 

[brkaus]

If it was 25k new, I'd rather pay for a new pack, and keep my old one. I could get a good fraction of that pack in the used market, if not just finding another use for the cells. Everyone that has ever tried has apparently been told they cannot keep their old pack.

That's one reason they won't. Too easy to part out, potentially at a profit.

 

[AWDtsla]

Right, but the max output during a launch went up from 1520 to 1760. That's a 16% increase in the power pulled from the pack...

Exactly. So what changed? Perhaps the diameter of the cell bond wire? Looks the same (from the picture). Perhaps the quality of the weld.

 

[AWDtsla]

That's one reason they won't. Too easy to part out, potentially at a profit.

So what? You already paid for YOUR pack. Why can't you keep it?

 

[brkaus]

So what? You already paid for YOUR pack. Why can't you keep it?

I don't see an issue with that, but why would they sell a new pack at only slightly over the parting out value? I'm just questioning the $25k price. Seams Tesla can get a better return on their investment putting the batteries into cars, power walls, and power packs.

 

[fiksegts]

awesome info and work, thanks for posting! I'm curious as the pack weights as well...

 

[dennis]

Thanks @wk057 , this is awesome. 2 quick questions:

- any idea why they made the HV connection incompatible and requiring an adapter part?
- given the increase in amperage, have you verified that the HV wiring in the 85/90 cars is of adequate size?

 

[wk057]

I'll try to get to some questions tomorrow. Beat tonight... was busy putting this 100 kWh pack to good use.

 

[vgrinshpun]

awesome info and work, thanks for posting! I'm curious as the pack weights as well...

According to the Manual P100D weighs 100lbs more than P90D. Assuming that individual battery cell weighs about 48g, additional cells in P100D add about 90lbs.

 

[AWDtsla]

I don't see an issue with that, but why would they sell a new pack at only slightly over the parting out value? I'm just questioning the $25k price. Seams Tesla can get a better return on their investment putting the batteries into cars, power walls, and power packs.

I'd question that price outright. 8 year warranty starts expiring in 3 years. Which means Tesla has only 3 years to reach $12k replacement cost on a 85 pack. That prediction was without the gigafactory, and without the gigafactory coming to scale production years before originally stated. The cost for a 100kWh pack should start approaching $10k by 2020.

 

[supratachophobia]

I'd question that price outright. 8 year warranty starts expiring in 3 years. Which means Tesla has only 3 years to reach $12k replacement cost on a 85 pack. That prediction was without the gigafactory, and without the gigafactory coming to scale production years before originally stated. The cost for a 100kWh pack should start approaching $10k by 2020.

Unfortunately, Tesla can charge whatever they want for battery upgrades regardless of pack/production costs. However, I'd still like to see an official replacement program. And once they stabilize prices with the gigafactory, we just might. It makes more sense that way since you don't have a such a huge disparity in cell costs from year to year.

 

[BestRadar]

Unfortunately, Tesla can charge whatever they want for battery upgrades regardless of pack/production costs. However, I'd still like to see an official replacement program. And once they stabilize prices with the gigafactory, we just might. It makes more sense that way since you don't have a such a huge disparity in cell costs from year to year.

I think if they put up replacement prices it would ease many customers concerns. At this point if a battery fails out of warranty customers have no idea what a replacement could cost. Also a compatibility guide would be great so that customers with lets say an existing customers 85 or 90 batteries would know if they could upgrade to a 100 down the line at some point.