Take out HV batt pack / cut out bad cell? (S P85+)

[vcor]

...I don't see how structural battery helps the key factory on battery reliability....

We will not know for many years if the new structural pack delivers on reliability. Many new design changes should result in better long-term reliability:

1) Fewer electrical connections are a huge advantage. Every connection is a weak point that may fail over time due to corrosion or vibration. The structural pack has about 1/10 the number of connections, so failures from this should be about 1/10 that of other packs.

2) Reduced coolant connections - again, every connection is a risk point for failure. The fewer connections, resulting in fewer risk points. The structural pack has the fewest fluid connections of any pack to date.

3) Reduced number of coolant pipes. Using larger cells reduces the number of coolant channels required. This may increase reliability, although I've never heard of these failing even on the oldest packs.

4) Sealed BMS electronics. It appears the BMS electronics are far better sealed than in prior packs. While this makes the BMS electronics impossible to be fixed, it also shields them from the most common problem - corrosion of connections.

5) Sealing the entire pack in rigid foam further reduces vibration failure risks.

6) The 4680 battery cell design should be more reliable. The internal tab design will have little effect if a tab breaks internally as there are hundreds of tabs within the cell. On prior cells, a broken tab means the cell becomes open. Again, this has yet to be proven, but I suspect making a more reliable cell was a major consideration in the new cell design.

 

[islandbayy]

Whats is the original capacity on the model S 85 packs?
Is there different pack size gor model s 85?

(Would like to know the total capacity, not “usable”).

Per Jason's data (WK057)

==========>Original 60– ~61 kWh total capacity, ~58.5 kWh usable.
==========>85/P85/85D/P85D– ~81.5 kWh total capacity, ~77.5 kWh usable
==========>90D/P90D– ~85.8 kWh total capacity, 81.8 kWh usable
==========>Original 70– ~71.2 kWh total capacity, 68.8 kWh usable
==========>75/75D– 75 kWh total capacity, 72.6 kWh usable
==========>Software limited 60/60D– 62.4 kWh usable
==========>Software limited 70/70D– 65.9 kWh usable
==========>100D/P100D– ~102.4 kWh total capacity, usable capacity not available at this time

 

[howardc64]

We will not know for many years if the new structural pack delivers on reliability. Many new design changes should result in better long-term reliability:

1) Fewer electrical connections are a huge advantage. Every connection is a weak point that may fail over time due to corrosion or vibration. The structural pack has about 1/10 the number of connections, so failures from this should be about 1/10 that of other packs.

2) Reduced coolant connections - again, every connection is a risk point for failure. The fewer connections, resulting in fewer risk points. The structural pack has the fewest fluid connections of any pack to date.

3) Reduced number of coolant pipes. Using larger cells reduces the number of coolant channels required. This may increase reliability, although I've never heard of these failing even on the oldest packs.

4) Sealed BMS electronics. It appears the BMS electronics are far better sealed than in prior packs. While this makes the BMS electronics impossible to be fixed, it also shields them from the most common problem - corrosion of connections.

5) Sealing the entire pack in rigid foam further reduces vibration failure risks.

6) The 4680 battery cell design should be more reliable. The internal tab design will have little effect if a tab breaks internally as there are hundreds of tabs within the cell. On prior cells, a broken tab means the cell becomes open. Again, this has yet to be proven, but I suspect making a more reliable cell was a major consideration in the new cell design.

All engineering based improvements by engineers.. which is certainly good.

But basic Lithium Ion dendrite formation causing cell shorts is chemistry and physics problem. Has been and still is the hottest research area for Lithium Ion battery (actually rechargeable battery's bridging shorts between anode cathode has been common problem for 100 years in ALL rechargeable chemistries) No evidence of solution in sight.

Current disclosures are lots of info from Engineers but very little from Chemists and Physicists. I'm still slowly learning all the fundamentals on my own. For example, what gives hydrocarbons fuel its relative stability (wide temp range storage. lower exothermic reactivity to the environment's chemistry) yielding simple tanks, high energy density (10x LiOn, seems like a lot more bonds/volume and 1/2 of reagents is external (O2)), and liquid for conformal storage shape (airplane wings). Maybe its due to the C-C C-H bonds where the energy comes from? Rechargeable chemistries are ionic bonds. Anyway, best for chemists/physicists to chime in why rechargeable chemistry longevity is such a fundamentally challenging problem. Its more than engineering.

====

BTW, been wondering what Tesla's battery pack distribution location look like... I doubt its desirable to stack batteries packs together densely... I'd imagine there is fire wall between small groups of packs. Otherwise, 1 cell's in exothermic runaway reaction will take out all the assets.

 

[vcor]

A lot of battery cell design changes over the last 10 years, but that's not my expertise, so I don't know how current cell design changes affect the dendrite formation. Since cell cycle frequencies seem to have increased I expect dendrite formation to have been reduced - at least enough to not be an issue for 15-20 years in typical vehicle use. Doesn't seem to be a concern for owners as the pack range will be at end of life (70%) first.

I've heard, but cannot confirm that a single-cell runaway will not take out a Tesla battery pack, but multiple cells (i.e. from an accident that damages multiple batteries) will. This is more problematic with prismatic cells used by some other EVs, where they are stacked together in a module. One cell failure will clearly take out all the cells in the module as there is no isolation between cells like the metal cans that Tesla uses. It's less clear if a module failure will take out the entire pack. The Bolt fires appear to be this type - a single-cell failure takes out the entire pack. That said, single-cell failures on a Tesla where it catches on fire seem to be exceptionally rare when not accident induced. Then again, we may not know when this occurs if the damage is contained in a single cell. Perhaps wk056 can chime in with what they've seen.

 

[howardc64]

Since cell cycle frequencies seem to have increased I expect dendrite formation to have been reduced - at least enough to not be an issue for 15-20 years in typical vehicle use. Doesn't seem to be a concern for owners as the pack range will be at end of life (70%) first.

Don't think can make that assumption. Still the #1 real research focus for lithium ion batteries. It is a very fundamental basic chemistry problem trying to do forward and reverse chemical reaction 500-1000x over a tiny anode cathode channel gap. But of course big commercial producers are eager to PR leaps and bounds advancements.

70% range problem was solved simply through large capacity packs. More ions = less % usage / mile. Tesla didn't do anything magical over original Leaf other than ~4x battery capacity. Leaf's 30-40% range loss @ 100k miles / 4 ~= Tesla's range loss @ 100k miles. Active thermal mgmt for < 25kWh EVs didn't help much as small capacity range loss dominates.

 

[allas1]

Hi Guys!

12 days after my warranty my Tesla Model S P85+ standing here with HV failure. It has get all service during life, even Battery service 8th of march 2022. and running well.But suddenly on morning it won't start. So i get a repair offer from tessla because they just say sorry out off warranty. Hey come on Tessla 12 days? I have got things on goodwill from both VW, BMW, Mercedes that been out off warranty.

Anyhow now to how i will do to fix it.

I will go to take out my HV battery to do like Grubber motors, Locate the broken cell and cut it off.
However, I can not find a diagram of the battery cells or blocks. Think each "pack" of a total of the 30 must have a "name" in a schedule?

Then the next question. If I use Scan my tessla? Is it possible to use it to find the right battery pack and pre-manually meet each individual cell to stt locate the broken one and cut it off?

Do the car needs to reprogrammed after these procedures?

All help and answers will be helpful! And i will post all things here incl picture of the operation!

Thanks from Sweden!

Hej! Tog du bort en cell eller hur löste du problemet?
Är själv i samma sits och tänkte prova att ta bort den dåliga cellen.

Med vänlig hälsning, M

 

[Cheese Guy]

Hej! Tog du bort en cell eller hur löste du problemet?
Är själv i samma sits och tänkte prova att ta bort den dåliga cellen.

Med vänlig hälsning, M

Service says $22k for new battery on 2012 Model S

" I've been debating on what exactly to do with my public info sharing and contributions for a while now since my posts here are restricted. ... Anyways, thanks for the support!" Could you "blog" on your own website so you would not be "moderated" but instead would be a moderator...

teslamotorsclub.com

 

[olddrew]

So the discussion I've been seeing around failing Tesla battery packs comes down to basically 3 different techniques:
1. Clip the cell fuse within the module (Gruber's method)
2. Replacing the failing module with one that's as closely matched as possible to the other 15
3. Replacing the whole battery (either from Tesla or a 3rd party).

Why can't the individual parasitic 18650 cells be cut out and replaced? This wouldn't be an EXACT match, but it would be 1/16th of a brick, and 1/74th of a full module of a change. Assuming the new 18650 cell was the same as the rest of the module's cells, it would be the closest to an exact balance as possible.

Just wondering why we can't do it that way...

 

[brainhouston]

4. Clip one cell from all 96 bricks to keep things in balance but u loose capacity..

Why can't the individual parasitic 18650 cells be cut out and replaced? This wouldn't be an EXACT match, but it would be 1/16th of a brick, and 1/74th of a full module of a change. Assuming the new 18650 cell was the same as the rest of the module's cells, it would be the closest to an exact balance as possible.

Just wondering why we can't do it that way...

its been done, just high risk n not worth the effort i think...

 

[GHammer]

So the discussion I've been seeing around failing Tesla battery packs comes down to basically 3 different techniques:
1. Clip the cell fuse within the module (Gruber's method)
2. Replacing the failing module with one that's as closely matched as possible to the other 15
3. Replacing the whole battery (either from Tesla or a 3rd party).

Why can't the individual parasitic 18650 cells be cut out and replaced? This wouldn't be an EXACT match, but it would be 1/16th of a brick, and 1/74th of a full module of a change. Assuming the new 18650 cell was the same as the rest of the module's cells, it would be the closest to an exact balance as possible.

Just wondering why we can't do it that way...

Just read wk057's explanation in this thread and you'll see why #1 and #2 don't work.

 

[AAKEE]

Just read wk057's explanation in this thread and you'll see why #1 and #2 don't work.

Can we still thrust wk057’s statements or could they have been made for other reasons?

 

[GHammer]

Can we still thrust wk057’s statements or could they have been made for other reasons?

In the whole business debacle I tend to believe his version of events over that of the people that bought him out. In any case I have no reason to doubt his technical competence and many of his statements regarding pack repairs predate his service contract offerings.

Edit: His statements regarding cell level or module level repair have also been backed up by the other major 3rd party battery pack supplier.

 

[olddrew]

Just read wk057's explanation in this thread and you'll see why #1 and #2 don't work.

I understand his arguments, and those were my initial thoughts too when I saw Gruber's technique.

That said, # 2 (module replacement) I'm not totally against the idea of, at least in terms of the technical premise. I've rebuilt more Prius hybrid battery modules than I can remember using a similar technique, and had no problem warrantying them when I did that as a side gig. I just wonder if his opinion was formed early in his dealings based on a few events that would otherwise be outliers (and his opinion never changed) because other people seem to be doing this process with success.

My real question of why the individual cells aren't more frequently changed (other than that one shop overseas who won't share much info on their procedure, which was a big turn off for me...I honestly didn't finish watching their video until brainhouston reposted it because of that) was based on curiosity, and it just seeming like it was a better idea overall... If you have a shop with a lift and lift table, you probably have a TIG welder to spot weld a battery, or can afford a specific battery spot welder. I haven't opened up a Tesla battery yet (hopefully in the next few days!), so I wasn't sure if there was some specific reason I hadn't seen any US shops doing that, and why a shop as big as Gruber wasn't doing it.

If it was epoxied in with some crazy adhesive like the newer batteries that basically guaranteed you'd destroy the case/module trying to get a single cell out, I could understand. From what I've seen so far, a Dremel, pliers, small wire snips, and/or a 3/4"(19mm) hole saw, and some finesse should be all that's needed to get a cell out of the pack.

I feel a write-up and/or YouTube video coming!

 

[brainhouston]

Can we still thrust wk057’s statements or could they have been made for other reasons?

i tend to believe the latter
there've been multiple module swaps done on this forum n fb 029 group with good results so far.
even recell chimed in n said they did frankenstein pack (16 diff modules) that works, key is to match CAC withing the BMS thresholds

My real question of why the individual cells aren't more frequently changed (other than that one shop overseas who won't share much info on their procedure, which was a big turn off for me...I honestly didn't finish watching their video until brainhouston reposted it because of that)

same, they act like they got some sort of multi billion dollar discovery lol

If it was epoxied in with some crazy adhesive like the newer batteries that basically guaranteed you'd destroy the case/module trying to get a single cell out, I could understand. From what I've seen so far, a Dremel, pliers, small wire snips, and/or a 3/4"(19mm) hole saw, and some finesse should be all that's needed to get a cell out of the pack.

it IS epoxied in there but i think only bottom maybe, can't recall for sure
but i think collateral damage is the main turn off, too risky, u can damage cooling jacket or nearby cell or short something n damage whole module...

I feel a write-up and/or YouTube video coming!

Do it!

 

[Crutonius]

Can we still thrust wk057’s statements or could they have been made for other reasons?

I'm inclined to trust him here. He's a bad businessman, not a bad engineer.

 

[NV Ray]

I understand his arguments, and those were my initial thoughts too when I saw Gruber's technique.

That said, # 2 (module replacement) I'm not totally against the idea of, at least in terms of the technical premise. I've rebuilt more Prius hybrid battery modules than I can remember using a similar technique, and had no problem warrantying them when I did that as a side gig. I just wonder if his opinion was formed early in his dealings based on a few events that would otherwise be outliers (and his opinion never changed) because other people seem to be doing this process with success.

My real question of why the individual cells aren't more frequently changed (other than that one shop overseas who won't share much info on their procedure, which was a big turn off for me...I honestly didn't finish watching their video until brainhouston reposted it because of that) was based on curiosity, and it just seeming like it was a better idea overall... If you have a shop with a lift and lift table, you probably have a TIG welder to spot weld a battery, or can afford a specific battery spot welder. I haven't opened up a Tesla battery yet (hopefully in the next few days!), so I wasn't sure if there was some specific reason I hadn't seen any US shops doing that, and why a shop as big as Gruber wasn't doing it.

If it was epoxied in with some crazy adhesive like the newer batteries that basically guaranteed you'd destroy the case/module trying to get a single cell out, I could understand. From what I've seen so far, a Dremel, pliers, small wire snips, and/or a 3/4"(19mm) hole saw, and some finesse should be all that's needed to get a cell out of the pack.

I feel a write-up and/or YouTube video coming!

A good place to get info Facebook BMS_u029/018

FAQs from aformentioned Group FAQs

 

[Recell]

important clarification. we’ve said module matching can work, but it’s not especially sustainable. 18-24 months is the max we’ve seen it last, and you’ve absolutely got to nail the module match.

the far more durable approach is to reconfigure the pack into a 70/350 or 75/350

it’s one thing to get a pack back on the road, keeping it there is another.

 

[BPeter]

important clarification. we’ve said module matching can work, but it’s not especially sustainable. 18-24 months is the max we’ve seen it last, and you’ve absolutely got to mail the module match.

the far more durable approach is to reconfigure the pack into a 70/350 or 75/350

it’s one thing to get a pack back on the road, keeping it there is another.

How is it that people are able to take modules from these older S/X packs and do EV conversions with them?
Are they always using modules from the same donor pack?
Are these systems unsafe due to the mismatch?
Do they have a better way to balance than what is built into the Tesla pack?
Is the Tesla BMS too picky?

 

[brainhouston]

Do they have a better way to balance than what is built into the Tesla pack?
Is the Tesla BMS too picky?

i believe so
i think EV conversions use other BMSs, maybe even open source and possibly with active BMS
Tesla BMBs can only balance (drain) very small amount/current so it can't deal with large imbalance
thats my understanding

 

[vcor]

Is the Tesla BMS too picky?

Not really. I suspect you could design a BMS to handle larger discrepancies, but you'd also be reducing the pack capacity by doing it. The worse/bad module reduces the life of the remaining modules as they are constantly compensated to try and adjust to match the bad module. Efficiency also goes down as the BMS generates waste heat as it attempts to make the needed adjustments.

Using mismatched modules as a one-off for some ICE to EV retrofit or home projects may not matter as much. You may not care about longevity. These projects are often a "can it be done" cheaply rather than done well.