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Recell: certified replacement battery packs for low-range/bricked Model S

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Thanks for the feedback. I'm very curious to hear how this repair holds up. Be on the lookout for any weirdness like the battery shutting down even though it still seems to have plenty of charge left in it.
@Crutonius, really good callout. The BMS on the older Tesla's don't do especially well on the bottom end - as the modules age, anything below 40 miles can be dicey. But... really depends on the pack.

Recently, we had a pack come in with great underlying fundamentals - both capacity and balance, some of the best we've seen - however there were two BMB's that did the pack a dirty - one had failed on Brick6, eventually throwing the module out of balance, and a second BMB, as we learned after more detailed analysis, was on it's way to failing as well. Replaced the necessary bits, rebalanced the pack, completed our short and long-range tests and the pack now delivers 250+ miles top to bottom.

With other packs, the modules come in completely out sorts, with capacity and balance all over the place. When that happens, it's a full pack swap. No way around it.
 
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It's a shame that they are so far from me (they are in San Antonio, I'm in Seattle) so shipping costs added up but Id HIGHLY recommend them!

Indeed - thank you @grahamtwatson!

Our main service center and warehouse hub are currently just down the road from the Tesla Gigafactory in Austin - that's by design ;)

But with business growing rapidly, we are actively scouting out Service Center locations in Los Angeles/Southern California, Bay Area/Central Valley, Seattle and the Mid-Atlantic/Tri-State area. We'll be sure to keep folks posted as we open new locations...
 
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As a follow up to this, I did send my 2013 85 S to Recell, and I must say I'm delighted. They dropped the battery, replaced the faulty module as well as the main fuse and contactors, found and fixed an issue with the battery management board on a different module, balanced it all up and thoroughly tested it. They didn't charge (forgive the pun) any extra for the additional problem they found. Communication was outstanding, I've never had anything like it before. including a two year warranty, the cost was about $7.5k. It's a shame that they are so far from me (they are in San Antonio, I'm in Seattle) so shipping costs added up but Id HIGHLY recommend them!

This concerns me because wk057 says replacing a module will never last. Within a year, the BMS will detect the replaced module as too different from the rest of the modules and shut down the pack.

But ce2078 of Hybrid ReVolt says he’s been able to replace modules by also downgrading the firmware on MCU1 cars to a version with less strict module matching requirements in order to make the fix last longer. Unfortunately that eliminates some features available in newer firmware, like seeing the number of stalls in use at superchargers, and if you get the car serviced by Tesla they'll upgrade the firmware and the pack will show up as broken. Did you lose that feature, indicating re cell uses that tactic? Or have they found a different tactic to make the packs last up to their warranty? It's still likely not going to last a lot longer than the warranty, unfortunately.

For those looking for battery or other out of warranty service in Southern California or AZ, contact Hybrid ReVolt who also works with EV Fix Me in socal.
 
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It usually only takes one full day of supercharging powered driving (several cycles worth of charges back to back) to really imbalance a pack with a mismatched module. Regular daily use will also slowly grow the mismatch imbalance to uncorrectable levels. This is because the BMS's ability to correct an imbalance is extremely limited. (Edit: Keep in mind when I say "imbalance" I'm not just referring to voltage deltas between cells... the BMS tracks way more than this.)

The only way a module replacement can last is if the car is used way less than average, and rare to no supercharger trips. The longer the car sits, the more time the BMS has to correct an imbalance. I did some napkin math on this in another thread somewhere, but I think it worked out to something like 36 hours idle for every 100 miles of use (or something like that, don't have the numbers in front of me) required to have a hope of keeping a best possible unit, but still inevitably mismatched module, in line with the rest of the pack. The imbalance is also cumulative, and the time needed to correct it is cumulative.

The core issue is imbalance under load/charge. You can put a pack back together with 16 modules from 16 different donor packs, and at rest they'll all be in balance. As soon as you put them under load or charge, however, the differences in their lives become obvious and those imbalances grow in a positive feedback loop over time. Same applies to a pack with 15 original modules and one oddball. Sure, you might match some metrics with the original battery pack. But it's pretty unlikely (in practice impossible) to match all of the needed metrics to make it functional indefinitely and prevent the positive feedback loop from growing an imbalance in voltage and/or capacity.

I actually have a couple of modules from a system where a customer tried to mismatch modules in series in a project with an inadequate BMS in a non-EV project. (The customer never told us this was what he was doing, btw.) Eventually the customer complained that there were a couple of modules that were showing "weird readings" when in use, and his system seemed to have drastically lower capacity than when he initially set it up. We got these modules, and it turns out entire cell groups were completely degraded. As in, it would take next to no amount of energy to get them up to full charge voltage, and they'd provide almost no energy draining to 0% voltage. In his system under load, the current from loads/charging would make the voltage of these groups fluctuate wildly. Turns out he was doing pairs of modules in series for a 48V setup, but was not matching the modules that were paired up together with modules from the same original battery pack... leading to a feedback loop that quickly degraded the most mismatched groups. His third-party BMS setup didn't care about capacity or voltage imbalance deltas, as long as no cells ever went above or below safety set points... which fortunately never happened. But since operation was allowed to continue, despite these gross mismatches, some modules slowly killed themselves.

This is what Tesla's BMS tries to prevent by monitoring far more metrics than just voltage. They calculate out the capacity of every cell group individually. They calculate out the impedance of every cell group individually. They map impedance vs temperature for every cell group. They map the surface charge capacity of every cell group. They map impedance vs load/charge for every group. And way way more. In a normal pack, when some of these don't match up, that's an indication of a problem, and Tesla's BMS reacts accordingly. A mismatched module induces differences in these values. It may take some time for the BMS to become aware (some of these metrics are calculated slowly over hundreds or thousands of miles of use), but it will eventually realize something is screwy and react accordingly.

TL;DR - Module replacements are not repairs.
 
@wk057 Have been waiting for your feedback on this and you didn't disappoint. Many thanks for the detailed information.

We don't even have any comparable after-warranty service here in the UK, but in the next few years as more garages open up to fixing Teslas/EV in general it'll be crucial to know whether their repair will be sustainable.

There's no chance I'll take my car to you (and not for lack of want!) but I'll be looking forward to when/if you sell the battery monitor overseas :).
 
We don't even have any comparable after-warranty service here in the UK, but in the next few years as more garages open up to fixing Teslas/EV in general it'll be crucial to know whether their repair will be sustainable.
It looks like a shop in Norway is going to start battery repairs, and it sounds like part of what they are doing is making tools/procedures available for others. It will be interesting to see if they actually show what they do to repair packs.
 
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I am curious to know how Recell works to prevent issues over the long term so that customers don't have to come back a year later due to mismatched modules / cells after a main battery repair. Do they match replacement modules with similar age, voltage and current characteristics when compared with the main pack? It would be nice if new or close to new modules could be used and the BMS would be able to smartly adapt. How are these repairs holding up after a year when customers normally charge to 90%? Are the batteries able to stay balanced? Tesla told me that you now only have to charge to 90% and the batteries will automatically balance themselves.
 
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I am curious to know how Recell works to prevent issues over the long term so that customers don't have to come back a year later due to mismatched modules / cells after a main battery repair. Do they match replacement modules with similar age, voltage and current characteristics when compared with the main pack? It would be nice if new or close to new modules could be used and the BMS would be able to smartly adapt. How are these repairs holding up after a year when customers normally charge to 90%? Are the batteries able to stay balanced? Tesla told me that you now only have to charge to 90% and the batteries will automatically balance themselves.

That's the million dollar question.

It has to be possible to match a cell, just way more difficult than it sounds. Apparently not even Tesla is capable of this.

I'd feel a lot better about these services if I saw more feedback about them. Ominously one of the businesses that's cited the most, grubermotors, isn't accepting new business and no one has left feedback for them on yelp or any other review service for over a year.
 
Ominously one of the businesses that's cited the most, grubermotors, isn't accepting new business and no one has left feedback for them on yelp or any other review service for over a year.


This is the second time Gruber Motors is severely hit by a fire

I'll just leave this here.
 
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I just need my contractors replaced. Do you know someone who will do this? Tesla won’t do it at the service level because 3rd party vendor worked on the battery in the past.
Probably wouldn't post a phone number on a public forum... should probably edit that.

Pretty sure you have a ticket in with us and we were trying to gather more information, since most likely replacing the contactors is not the actual issue based on what's been described. (We're not the 3rd party, btw)
 
I'd feel a lot better about these services if I saw more feedback about them. Ominously one of the businesses that's cited the most, grubermotors, isn't accepting new business and no one has left feedback for them on yelp or any other review service for over a year.

Gruber replied to my enquiry about repairing my dead battery with "At the moment we are not receiving any vehicles due to a significant amount of Model S’s undergoing similar battery related issues. It will be an 8 month wait time until we can touch any cars." which doesn't quite jive with their recent lack of reviews. Definitely sounding very suspicious.
 
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TL;DR - Module replacements are not repairs.

once again, whole heartedly agree. snipping cells and module swapping is a hard no. matching capacity, load tolerance, impedance are the only way packs remain in balance. at scale, those are achievable, but as both @wk057 and @Recell have posted here and elsewhere, far better to swap out the pack with an intact, certified and road-tested pack.

in fact, we hope to post pics of our mobile road lab in the weeks ahead. <prays to the schedule gods...> ;)

"This Is The Way"
 
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whole heartedly agree. snipping cells and module swapping is a hard no. matching capacity, load profile, impedance are the only way packs remain in balance. those are achievable, but as both @wk057 and @Recell have posted here and elsewhere, far better to simply swap out the pack with an intact, certified and road-tested pack.
You say that but this person claims you replaced a module in their pack:

As a follow up to this, I did send my 2013 85 S to Recell, and I must say I'm delighted. They dropped the battery, replaced the faulty module as well as the main fuse and contactors, found and fixed an issue with the battery management board on a different module, balanced it all up and thoroughly tested it.
Was it not a battery module that was replaced?
 
we are always happy to answer questions, offer technical feedback, etc. - like srsly, always happy! 😀

however, we have a long-standing policy of not discussing or commenting on work we've done for customers in public forums. hopefully that makes sense. as our customers will attest, we really do take your privacy seriously. 👍
 
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however, we have a long-standing policy of not discussing or commenting on work we've done for customers in public forums. hopefully that makes sense. as our customers will attest, we really do take your privacy seriously. 👍
Are you saying that while you don't recommend it, you will replace a module in a pack if the customer requests that as a fix?