Battery defect for IT brainstorming BMS_u029 - P85 MS 2013

[brainhouston]

I'm aware of the moister ingress issue and the short hose above the battery on some older cars, but I was not aware that these so-called "umbrella valves" are under the pack. I did ask @chrisro the question but he never replied (Post#46). Thank you for the response.

some info i posted for X how to check them, might be same for S...

Car died. BMS errors f123, w123, w073, w035, w142, w158

This is a very interesting thread! I recall from our house flood that the crew ran dehumidifiers until the rooms reached a target humidity. What if, when you believe the pack to be dry, you temporarily seal the pack but place a humidity probe in there (safety first!) for some period of time...

teslamotorsclub.com

 

[brainhouston]

In the case of the BMS_u018 modules, the cells themselves work perfectly fine with very very little self discharge and can soldier on - they are just tired and worn with less capacity than they once had, but otherwise perfectly operational. in fact, they can be repurposed/recycled for ‘secondary use’, just not in their current configuration as a Model S battery module.

I'm curious why these can't be used on S?
I understand range is gonna be limited but is BMS not going to allow it or some other reasons?...

 

[Droschke]

some info i posted for X how to check them, might be same for S...

Car died. BMS errors f123, w123, w073, w035, w142, w158

This is a very interesting thread! I recall from our house flood that the crew ran dehumidifiers until the rooms reached a target humidity. What if, when you believe the pack to be dry, you temporarily seal the pack but place a humidity probe in there (safety first!) for some period of time...

teslamotorsclub.com

Much appreciated. Very helpful.

 

[Recell]

I'm curious why these can't be used on S?
I understand range is gonna be limited but is BMS not going to allow it or some other reasons?...

in the case of a u018 the modules are desperately out of balance - in the example that was cited, 15 Ah within the same module. the module (in its current form) is simply at the end of its life. no reason however that the components can’t be repurposed for secondary use.

 

[aerodyne]

I'm aware of the moister ingress issue and the short hose above the battery on some older cars, but I was not aware that these so-called "umbrella valves" are under the pack. I did ask @chrisro the question but he never replied (Post#46). Thank you for the response.

Monroe Live has a YT vid showing similar valves during a teardown of the Refresh MS pack.

As time goes by, I am more and more dismayed about the lack of proper engineering of common issues such as corrosion, dissimilar metals protection, potting of critical electrical items,venting/drainage, shingling and sealing. It's almost as if spacecraft engineers working on single use rockets were involved.

The packs should not only be better sealed, but also be able to actively sense and dehumidify inside the pack as needed to prevent corrosion.

 

[ResHacker]

The packs should not only be better sealed, but also be able to actively sense and dehumidify inside the pack as needed to prevent corrosion.

Yes, that is something I'm also thinking about, this would be a perfect solution. It would require some device collecting humidity data on several points (probably all module chambers separately) inside the pack with some interface to be able to trigger a warning message to the outside.

 

[Recell]

The packs should be able to actively sense and dehumidify inside the pack as needed to prevent corrosion.

they do. now, whether it’s effective or not…

 

[ajadan]

in the case of a u018 the modules are desperately out of balance - in the example that was cited, 15 Ah within the same module. the module (in its current form) is simply at the end of its life. no reason however that the components can’t be repurposed for secondary use.

Is this (a u018 error) at all a case where the the “snip out” method of “fixing” the battery would work? It seems like creating a 95/96 brick, 396V battery by taking the one degraded brick out of circuit would maintain brick balance and “restore” range since the BMS limits capacity/range based on the worst brick.

Clearly I have no idea what I’m talking about, because this would seemingly be a very cheap approach compared to replacing a battery, but hasn’t been widely adopted.

 

[MP3Mike]

Is this (a u018 error) at all a case where the the “snip out” method of “fixing” the battery would work?

No. That isn't a fix for any issue.

 

[chrisro]

Vent valve is on the top of battery and a/c drain line is droping water close to this valve. Tesla's most stupid idea. In Reman packs this valve is removed.

Would you elaborate on what they are?

Vent valve is on the top of battery and a/c drain line is droping water close to this valve. Tesla's most stupid idea. In Reman packs this valve is removed.

 

[brainhouston]

Is this (a u018 error) at all a case where the the “snip out” method of “fixing” the battery would work? It seems like creating a 95/96 brick, 396V battery by taking the one degraded brick out of circuit would maintain brick balance and “restore” range since the BMS limits capacity/range based on the worst brick.

Clearly I have no idea what I’m talking about, because this would seemingly be a very cheap approach compared to replacing a battery, but hasn’t been widely adopted.

My understanding is it could work but there's no software/firmware support for it..
Theoretically you can snip out one cell in every brick to make it balanced but thats a lot of work and what if short time after another cell dies...

 

[ajadan]

No. That isn't a fix for any issue.

I essentially figured that, but I’m more curious as to why in this situation, as it would involve taking a full brick out of series, not an individual cell out of parallel. Individual cell removal has clearly not been an appropriate solution.

 

[Recell]

Is this (a u018 error) at all a case where the the “snip out” method of “fixing” the battery would work? It seems like creating a 95/96 brick, 396V battery by taking the one degraded brick out of circuit would maintain brick balance and “restore” range since the BMS limits capacity/range based on the worst brick.

Clearly I have no idea what I’m talking about, because this would seemingly be a very cheap approach compared to replacing a battery, but hasn’t been widely adopted.

while seemingly attractive, a 95/96 reconfiguration would involve SIGNIFICANT modification of a battery module, and would likely offset any benefit.

on the other hand, a 15/16 configuration (ie a 375V pack) is something someone oughta work on

 

[wk057]

while seemingly attractive, a 95/96 reconfiguration would involve SIGNIFICANT modification of a battery module, and would likely offset any benefit.

Yeah, definitely not practical.

on the other hand, a 15/16 configuration (ie a 375V pack) is something someone outa work on

Funny enough... "someone" is...

I already have configurations of 13, 14, 15 and 16 modules working in the S+X with the custom BMS I had originally designed for 057's non-OEM pack project. (I actually have a 14 module pack in my X right now for more testing and dev on this hardware... built out of a 2012 85 pack that had two bad modules, migrated to an X-compatible pack chassis.)

This wasn't that hardware's intended use, but it's a functional thing. I've mainly been debating if this is something to focus on making production ready for this purpose, and it seems like it might be time to do so. Unfortunately this currently comes with a lot of caveats, so would take a lot of time to flesh out those details and get it fully on par with Tesla's BMS in such a setup with Tesla modules since this wasn't originally designed with that use in mind.

The biggest problem is there's only so many OEM-valid configurations. Modifying these on Tesla hardware isn't really a viable option, since an OTA updates would basically brick the car at that point, or otherwise be impossible. The custom setup needed has to fake one of these OEM setups, and be able to handle any updates that come down the pipeline gracefully. There's also the matter of things like supercharging, where the protocol has evolved significantly over the past couple of years and probably will continue to do so (the BMS speaks directly to the supercharger, so the protocol is implemented there), meaning the custom hardware needs a sensible update mechanism as well to be a long term solution.

I've put in significant effort to make this possible, and am pretty proud of the work done on the custom pack project to cover all the edge cases on things like this. Unfortunately that project is pretty much dead in the water at the moment without someone with pretty deep pockets jumping on board to make it a reality. Migrating a lot of that work and knowledge towards alternative refurbishment options for existing packs is starting to look more reasonable given that the volume of such repairs is steadily increasing and a better solution is very much needed at this point.

 

[Recell]

indeed, the key is the updates. our base working assumption is to work with the existing OEM firmware - for a bunch of reasons actually.

we see so many solutions that involve rooting the MCU, etc.

absolutely no issue with that in principle, but it’s just so so far out of the grasp of the average car owner, not to mention instantly limiting their service options once they do.

it’s much like the old Android-vs-iOS debate, and before that, the never ending Linux debates. ‘but, but I can configure anything I want with [insert preferred Linux dist]’

yah great, configuring anything you want sounds awesome in principle, but how about the rest of the world? and, who’s going to provide them service and support?

 

[Recell]

Migrating a lot of that work and knowledge towards alternative refurbishment options for existing packs is starting to look more reasonable given that the volume of such repairs is steadily increasing and a better solution is very much needed at this point.

@wk057, definitely encourage/applaud the effort. we made the pivot to 14/16 and 15/16 configurations last fall with our RC+ series when it became clear that the only scalable solution for the growing number of BMS_u029 and (non-BMB/non-VSH related) BMS_u018 errors would be some kind of pack re-config.

 

[brainhouston]

@wk057, definitely encourage/applaud the effort. we made the pivot to 14/16 and 15/16 configurations last fall with our RC+ series when it became clear that the only scalable solution for the growing number of BMS_u029 and (non-BMB/non-VSH related) BMS_u018 errors would be some kind of pack re-config.

So, i'm a bit confused cause it seems u n wk saying diff things..
Does Tesla BMS support 15 modules??

 

[Recell]

no, the Tesla BMS does not have native/out-of-the-box support for 15 modules. there’s some some secret sauce involved to make a 15/16 work.

 

[wk057]

no, the Tesla BMS does not have native/out-of-the-box support for 15 modules. there’s some some secret sauce involved to make a 15/16 work.

^ This.

I do believe ReCell and I have different recipes for our secret sauces on this, though. haha

 

[BigNick]

^ This.

I do believe ReCell and I have different recipes for our secret sauces on this, though. haha

Carolina vs Texas BBQ?