Battery defect for IT brainstorming BMS_u029 - P85 MS 2013

[BIZTEam]

Hi

I got P85 out of warranty with unique battery issue. Let me start:
2 monts ago, battery reported BMS_u029 error - "Maximum battery charge level reduced".
We measuerd battery, we checked BMS logs and determined that Brick 6 in block 6 is bad, it has little self discharge. Tesla call that in their garage documents SHORT TO BRICK

Ok, no problem, we took it off, open, measuer on bench, 196Ah on block 6. Brick 6 we located 2 cells bad, changed them. Again checked self discharge dooring 6 day period and everything is ok. Returned everything back and car drives but error still there. We cant get rid of BMS_u019.

Tesla says clearly when error apears:
"The battery management system BMS has deteceted a potential weak short in a pack. BMS Detected the short by comparing the voltage change across all the bricks between two points when the pack is "resting". This was repeatedly done at different state of charge SOC levels to confirm the presence of a potential cell with an excessive self discharge."

And they say it is first triggered by BMS_a117_sw_delta_SOC_Weak_short

In another article they mention this BMS_u029 will apear again even if they change battery and some steps needed to be done.

1-
2-
3- "From Garage>tesladex infi, search for "nbms msn" and confirm the MSN value corresponds to the replacement pack msn currently installed within the vehicle.
* for vin to vin repair, the MSN vill be the sam as before
* if the MSN within garage does NOT match what is installed on the vehicle, do not perform the following steps below. Escalate the session as the manufacturing data hasnt been updated on the vehicle.
4- Confirm from Garage>Tasks that a Job Name "BMSSetDataValues" was run successfuly on the vehicle with different arguments from before the pack replacement.
*if a job name "BMSSetDataValues" was not ran......

Lot of other text copying some HEX value ....

Does anyone knows how to remove this remote service alert?

I tried all BMS resets available. I tried clear VAR and HOME to try blank tegra in system, didnt help. Tried Factory reset.

Need help and i would be happy to reward it.

 

[Bickar]

Hi


View attachment 807440



I got P85 out of warranty with unique battery issue. Let me start:
2 monts ago, battery reported BMS_u029 error - "Maximum battery charge level reduced".
We measuerd battery, we checked BMS logs and determined that Brick 6 in block 6 is bad, it has little self discharge. Tesla call that in their garage documents SHORT TO BRICK

Ok, no problem, we took it off, open, measuer on bench, 196Ah on block 6. Brick 6 we located 2 cells bad, changed them. Again checked self discharge dooring 6 day period and everything is ok. Returned everything back and car drives but error still there. We cant get rid of BMS_u019.

Tesla says clearly when error apears:
"The battery management system BMS has deteceted a potential weak short in a pack. BMS Detected the short by comparing the voltage change across all the bricks between two points when the pack is "resting". This was repeatedly done at different state of charge SOC levels to confirm the presence of a potential cell with an excessive self discharge."

And they say it is first triggered by BMS_a117_sw_delta_SOC_Weak_short

In another article they mention this BMS_u029 will apear again even if they change battery and some steps needed to be done.

1-
2-
3- "From Garage>tesladex infi, search for "nbms msn" and confirm the MSN value corresponds to the replacement pack msn currently installed within the vehicle.
* for vin to vin repair, the MSN vill be the sam as before
* if the MSN within garage does NOT match what is installed on the vehicle, do not perform the following steps below. Escalate the session as the manufacturing data hasnt been updated on the vehicle.
4- Confirm from Garage>Tasks that a Job Name "BMSSetDataValues" was run successfuly on the vehicle with different arguments from before the pack replacement.
*if a job name "BMSSetDataValues" was not ran......

Lot of other text copying some HEX value ....

Does anyone knows how to remove this remote service alert?

I tried all BMS resets available. I tried clear VAR and HOME to try blank tegra in system, didnt help. Tried Factory reset.

Need help and i would be happy to reward it.

Did you ever find any resolution?

 

[Electric700]

@wk057 should be able to help with this.

 

[BIZTEam]

Did you ever find any resolution?

Yes i did. Bms needs reprograming to clear flag.

 

[BIZTEam]

Solved

BMS_u029 BMS_u025 BMS Reset

BMS reprograming to remove BMS_u029 and BMS_u025 error flag

evclinic.eu

 

[El Lopo]

we took it off, open, measuer on bench, 196Ah on block 6. Brick 6 we located 2 cells bad, changed them. Again checked self discharge dooring 6 day period and everything is ok.

@BIZTEam what method did you use to isolate the two defective cells in the brick? did you use an IR camera (if so, what we’re the steps) or did you use a different method to measure resistance, short, etc.?

also, what tool(s) did you use to measure capacity? I’ve got a home brew setup for measuring Ah through a shunt, but wondering if you have something more accurate/professional.

 

[ce2078]

I have a device that you install in the car that turns off the bms_u029 error if the battery appears otherwise healthy. Works with both MCU1/2. I've been testing it on multiple cars since Nov22. I will be listing it on my website within the next week.

 

[NV Ray]

I have a device that you install in the car that turns off the bms_u029 error if the battery appears otherwise healthy. Works with both MCU1/2. I've been testing it on multiple cars since Nov22. I will be listing it on my website within the next week.

Your thoughts - @Recell , @wk057

 

[NV Ray]

I have a device that you install in the car that turns off the bms_u029 error if the battery appears otherwise healthy. Works with both MCU1/2. I've been testing it on multiple cars since Nov22. I will be listing it on my website within the next week.

Great news. Looking forward to seeing what you've come up with.

 

[Msolomi]

So will it show the accurate reading of the battery?

 

[ce2078]

So will it show the accurate reading of the battery?

Battery voltage, SOC, etc all reports exactly the same. I discovered this method of clearing the u029 error back in November 2022 and I've testing it with an initial batch of 25 plus another 50 more. So far its been 100% as long as you didn't have any other errors. The device monitors the battery itself and deactivates itself if your imbalance reaches 0.080V or another error appears.

Your thoughts - @Recell , @wk057

I know I'm not the most vocal online but how about "my thoughts". I've been working on Tesla's since early 2015 and likely had the very first Model S cell level battery repair on Oct 13th, 2017 - which that car is still on the road today with the same exact pack. In fact Gruber realized cell repair was possible after I recovered one of their Roadster sheets.

FYI - I have seen u029 on a car with an imbalance of 0.004V! I turned off/reset the BMS and left the whole pack unpowered for a month and the voltage's stayed exactly the same, so it wasn't a weak short or self discharge.

 

[Msolomi]

Battery voltage, SOC, etc all reports exactly the same. I discovered this method of clearing the u029 error back in November 2022 and I've testing it with an initial batch of 25 plus another 50 more. So far its been 100% as long as you didn't have any other errors. The device monitors the battery itself and deactivates itself if your imbalance reaches 0.080V or another error appears.


I know I'm not the most vocal online but how about "my thoughts". I've been working on Tesla's since early 2015 and likely had the very first Model S cell level battery repair on Oct 13th, 2017 - which that car is still on the road today with the same exact pack. In fact Gruber realized cell repair was possible after I recovered one of their Roadster sheets.

FYI - I have seen u029 on a car with an imbalance of 0.004V! I turned off/reset the BMS and left the whole pack unpowered for a month and the voltage's stayed exactly the same, so it wasn't a weak short or self discharge.

Will you please distribute your website so we can order as necessary . . Thanks.

 

[NV Ray]

Battery voltage, SOC, etc all reports exactly the same. I discovered this method of clearing the u029 error back in November 2022 and I've testing it with an initial batch of 25 plus another 50 more. So far its been 100% as long as you didn't have any other errors. The device monitors the battery itself and deactivates itself if your imbalance reaches 0.080V or another error appears.


I know I'm not the most vocal online but how about "my thoughts". I've been working on Tesla's since early 2015 and likely had the very first Model S cell level battery repair on Oct 13th, 2017 - which that car is still on the road today with the same exact pack. In fact Gruber realized cell repair was possible after I recovered one of their Roadster sheets.

FYI - I have seen u029 on a car with an imbalance of 0.004V! I turned off/reset the BMS and left the whole pack unpowered for a month and the voltage's stayed exactly the same, so it wasn't a weak short or self discharge.

As you know, the BMS_U029 error is becoming very common on early Model S's. Thanks for your thoughts. Again, look forward to seeing what you have discovered.

 

[Recell]

The key is that any solution that clears BMS errors must be diagnostic driven - able to interpret the thousands of data points generated by the BMS - and tackle the ROOT cause (in this case, module failure or potential module failure) vs. simply masking the issue. In that respect, simply clearing the error (which is NOT what @ce2078 appears to be describing) should be VERY concerning to owners, individually, and as a community.

Owners occasionally reach out to us asking if we can simply clear a BMS_u029 error, something we IMMEDIATELY decline, for two reasons:

• first and foremost, without understanding the underlying ROOT cause (e.g. potential module failure) that's just a really really bad idea. these BMS_u029 errors are being triggered for a reason, false positives are NOT common.
• there's considerable moral hazard (and just all round poor form) in an owner learning of a fatal error in their battery pack, having the error cleared, and then passing the issue onto an unsuspecting buyer. Of course, that's not something new - unscrupulous car owners/mechanics have been doing it for decades - it's just not something we would ever be party to.

One technical note: a single 3200 mAh cell failure (it only takes one...) can present with a SoC delta as little as 5mV-20mV. The upward bound of that, 20mV, is what we most often see on a BMS_u029.

 

[Recell]

Additionally, we would argue - and we used to say this ALL the time to Jack Rickard of EVTV fame - that any solution that attempts to override the BMS without addressing the root cause can/should be open source to ensure adequate community testing and verification. With these packs, there's simply too much riding on it.

 

[ce2078]

A very interesting point is Tesla has it coded in their software to ignore u029 if they want by setting a flag on the MCU. See image. Read what you want from that.

We have studied the u029 error a lot. It seems on older cars there are many false positives out there due to imbalanced CAC on aging packs. We try to ask everyone for individual cell voltages prior to selling them a device. But otherwise the device pairs with the car and records pack condition. Only if the pack seems healthy do we send the command to turn off the error. And with the device paired to a car you won't get someone who buys one to clear a fleet of cars. We may unpair/reset a device for a fee but that hasn't been decided yet and will likely be on a case-by-case basis.

As for open-source. I am willing to talk about some of what we do to qualify the pack, but will not open source it outright nor disclose exactly how we turn off the error. I've got nearly a year in on this and need to be paid for my time.

 

[NV Ray]

@ddb1001

 

[wk057]

The key is that any solution that clears BMS errors must be diagnostic driven - able to interpret the thousands of data points generated by the BMS - and tackle the ROOT cause (in this case, module failure or potential module failure) vs. simply masking the issue. In that respect, simply clearing the error (which is NOT what @ce2078 appears to be describing) should be VERY concerning to owners, individually, and as a community.

Owners occasionally reach out to us asking if we can simply clear a BMS_u029 error, something we IMMEDIATELY decline, for two reasons:

• first and foremost, without understanding the underlying ROOT cause (e.g. potential module failure) that's just a really really bad idea. these BMS_u029 errors are being triggered for a reason, false positives are NOT common.
• there's considerable moral hazard (and just all round poor form) in an owner learning of a fatal error in their battery pack, having the error cleared, and then passing the issue onto an unsuspecting buyer. Of course, that's not something new - unscrupulous car owners/mechanics have been doing it for decades - it's just not something we would ever be party to.

One technical note: a single 3200 mAh cell failure (it only takes one...) can present with a SoC delta as little as 5mV-20mV. The upward bound of that, 20mV, is what we most often see on a BMS_u029.

Additionally, we would argue - and we used to say this ALL the time to Jack Rickard of EVTV fame - that any solution that attempts to override the BMS without addressing the root cause can/should be open source to ensure adequate community testing and verification. With these packs, there's simply too much riding on it.

^ I concur with everything @Recell noted above.

A very interesting point is Tesla has it coded in their software to ignore u029 if they want by setting a flag on the MCU. See image. Read what you want from that.

View attachment 906556

We have studied the u029 error a lot. It seems on older cars there are many false positives out there due to imbalanced CAC on aging packs. We try to ask everyone for individual cell voltages prior to selling them a device. But otherwise the device pairs with the car and records pack condition. Only if the pack seems healthy do we send the command to turn off the error. And with the device paired to a car you won't get someone who buys one to clear a fleet of cars. We may unpair/reset a device for a fee but that hasn't been decided yet and will likely be on a case-by-case basis.

As for open-source. I am willing to talk about some of what we do to qualify the pack, but will not open source it outright nor disclose exactly how we turn off the error. I've got nearly a year in on this and need to be paid for my time.

This is nonsense.

First and foremost, do NOT under any circumstances purchase and use a device like this that attempts to disable or workaround a safety limitation on the HV battery. You know what the result can be? At best, you'll end up stranded. At worst your car, house, and loved ones burn to the ground. This isn't hyperbole, and isn't anti-Tesla FUD. In fact, the exact opposite. The BMS is explicitly there to prevent failures like these from becoming a catastrophic issue (fire, mainly). If you do something like this to prevent it from doing its job without addressing the actual issue, frankly you're an idiot and you deserve the resulting consequences.

The limitation is put there for a reason. I've found that in every single case where the BMS decided to impose this limit that the underlying data it was using to make that decision was 100% sound. It's always the result of a physical issue or failure of some kind, and the BMS must do this for safety purposes. There are no "false positives" here. Sometimes the underlying issue is a correctable one (bad sense board, for example). But that's not a flip-a-switch or a "spam the BMS with from an external device with 'reset this error' messages" solution. That's a physical service that needs to be performed to correct the issue. If you don't correct it, you're in trouble.

Edit: Further, there is NO WAY anyone can make a determination as to it being "safe" to use such a device based on ANY data that could possibly be provided to them. So that's complete nonsense. Any data they'd be getting would be from the BMS, and the BMS already decided it was unsafe. You really think Tesla wants the bad PR that results from all of these older packs running into issues like this? If they could be left alone to run without issue, Tesla would be the first to do something to clear the errors. But it's not safe to do so, and shouldn't be done.

Bottom line, just don't do this. Don't buy something like this. Don't risk your property and the lives of yourself and others on it. This is not a joke. Honestly, it's reckless and dangerous to even suggest such BS, and I hope someone you sell this to sues you into oblivion when their home burns down.

Edit: Apologies if I sound crude or harsh here, but this is pretty serious and is a topic that really fires me up when people do dumb things with these HV systems.

 

[wk057]

While I'm not 100% sure it's the right thing to do, the only incentive I think I can provide for people like this to not try and profit from destroying people's property would be to just publicly release an open-source method for resetting the error.

So I think that will be my nuclear deterrent. Don't waste effort trying to sell this. If people want to blow up their cars, I'll just tell them how to do it for free.

At best, it'll make Tesla patch it out and make any such device useless anyway. (Edit: Actually, I've just reached out to Tesla directly to note that there are plans to try and circumvent this safety mechanism and the diagnostic/debug methods to get around it should be patched out ASAP.)

 

[Recell]

RIP Jack Rickard - a true, if not cantankerous, genius - but there was no way we were ever touching his BMS controllers without open sourcing the software. just no way.