BMS-029 - Tesla Must Do Better

I am an early adopter of Tesla. I bought my Model S in Feb of 2015, laying out close to 90k for a car – which is something I would have never dreamed of doing previously. But I believed in the mission, I believed in the car – so I traded in my Kia Optima and subjected myself to this grand experiment. This was the days where the masses really didn’t know what Tesla was – I would get stopped in parking lots and get strange looks on the road – and I gave makeshift mini-presentations about how this was the future of transportation.

Fast forward 8 years and 3 months later…. After Supercharging I received an error on my screen that said “maximum battery charge level reduced” and gave the code BMS_029. After 8 years and 85k miles of very happy ownership – dealing with the usual door handle replacements, window regulator breaks, new MCU, new front dash screen etc – I now realized I was faced with something much more serious.

I planned on keeping my car indefinitely. I love the car. I have never loved a car, but I do love this car.

3 months after my battery warranty expired, I have this error that is going to limit me to about 35% charge, and from everything I read online it is basically a battery death sentence. The Tesla equivalent of the “blue screen of death”. I went to the Tesla Service App, and explained the error and a screenshot – and got back a 15k estimate. No phone call, no options, no offer of repair, no diagnostics - just give us 15k and we will fix it.

Thank goodness for the online community. I found a Facebook group dedicated to this, and lots of help at Teslamotorsclub. I am not an engineer. I am simply a normal consumer. I feel like that needs to be said because if not for the amateur Tesla engineers out there, and aftermarket technicians – I feel like there would be zero information about this because Tesla isn’t talking or explaining. They simply text you back an estimate in an app, with one option – pay us or your car is dead – bricked.

So after doing lots of reading online – and talking to several experts – these are the options:

• Error removal through software. There are people out there who will (for about $500), simply remove the error so that you can go back to where you were the day before this dreaded error showed up.
• Pay anywhere from 8k to 9.5K to ReCell or another 3rd party for a remanufactured battery. You will get a battery pack from a car that they previously replaced, and remanufactured for you. Your battery will then be remanufactured and sold to someone else. You will get a battery pack that is dated anywhere from 2012 to 2015 and a 2 year 25k warranty.
• Pay Tesla about 15k for exactly what ReCell does, but get a 4 year 50k warranty.
• Buy a brand new 90KWH battery from Tesla for about 19k, and get a 4 year 50k warranty.

Option 1 seems like the absolute worst option. It seems like this is widely advised against, as this simply removes the error but doesn’t fix the root cause – which could be catastrophic. This part seems obvious. But hiding under the surface is a very big problem for Tesla – and for Tesla owners – the resale market can never be trusted. When I got this error – overnight – my resale value went from 30k to 10k. If I can remove this error, it goes back up to 30k. So it is obvious that there will be lots of unsuspecting buyers who end up with a car that is going to get the error again – or a potential big problem with the battery – either from a dealer who buys it for 10k and removes the error and sells for 30k, or an individual. This seems like a PR disaster for Tesla – and a horrible situation for consumers. It has already happened multiple times.

Option 2 and 3 are very similar – really just warranty differences. But in the end, if you can get a brand new battery for 4k more, and you plan on keeping the car for a long time, ReCell and Tesla need to do a better job of educating the average consumer (like me) that a reman battery with 8-10 year old cells has a value proposition vs a brand new battery. I fully support ReCell and their mission, because they are doing what Tesla does and beating them on price – and for the right person – it is a great option.

I chose option 4. I hate that I am laying out 19k to basically get back to where I was before the error. But at the same time – with the limited information I have – especially from Tesla – and very limited options – it is the best decision for me. My car is at Tesla right now sitting waiting for the work to be done.

Tesla needs to do a much better job addressing this, and develop a program that has better education and options. Are they trying to get the early cars off the road? Are they trying to get the unlimited supercharging cars off the road? They are getting my battery as part of the 19k repair – and they will remanufacture that and sell it to someone else for 15k. How much work and cost goes in to the remanufacturing? What if it is a circuit board or a few cells or even a module on my battery – that costs them close to nothing in comparison to the 15k they will flip it for – is that fair that I pay 19k on a car that is only worth 30k, and they ALSO get my battery?

Tin foil hat time…. I don’t necessarily believe any of the following to be true – but as Elon likes to say on Twitter – “I am just asking the questions”. What if there was a company that could press a button and send an error to a car fresh out of warranty, and essentially brick it knowing that they then would charge between 15k and 19k to replace it, and in return get a battery that they will sell to the next person they send the error to?

It seems a lot of cars are getting this error just after 8 years. Tesla – isn’t it in your best interest to be more transparent about issues, education, and options? Do you not care that the people this is happening to are the same people who in part built the company to what it is today? I have probably sold 20 people over the years on buying cars, and I have bought a MY. I am not suggesting Tesla owes us anything – but it just seems like a smart business decision to better handle this.

There are lawsuits already out there. Who knows. One persons opinion… This experience has seriously diminished my faith and experience in Tesla. I am biting the bullet – spending 19k on a car that will only be worth 30k when done – but I will always wonder if the BMS_029 error was just a software glitch, a $50 circuit board, a real problem that just happened to occur at 8 years and 3 months – or something much more sinister.

Come on Tesla, you can and need to do better.

"2014 Tesla Model S" by harry_nl is licensed under CC BY-SA 2.0.
Image added for Blog Feed thumbnail

 

[father_of_6]

It is really awful to learn that packs are becoming harder to service. Makes the whole sustainability argument go completely out the window.

But not if they're entirely recyclable.

 

[maximizese]

But not if they're entirely recyclable.

There's a big difference between recyclable and recycled. There's been a huge amount of greenwashing from the petroleum industry over decades with respect to recyclable plastics. Only a small percentage has actually been recycled but the triangle-arrow logo on the bottom absolves the consumer and allows them guilt-free consumption. Now, I'm not sure what proportion of battery packs have been or will be recycled (it's an emerging idea right now) and I'm not one to think that things won't change with progress, but I'd like to see actual data as oppose to assumptions. I was shocked to learn how much of our recyclables gets shipped out to China from the US because of the economics...and now China rejects our recyclables because of tariffs.

 

[MP3Mike]

Now, I'm not sure what proportion of battery packs have been or will be recycled (it's an emerging idea right now)

Likely 100% will be recycled, they are just way too valuable to throw away, unlike plastic. It wasn't too long ago that I think Tesla said that they were recycling 50 end-of-life packs per week.

 

[MP3Mike]

Circuit breakers, fusible links. Probably some other methods if I looked into it more.

Something I thought I would mention, in case you didn't know, every cell is connected to the busbar for the group of cells with fusible links. Of course, if the cell shorts out and blows one, or both, of those fusible links your pack will only work for a little bit longer until that group of cells gets too far out of balance...

 

[Crutonius]

Something I thought I would mention, in case you didn't know, every cell is connected to the busbar for the group of cells with fusible links. Of course, if the cell shorts out and blows one, or both, of those fusible links your pack will only work for a little bit longer until that group of cells gets too far out of balance...

The fact that the modules are in series changes my opinion on the matter a bit. I still think the option to remove a problematic pack is doable just not in a way that doesn't require accessing the pack.

While we're on the subject, why are the packs in series? That sounds counterintuitive.

 

[MP3Mike]

While we're on the subject, why are the packs in series? That sounds counterintuitive.

Because you need the voltage higher to reduce the amperage, such that you can use smaller wires/fuses/contactors/etc...

If you put all of the ~50v modules in parallel instead of needing to spec for ~1,000 amps you would need to spec for ~8,000 amps. That would result in needing a lot more copper, increasing costs a lot, and would have higher losses from resistance creating more heat, that would likely require cooling more components.

 

[Crutonius]

Because you need the voltage higher to reduce the amperage, such that you can use smaller wires/fuses/contactors/etc...

If you put all of the ~50v modules in parallel instead of needing to spec for ~1,000 amps you would need to spec for ~8,000 amps. That would result in needing a lot more copper, increasing costs a lot, and would have higher losses from resistance creating more heat, that would likely require cooling more components.

What I meant was why aren't the cells arranged so that the modules output 400v?

 

[MP3Mike]

What I meant was why aren't the cells arranged so that the modules output 400v?

I'm not sure, but I'm sure that Tesla, and every other OEM, knows what they are doing, and none of them are doing that.

I'm sure a big portion of it is safety. It is much safer to work on 50v modules, than 400v modules. Some OEMs even put a disconnect in the middle of the pack, so that the pack voltage is split in half before you open it.

In the end, it doesn't really matter, as Tesla has redesigned things and there are only 4, or 5, modules in the current pack designs now. (But the modules still aren't 400v.) So, bypassing 20-25% of your pack for a module failure really wouldn't make sense.)

 

[father_of_6]

So, bypassing 20-25% of your pack for a module failure really wouldn't make sense.

It does to me. I'm not saying anyone will be happy about losing 20% of their range overnight, but it's better than losing your whole pack and paying $15k.

I only charge to 50%, and don't often use more than 10-20% daily. While I'd be upset about a dead module, my daily driving needs wouldn't be impacted if I lost 3 out of 5 modules. When the 4th one went, I'd still be able to do most of my driving, but would obviously be preparing to replace the pack.

That type of pattern could add a decade of use onto a pack's lifespan. This assumes that a cell failure in one module has no bearing on the health of the cells in the other modules. It would also be ideal if disabling a module could be done without servicing the vehicle.

 

[brainhouston]

FYI, S/X modules are 25V not 50..

If say for a 4 module battery like 3/Y, Tesla made each one a 400V n put 4 in parallel with hardware inside the pack to auto cut a failed one, I could see this as a possibility w/o opening the pack at all, but i'm no battery engineer so not sure what else goes into consideration...
Maybe some day pack design will change... we shall see..

 

[Wim_V]

Wiring modules in parallel, would mean that you need a separate BMS for each module. For a 400 V system with 16 modules in parallel, that’s 16 times a fully 96S BMS, 16 times 96S cell tap wirings…

It will also have a big impact on safety when working on packs. You won’t be able to break down the pack in modules that are safe to handle (voltage wise).

 

[Crutonius]

Wiring modules in parallel, would mean that you need a separate BMS for each module. For a 400 V system with 16 modules in parallel, that’s 16 times a fully 96S BMS, 16 times 96S cell tap wirings…

It will also have a big impact on safety when working on packs. You won’t be able to break down the pack in modules that are safe to handle (voltage wise).

They would all require a separate BMS? Are you sure about that? I'm not sure what you meant by 16 times 96s cell tap wires

400v is higher than 25v obviously. But we're not talking about the sort of voltages you see on high tension lines. This is doable.

 

[Wim_V]

They would all require a separate BMS? Are you sure about that? I'm not sure what you meant by 16 times 96s cell tap wires

Yes a BMS per module in parallel is necessary, otherwise you would need to connect the parallel groups between the modules. That would mean a 96 pin connector from and to each module. Not really practical at 400 VDC (insulation, arcing…).
The tap wires are used to measure cell voltages and balance the cells. For each cell group in series, there is a connection between the cell group and the BMS. This sounds simple (and it is for low voltage modules), but it gets complicated very quickly. They must be able to measure very accurately, keep enough isolation (to prevent arcing or interference) and balance the cells (and doing this with the same wiring, will interfere with the measurement). Each tap wire is also a possible failure point (and even is a common failure mode of the Model S packs).

400v is higher than 25v obviously. But we're not talking about the sort of voltages you see on high tension lines. This is doable.

400 VDC my not sound much, but you're dealing with batteries that can deliver thousands of amps when shorted. Arcing is also a much bigger problem with DC compared to AC. Not a problem for a factory assembly line (like the 4680 structural pack), but something to keep in mind if you would want to design a pack that can be repaired in a repair shop (for an acceptable price).

 

[ucmndd]

But we're not talking about the sort of voltages you see on high tension lines.

They put those lines a hundred feet in the air for a reason.

 

[brainhouston]

They put those lines a hundred feet in the air for a reason.

Urban legend also says NOT to walk under those in the rain

 

[mjwojtukiewicz]

I am an early adopter of Tesla. I bought my Model S in Feb of 2015, laying out close to 90k for a car – which is something I would have never dreamed of doing previously. But I believed in the mission, I believed in the car – so I traded in my Kia Optima and subjected myself to this grand experiment. This was the days where the masses really didn’t know what Tesla was – I would get stopped in parking lots and get strange looks on the road – and I gave makeshift mini-presentations about how this was the future of transportation.

Fast forward 8 years and 3 months later…. After Supercharging I received an error on my screen that said “maximum battery charge level reduced” and gave the code BMS_029. After 8 years and 85k miles of very happy ownership – dealing with the usual door handle replacements, window regulator breaks, new MCU, new front dash screen etc – I now realized I was faced with something much more serious.

I planned on keeping my car indefinitely. I love the car. I have never loved a car, but I do love this car.

3 months after my battery warranty expired, I have this error that is going to limit me to about 35% charge, and from everything I read online it is basically a battery death sentence. The Tesla equivalent of the “blue screen of death”. I went to the Tesla Service App, and explained the error and a screenshot – and got back a 15k estimate. No phone call, no options, no offer of repair, no diagnostics - just give us 15k and we will fix it.

Thank goodness for the online community. I found a Facebook group dedicated to this, and lots of help at Teslamotorsclub. I am not an engineer. I am simply a normal consumer. I feel like that needs to be said because if not for the amateur Tesla engineers out there, and aftermarket technicians – I feel like there would be zero information about this because Tesla isn’t talking or explaining. They simply text you back an estimate in an app, with one option – pay us or your car is dead – bricked.

So after doing lots of reading online – and talking to several experts – these are the options:

• Error removal through software. There are people out there who will (for about $500), simply remove the error so that you can go back to where you were the day before this dreaded error showed up.
• Pay anywhere from 8k to 9.5K to ReCell or another 3rd party for a remanufactured battery. You will get a battery pack from a car that they previously replaced, and remanufactured for you. Your battery will then be remanufactured and sold to someone else. You will get a battery pack that is dated anywhere from 2012 to 2015 and a 2 year 25k warranty.
• Pay Tesla about 15k for exactly what ReCell does, but get a 4 year 50k warranty.
• Buy a brand new 90KWH battery from Tesla for about 19k, and get a 4 year 50k warranty.

Option 1 seems like the absolute worst option. It seems like this is widely advised against, as this simply removes the error but doesn’t fix the root cause – which could be catastrophic. This part seems obvious. But hiding under the surface is a very big problem for Tesla – and for Tesla owners – the resale market can never be trusted. When I got this error – overnight – my resale value went from 30k to 10k. If I can remove this error, it goes back up to 30k. So it is obvious that there will be lots of unsuspecting buyers who end up with a car that is going to get the error again – or a potential big problem with the battery – either from a dealer who buys it for 10k and removes the error and sells for 30k, or an individual. This seems like a PR disaster for Tesla – and a horrible situation for consumers. It has already happened multiple times.

Option 2 and 3 are very similar – really just warranty differences. But in the end, if you can get a brand new battery for 4k more, and you plan on keeping the car for a long time, ReCell and Tesla need to do a better job of educating the average consumer (like me) that a reman battery with 8-10 year old cells has a value proposition vs a brand new battery. I fully support ReCell and their mission, because they are doing what Tesla does and beating them on price – and for the right person – it is a great option.

I chose option 4. I hate that I am laying out 19k to basically get back to where I was before the error. But at the same time – with the limited information I have – especially from Tesla – and very limited options – it is the best decision for me. My car is at Tesla right now sitting waiting for the work to be done.

Tesla needs to do a much better job addressing this, and develop a program that has better education and options. Are they trying to get the early cars off the road? Are they trying to get the unlimited supercharging cars off the road? They are getting my battery as part of the 19k repair – and they will remanufacture that and sell it to someone else for 15k. How much work and cost goes in to the remanufacturing? What if it is a circuit board or a few cells or even a module on my battery – that costs them close to nothing in comparison to the 15k they will flip it for – is that fair that I pay 19k on a car that is only worth 30k, and they ALSO get my battery?

Tin foil hat time…. I don’t necessarily believe any of the following to be true – but as Elon likes to say on Twitter – “I am just asking the questions”. What if there was a company that could press a button and send an error to a car fresh out of warranty, and essentially brick it knowing that they then would charge between 15k and 19k to replace it, and in return get a battery that they will sell to the next person they send the error to?

It seems a lot of cars are getting this error just after 8 years. Tesla – isn’t it in your best interest to be more transparent about issues, education, and options? Do you not care that the people this is happening to are the same people who in part built the company to what it is today? I have probably sold 20 people over the years on buying cars, and I have bought a MY. I am not suggesting Tesla owes us anything – but it just seems like a smart business decision to better handle this.

There are lawsuits already out there. Who knows. One persons opinion… This experience has seriously diminished my faith and experience in Tesla. I am biting the bullet – spending 19k on a car that will only be worth 30k when done – but I will always wonder if the BMS_029 error was just a software glitch, a $50 circuit board, a real problem that just happened to occur at 8 years and 3 months – or something much more sinister.

Come on Tesla, you can and need to do better.

View attachment 944839
"2014 Tesla Model S" by harry_nl is licensed under CC BY-SA 2.0.
Image added for Blog Feed thumbnail

I've read a number of your subsequent posts. You sound like you can't afford to fix the car but then you say maybe you'll look at a Lucid (120K >?)
Battery packs are recycled. As a matter of fact a former Tesla engineer started a company that recycles the minerals out of the battery packs for re-use.
If you're not short on money sell the car as-is and buy a new model S (or is it a Leaf or Lucid-can't keep track) OR go for the Re-Cell.

 

[Mhoepfin]

20-80 seems to work very well for me. Charging daily to 80% vs 90% the degradation reduction is very noticeable. I actually don't need the entire 80% for my daily commute so have been changing to 70%. I get back home right at 20%.

Interestingly I haven’t had home charging for the last 3 years. So it’s been supercharging only for the last 40k miles and I now have 83k miles. My car sits and slowly drains most of the time from about 75% down to 20% and then I supercharge again, rinse and repeat. Live in coastal area of southeast where it’s hot and Humid. Also we road trip a good bit. Anyway I’ve been impressed by the very minimal degradation in my 2015 85 pack that is only supercharged.

 

[sleepydoc]

But hiding under the surface is a very big problem for Tesla – and for Tesla owners – the resale market can never be trusted. When I got this error – overnight – my resale value went from 30k to 10k. If I can remove this error, it goes back up to 30k. So it is obvious that there will be lots of unsuspecting buyers who end up with a car that is going to get the error again – or a potential big problem with the battery – either from a dealer who buys it for 10k and removes the error and sells for 30k, or an individual. This seems like a PR disaster for Tesla – and a horrible situation for consumers. It has already happened multiple times.

Ultimately, the problem here is fraud on the part of the seller. Akin to someone selling a car and not disclosing a major engine or structural issue without disclosing it. I can’t blame Tesla for this as they have no control over what others do; the only thing they can do is make the software more difficult to hack or otherwise detect a ‘hack patch’ so it can’t be covered up.

I’m sorry this happened to you. A battery pack should last more than 8 years and 85,000 miles without a catastrophic failure like this. To me, that is the bigger issue for Tesla. I don’t know what the underlying problem is that’s causing it - it could be a design flaw with the battery, issues with the individual cells, a charging software issue, a charging hardware issue or something else. In the public’s eye they see ‘Tesla,’ but not only is Each car model different, the batteries have evolved over time, too so one can’t necessarily generalize from your car to my 2020 Model Y. That will likely still happen, though and in that respect this is a problem for Tesla.

The other concern I have is whether this is an issue introduced by poor software. Tesla has a long history of introducing buggy software and then pushing out patches to fix the bugs. No one outside of Tesla knows exactly what changes in each version beyond the summaries in the release notes so all of us may have a ticking time bomb in our firmware.

On the tinfoil hat side these theories will always be around. There are people that claim Apple intentionally bricks their phones to force you to buy a new one. Same theory, different product. Bottom line - if you distrust the company that much you shouldn’t buy the product.

 

[father_of_6]

Ultimately, the problem here is fraud on the part of the seller. Akin to someone selling a car and not disclosing a major engine or structural issue without disclosing it. I can’t blame Tesla for this as they have no control over what others do; the only thing they can do is make the software more difficult to hack or otherwise detect a ‘hack patch’ so it can’t be covered up

You're suggesting the previous owner had a failing battery and had someone software reset the BMS to hide it?

I wasn't considering that angle, I just assumed this was run of the mill battery failure, but that's totally possible.

 

[father_of_6]

If that were the case, perhaps the OP can get historic data from Tesla and small claims the seller.