HVB battery capacity - is there any way to determine its current capacity?

[Rivian Roamer]

I was able to check the Energy to Empty (EtE) at 100% using a OBDII scanner on my Mach-e. This is only relevant because I observed a loss of 5 kWh or more in the winter. Battery capacity does decrease when the battery is cold, and could explain what you saw.

The BMS calculates the SoH, so I wish we could see it via the API. I understand why Rivian hides it, because it has caused some stress in the Mach-e owner community. When I traded in my Mach-e, the SoH was reported by the BMS as 89%. I was able to confirm that by checking the EtE at 100%. It certainly didn't make me happy.

Yeah. I’ve had the chance to sit down with the Rivian team and leadership a few times. Battery capacity is something I asked for and for similar reasons as you stated was shot down.

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[CharonPDX]

Okay. Here’s another question that nobody will have an answer to. If the available HVB battery can vary so much depending on conditions, why did Rivian claim the battery had 131 kWh useable. Seems like that could be very misleading. I don’t recall it saying 131 kWh under certain conditions. Now, i can’t seem to find where Rivian had posted that. Maybe they took it down.

Because that's how Lithium Ion batteries work. There is no 100% foolproof under all possible circumstances method to measure the current capacity of a LiIon battery. BMS systems make educated guesses based on recent charge/discharge conditions. The only way to truly do it is to completely discharge the pack all the way to actual-zero-percent, then fully recharge it to actual-one-hundred-percent.

Which basically no EV lets you do, to protect the battery.

Rivian knows the rated capacity of the cells they use, they multiply them together, they get a "total capacity" figure, then they tell you how much the BMS should let you use.

The link you're thinking of is: https://rivian.com/support/article/what-is-the-usable-kwh-capacity-of-your-battery-packs
Which they only put up in early 2024. For the first two years of vehicle shipments, Rivian absolutely refused to give an actual battery capacity figure. Just "miles of EPA rated range."

 

[Singletracker]

This is all very interesting and not at all what I expected. Sounds like useable HVB capacity is a moving target. Now, I’ve got even more questions, but I think I’ll just relax, for the time being

 

[Budman]

This is how I did it. I think this is a reliable method
https://www.rivianforums.com/forum/...just-3-degradation-2022-r1t-quad-motor.27821/

 

[mkhuffman]

This is how I did it. I think this is a reliable method
https://www.rivianforums.com/forum/...just-3-degradation-2022-r1t-quad-motor.27821/

You do great work!

Yeah. I’ve had the chance to sit down with the Rivian team and leadership a few times. Battery capacity is something I asked for and for similar reasons as you stated was shot down.

As a new owner, I have not had time to observe if the estimated range at 100% changes over time or based on battery temperature. If it does, it probably means the estimated range is using the EtE estimate from the BMS.

And that means the range estimate at 100% can be used to determine SoH. All that is needed is to compare the current range estimate at 100% for what it was when new, which I think correlates with the EPA range (if in the mode they tested it).

Because I generally ignore the GOM, I don't remember exactly what it displayed all the times I have charged to 100%. I now wish I had that documented. I am going to start with the next time I charge it to 100% and track that number to see how it changes over time.

@Rivian Roamer - does the API provide the range estimate, or is that calculated inside the truck only? It is reported in the phone app, which suggests it can be pulled from the API. Maybe that data point could be captured if it is reported, as a work around for SoH?

Edit: I see you are already reporting it:

Can we track that, or are you calculating that range estimate? I would like to capture that number every time it charges to 100%. Of course the drive mode is wrong. LOL.

It would be cool to correlate that with battery temperature also. Ideally Rivian is reporting less range is available when the battery is cold.

 

[sub]

This is all very interesting and not at all what I expected. Sounds like useable HVB capacity is a moving target. Now, I’ve got even more questions, but I think I’ll just relax, for the time being

It is somewhat like the HP output of an ICE vehicle. It is advertised as one thing but the actual output varies with the weather/location and It inevitably goes down as the vehicle ages. And dispite this being a major selling point for a lot of people there is no practical way to know where you are at any given moment. Have you ever seen an ICE car with a real time max HP available gauge?

One difference is that the EV does have more information hidden inside than it is willing to share. It hides the information because exposing it will result in thousands of complaints from people who's vehicles are just fine. This has already happened twice to Rivian. Once when they did expose a battery health metric, and then again when they added motor and battery temperature gauges. I doubt we see them repeat that mistake and give more data anytime soon.

 

[mkhuffman]

@Rivian Roamer - I am sure you have looked at this, but it appears ABRP is getting the data we can use to calculate SoH:

 

[Rivian Roamer]

@Rivian Roamer - I am sure you have looked at this, but it appears ABRP is getting the data we can use to calculate SoH:

That's not reliable for SoH. That's net battery capacity * charge %, I recommend reading through previous posts in this thread.

This is why I put a tooltip on Rivian Roamer to help educate folks.

 

[Blueassassin]

The ABRP worked for me thank you I've never checked mine and have a launch edition. But after doing the math im over 98% still so that makes me feel good.

 

[Rivian Roamer]

You do great work!



As a new owner, I have not had time to observe if the estimated range at 100% changes over time or based on battery temperature. If it does, it probably means the estimated range is using the EtE estimate from the BMS.

And that means the range estimate at 100% can be used to determine SoH. All that is needed is to compare the current range estimate at 100% for what it was when new, which I think correlates with the EPA range (if in the mode they tested it).

Because I generally ignore the GOM, I don't remember exactly what it displayed all the times I have charged to 100%. I now wish I had that documented. I am going to start with the next time I charge it to 100% and track that number to see how it changes over time.

@Rivian Roamer - does the API provide the range estimate, or is that calculated inside the truck only? It is reported in the phone app, which suggests it can be pulled from the API. Maybe that data point could be captured if it is reported, as a work around for SoH?

Edit: I see you are already reporting it:

Can we track that, or are you calculating that range estimate? I would like to capture that number every time it charges to 100%. Of course the drive mode is wrong. LOL.

It would be cool to correlate that with battery temperature also. Ideally Rivian is reporting less range is available when the battery is cold.

Rivian does funny business with this, it's not reliable for determine SoH.

You can determine this by charging to 100%, you'll see at some point it stops incrementing the range. This is because Rivian sets aside some of the battery for buffer so that your 100% range doesn't drop and cause people to panic.

I do have effective range which is calculated based on your past 30 days of driving, but that requires the paid tier since I use driving sessions to calculate it.

When there is a reliable way to track SoH, I'll do it. But right now there isn't and reporting it would just mislead people.

 

[MountainBikeDude]

Thank you. That is exactly what I was looking for. Now, you are batting .500 - Hall of Fame material

I’ve seen gross battery capacity listed at 135 kWh.

That's what the pack used to be named, which is why there's a great deal of older materials out there that reference it as 135kWh, as well as the old max pack @180kWh

 

[1stPlace]

Thank you. That is exactly what I was looking for. Now, you are batting .500 - Hall of Fame material

I’ve seen gross battery capacity listed at 135 kWh.

I did a full 0-100% charge and just looked at the energy sent to the battery: https://www.rivianforums.com/forum/...est-at-56k-miles-for-le-quad-large-r1s.40949/

You’ll notice in that thread, it was noted that gross capacity based on actual salvaged batteries is 141kWh for the OG Gen 1 large pack. I think very early car media reports said 135kWh, but the eBay listings prove that incorrect.

Anyone can do the test that I did if they really want to know current usable capacity, but my conclusion after having done it, is that my batteries are just fine. There is enough buffer from the locked portion of the pack that 1 or 2 % / year degradation could occur, but at that level, who cares…nothing is actionable. Just worth doing the test if you actually think you notice degradation in a few years.

 

[portdirect]

Yeah the gross capacity is being met.

The net capacity (as reported by Rivian) changes as they set aside some reserve. I wish they would share the gross as well.

There’s always the sticker on the pack itself showing nominal gross capacity (this is mostly a bad nerd joke - nominal gross capacity doesn’t tell us much about the actual gross capacity in practice).

 

[Rivian Roamer]

I did a full 0-100% charge and just looked at the energy sent to the battery: https://www.rivianforums.com/forum/...est-at-56k-miles-for-le-quad-large-r1s.40949/

You’ll notice in that thread, it was noted that gross capacity based on actual salvaged batteries is 141kWh for the OG Gen 1 large pack. I think very early car media reports said 135kWh, but the eBay listings prove that incorrect.

Anyone can do the test that I did if they really want to know current usable capacity, but my conclusion after having done it, is that my batteries are just fine. There is enough buffer from the locked portion of the pack that 1 or 2 % / year degradation could occur, but at that level, who cares…nothing is actionable. Just worth doing the test if you actually think you notice degradation in a few years.

Even this isn't as accurate as many think. Energy use calculation has a pretty decent standard deviation.

Trying get an accurate SoH is a bit like chasing waterfalls, you're not going to get the information you're after with a useful p-value.

 

[1stPlace]

Even this isn't as accurate as many think. Energy use calculation has a pretty decent standard deviation.

Trying get an accurate SoH is a bit like chasing waterfalls, you're not going to get the information you're after with a useful p-value.

Not sure what you mean, I didn't measure energy use (or SoH), I measured energy added to the battery. I doubt the standard deviation of that calculation in Rivian's Energy App is significant or more than a single percentage point.

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