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

[MountainBikeDude]

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've seen this behavior often times when charging to full 100%. It'll hit the full 458km rating (for my 20"AT setup) around 97% and then continue charging for a further 3% give or take and a few additional kWh before finally stopping. I've assumed that Rivian won't allow the EPA rating change upward, only downward as the battery capacity degrades over the years?

When SOH was accessible via the RiDE menu up until around a year ago?! mine went from being around 96% for a few months, to then dropping to 95% just prior to it being removed. I think I had roughly 30 or 35,000kms on the ODO at that point.

Since my deposit in 2019, I've learned a great deal about EV's, from different battery chemistry advantages, disadvantages, to best practices etc. A main takeaway is that battery chemistry and BMS algorithms have advanced quite a bit, and we don't see as much degradation in batteries produced 5 years ago as we did in ones produced 7-10 years ago over the same duration/mileage.

I care about SOH just because I like data. Would it alter the way I use the vehicle? Likely no. I try to keep my charge/discharge window to around 70-45-70% for most of my driving over the last year. I'll charge up higher and use the battery more throughout the breadth of the pack whenever I need to and let the BMS etc do the heavy lifting.

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[Rivian Roamer]

I've seen this behavior often times when charging to full 100%. It'll hit the full 458km rating (for my 20"AT setup) around 97% and then continue charging for a further 3% give or take and a few additional kWh before finally stopping. I've assumed that Rivian won't allow the EPA rating change upward, only downward as the battery capacity degrades over the years?

When SOH was accessible via the RiDE menu up until around a year ago?! mine went from being around 96% for a few months, to then dropping to 95% just prior to it being removed. I think I had roughly 30 or 35,000kms on the ODO at that point.

Since my deposit in 2019, I've learned a great deal about EV's, from different battery chemistry advantages, disadvantages, to best practices etc. A main takeaway is that battery chemistry and BMS algorithms have advanced quite a bit, and we don't see as much degradation in batteries produced 5 years ago as we did in ones produced 7-10 years ago over the same duration/mileage.

I care about SOH just because I like data. Would it alter the way I use the vehicle? Likely no. I try to keep my charge/discharge window to around 70-45-70% for most of my driving over the last year. I'll charge up higher and use the battery more throughout the breadth of the pack whenever I need to and let the BMS etc do the heavy lifting.

Yeah, I think what you're seeing is Rivian stopping even though your battery has more range in it.

I get why people want to see it, I'm a nerd myself and that's why I built Rivian Roamer.

For most though, unless it's reliable it's just not very useful. It leads to discussions where people obsess over SOH when in reality it doesn't make a perceivable distance in day to day use.

 

[Rivian Roamer]

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.

Even that number isn't precise. It's accurate, just not precise.

EDIT: As someone who has root access to their vehicle, I can assure you much of the customer-facing energy reporting information isn't as useful as many think. I've seen variance by as much as 2-5% when reporting.

EDIT 2: I think much of this is due to rounding that they do in places, if you open the energy app while driving that shows Gear Guard, watch the efficiency metric number. You'll see a sawtooth pattern due to them using whole numbers in some places they shouldn't.

 

[mkhuffman]

Even that number isn't precise. It's accurate, just not precise.

EDIT: As someone who has root access to their vehicle, I can assure you much of the customer-facing energy reporting information isn't as useful as many think. I've seen variance by as much as 2-5% when reporting.

EDIT 2: I think much of this is due to rounding that they do in places, if you open the energy app while driving that shows Gear Guard, watch the efficiency metric number. You'll see a sawtooth pattern due to them using whole numbers in some places they shouldn't.

This all makes sense, because you and others have pointed out, measuring the charge level of a battery is an approximation, not an exact answer. You can measure volume of fluid in a tank, but measuring charge level is an estimate. And estimates have errors. Also, the capacity of the battery is significantly impacted by temperature, introducing more variations and errors.

That said, what about measuring the power delivered via the EVSE? My Emporia EVSE does a great job measuring exactly how much power is delivered. I think if you record the power delivered according to the EVSE for a 0-100% charge, and remove charging losses, you should have a pretty accurate estimate regarding how much power Rivian lets the battery hold.

Of course to determine SoH, you would need to do repeated 0 to 100% charges and compare the results over time. What a pain. You could just compare it to the "official" capacity Rivian provides. Still, to see changes over time you would need to keep doing that test.

 

[Rivian Roamer]

This all makes sense, because you and others have pointed out, measuring the charge level of a battery is an approximation, not an exact answer. You can measure volume of fluid in a tank, but measuring charge level is an estimate. And estimates have errors. Also, the capacity of the battery is significantly impacted by temperature, introducing more variations and errors.

That said, what about measuring the power delivered via the EVSE? My Emporia EVSE does a great job measuring exactly how much power is delivered. I think if you record the power delivered according to the EVSE for a 0-100% charge, and remove charging losses, you should have a pretty accurate estimate regarding how much power Rivian lets the battery hold.

Of course to determine SoH, you would need to do repeated 0 to 100% charges and compare the results over time. What a pain. You could just compare it to the "official" capacity Rivian provides. Still, to see changes over time you would need to keep doing that test.

There are multiple transition points between EVSE and energy into the battery. Then there is the factor if the vehicle is using shore power to power systems as well.

The closest you can probably get is drive from 100% to 0%, but even that has heat losses.

 

[1stPlace]

@mkhuffman You would be correct about measuring at the EVSE, however, the car also uses energy while charging for cabin and battery temp regulation as well as "accessories" when you look at the in-vehicle charge summary. It is picture 3 and 4 in my previous thread: https://www.rivianforums.com/forum/...est-at-56k-miles-for-le-quad-large-r1s.40949/

While I accept the points made by @Rivian Roamer I still believe the test/method I employed is currently the most accurate way at this time for regular owners to measure current usable capacity and find out they really didn't need to.

 

[Rivian Roamer]

@mkhuffman You would be correct about measuring at the EVSE, however, the car also uses energy while charging for cabin and battery temp regulation as well as "accessories" when you look at the in-vehicle charge summary. It is picture 3 and 4 in my previous thread: https://www.rivianforums.com/forum/...est-at-56k-miles-for-le-quad-large-r1s.40949/

While I accept the points made by @Rivian Roamer I still believe the test/method I employed is currently the most accurate way at this time for regular owners to measure current usable capacity and find out they really didn't need to.

It is indeed the most accurate right now.

 

[mkhuffman]

I think SoH is useful information when shopping for a used BEV. I personally would pay more money for a used BEV with 95% SoH compared with one with a 85% SoH. Maybe an industry standard way of reporting this will be accepted in the future to help used car buyers make better decisions.

The water becomes muddy if Rivian decreases the buffer size as the vehicle ages, so it seems like the SoH should be related to available capacity, not total capacity. How far you can go on a 100% to 0% trip is what really matters. Anything below 0% is emergency use only, IMO, and not to be counted on.

 

[Rivian Roamer]

I think SoH is useful information when shopping for a used BEV. I personally would pay more money for a used BEV with 95% SoH compared with one with a 85% SoH. Maybe an industry standard way of reporting this will be accepted in the future to help used car buyers make better decisions.

The water becomes muddy if Rivian decreases the buffer size as the vehicle ages, so it seems like the SoH should be related to available capacity, not total capacity. How far you can go on a 100% to 0% trip is what really matters. Anything below 0% is emergency use only, IMO, and not to be counted on.

Yeah it gets really muddy with Rivian due to the fact that not only do they have an internal buffer, they reserve capacity and don't make either amount very clear.

What's interesting is I've observed owning 3 Teslas and now 3 Rivians over 8 years. Babying your battery seems to do more harm than good. Driving it regularly, not stressing sitting at extremes, etc. Those vehicles have always had less degradation for me.

Which make some wonder if it's just BMS calibration more than anything.

 

[mkhuffman]

Yeah it gets really muddy with Rivian due to the fact that not only do they have an internal buffer, they reserve capacity and don't make either amount very clear.

What's interesting is I've observed owning 3 Teslas and now 3 Rivians over 8 years. Babying your battery seems to do more harm than good. Driving it regularly, not stressing sitting at extremes, etc. Those vehicles have always had less degradation for me.

Which make some wonder if it's just BMS calibration more than anything.

The range of my Mach-e was definitely impacted by battery degradation. I am sure the SoH provided by the BMS was not very accurate, and more of a ballpark estimate, but it correlated well with my driving experience. Same drives resulted in lower SoCD at arrival. But Ford was not playing around with buffers. From my understanding, the buffer was only changed to existing cars once - a few months after I purchased mine. It went from 89 kWh available to 91 kWh.

I have no proof, just a suspicion, but I think the degradation of the battery in my Mach-e was due to lots of WOT accelerations. I pushed it to the floor almost every time I drove it. I was careful with the battery otherwise, only charging to 100% before a long drive when it was needed.

Hard accelerating is the only thing I can think would have caused it. I could be wrong, and maybe it was just age and normal wearing out of the battery. IDK. But my battery seems to have degraded faster than most others on the Mach-e forum I participate in.

 

[Rivian Roamer]

The range of my Mach-e was definitely impacted by battery degradation. I am sure the SoH provided by the BMS was not very accurate, and more of a ballpark estimate, but it correlated well with my driving experience. Same drives resulted in lower SoCD at arrival. But Ford was not playing around with buffers. From my understanding, the buffer was only changed to existing cars once - a few months after I purchased mine. It went from 89 kWh available to 91 kWh.

I have no proof, just a suspicion, but I think the degradation of the battery in my Mach-e was due to lots of WOT accelerations. I pushed it to the floor almost every time I drove it. I was careful with the battery otherwise, only charging to 100% before a long drive when it was needed.

Hard accelerating is the only thing I can think would have caused it. I could be wrong, and maybe it was just age and normal wearing out of the battery. IDK. But my battery seems to have degraded faster than most others on the Mach-e forum I participate in.

There are so many variables that go into it. My 2020 Y I drove over 70k miles in 3 years. Most of that in extreme conditions (-15F, 120F) and almost exclusively supercharging. When I traded it in I had only 3.5% degradation.

 

[Singletracker]

This is all very interesting stuff you guys are throwing out there. I have a much clearer picture of the whole SoH issue. Thank you!!

I am not terribly concerned that maybe my useable battery capacity has been reduced a bit. As has been noted, in the real world, it probably doesn’t make much difference. I track virtually all my drives (miles, kWh used, and m/kWh) and then look to come up with an approximation of range for a full charge. In order to calculate range, I need to have some idea of my actual useable battery capacity. After 25K miles, how far has it dropped from 131 kWh, or has it? Has Rivian actually released some of the battery buffer to increase the useable amount? That would not surprise me, at all. I have seen significant, random, inexplicable performance changes pop up out of nowhere. I always assumed Rivian was tinkering in the background. Right now, I‘m using an arbitrary number, 129 kWh, for my calculations. But, it could be more or could be less

 

[mkg3]

This is all very interesting stuff you guys are throwing out there. I have a much clearer picture of the whole SoH issue. Thank you!!

I am not terribly concerned that maybe my useable battery capacity has been reduced a bit. As has been noted, in the real world, it probably doesn’t make much difference. I track virtually all my drives (miles, kWh used, and m/kWh) and then look to come up with an approximation of range for a full charge. In order to calculate range, I need to have some idea of my actual useable battery capacity. After 25K miles, how far has it dropped from 131 kWh, or has it? Has Rivian actually released some of the battery buffer to increase the useable amount? That would not surprise me, at all. I have seen significant, random, inexplicable performance changes pop up out of nowhere. I always assumed Rivian was tinkering in the background. Right now, I‘m using an arbitrary number, 129 kWh, for my calculations. But, it could be more or could be less

Maybe a different paradigm is needed.

If you think about an EV more of a laptop with wheels than a vehicle with computer on board, one can get to needing to replace every few years (4~6 yrs). An upgrade cycle, as it were.

Most of us do this already with our computing devices and smartphones and think nothing of it. Since it's a vehicle, we apply our long standing ICE vehicle mentality of keeping it, maintaining it, fixing it and drive it for a long time.

Clearly, one can drive any EV for a long time, just like you can continue to use old smartphones or laptops. The thing is that the technology and SW capabilities are moving beyond the vehicles we own so has less capabilities than new vehicles. Yes firmware updates absolutely helps and make it better but not all the capabilities (just look at gen 1 vs gen 2 already).

Because of this phenomenon, I will not get an EV that costs more than what I am willing to spend for the 4~6yr life span. Clearly the value proposition is different of each person.

Make no mistake that R2 will be far more advanced technically than gen 2 R1, albeit not as big or have the higher end appointments.

 

[Rivian Roamer]

In 8 years I've owned 4 generations of EVs. The more tech-forward you are the more likely you are to keep upgrading.

The first 3 I cared about degradation. With my Rivians, I stopped caring.

Not telling anyone how to feel but I strongly expect at some point in the future people will stop paying attention to it entirely. Unless it's somehow some massive amount.

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