Probably overreacting but... Losing capacity fast?

[smashweights]

So I bought my Rivian with about 40k on it. First checked Rivian roamer after the winter while reasonably warm and was sitting around 128.4kWh capacity, pretty good only losing about 3kWh (2%) over 4 years and 40k miles. It was around 128kWh last week, took my first big charge round trip of around 250mi in an area without any charging infrastructure. Charged to 95% and drove it down to 7% by the time I got home. Since recharging it's consistently showing about 127.1kWh capacity with similar temps. Can I really expect to permanently lose nearly 1kWh of capacity with such a cycle? Seems rather excessive...

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[Rivian Roamer]

So I bought my Rivian with about 40k on it. First checked Rivian roamer after the winter while reasonably warm and was sitting around 128.4kWh capacity, pretty good only losing about 3kWh (2%) over 4 years and 40k miles. It was around 128kWh last week, took my first big charge round trip of around 250mi in an area without any charging infrastructure. Charged to 95% and drove it down to 7% by the time I got home. Since recharging it's consistently showing about 127.1kWh capacity with similar temps. Can I really expect to permanently lose nearly 1kWh of capacity with such a cycle? Seems rather excessive...

Battery capacity measurement is fickle.

Both of the measurements are probably off as they are often just estimates. On top of that, Rivian doesn't expose gross capacity but instead, net. There is some funny things Rivian does with capacity.

Here's my R1T.

 

[smashweights]

Battery capacity measurement is fickle.

Both of the measurements are probably off as they are often just estimates. On top of that, Rivian doesn't expose gross capacity but instead, net. There is some funny things Rivian does with capacity.

Here's my R1T.

Well that makes me feel better. I wasn't sure how much to read into those values. Made me worried I was gonna trash my battery in a few trips.

I know the Large pack NCA chemistry doesn't need large charges to calibrate like LFP but wonder if the earlier was more incorrect since I've never gone outside of about 30-70% SOC for nearly 6 months of ownership.

 

[jrmbadger]

Nothing really to worry about.

Degradation can be caused by many factors, but, as I understand it, the biggest factor is cell aging. Cell aging degradation happens on a non-linear basis with the highest amount seen in the first year and decreasing amounts every year after that.

Charging to 100% does stress the battery some, but occasionally doing it isn't really a big deal. Its best to try and plan the battery to be at 100% just before you leave.

The amount of charge in a battery is notoriously difficult to measure and varies wildly with temperature, ambient conditions, state of charge, etc.... A couple of KWH variance in measurement is probably within the margin of error. (As @Rivian Roamer pointed out)

My advice: Drive it and dont worry. But, if you REALLY REALLY REALLY care about minimizing degradation, go to the Tesla Motor Club forum and search for a user named AAKE. But, it's a big rabbit hole and probably not worth the inconveniences to save a couple percent range.

 

[UnsungZero_OldTimeAdMan]

Nothing really to worry about.

Degradation can be caused by many factors, but, as I understand it, the biggest factor is cell aging. Cell aging degradation happens on a non-linear basis with the highest amount seen in the first year and decreasing amounts every year after that.

Charging to 100% does stress the battery some, but occasionally doing it isn't really a big deal. Its best to try and plan the battery to be at 100% just before you leave.

The amount of charge in a battery is notoriously difficult to measure and varies wildly with temperature, ambient conditions, state of charge, etc.... A couple of KWH variance in measurement is probably within the margin of error. (As @Rivian Roamer pointed out)

My advice: Drive it and dont worry. But, if you REALLY REALLY REALLY care about minimizing degradation, go to the Tesla Motor Club forum and search for a user named AAKE. But, it's a big rabbit hole and probably not worth the inconveniences to save a couple percent range.

So does running it down to 7%. General consensus is to play between 20-80% as much as possible isn’t it? Not that going over or below would instantly cause irreparable harm. Just that larger charge deltas, frequently, add up to full cycles sooner? Engineering Explained videos on NMC and LFP do’s and don’ts explain it much better.

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