Battery Longevity Charge Limit

[shimps1]

After having our R1S for a bit over a month, I have found we very rarely drop below 40%, with the charging limit set to 70%. I know Rivian says 70% is fine for battery health, but are there gains in the margins to maybe drop the charging limit down to 60%, or even 55%?

My only concern would be the days we do use 30ish%, we'd be dropping the battery to around 25-30%, is that harmful?

Definitely overthinking it, but it's fun to have a new toy and want to take care of it.

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[COdogman]

I definitely understand where you are coming from, but all the research on EV batteries has shown they are much more durable and last longer than previously thought. I’m sure lowering your limit might help, but unless you are doing all the wrong things to that battery it will probably last far longer than the rest of your S.

 

[sub]

I think you are over thinking it.

I did the same thing initially with my Model 3, keeping my battery as close to 50% as I could. And after a year, my degradation was essentially exactly the same as people who charged to 90% every day. So I started charging to 90% every day, and my degedation is still almost exactly the same as everyone else's.

While I don't doubt that in general keeping the battery centered around 50% is ideal, I think the difference between 30%, 50%, and 70% is imperceptible in the real world.

I suspect Rivian agrees and that is why initially it only permitted 3 choices. 70% 85% and 100%. The ability to select any random number was probably added due to customer demand rather than any real-world benefit to being able to specify other numbers that exactly match your daily usage.

 

[mikehmb]

The biggest impact on battery health is this: storage of the vehicle at a very high (100%) or very low (<10%) SOC.

If you really want to extend the life of the battery, there’s also ample evidence that depth of discharge between charge cycles matters, over the long-term and many many charge cycles.

FYI my truck is on the charger at 58%, and about to get a charge up to 100% tonight (in off-peak hours) because we’re road-tripping tomorrow.

 

[shimps1]

If you really want to extend the life of the battery, there’s also ample evidence that depth of discharge between charge cycles matters, over the long-term and many many charge cycles.

Can you expand on this? Not sure what it means exactly.

 

[Donald Stanfield]

70% is fine. It's probably better to keep it 70-40 than 60-30 health wise. You want to keep it ideally around 50 but realistically anywhere in that middle you're going to be fine. I've had mine a year now and have no issues.

 

[mikehmb]

Can you expand on this? Not sure what it means exactly.

In short: charging from 50% to 75% 4 times is less impactful on battery health than going 0->100%.

I’ll try to dig up the stats that someone else posted here on the forum.

 

[BCondrey]

Don't overthink charging.

 

[Blackrock2014]

Another thing to consider is that the "battery" is actually hundreds of batteries, and they are managed by a battery management system. If anything like tesla, charging and discharging of each individual battery is managed for longevity. This is another reason we should charge to 100% infrequently because the BMS can't do its fancy rotation of charge per cell. Also, 70% charge likely won't charge each cell to 70%, but rather doing rotations for battery health and longevity.

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