Rivian R1T charging curve test 20-80% [by TFL]

[ajdelange]

With our old X, we charged to 100% more times than I'd have liked, and flirted with the bottom 5% just as often. Those are pretty harmful things to do to a battery and our range degradation confirmed this for us.

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[branden]

Was it a 90kWh pack? Those degrade if you look at them wrong

 

[Zoidz]

The recommendation to not charge to 100% is there for warranty purposes of battery longevity. If that is a concern it is actually better to charge the car to 100% on level 2 vs having to charge more on level 3 DCFC.

That's a fair statement. There are studies that show higher battery degradation when consistently charging L3 as compared to consistenly charging L2. This study shows a 5% additional degradation. L3 heat generation plus battery chemistry matter.

 

[ajdelange]

Sure there are studies. Hundreds and hundreds of them. How do we think the OEMs come up with their recommendations? Plus common sense tells us that if a Li+ ion arrives at the anode and the majority of the intercallation sites are occupied it is more likely to react with the SEI than if there are plenty of sites available.

 

[Forager]

Is there a way to input a charging curve into ABRP? The alpha Rivian seems to assume linear charging at a rather high rate. No wonder my test itineraries were improbably quick ?

 

[Inkedsphynx]

Halfway through the 'Should you charge to 100%' portion of this thread I mentally checked out and can't read any more.

I want to say though, with the amazing battery warranty Rivian is offering.... WHO THE HELL CARES. Drive your truck however you want and if your degradation is high enough, get it replaced under warranty. If it's not high enough... what are we really talking about here?

 

[ajdelange]

Is there a way to input a charging curve into ABRP? The alpha Rivian seems to assume linear charging at a rather high rate. No wonder my test itineraries were improbably quick ?

No need. Charging is actually pretty linear. If you take a charging curve and compute SoC vs time you will find that while there is deviation the resulting curve is pretty linear.

 

[ajdelange]

with the amazing battery warranty Rivian is offering.... WHO THE HELL CARES.

A lot of people, mainly those who intend to keep the truck past the warranty period but quite a few obsessive nerds (like me) too.

 

[SolartoEV]

I love the theory of only using the middle portion of your battery.

It's like dating somebody who is attractive and fun in college and but only going at it for 30 seconds because you might not be with them the rest of their lives and you don't want to use it up for the next person.

There's a much more vulgar description of this but I kept it PG.

Lots of people don't drive their sports cars fast or hard or don't want to put miles on them because of "long term value loss". Or you can just use it while it's fun and then buy a new one.

Leonardo Dicaprio has the same theory as me.

 

[Inkedsphynx]

A lot of people, mainly those who intend to keep the truck past the warranty period but quite a few obsessive nerds (like me) too.

If you were truly obsessive, you'd be calculating how much time out of your life you've wasted in this thread vs how much time the opportunity cost equates to in losing some percentage of overall battery capacity, since lost battery capacity is really just a cost function in time, resulting in you charging more frequently than someone with less degradation.

For extra credit, factor in all the time you sit around thinking or worrying about when you should or should not charge to 100%.

I'm willing to bet the extra ~10 miles of range you might have in 10 years vs someone who doesn't care might have isn't going to be worth the price in time you've paid over those 10 years worrying about it.

Bonus question: Do you always stop your phone charging before 100%? Same principle applies there, right?

 

[ajdelange]

If you were truly obsessive, you'd be calculating how much time out of your life you've wasted in this thread

I am and I have but.

resulting in you charging more frequently than someone with less degradation.

Overall charging time really depends on the miles you drive more than your battery's degradation except, of course, that you will spend more time overall charging if you charge to higher SoC.

For extra credit, factor in all the time you sit around thinking or worrying about when you should or should not charge to 100%.

Don't do it. Don't think about it. But I do think a lot about charging strategies, consequences, mechanisms etc. I was an engineer and worked on a lot of optimization problems. That's what engineers do. We can't turn our brains off when we retire.

I'm willing to bet the extra ~10 miles of range you might have in 10 years vs someone who doesn't care might have isn't going to be worth the price in time you've paid over those 10 years worrying about it.

You'd lose. i never worried about it. Thinking about it is different. Those hours have been as enjoyable as those spent on any other interesting problem.

Bonus question: Do you always stop your phone charging before 100%? Same principle applies there, right?

Interesting question. Answer: No I don't because Apple takes care of that for me. I noted when I got this last phone that there was a piece of paper in the box. It explained, at quite great length, that charging a lithium battery over 80% was bad for it and that the phone, therefore, contained algorithms to keep that from happening. Now I don't know in detail what these algorithms do exactly buy they supposedly keep SoC < 80%.

 

[kylealden]

That's OK as I have said in several of these posts but to suggest that people are weird if they don't do that on a regular basis explicitly contravenes Rivian's and Tesla's recommendations with respect to battery management.

To be fair (as someone who has specifically used the word "weird" ?), I don't think anyone is implying you charge to 100% regularly or often. I expect to keep my R1T at 70% for daily driving.

But for road trips? I'll charge however much I need to get where I'm going. The incremental damage to the battery from any given charge is basically 0; it's going to come out in the wash with other factors like temperature, age, manufacturing variances, etc.

The "weirdos" are the ones who bend over backwards to explain how my R1T actually only has 100 miles range because you have to shave 20% off both ends and then cut it in half in case you're towing in the winter or whatever. That's a bunch of horseshit. Range doesn't matter for most daily driving scenarios (150+ is plenty for virtually anyone, so 60% with generous margins is fine); and for road trips, nobody should be stressing about the marginal impact of using the whole battery when you need it.

So yes, the "real range" is the whole battery; but don't top it off (or bottom it out) for no reason.

 

[freshpow]

Newbie here. I found the following descriptions in the R1T's owner manual:

Set the Charge Limit
You can set the charge limit to optimize battery health and range depending on your driving needs. Go to Vehicle, and then choose Energy. You can choose Daily, Extended, or Trip.

Daily minimizes daily charge time.
Extended lets you travel farther on a single charge.
Trip maximizes range and takes more time to charge.

They don't provide any more detail so hoping one of you experts can help explain the differences in easy to understand terms. My interpretation is that "daily" would not let you charge past ~80% and that "trip" would allow you to charge up to "100%". Is that right? And what the heck is "extended"?

 

[kylealden]

Newbie here. I found the following descriptions in the R1T's owner manual:

Set the Charge Limit
You can set the charge limit to optimize battery health and range depending on your driving needs. Go to Vehicle, and then choose Energy. You can choose Daily, Extended, or Trip.

Daily minimizes daily charge time.
Extended lets you travel farther on a single charge.
Trip maximizes range and takes more time to charge.

They don't provide any more detail so hoping one of you experts can help explain the differences in easy to understand terms. My interpretation is that "daily" would not let you charge past ~80% and that "trip" would allow you to charge up to "100%". Is that right? And what the heck is "extended"?

"Daily" is 70%
"Extended" is 85%
"Trip" is 100%.

These figures are more conservative than Tesla's rough guidance ("Daily" is a slider range that goes up to 90%) and Delon's statement (radically diminishing returns below 90%), but still plenty for any realistic daily driving.

I have always used 90% in my Teslas because I only have an L1 charger and need to be able to top it off to 100% overnight for longer drives like ski trips; I'll be installing an L2 for the Rivian since the pack is so much bigger, so 70% shoudl be fine.

 

[ajdelange]

I'm not clear as to whether one can pick an arbitrary charge limit (such as 72%) or whether one must pick one of 3 preset limits assigned to Daily, Extended or Trip. Whatever the case, the lower the state of charge limit you pick the less time it will take the charger to get you there. It's also pretty obvious that battery charged to 80% will take you twice as far as one charged to 40%. What is less obvious it that a battery that is charged to 90% will degrade (lose active lithium) faster than one charged to 50%. The debate is as to whether
a)That's true (it is)
b)The degradation is significant
c)You care.

b) and c) are up to you to decide.

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