How often is 100% SoC "safe"

[Dgephri]

Portland has a snap of bad weather (like many places right now).

I've got to take my electric snow blower and attack the snow tomorrow.

I've got two 550w chargers for the snowblower batteries and hope to cycle pairs as long as my body holds up pushing the blower.

I decided to bump up from 85% given cold, snow, wind, wet, and rough roads plus what might be several hours charging 1100 watts for the work.

What's a guideline for 100% exceptions? 5x a year, 5% of your charge cycles: how can we estimate degradation?

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[quartz]

Full SoC is stressful on the battery, yes, but much more so with prolonged non-use, like if you charged full and left it in the garage for two weeks. Consider other important factors, like rapidness and deepness of discharge/recharge—I.e. going from 100%-0%-100% over short interval is going to put max strain on the battery. Sitting at 100% for 12 hours—not so much.

 

[kizamybute']

I still wonder about this.

My Rivian Service Center always charges every truck to 100%. Mine when it was new and after 3 service calls as well as each of the 3 loaners I've had. They're apparently not concerned.

My dad had the same identical Tesla Model S as I did. He charged to 100% every time. I always charged to the recommended 90%. After 3 years, his car had more range remaining on a full charge than mine did.

The cars might not have sat for 2 weeks at full charge, but definitely did for at least a couple of days. I think they have a built-in buffer already. Also, with Rivian's high Vampire drain, it doesn't stay at 100% SOC for very long anyway. I've done it and come out to 93-94% two days later.

I usually charge to 85%, but don't worry about going to 100% either. If you plan to keep it for 10 years, that's probably how long it would take for any difference to show up, if any difference shows up at all.

Just going based on some real world data that I've observed. Certainly nothing scientific. Rivian doesn't seem too concerned. Tesla did just fine with three years of charging to 100%. Just my uneducated 2 cents.

 

[sacramentoelectric]

Maybe the R1 platform’s extreme vampire drain is a feature to help keep the pack from sitting very long at 100% state of charge?

 

[elektrode]

Maybe the R1 platform’s extreme vampire drain is a feature to help keep the pack from sitting very long at 100% state of charge?

“I’ve come to suck your b’100’d”

 

[rodhx]

Portland has a snap of bad weather (like many places right now).

I've got to take my electric snow blower and attack the snow tomorrow.

I've got two 550w chargers for the snowblower batteries and hope to cycle pairs as long as my body holds up pushing the blower.

I decided to bump up from 85% given cold, snow, wind, wet, and rough roads plus what might be several hours charging 1100 watts for the work.

What's a guideline for 100% exceptions? 5x a year, 5% of your charge cycles: how can we estimate degradation?

The answer is charge to whatever level you need, whenever you need, but stopping at 70% or 85% is good best practice on a routine basis if you don't need more. Running the pack down when you can is good exercise as well.

 

[Dgephri]

Thanks for your input everybody.

Now, I go, to snow. Blow

 

[countab45]

is it bad that i have not run mine below like 25% since i picked it up? haha. im too nice to the truck i think.

 

[quartz]

here’s a good summary from a recent research paper:

Previous studies have shown that temperatures between 5°C and 20°C are recommended to prolong battery life when storing Li-ion batteries, 20°C or slightly below is recommended to prolong battery life when cycling Li-ion batteries, and 27°C is recommended for maximum battery runtime. When storing Li-ion batteries, 50% of SOC is recommended because the higher the SOC, the faster the battery degradation. Too low a SOC also accelerates capacity degradation and increases battery IR. When cycling Li-ion batteries, the cycle bandwidth from 25% to 85% SOC is used by industrial devices such as EV to prolong battery life [16]. The charge voltage of 3.92V [16] and DOD of around 50% are recommended to achieve optimal battery life [19]. For energy Li-ion batteries, a C-rate of 0.8 C or below is recommended to prolong battery life. The higher the C-rate, the faster the Li-ion battery degrades. For power Li-ion batteries, C-rates are specified by manufacturers and are much higher than for energy ones.

Source: https://mospace.umsystem.edu/xmlui/bitstream/handle/10355/73777/Xiong-Shihui-Research.pdf

 

[kizamybute']

Don't we have something like a 70% SOC guarantee after 8 years? If that's case, better to try and use it up to get it below 70% before 8 years, then get a fresh battery. Otherwise, you're stuck with maybe a 75% SOC battery beyond 8 years. This is all if you plan to keep the truck that long? If not, wouldn't worry about it.

 

[Hyro]

I think you'd have to work INCREDIBLY hard to degrade a battery below 70% SOC over 8 years. I view that warranty as really covering long-term defects.

Charge state is a thing I worry about re: the big one (the earthquake, that is). We're an all EV family now (R1T + Polestar 2), and in the PNW I have a low-level worry about the Cascadia fault and wanting to make sure I could get out of the impacted area in the event of the 9.0 that has a ~15-30% likelihood of occuring in the next 30 years. I keep the R1T charged to 70% every night, as I'm pretty confident that's enough to get us east of the cascades if I baby the truck. In such an event, bridges will all be down... good thing the Rivian can wade so deep!

 

[Jhawk]

We bought our 2013 Model S as a certified pre owned car in 2017 and owned it for 6 years. During that time I only charged to 80% daily and charged to 100% maybe 4-5 times a year on average and always tried to time it to reach 100% when we were ready to leave. We rarely used DC fast charging, less than 10 times a year I would say on average. We just sold it after getting our R1T and total range loss at 100% SOC during our 6 years of ownership was less than 8%.

I plan to manage my charging the same with the Rivian and hope for similar battery degredation performance.

 

[2025R1S]

From what I understand, this is why the LFP battery technology is better than the existing designs.

Tesla uses it in their Austin built Model Y, and the Model 3 RWD. Our home has LFP batteries to store excess solar. The installers said they can handle a high number of cycles and will experience minimal battery degradation.

I am led to believe that constantly charging NMC batteries to 100% will cause (more) battery degradation. This means worse range for us.

 

[PappaBolt]

in the PNW… the 9.0 [earthquake] that has a ~15-30% likelihood of occuring in the next 30 years.

30% chance of the big one? Not sure it’s that high a chance but I do share your concern about recharging during the apocalypse.

 

[racekarl]

From what I understand, this is why the LFP battery technology is better than the existing designs.

Tesla uses it in their Austin built Model Y, and the Model 3 RWD. Our home has LFP batteries to store excess solar. The installers said they can handle a high number of cycles and will experience minimal battery degradation.

I am led to believe that constantly charging NMC batteries to 100% will cause (more) battery degradation. This means worse range for us.

An LFP battery of the same physical size and weight will have less initial capacity than an NMC battery. The NMC battery could suffer degradation over time and still be ahead of a comparable LFP pack overall.

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