Charging battery to 90% vs 100%?

[Michael Kelly]

I keep hearing that we shouldn't consistently be charging our batteries to full, instead cutting them off at roughly 90%. At Rivian are we to take this info consideration? Would love to hear from the engineers

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[Redline]

I keep hearing that we shouldn't consistently be charging our batteries to full, instead cutting them off at roughly 90%. At Rivian are we to take this info consideration? Would love to hear from the engineers

I charge mine to 70% daily. This is pretty well known in the EV industry. If you charge it more from time to time, you'll be just fine.

 

[ads75]

Rivian (probably their engineers that the OP mentioned) recommends 70% for daily charging, not 90%. The 70% recommendation does not bother me since I usually drive less than 150 miles a day. If I have a longer trip, I will charge to or close to 100%.

 

[cbrcanuck]

Lots of discussion on here on this topic, lots of great info. Let the search be your friend here. In summary - the consensus seems to be your ideal range is 30-70% daily, charge up high for a road trip when you need it, but minimize time it sits at a high state of charge.

 

[KBabione]

Our guide told us that, day-to-day, to charge it between 60-80%. Enough so that you have plenty of juice to do your daily running around, but only charge above that if you know that you have a big trip the next day. At our house we put it on the charger when it drops below 50% and charge to 75%, but we've definitely charged to 100% before heading out on bigger trips.

One note (and, if you've been charging to 100% I'm sure you've already seen this)...You'll get a message telling you that regenerative braking is limited when you're at 100%. Basically it means that the cup is full and you can't add more power to the battery from braking so your regen "credit" is wasted.

 

[Dark-Fx]

In optimal temperatures you won't see regen reduction until 93% according to Rivian. I regularly charge to 85% and haven't noticed any degradation yet, but I haven't heard it Rivian is actually exposing that yet from anyone.

 

[Electrified Outdoors]

NCM batteries are susceptible to accelerated degradation when charging above 90% or discharging below 10%. I charge mine to 70% and the wife likes to have s little more reserve so she charges to 80%.

For long road trips once in a while its fine to charge to 100% if necessary.

LFP batteries (i believe the standard battery will use this chemistry) can be charge to 100%.

These limitations are not Rivian specific. They apply to any EV. Tesla is a good comparison as they use NCM and use LFP for their standard range entry level models.

 

[shamoo]

The vehicle itself has presets for 70%, 80%, and 100%. I was told by at delivery that:
- 70% is "normal battery degradation"
- 80% is "increased battery degradation"
- 100% is "for long trips only, don't use this daily"

Of course you can move the slider to any number you wish.

While you can take what the delivery guy says with a grain of salt, the fact that the vehicle itself has presets probably means the engineers thought these were a good balance between longevity/health and "legal" info in case something happens with your battery.

The bottom line is, don't charge to 100% all the time unless you need it. If you don't need the range, charge to what you need on a weekly basis. Maybe that's 40% only. Maybe that's 70%. If you don't need it, why charge higher? Maybe increase it a bit on Fridays/Weekends for any larger trips.

 

[mikehmb]

You just reminded me to charge, thank you.

ETA - the biggest driver of degradation (and now I can’t find the report) is depth of discharge and subsequent recharge. If you consistently go 80 -> 20 -> 80, things will degrade faster. But if you go 70 ->50 -> 70, it is apparently much happier longer term. Someone else here will find and post that report, I’m sure.

My round-trip is about 100 miles when I make the commute, so I try to grab some charge at the office then bring it back to 70% when I get home. I generally use 14% each direction.

—
The chemistry of the cells used in the Rivian packs doesn’t like to be stored long-term at 100%. So if you need the full capacity, go ahead and charge it to there and use it. Just don’t plan to leave it there for long periods of time. In my case, if I have to hit 100, I try to time it so it gets there a couple of hours max before i set off.

FWIW our eGolf (now my daughter’s eGolf) has consistently been charged to 100%, but is never stored at 100%. There’s zero noticeable degradation. I suspect there’s more battery buffer there than in other EVs. I’m not suggesting you do this - just a datapoint on a very different car.

 

[Gkfisher]

Great advice here. I would add, don’t overly stress about going below 20 or above 70 - fast charging or slow charging, etc.

Doing these “less optimal” things even several times a month will have an almost imperceptible effect. Exclusively fast charging may degrade by up to .5% faster (~2miles range impact on 330 range) over 3 years (40k miles). Charging to 100% several times through the year AND using it right away - maybe another .1%. Depleting to 5% and charging back up when you get home - nearly negligible effect.

The spare capacity, BMS, and thermal monitoring all actively work to take the role of figuring out how to protect the battery where it matters.

It’s fun to learn about all of this but at the end of the day as long as you’re not completely trashing the battery (Bricking car from going below 0, charging to 100 on fast charger and then not driving anywhere, etc. ) - you’re likely not going to affect total range of the truck by more than 20 miles over the course of a 7+ year ownership period.

Note: All batteries degrade due to time and use such that they are going to give up a base amount of about 2% a year. Most vehicles have 90% of capacity still after 7+ years. So at best your choices may determine if it’s 88% or 92%.

I have owned EVs for many years and found this to be the case with VWs, Tesla, and Hyundai. I expect no different from Rivian.

 

[Sevn86]

I drive 137 miles round trip for work daily. Charge to 80% each night and as soon as I get to work I plug up (finally got a charging outlet there) so by the time I leave I’m back at 80%. Get home and charge up again. I’m always charging. Now I do increase my charge percentage at work on Tuesdays to 90% as I know I’ll be off the next two days so that way I have enough “free” charge to use. I then charge it to 80% on Thursday nights for work again on Friday.

 

[UnsungZero_OldTimeAdMan]

I keep hearing that we shouldn't consistently be charging our batteries to full, instead cutting them off at roughly 90%. At Rivian are we to take this info consideration? Would love to hear from the engineers

Look at the charging screen. It is essentially what is recommended. 70% daily. 85% extended. They could've written software to any percentage. They chose those specfically.

 

[WSea]

Our guide told us that, day-to-day, to charge it between 60-80%. Enough so that you have plenty of juice to do your daily running around, but only charge above that if you know that you have a big trip the next day. At our house we put it on the charger when it drops below 50% and charge to 75%, but we've definitely charged to 100% before heading out on bigger trips.

One note (and, if you've been charging to 100% I'm sure you've already seen this)...You'll get a message telling you that regenerative braking is limited when you're at 100%. Basically it means that the cup is full and you can't add more power to the battery from braking so your regen "credit" is wasted.

Same 50-75 range except to 100 right before leaving on longer trip

 

[huskybrewing]

I'm currently trying to stick between roughly 40% and 60%, but that's really babying it. I'm trying to compensate a little for the 100% charges and intense battery usage when we travel while towing a 4000 lb trailer.

 

[lefkonj]

When I picked mine up was told 85% most of the time, if you need the miles for a trip go to 100%.

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