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80,90,or100% ?

3978 Views 83 Replies 35 Participants Last post by  NortonCommando
New to EV with my 2023 Bolt.
factory setting is to charge to 100%
My electrician told me to change setting to either 80 or 90 % unless I鈥檓 taking an extended trip
What is recommended?
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80 or 90 % unless you're taking an extended trip.
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20-80% is the best range to stay in. If I鈥檓 doing a road trip I鈥檒l charge to 100% and set my departure time so I鈥檓 unplugging within an hour of my departure. I鈥檝e also read it鈥檚 good to charge to 100% every 90 days or so to balance the cells.
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80 or 90 % unless you're taking an extended trip.
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20-80% is the best range to stay in. If I鈥檓 doing a road trip I鈥檒l charge to 100% and set my departure time so I鈥檓 unplugging within an hour of my departure. I鈥檝e also read it鈥檚 good to charge to 100% every 90 days or so to balance the cells.
You want to stay out of the upper and lower 10-15% of the pack for routine charging, which keeps you in the area of the charge curve that puts the least stress on the cells. There's some permanently unused headroom in the pack, so charging to 90% is fine.

I'm one of those folks who charges to 100% every fourth or fifth time to let the BMS balance and recalibrate. Don't overthink this, you could charge to 100% every single time and the only real ramification is perhaps the battery capacity will degrade an extra percent or two every 100,000 miles.

I also like to let the car stay plugged into the charger for at least 4 hours after the traction battery is charged so it'll have a chance to charge the 12V battery too. Lead acid batteries take a long time to charge from 80% to 100% and their life suffers significantly if they're discharged more than 50% and/or not given a full recharge every week or so. For that reason, I always charge the car at least on a weekly basis. The car itself will keep the 12V battery from dropping too far but won't give it a full charge as frequently as I'd like unless it's plugged in.
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You want to stay out of the upper and lower 10-15% of the pack for routine charging, which keeps you in the area of the charge curve that puts the least stress on the cells. There's some permanently unused headroom in the pack, so charging to 90% is fine.

I'm one of those folks who charges to 100% every fourth or fifth time to let the BMS balance and recalibrate. Don't overthink this, you could charge to 100% every single time and the only real ramification is perhaps the battery capacity will degrade an extra percent or two every 100,000 miles.

I also like to let the car stay plugged into the charger for at least 4 hours after the traction battery is charged so it'll have a chance to charge the 12V battery too. Lead acid batteries take a long time to charge from 80% to 100% and their life suffers significantly if they're discharged more than 50% and/or not given a full recharge every week or so. For that reason, I always charge the car at least on a weekly basis. The car itself will keep the 12V battery from dropping too far but won't give it a full charge as frequently as I'd like unless it's plugged in.
Thank you for your input馃憤
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I am always the contrarian on this... and this site has many long threads on this topic with oodles of charts and lots and lots of facts theories.

I'll quote this line:

"Don't overthink this, you could charge to 100% every single time and the only real ramification is perhaps the battery capacity will degrade an extra percent or two every 100,000 miles."

Based on that statement I would argue that if you only charge to 80% then your battery is already degraded since you are not getting the performance you paid for.

But my opinion is only an opinion (and not a popular one). I bought the car for me, not the next person to drive it, and with the vagaries of the charging infrastructure I want my tank full.
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I am always the contrarian on this... and this site has many long threads on this topic with oodles of charts and lots and lots of facts theories.

I'll quote this line:

"Don't overthink this, you could charge to 100% every single time and the only real ramification is perhaps the battery capacity will degrade an extra percent or two every 100,000 miles."

Based on that statement I would argue that if you only charge to 80% then your battery is already degraded since you are not getting the performance you paid for.
It's not "theory". Who is this quote from? Where does such data/claim come from?

You do realize that the battery warranty allows for up to 40% capacity loss within the 8 years/100K miles, whichever comes first, right?

If you don't need 100% every time, there's no reason to charge it to 100% each time. Sure, do it when you need it.

Notice slide 8 of https://www.nrel.gov/docs/fy16osti/66708.pdf suggests that a lower average SoC is better? Bolt uses an NMC-based battery. If you charge to 100% then say 1% to 20% each time, what do you think the average SoC will be vs. someone w/the same usage and charging to something lower like 80%?

I wouldn't go as far as VW (Charge to 100%? 80%?) where they don't want people parking their cars at above 80% or below 30% for more than 12 hours. They were also using LG Chem back then, like Bolt.

One roundtrip of my commute only uses about 10% of my battery on my former Bolt and current '22 Niro EV. If I charged to 100% each time at work, my average SoC is most of the time is going to be above 90%.

The times I need to actually charge my former Bolt or current Niro EV to 100% is only a few times/year.

Notice page https://www.chevrolet.com/bypass/pc...Bolt_EV_OM_en_US_U_84953304C_2023MAR10_3P.pdf page 223 recommends long-term storage at 30%? This is inline w/known li-ion battery science. These aren't lead acid batteries which DO like being full.

We've been through this many times (e.g. What % Should I Charge To?) and it seems you also participated there.
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You want to stay out of the upper and lower 10-15% of the pack for routine charging, which keeps you in the area of the charge curve that puts the least stress on the cells. There's some permanently unused headroom in the pack, so charging to 90% is fine.

I'm one of those folks who charges to 100% every fourth or fifth time to let the BMS balance and recalibrate. Don't overthink this, you could charge to 100% every single time and the only real ramification is perhaps the battery capacity will degrade an extra percent or two every 100,000 miles.

I also like to let the car stay plugged into the charger for at least 4 hours after the traction battery is charged so it'll have a chance to charge the 12V battery too. Lead acid batteries take a long time to charge from 80% to 100% and their life suffers significantly if they're discharged more than 50% and/or not given a full recharge every week or so. For that reason, I always charge the car at least on a weekly basis. The car itself will keep the 12V battery from dropping too far but won't give it a full charge as frequently as I'd like unless it's plugged in.
Won't the traction battery keep the 12 volt charged, while the car is on, regardless of whether it is plugged in?
I am always the contrarian on this... and this site has many long threads on this topic with oodles of charts and lots and lots of facts theories.

I'll quote this line:

"Don't overthink this, you could charge to 100% every single time and the only real ramification is perhaps the battery capacity will degrade an extra percent or two every 100,000 miles."

Based on that statement I would argue that if you only charge to 80% then your battery is already degraded since you are not getting the performance you paid for.

But my opinion is only an opinion (and not a popular one). I bought the car for me, not the next person to drive it, and with the vagaries of the charging infrastructure I want my tank full.
Thank You for your opinion........I have read from Chevy engineers that EV owners should not "overthink it"
What is recommended?
Here's a nice, easy to understand explanation of battery health from Recurrent.
EV Battery Health after 250 Million Electric Car Miles
These people monitor and study thousands of EV batteries.
Won't the traction battery keep the 12 volt charged, while the car is on, regardless of whether it is plugged in?
Well, you could leave the car on all the time and never have to worry about coming out to a dead 12V after a week of not driving. But it's easier for the car to maintain both batteries when it's plugged in. When the car is off and unplugged, it checks the 12V every four days. When it's plugged in , it checks it every six hours. Also, when it's plugged in, it will start charging the 12V sooner than when unplugged.

Imagine now that you make about a dozen 5-minute drives over a week's time and the car never runs long enough to fully recharge the 12V battery. It just gets lower and lower. Eventually it will get low enough that the car will charge it a little even when it's off and unplugged. But that chronic low voltage will take a toll on the 12V battery.
Based on that statement I would argue that if you only charge to 80% then your battery is already degraded since you are not getting the performance you paid for.
That is something I never thought of and you are correct. Way too much time is given to worrying about the health of the battery 10 years or so down the line.
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When I'm at HOME paying for power I have my settings at 80%. When I'm AWAY riding my bike at the park with free power I have my settings at 100%. I haven't had to pay for power away from home yet.
Won't the traction battery keep the 12 volt charged, while the car is on, regardless of whether it is plugged in?
No, 12V battery maintenance is far more aggressive when plugged in. A friend was having issues with the 12V on his 2019 Bolt, his routine was to plug in once a week due to limited miles. He replaced the 12V and within a few weeks, problems returned. I suggested changing his habits and follow the ABC rule (Always be Charging), he reports that his 12V issues have vanished since following the ABC rule.
I have read from Chevy engineers that EV owners should not "overthink it"
I suspect GM engineers changed their opinions as a result of the recall.
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Not sure if anybody posted already; I just skimmed real fast -
charging less than 100% allows you to use one pedal driving.

If 90 is better than 100, and 80 is better than 90 - so 65 is the best? :ROFLMAO:
Product Azure Rectangle Slope Font

Just kidding - stick with 80% if that's all you need for the day.
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The state of the batteries at 100% charge is well known, and this holds true for all rechargeable lithium based batteries (except lifepo4), 100% charged is the point of highest stress on these lithium cells. So charging to 100% every time does increase degradation, its not immense an extra 3-5% over 100k miles. It increases the possibility of failure, again not immensely but at 100% your chances are higher than those that only charge to 80-90 percent. Because of the battery recall the diagnostics and monitoring of the battery are much more aggressive than previous, so your chances of a fire are much lower as it seems to be doing a much better job at detecting the conditions that lead to a fire. There have been multiple posts here in this forum from members who have gotten the alert to not drive and get the battery serviced, aka, replaced.

Having said all of that, you should charge the way that fits your lifestyle and driving needs. If you need to be at 100% to get your normal drives in, charge to 100%. If you have shorter drives and don't need to be at full charge, set it lower and charge more often. Myself, I have hilltop on (I have a 2017 so I can't set a target percent) and I leave it that way unless I know I need to take a long drive. I do it more because I like to have regen 100% available from the start of my drives and I rarely do a trip that needs even half of the battery.

So while it is good to know all of that, as I said, the reality is you figure out what fits you and charge to fit that. Short of draining the battery below 15% often you really can't screw them up easily.
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