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Best practice for battery recharging with set commute
- Thread starter Plasmatt
- Start date
UncertainTimes
Active Member
We’ll first don’t go below 20%. And second just charge everyday to 80% don’t overthink it. Manual says keep it plugged in.
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If I was only doing that twice a week, I would charge to 95% on those two days, and the rest of the time I was driving around town I would probably charge to 50-60%.
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Yes. Just don’t know what is better fir it. Charging higher and ending higher or charging lower and ending lower. Maybe I’m caught up in small details.
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ATPMSD
Active Member
You will get all kinds of advice from a lot of very well intentioned people, but don’t over think this:
- Never let the car drop to 0% SOC. Never!
- If you do not have an LFP battery you can charge to 90% everyday, which is the top of the “Daily” bar on the Charging Screen. If you have an LFP battery you can go to 100% everyday. You can tell you have an LFP battery as there is no “Daily” and “Trip” divisions on the charging screen.
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IMO, yes, you are.
Its more important that you not run out of power on the trip than it is to "stay below 90%", especially if you are going to drive the car right after charging to that percentage.
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The OP said "M3P" which in this context should be a "model 3 performance". There arent currently any LFP model 3 performance vehicles so while your LFP explanation is spot on, this OPs vehicle isnt impacted by LFP battery charging instructions.
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Do you have charging at work or Superchargers en route? I do a 250 mile round trip once a week. My goal is to stay between 20% and 90% for long-term battery health.
On non-commute days, I charge to 70%. The night before my commute, I charge to 90% and use ~55% on the trip in. Then I either charge for 4hrs at a Chargepoint L2 at the office (after 4 hours the fees go up 6x), or I stop at a rest area with a supercharger on the way home (realistically, I need a bathroom break by then, anyway). Either one gets me home with at least 20% remaining.
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That a forum myth.
Lithium batteries are most Happy at low SOC, both regarding calendar aging and cyclic aging. Down to 0% true SOC is safe ( 0% means discharge to the low limit according to the battery manufacturer).
Tesla use a low buffer so 0% on the screen is about 4.5% true SOC, which is VERY safe. The only lower limit needed is the drivers personal reserve to not get range anxiety.
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There is not a very big difference between 85-5% and 90-10%.
85-5% causes a little less wear on the battery, but not a huge difference.
Having the car standing at high SOC during nights etc causes more wear (calendar aging).
You should not be afraid to drive down to low SOC or leave the car with low SOC (for shorter periods, for months the SOC need to be such as the battery not go totally empty).
So the recommendation for the commuting is to have enough SOC to not get range anxiety. How much you need is a personal question. If you are happy with low SOC, lower is better.
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This is how lithium batteries degrade from time (calendar aging): (Long range and Performance use NCA in US)
- The lower the SOC, the lower the calendar aging.
- For cyclic aging, the smaller the cycles is the less is the cyclic aging (degradation).
- For cyclic aging, the lower the cycles in SOC-range, the less is the cyclic aging.
For all three statements, ”the lower” means down to 0% SOC.
This is coming from the research, and all the research results tell the same. There is really no uncertainty about it.
The ”stay above 20%” has no bearing and tesla do not tell us to do this at all.
Other forum rumours is that 80% is the best SOC to preserve the battery. Its not.
Another one is that 100% SOC is really bad and you shouldnt leave the car for long. In reality it is not that much worse than leaving the car at 90%. There is no reason to leave the car at 100%, so its best not to…but on the other hand, its not as bad as the forum rumors say.
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Point #1 has no bearing on battery life, as it is safe and do not cause any exessive wear on the battery.
Poin t#2 is as per Teslas advice. Doing this should make the car still hold the battery above the warranty limit after 8 years, but it do not preserve the battery. 90% is not the best SOC to use if you would like to reduce the degradation or keep the range.
Following Teslas simple advise will do it. The battery will hold the 8 years, but the degradation might not be the lowest possible.
So, everyone has the choise to either follow the Teslas easy few advises, and then preferably not follow the forum rumors wrong advise or to try to keep degradation low. Its a matter of personal choise.
The basics for overall battery pack life is:
- Charge often. Small cycles reduce the degradation a lot over a cars life.
- Do not charge more than you need for the drive between the charging sessions. Just what you need, and maybe not get range anxiety.
- Charge late so the car stands with a lower average SOC.
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ucmndd
Well-Known Member
Charge high enough to have a reasonable buffer at the end of your trip. You never know what’s going to happen, when you might need to make a detour, get stuck in traffic, etc. I would not risk arriving home at 5% just to avoid charging to a higher level because of some baseless worry of “battery damage”.
Ignore anyone who says “never go below 20%” or any other such nonsense.
If I were you I’d charge to 95% or even 100% before those long commute days (and in fact that’s exactly what I do and have done easily a hundred times). There’s no good reason not to.
Ignore anyone who says “never go below 20%” or any other such nonsense.
If I were you I’d charge to 95% or even 100% before those long commute days (and in fact that’s exactly what I do and have done easily a hundred times). There’s no good reason not to.
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You can't supercharge along the way? You're in Washington State, and it's currently Summer. In Winter, you're not going to make it! So, you have to supercharge. In that case, if pack life is very important to you, then follow Aakee's advice. I'd personally keep the pack under 60% during the week, and then hit a supercharger on the commute. That's the best for pack life.
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No it is not.It does if you run it down to 0%, which is bad for the battery and potentially a battery killer.
A lithium battery that is drained below 0% (overdischarged) have a good chance to get damaged.
0% SOC (the battery manufacturers 0%, not the Tesla on screen SOC) is defined as the discharge voltage limit. This is not a completely empty battery. For NCA cells this is 2.5V / cell.
This discharge level is completely safe, and the battery will have the lowest calendar aging / degradation at this SOC level.
It is very clear that 0% SOC is not only completely safe, its avtually the best SOC to have a lithium battery at.
The research is not unsure at all on this point.
Tesla use a 4.5% buffer below 0% on-screen-SOC. This means that 0% SOC on the tesla screen is about 4.5% true SOC. This is not in anyway close to a overdischarged battery. Tesla disconnects the battery via the contactors before it reaches dangerously low levels.
If low SOC was dangerous my battery would have gotten damaged, as I have been to 0% and below several times. Two times down to about -2% and to zero sereval times.
Down to 0%, last time was about one week ago when I did a degradation test. My 2021 M3P with 46.000km still has 79 kwh capacity, which means my car is among the M3P ‘21 with the lowest degradation.
According to teslafi, my car has the highest range of the M3Ps that has reach the same mileage. I often arrive with below 20%, and let it stand until next morning when the charging commence.
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Thank you Aakee, Really appreciate your detailed comments.
So what I understand so far, it does not matter if one has NCA or LFP battery.
Keep your battery SoC to as low as possible without affecting your daily commute.
This will help lower battery calendar degradation.
I have Tesla RWD with LFP battery and drive everyday to approx 18-20%. So if I keep my battery to charge daily to 40% is that OK.
When I come home battery is around 22% but I delayed charge it so it is at 40% mark by 8AM.
Please let me know if I am doing any thing incorrect here.
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