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Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health
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pdx_m3s
Active Member
Since I haven't been driving much recently, I've changed my charging habits to only charge when I get below 50% and then charge up to 90%. This is as opposed to keeping it topped up to 70%. I've regained 2-3 miles. Sitting at 231 miles out of the original 240. May 2019 SR+ ~5,400 miles.
I wish Tesla offered a warranty of degradation based on mileage. Right now it is just a 30% loss, regardless of mileage or use. There should be a curve. If we lost more than 10% by xxxxxx miles and 20% by yyyyyy miles, etc..
I know that they are just covering catastrophic range loss, but some of these losses seem significant for the miles driven. In Tesla’s recent impact report, they shared a graph that shows 10% average loss at 200,000 miles... I am almost at 10% loss by 18k miles.
I know that they are just covering catastrophic range loss, but some of these losses seem significant for the miles driven. In Tesla’s recent impact report, they shared a graph that shows 10% average loss at 200,000 miles... I am almost at 10% loss by 18k miles.
Hi. Totally new to this forum, and to forum-posting in general. I sort of searched for this topic, but didn't find anything on here on this question specifically I have a question about charging.
I've had my Model 3 Long Range since September 2018. Pre-Covid, I did 95% of my charging at work, so I stuck to the 20% Min / 80% Max rule almost all the time.
Now, in Covid-world, I work from home, so I have to charge at home. I have a 220 outlet, but because of logistics, it's a bit inconvenient to use. SO, there are times that I want to get more range than the 20/80 allows for.
My question is this - am I being better to my battery by charging to 95%, then taking it no lower than approximately 20%, or would it be more beneficial to the long-term battery life if I charge to only 80%, but take the car down to 5 to 8 % ?
For argument's sake, lets say that I -have- to do this three to four times per month.
Again - please forgive me if I posted in the wrong place.
Thanks !
I've had my Model 3 Long Range since September 2018. Pre-Covid, I did 95% of my charging at work, so I stuck to the 20% Min / 80% Max rule almost all the time.
Now, in Covid-world, I work from home, so I have to charge at home. I have a 220 outlet, but because of logistics, it's a bit inconvenient to use. SO, there are times that I want to get more range than the 20/80 allows for.
My question is this - am I being better to my battery by charging to 95%, then taking it no lower than approximately 20%, or would it be more beneficial to the long-term battery life if I charge to only 80%, but take the car down to 5 to 8 % ?
For argument's sake, lets say that I -have- to do this three to four times per month.
Again - please forgive me if I posted in the wrong place.
Thanks !
No need to do anything special with charging. In fact, Lithium Ion batteries like shallower charge and discharge cycles. However, there is no evidence yet correlating a certain charging cycle is better or worse than another. Tesla’s only recommendation is clearly listed in the app. The daily charge level should be set somewhere between 50-90% and above 90% for Trips only.
My best advice is to not worry about it much. I charge every day and some people charge every few days.
You do not need to bring it to a low state of charge. If you do it occasionally that is fine, but not a few times a month.
My best advice is to not worry about it much. I charge every day and some people charge every few days.
You do not need to bring it to a low state of charge. If you do it occasionally that is fine, but not a few times a month.
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Basically your question boils down to is it worse to charge it up past 90%, or worse to run it down below 10%. They're both supposedly bad for your battery, if you leave it at those levels for too long. Since you seem to need 75%, why not try 90 to 15. That's considered safe.
Too much overthinking. Set it to 90%, plug it in every day at home, and forget about it. If you need a longer trip occasionally, bump up to 100% beforehand.
Save the brain cells for driving and maybe some sacrificial ones to a good beer.
The rest is over analysis.
(There’s a specific reason to choose 90% and not 80% by the way. The battery management system will kick in some cell rebalancing when the car is idle but above 85% state of charge. Will it matter? Maybe, maybe not. But it works very slowly over a period of days or even weeks.)
I've never seen anything that talks about how 'long is too long'. If I charge to 95%, then start driving two hours later, is that 'too long', or do they mean don't charge to 100% and leave it undriven for a week ?
90/15 makes sense; I was just trying to determine that if i -must- do one or the other (take it to 95 or 100, vs. down to 5) on occasion, which is worse. (Where the plug is at home, it just is not practical for me to charge daily, nor do I want to spend the money to do any work as far as installing a new outlet)
Probably no difference in the big picture.
Dariushd
Member
Heya, so after I noticed some range loss in the car's display screen, I started using TeslaFi to record charging starting in November of 2019; after 10 months of owning my M3 (delivered 12/2018).
Batteries degrade over time, so it's not unexpected. But I'm not sure that it seems as if my m3 is perhaps a little faster degrading than what I'm reading on average. Not freaked out or upset (anymore), so, looking at it academically:
So here is my degradation chart from TeslaFi. Please note it started after 10 months of ownership after I went from 310 to about 300 max, so TeslaFi states a 4.55% loss, but if you calculate from the original day one mark of 310, I'm at about a 7% loss (see image). My max is estimated by TeslaFI to be at 286 miles now, a "loss" of 24 from the original 310.
To put context to this, I have supercharged maybe 5 times ever, and that was in the first 6 months of ownership, otherwise I exclusively charge at home on my Tesla Wall Charger. I charge almost every day (sometimes I will miss 2-3 days of charging if I'm not driving much). In addition, the first 9-10 months of ownership, I drove like a d**k most of the time, but have since mellowed out (much less stomping on the accelerator on a whim). And with COVID the past 2 months I have not driven much at all (you can see a sudden drop end of April) after which I started plugging in the car more often (you see a slow rise) and then a sudden drop again this last few weeks (with a big spike down for the week I did not charge my car at all):
I dunno if this helps anyone else comes to terms with "range loss" as it were, or if anyone can say if this is anymore or less than what they've seen, but just putting it out there...
Batteries degrade over time, so it's not unexpected. But I'm not sure that it seems as if my m3 is perhaps a little faster degrading than what I'm reading on average. Not freaked out or upset (anymore), so, looking at it academically:
So here is my degradation chart from TeslaFi. Please note it started after 10 months of ownership after I went from 310 to about 300 max, so TeslaFi states a 4.55% loss, but if you calculate from the original day one mark of 310, I'm at about a 7% loss (see image). My max is estimated by TeslaFI to be at 286 miles now, a "loss" of 24 from the original 310.
To put context to this, I have supercharged maybe 5 times ever, and that was in the first 6 months of ownership, otherwise I exclusively charge at home on my Tesla Wall Charger. I charge almost every day (sometimes I will miss 2-3 days of charging if I'm not driving much). In addition, the first 9-10 months of ownership, I drove like a d**k most of the time, but have since mellowed out (much less stomping on the accelerator on a whim). And with COVID the past 2 months I have not driven much at all (you can see a sudden drop end of April) after which I started plugging in the car more often (you see a slow rise) and then a sudden drop again this last few weeks (with a big spike down for the week I did not charge my car at all):
I dunno if this helps anyone else comes to terms with "range loss" as it were, or if anyone can say if this is anymore or less than what they've seen, but just putting it out there...
The range fluctuates according to how the "estimate" is estimated. Battery degradation is always negative, it does not "fluctuate" like you see in the above graph.
Seeking out these numbers causes needless anxiety.
Seeking out these numbers causes needless anxiety.
Because I'm a bit worried that my M3 LR battery has lost the capacity a bit too fast over 22 months of my ownership (Aug 2018 delivery), I did some calculation today.
At 75% charge (I charged up to 90% and drove a few tens of miles), the energy app showed that the projected range is 220 miles based on the average energy consumption rate of 241 Wh / mile for the last 30 miles.
That means the 75% charge level corresponds to 53.24 kWh (= 241 Wh/miles * 220 miles = 53240 Wh). At 100%, it'd be 70.99 kWh (53.24 kWh / 0.75)
M3 LR battery size is supposed to be 75kWh at the delivery. So, my M3 lost 4 kWh over the last 22 month (12k miles driven), which is about 5.3% loss over 22 months/12k miles. If the battery loss were linear with the miles driven (I know it is NOT), I'd loss more than half of the battery capacity over 120k miles.
I wonder what others have experienced with their M3. I'd rather talk in terms of kWh (the battery capacity) instead of the range/miles because the range estimate brings in a number of other factors.
At 75% charge (I charged up to 90% and drove a few tens of miles), the energy app showed that the projected range is 220 miles based on the average energy consumption rate of 241 Wh / mile for the last 30 miles.
That means the 75% charge level corresponds to 53.24 kWh (= 241 Wh/miles * 220 miles = 53240 Wh). At 100%, it'd be 70.99 kWh (53.24 kWh / 0.75)
M3 LR battery size is supposed to be 75kWh at the delivery. So, my M3 lost 4 kWh over the last 22 month (12k miles driven), which is about 5.3% loss over 22 months/12k miles. If the battery loss were linear with the miles driven (I know it is NOT), I'd loss more than half of the battery capacity over 120k miles.
I wonder what others have experienced with their M3. I'd rather talk in terms of kWh (the battery capacity) instead of the range/miles because the range estimate brings in a number of other factors.
pdx_m3s
Active Member
5% is pretty typical over a 1-2 year period. Capacity loss (degradation) is not linear. Look at any of the long-term scatter plots with a trend line, and you will see that they are not linear, but rather logarithmic.
If your chart starts in November, then the decline and rise could very well be seasonal variation due to cold. Teslafi has been shown to use the SOC api that is temperature-dependent. That's the red line area.
Then the green line area seems very consistent at 296 miles, so 4.5% down from 310 miles. Based upon what you wrote, it seems to make sense to keep the car plugged in, when not in use, so that the BMS doesn't get confused.
I don't know that keeping the car plugged in affects the BMS, other than low depth of discharge cycles makes it harder for the BMS to predict the battery capacity.
To resolve unbalanced bricks, store the car at 90% SOC.
To resolve errors in the BMS capacity prediction, cycle the battery below 15% and recharge above 90%.
Both of these, if done frequently or habitually, can cause increased degradation.
More explanation in my post here: Tesla Official Statement on Range
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Torque Monster
Member
I calculate my own range by dividing 75,000 by my 'Lifetime" trip meter's kWh/mi and multiplying by the percentage remaining of the battery. and get within 1 to 3 miles of what the BMS shows. I was freaking out for a few months before I figured how to do this.
To maintain battery health:
1) Use your car in percent mode (not miles or km). This will enable you to focus on what is important.
2) Don't go below 15% unless you have a good reason.
3) Don't charge above 80% unless you need the extra miles (or want the peace of mind).
4) Never" touch the shore" or try to manipulate your state of charge in any way.
5) Never try to do anything related to or for the purpose of "balancing". Tesla knows how to balance in a very sophisticated way. Bleed balancing that requires charging to over 90% is archaic. Things you might do related to advice you get about balancing are almost all harmful to the 4500 21700 cells in your battery and they produce no benefit.(By the way, balancing is related to cells in series, not cells in parallel. Weak batteries can be driven to zero or negative voltage by stronger batteries pushing current through them. When that happens, the weak cells get weaker...)
6) Acceleration is a personal choice, but be aware that when you are draining your battery at 5C, that is not ideal for longevity. Feel free to enjoy the acceleration, but understand there is a small tradeoff. This is not unique to Tesla; it is a characteristic of all Li-ion cells
The most important of these are 2, 4 and 5 imo, although I feel that following 1), though it seems arbitrary, is surprisingly helpful.
1) Use your car in percent mode (not miles or km). This will enable you to focus on what is important.
2) Don't go below 15% unless you have a good reason.
3) Don't charge above 80% unless you need the extra miles (or want the peace of mind).
4) Never" touch the shore" or try to manipulate your state of charge in any way.
5) Never try to do anything related to or for the purpose of "balancing". Tesla knows how to balance in a very sophisticated way. Bleed balancing that requires charging to over 90% is archaic. Things you might do related to advice you get about balancing are almost all harmful to the 4500 21700 cells in your battery and they produce no benefit.(By the way, balancing is related to cells in series, not cells in parallel. Weak batteries can be driven to zero or negative voltage by stronger batteries pushing current through them. When that happens, the weak cells get weaker...)
6) Acceleration is a personal choice, but be aware that when you are draining your battery at 5C, that is not ideal for longevity. Feel free to enjoy the acceleration, but understand there is a small tradeoff. This is not unique to Tesla; it is a characteristic of all Li-ion cells
The most important of these are 2, 4 and 5 imo, although I feel that following 1), though it seems arbitrary, is surprisingly helpful.
I am confused by this...are you saying that balancing produces no benefit or that the service manual direction for brick balancing, by charging to above 4.0V per brick, is not required as it has been replaced by a more "sophisticated way"?
4.0 volts per brick (i.e., per cell) sounds harmless to me. That is only about 83%. I would say that going any higher simply for the purpose of balancing is unnecessary and unwise. If you never take a trip that that requires charging to 90% or so, then I would say that simulating that (charging to 90%) every 6 months or so is not a bad idea. I think the number of people that applies to is close to zero.
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