How many charge to 100%

[JimBob]

I always charge to 100% at home... Degradation is inevitable and mostly comes from overheated DC fast charging.

This is not correct. Batteries degrade because of an increase in parasitic reactions. This occurs because of heating caused by fast charging AND time spent at high voltage levels. Increased time at high voltage levels also increases the risk of thermal events (fire).

Quite a bit of literature on this subject. Here is one https://electrek.co/2018/05/04/are-you-killing-your-lithium-batteries/ which will refer you to others.

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[J0EL]

I was able to drop 1% per hour by activating the climate. I activated it 5 times last night bringing it down to 95%. Hopefully my a/c is fine.

 

[feye]

Quite a bit of literature on this subject. Here is one https://electrek.co/2018/05/04/are-you-killing-your-lithium-batteries/ which will refer you to others.

A bit of an old article.

• "While DC fast charging is convenient when you need to get back on the road quickly, it is terrible for battery life if performed often." - I basically never do this.
• Taycan has slightly different cell chemistry, nobody knows exactly how it will perform in the long run.
• Cannot charge to 100% anyway, because of the built-in buffer.
• I only need 80k km out of my Taycan before I sell it. I have so far about 32 charging cycles. In average I got out 401 km per cycle. I need another 165 cycles before I sell the car.

Lets get a bit of degradation so I end up just over 200 charging cycles. The battery should easily last for 1500 charge cycles... Why worry about something, that is totally irrelevant to me? What am I missing?

 

[JimBob]

Porches sets the 80/85% recommendation for a reason. You substituted your judgement for theirs. Fine for your car but maybe not for others.

 

[feye]

Porches sets the 80/85% recommendation for a reason. You substituted your judgement for theirs. Fine for your car but maybe not for others.

The Porsche recommendation might have more to do with protecting their battery warranty war chest.

 

[JimBob]

The Porsche recommendation might have more to do with protecting their battery warranty war chest.

That's probably part of it, along with the crummy warranty on the battery in the first place that all EV's have. But the facts of what causes battery degradation are well known. Right now owners are ignorant of what the actual capacity of their battery is and how it changes over time. The only one who has a good idea is the manufacturer.

 

[Kingske]

Thank you for replying.
I turned on the A/C from my Connect app.
Hopefully this does something.

edit: 15 minutes A/C on... lost 3 miles of range but battery stays at 100

Efficiënt A/C because of the heat pump?

 

[TycanNewHampshire]

I have been doing a lot of reading from this post and others and come to a couple of 'givens' that I hope are affirmed by others here.
1. 100% is not 100% of the battery capacity, but 100% of what the owner can charge to.....there is more capacity built in due to safety/reliability.
2. similar to above, 0% has a reserve but shuts down at a SOC that allows the battery to still remain viable and minimally damaged.
3. Batteries develop some what of a 'memory' and chemical reactions must be used or lost.

Taking these into account, I have come up with my own thoughts on battery charging on the daily as well as full charging/discharging.
1. I am estimating that our displayed SOC% is actually 8-15% delta of true capacity on the top/bottom side of charging (e.g. if you are at 100% SOC displayed, there is another 10% available to charge, if the software let you....or if you are at 1% charge, you are actually at around 6% charge of the actually battery).
2. Studies for battery longevity have shown data that if you keep the average charge around 70-80% of charge, this offers the longest usable battery efficiency.
3. Use or lose. However, if you simply keep it around a certain charge, it is more difficult for the chemical reactions to occur in the unused/stable portions of the battery.

Therefore, I am thinking the following is a 'reasonable assumption' to ensure healthy batteries for long periods.
1. Charge to 100% SOC at a regular basis, with slow rates of charge, and use the vehicle afterword on a trip that brings it back down to 70-80% (perhaps weekly, or biweekly).
2. I feel 85% is actually closer to the sweet spot of true-75% charge capacity, despite recommendations for 80% daily (I might even caution on the side fo 90% vs. 80%).
3. Resetting the 'chemical memory', seems like a reasonable practice to be combined with the 100% charge and running this down to around <5%, with timing to get back to your home/slow charger to bring this back up. Perhaps frequency on this is better suited for the monthly/bimonthly/quarterly interval.

Would love feedback, I understand this is not published recommendations from Porsche, however all have studies behind the reasoning and am open to criticism and critique if you feel that I might be causing damage or undue wear on the batteries. However, at this point, I am feeling pretty good from the data out there, that this is a prudent and proven way to maintain performance and battery longevity.

 

[JimBob]

With respect to your points:

1. Yes
2. Yes
3. No

1. Useable capacity is 83.7 kWh and total capacity is 93.4 when the battery is new
2. That is manufacturers recommendation
3. No

1. No. That is not the manufacturers recommendation
2. No facts to substantiate
3. Not applicable to Lithium Ion batteries

 

[TycanNewHampshire]

With respect to your points:

1. Yes
2. Yes
3. No

1. Useable capacity is 83.7 kWh and total capacity is 93.4 when the battery is new
2. That is manufacturers recommendation
3. No

1. No. That is not the manufacturers recommendation
2. No facts to substantiate
3. Not applicable to Lithium Ion batteries

Thanks for the feedback @JimBob . I will take it under advisement. I would agree that this is not the manufacturers recommendation (as I stated in the beginning), as well as that it is 'generally perceived' that Li Ion batteries don't have a memory. However, I work in the clinical trials world for Pharma as well as med-device and have been following studies that suggest that there is a correlation to memory in Li Ion batteries as well.
Here is a quick link: https://pubmed.ncbi.nlm.nih.gov/23584142/
I won't post a reference to all of my sources, but I am not just stating I have seen data to say 'no facts to substantiate'.

 

[feye]

Taking these into account, I have come up with my own thoughts on battery charging on the daily as well as full charging/discharging.

Excellent! The more varied approaches we have the better we understand what we can do with this car.

Whatever I write here, it is never meant to give advice, but rather just sharing what I do.

I always charge to 100% because I want a real car, not a T toy. I want to see what my Taycan is made of!

If the battery degradation is too much after a few years, I sell the car and rethink my approach. The degradation on my MS90D is at least 10% and we toyed it with always slow AC charging to 85%.

 

[epirali]

I always charge to 100% because I want a real car, not a T toy. I want to see what my Taycan is made of!

If the battery degradation is too much after a few years, I sell the car and rethink my approach. The degradation on my MS90D is at least 10% and we toyed it with always slow AC charging to 85%.

I think this is a good point. We are not talking about any safety issues (please there is no real fear of fires from batteries, look at number of reports vs number of cars out there and you will realize you are more likely to be hit by lightening). And worst case just using the car means a bit faster battery degeneration, NOT loss of function or that the car becomes worthless.

I personally take the “best practices” approach, but its just the way I am with most things. I am not worried about keeping the car for many years (I am thinking maybe 3 or 4). But I also don’t think there is any reason to stress or use less than optimal practice for no real reason. When I need range, or the few times I want to do the “best” launch control I will charge to 100 and not think about it. But I see no reason to do it daily specially when I can so easily set a charge level that is all I need.

I know Jaguar simply took all these ideas away from the I-Pace. They pretty much just said “plug it in, charge it, drive it.” It always charges to 100% of usable capacity. That doesn’t mean their batteries are any different, they probably just decided the more their EV was just like a car and the less you had to think about it the easier it was to adopt.

 

[JimBob]

There are attempts by certain governments i.e. California to introduce legislation that would require automakers to provide owners with the actual remaining capacity of the battery. Maybe displayed on the dash. Right now we have no idea as to what it is and given the battery is the most expensive component in the car and needs to last many years, that makes a lot of sense.

If so, it would quickly become apparent as to who has been swimming naked (pp Warren Buffet).

It just makes all the sense in the world to follow the manufacturers recommendations.

 

[feye]

I think this is a good point. We are not talking about any safety issues (please there is no real fear of fires from batteries, look at number of reports vs number of cars out there and you will realize you are more likely to be hit by lightening). And worst case just using the car means a bit faster battery degeneration, NOT loss of function or that the car becomes worthless.

The problem is, that we really don't know what this "high silicon" battery is made of, and how it performs in the long run. Maybe my approach has the least amount of degradation. Maybe my approach has a high amount of degradation but still get the most km driven out of the available charge cycles... Anybody knows more about "high silicon"?

But I also don’t think there is any reason to stress or use less than optimal practice for no real reason. When I need range, or the few times I want to do the “best” launch control I will charge to 100 and not think about it. But I see no reason to do it daily specially when I can so easily set a charge level that is all I need.

Exactly! And just to be sure, I never charge daily, unless, I drive the battery empty in one day.

I know Jaguar simply took all these ideas away from the I-Pace. They pretty much just said “plug it in, charge it, drive it.” It always charges to 100% of usable capacity.

Isn't that even the approach of the Taycan, considering, that there is a default profile which charges to 100%, but no default timer, which would limit the charge?

 

[feye]

There are attempts by certain governments i.e. California to introduce legislation that would require automakers to provide owners with the actual remaining capacity of the battery. Maybe displayed on the dash. Right now we have no idea as to what it is and given the battery is the most expensive component in the car and needs to last many years, that makes a lot of sense.

If so, it would quickly become apparent as to who has been swimming naked (pp Warren Buffet).

That would be excellent!!! I really would love to know that! I even consider spending about 1k USD to buy the Porsche PIWIS-3 to read out all the battery info. Anybody know a cheaper better option?

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