Battery Degradation

[Loltheinternet]

Do you know how "State of Health" is calculated? And what the difference between the two "SoH" values is?

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[Dee]

Do you know how "State of Health" is calculated? And what the difference between the two "SoH" values is?

No idea.
SoH is battery life.
SoC is battery charge level, no difference.

 

[Loltheinternet]

No idea.
SoH is battery life.
SoC is battery charge level, no difference.

Fair enough. FWIW - there were two different SoH values in the screenshot you posted - uppermost right and lowermost right.

 

[Deleted member 7736]

On the topic of battery degradation and DC fast charging, I'm wondering to what extent everyone here avoids DC fast charging to minimize battery degradation. I have a PMCC installed in the garage, but we also have an EA station with multiple 150kW stalls less than a mile from the house. Since we get 3 years of free 30 min. charges, I've gotten in the habit of using the EA station once or twice a week. In the time it takes me to walk to the Starbucks down the street and back, I've taken the car from 40% to 85% for free, but if this is coming at the expense of increased degradation to the battery I'll rely more on charging at home at night. FWIW - I have "battery friendly" fast charging enabled. How worried should I be about DC fast-charging if I'm only charging to 85%?

 

[DerekS]

On the topic of battery degradation and DC fast charging, I'm wondering to what extent everyone here avoids DC fast charging to minimize battery degradation. I have a PMCC installed in the garage, but we also have an EA station with multiple 150kW stalls less than a mile from the house. Since we get 3 years of free 30 min. charges, I've gotten in the habit of using the EA station once or twice a week. In the time it takes me to walk to the Starbucks down the street and back, I've taken the car from 40% to 85% for free, but if this is coming at the expense of increased degradation to the battery I'll rely more on charging at home at night. FWIW - I have "battery friendly" fast charging enabled. How worried should I be about DC fast-charging if I'm only charging to 85%?

I'll let you know if I end up having actual degradation or not. I've done a fair amount of DC fast charging.

 

[Stoneageman]

On the topic of battery degradation and DC fast charging, I'm wondering to what extent everyone here avoids DC fast charging to minimize battery degradation. I have a PMCC installed in the garage, but we also have an EA station with multiple 150kW stalls less than a mile from the house. Since we get 3 years of free 30 min. charges, I've gotten in the habit of using the EA station once or twice a week. In the time it takes me to walk to the Starbucks down the street and back, I've taken the car from 40% to 85% for free, but if this is coming at the expense of increased degradation to the battery I'll rely more on charging at home at night. FWIW - I have "battery friendly" fast charging enabled. How worried should I be about DC fast-charging if I'm only charging to 85%?

Supposedly the DC charging is bad for the battery due to high heat, at least that is how I understand it to be. I know for a fact that in the earlier days of tesla when they gave everyone who owned model S free charging, they advised against using it all the time because it would increase the degradation. There are plenty of horror stories of those whose batteries wouldn't hold charges anymore because they only relied on fast charging. Though those were some of the first generations of Teslas and it could just be the batteries weren't as great back then. I am sure that because consumers are better educated on this topic so the decreased wear on the battery could also be due to that factor. Personally I use DC charging on my Audi almost exclusively because it is a lease and its going back after three years so it doesn't matter to me. My porsche is always charged up at home.

 

[iten]

Does anyone know whether a slow DC charger (18-24kw) will cause more degradation than using a AC charger at similar speed (22kw)? Assuming all other contributing factors are the same.

 

[W1NGE]

Does anyone know whether a slow DC charger (18-24kw) will cause more degradation than using a AC charger at similar speed (22kw)? Assuming all other contributing factors are the same.

Not come across such low DC charging before.

No idea but highly doubt it. Less wear and tear on your onboard AC charger (apart from not being used) as there is no need to convert to DC before charging the battery.

 

[MartyMeatball]

I have about 10K miles on my 2021 and haven't noticed any battery degradation.

However, I never use DC fast chargers, never charge above 80% and never let the battery get below 20%. If I'm not going to be using the car for more than a few days I try to make sure the battery is around 50%.

The reason I do all this is because of my experience with RC planes/cars. I learned over the years that not charging/discharging fully and storing at around 50% achieves the longest battery life.

 

[taycanlovers]

i do this w

App which works with the Taycan:
https://play.google.com/store/apps/details?id=com.ovz.carscanner

Dongel/adapter:
https://www.ebay.nl/itm/373434002766

is use OBDAPP for quering battery data, works also fine!

 

[Deleted member 7736]

Is this an app you've created? Seems like you've promoted it in several threads now.

 

[ben1]

Going above 80% is not that bad. Staying below 20% for long time or exposing the battery to high temperatures are worse.
What destroys the battery most is the high temperature, not the high current.
That is why DC fast charging should be avoided. The cooling system will try to keep the temperature as high as possible (for faster charging) but not too high to cause damage.
But the problem is that it is not perfect in keeping the same temperature through-out the whole pack. Some parts will get too hot.
I read that the Taycan and the Tesla's are quite good in keeping the same temperature in the entire pack compared to some other cars.

About the 20% minimum level: I saw this a lot in practice with phones. If you keep your phone always above 20% the battery lasts much longer. Even if phones do not have very good cooling.

Typical for li-ion chemistry is in good cooling setups like EV's that do not DC charge too often:
-6% loss the first year
-1% every next year
My 6 year old tesla had 6%+5x1% = 11% loss. That is also what I also saw in practice.
A 10 year old car should be around 15%. Still acceptable for most cars.

I think you should not use the guess-o-meter to measure battery degradation. You should really drive 100% to 0% in the same conditions.

 

[W1NGE]

Going above 80% is not that bad. Staying below 20% for long time or exposing the battery to high temperatures are worse.
What destroys the battery most is the high temperature, not the high current.
That is why DC fast charging should be avoided. The cooling system will try to keep the temperature as high as possible (for faster charging) but not too high to cause damage.
But the problem is that it is not perfect in keeping the same temperature through-out the whole pack. Some parts will get too hot.
I read that the Taycan and the Tesla's are quite good in keeping the same temperature in the entire pack compared to some other cars.

About the 20% minimum level: I saw this a lot in practice with phones. If you keep your phone always above 20% the battery lasts much longer. Even if phones do not have very good cooling.

Typical for li-ion chemistry is in good cooling setups like EV's that do not DC charge too often:
-6% loss the first year
-1% every next year
My 6 year old tesla had 6%+5x1% = 11% loss. That is also what I also saw in practice.
A 10 year old car should be around 15%. Still acceptable for most cars.

I think you should not use the guess-o-meter to measure battery degradation. You should really drive 100% to 0% in the same conditions.

Since the recent uPdate I've been reading the updated documentation and the 'recommended' 80% daily charging is explained away by using time spent charging as the reason (hitherto we've all waxed lyrical on battery management, longevity and all of that). The reason given is that once you reach 80% then the rate and therefore speed of charging slows down considerably (as we all know) and so no need to waste time getting to 85% or higher and spend that 'lost' time on the road.

Whilst this may be the latest guidance from Porsche they appear to have overlooked that low power AC charging e.g. 7.4kW rarely drops below 6kW towards the target charge - hardly material.

Ultra fast DC charging as you point out generates much more heat and therefore caution is needed and probably even less need to charge regularly this way beyond 80% - 85% if you want to be kind to your battery.

I conclude therefore that daily charging on single phase 32A (7.4kW) to 80% - 85% is nothing to worry about on the degradation front. Degradation is unavoidable at the end of the day and it just a question of how much you may notice (or not).

 

[taycanlovers]

Is this an app you've created? Seems like you've promoted it in several threads now.

sadly no but would be good to have it created own

 

[mystermykee]

On the topic of battery degradation and DC fast charging, I'm wondering to what extent everyone here avoids DC fast charging to minimize battery degradation. I have a PMCC installed in the garage, but we also have an EA station with multiple 150kW stalls less than a mile from the house. Since we get 3 years of free 30 min. charges, I've gotten in the habit of using the EA station once or twice a week. In the time it takes me to walk to the Starbucks down the street and back, I've taken the car from 40% to 85% for free, but if this is coming at the expense of increased degradation to the battery I'll rely more on charging at home at night. FWIW - I have "battery friendly" fast charging enabled. How worried should I be about DC fast-charging if I'm only charging to 85%?

I used to do the same--charge at EA about 2-3 times a week to 85% because it was free. I did this for about three weeks until I was educated about battery degradation using DC fast charging on a regular basis. Since then I've used home/work level 2 charging. With my daily driving habits, charging to 80% is about 30kwH, and on an EV rate plan it's 24cents during off peak hours. That's about $8/night. Small price to pay to slow battery degradation.

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