Why is 85% battery recommended as the normal maximum?

Talisker

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I was diligently charging the Taycan to 85% unless I had a long trip planned, when a friend who is an EV veteran told me that the 85% is only for when you are using fast chargers, due to the heat and that with the low wattage domestic chargers 100% would be okay all the time.

Has anyone looked into this, which is true and why?
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I was diligently charging the Taycan to 85% unless I had a long trip planned, when a friend who is an EV veteran told me that the 85% is only for when you are using fast chargers, due to the heat and that with the low wattage domestic chargers 100% would be okay all the time.

Has anyone looked into this, which is true and why?
My dealer suggested that I charge up the car to 100 percent on a daily basis. I understand that the battery technology is different to other brands and that there is no need to charge to a lower limit in order to extend the life of the battery.
 

evanevery

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My dealer suggested that I charge up the car to 100 percent on a daily basis. I understand that the battery technology is different to other brands and that there is no need to charge to a lower limit in order to extend the life of the battery.

There are other threads in this forum which provide formal reference to Porsche's recommendation for 85% as a "typical" daily limit. I'll let you search for those if you want to read them and verify their source...

The reason is for speed, efficiency, and to extend the battery life. As a battery approaches 100%, the charging process has to slow down and be more careful not to overcharge the battery. Tesla's example (for 90%), is akin to "filling a glass of water perfectly to the top". Its easy to rapidly fill to 85-90%, but we must slow down substantially as we approach the rim of the glass.
 

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There are other threads in this forum which provide formal reference to Porsche's recommendation for 85% as a "typical" daily limit. I'll let you search for those if you want to read them and verify their source...

The reason is for speed, efficiency, and to extend the battery life. As a battery approaches 100%, the charging process has to slow down and be more careful not to overcharge the battery. Tesla's example (for 90%), is akin to "filling a glass of water perfectly to the top". Its easy to rapidly fill to 85-90%, but we must slow down substantially as we approach the rim of the glass.
Just checked - and you are absolutely correct. I have fired an email off to my dealer. It's absolutely unacceptable that they do not have the knowledge of their own product!
 

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Just checked - and you are absolutely correct. I have fired an email off to my dealer. It's absolutely unacceptable that they do not have the knowledge of their own product!
No worries. Simply configure the car for a normal daily charge limit of 85% and then plug it in whenever you have a charger available (every night at home if you can).

The only time you would need to temporarily change that setting is if you have a long drive scheduled for the next day.
 
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Talisker

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There are other threads in this forum which provide formal reference to Porsche's recommendation for 85% as a "typical" daily limit. I'll let you search for those if you want to read them and verify their source...
I did a search on "85%" and it came up with nothing, hence the thread
 

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Page 66 owner's manual:
Use the timer or profile function to set the highvoltage
battery to charge to a maximum 85% for
the vehicle’s daily use, excluding long-distance
trips.
 

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Last edited:

feye

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Tesla's example (for 90%), is akin to "filling a glass of water perfectly to the top". Its easy to rapidly fill to 85-90%, but we must slow down substantially as we approach the rim of the glass.
As much as I understand this, Porsche reserved a large enough buffer in the battery on both ends, that you can charge it up to 100%. Degredation of the battery does not only depend on how full you charge it. There are a lot of other factors, some of which we have no control over. I will always charge the car to 100%, when I come home and it is low enough for the next day.
 

evanevery

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As much as I understand this, Porsche reserved a large enough buffer in the battery on both ends, that you can charge it up to 100%. Degredation of the battery does not only depend on how full you charge it. There are a lot of other factors, some of which we have no control over. I will always charge the car to 100%, when I come home and it is low enough for the next day.
Porsche, specifically, recommends charging only to 85% on a daily basis. See page 66 of the owners manual. Feel free to depart from the formal recommendation if you think you know better...
 

feye

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Porsche, specifically, recommends charging only to 85% on a daily basis. See page 66 of the owners manual. Feel free to depart from the formal recommendation if you think you know better...
I don't know better, but I want to use the car and that means to keep it simple and have the full range available.

90% charge on my MS90D should be about equal to 100% in my new Taycan because of the buffer they put in place.

Please keep in mind, that I will not charge the car every day. I might only charge it twice a week, depending on how much I need it. This gives me an acceptable amount of charging cycles over total ownership.

I regard the recommendation if you insist of charging the car every day, no matter how full the battery is.
 

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I don't know better, but I want to use the car and that means to keep it simple and have the full range available.

90% charge on my MS90D should be about equal to 100% in my new Taycan because of the buffer they put in place.

Please keep in mind, that I will not charge the car every day. I might only charge it twice a week, depending on how much I need it. This gives me an acceptable amount of charging cycles over total ownership.

I regard the recommendation if you insist of charging the car every day, no matter how full the battery is.

Totally agree. I'd prefer to charge to 100% as well. And I do plan on charging every day. I want to make it a habit after I park in my garage to plug in the charger, otherwise I'm afraid I might forget to plug it in when I should. Isn't there a buffer (as mentioned above) that keeps you from charging to such a high level that you'd harm the battery?
 

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The buffer is more on the bottom than it is on the top. While sitting at 100% charge isn't great for the batteries, going to 0% actual charge will destroy them. If you charge to 100% and then brake, you'll probably see that the max regen isn't anywhere near where it would be if you weren't at 100%, because the battery is actually full, and there's nowhere to put the extra energy.
 

evanevery

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...Isn't there a buffer (as mentioned above) that keeps you from charging to such a high level that you'd harm the battery?
If they artificially limited the battery charging to 85% at all times, then you would not be able to use the full charge on the occasional times you would really want it. (Like for long trips)

The charge level on my Model X is simply set to 90% (the Tesla recommendation) and I just plug it in whenever it gets parked in the garage. Anytime, every time, its just part of our "Parking routine". I've only needed to bump the charge level to 100% maybe 6 times in the whole past year. I'm glad I could and its not hard on the battery if you do this occasionally.

If you artificially mandated a "buffer" to do this just so you could set the charge to "100%" then you would lose the ability to ACTUALLY charge the battery to 100% when you really needed it. Is there something special about a fake "100%" setting that makes you unhappy to use an actual 85% setting for the very same results? (Other than permanently losing access to the remaining 15%...)

My TurboS is on the truck and arriving this week. I plan to treat it similarly (except setting the normal/daily charge level to 85%)
 

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Anytime, every time, its just part of our "Parking routine".
Agree.

I think that is just part of the EV routine, that although very easy to do, is just different for people who have only had an ICE.

Weird for me to plug in when I have "only" 70% and don't plan much driving the next day, but I do it anyway and just have no worries.
 
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