State of Charge vs Charge Cycles

[Ajjra]

In the interest of preserving the life of my Taycan battery, I’m trying to learn what has a greater impact on service life - SOC or cycles? I’m considering if I should be topping off to 85% every night whether I need to or not.

For example, if the battery is currently at 60% does it make sense to charge to the recommended 85% SOC now or is it better to leave it at 60% and use it a bit here and there until the. SOC reaches, say, 40% or even 30% and then charge?

Also does it matter if the car sits at 50% for a week or would it have been better for long term battery life to have topped back up again?

This is all independent of usage needs which would be my primary consideration before battery care. I live in an area where I would take several short trips.

I have been unable to find an authority on this as it pertains to EV’S

Thanks in advance.

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[B61]

Same questions here.
I drive up to 100km daily and I can charge at work (@22kw) or at home (@11kw).
By now, I was driving till 25-30% than charing up to 85%...
In case that I'll have longer trip, I'll charge 100% overnight before the journey...

 

[W1NGE]

In the interest of preserving the life of my Taycan battery, I’m trying to learn what has a greater impact on service life - SOC or cycles? I’m considering if I should be topping off to 85% every night whether I need to or not.

For example, if the battery is currently at 60% does it make sense to charge to the recommended 85% SOC now or is it better to leave it at 60% and use it a bit here and there until the. SOC reaches, say, 40% or even 30% and then charge?

Also does it matter if the car sits at 50% for a week or would it have been better for long term battery life to have topped back up again?

This is all independent of usage needs which would be my primary consideration before battery care. I live in an area where I would take several short trips.

I have been unable to find an authority on this as it pertains to EV’S

Thanks in advance.

Top up charging doesn't constitute a charging cycle -SOC needs to be much lower (< 10%) and then charged more or less full. You'll get a more authoritative response from others on the forum but top ups are fine and you have an 8 year battery warranty to provide a degree of protection.

 

[Scandinavian]

One charge cycle is defined as a full charge from 0% to 100%. So if you normally do small top ups of say 25% you will make 4 such charges to equal one charge cycle. Some recommenadtions for long battery life have been to avoid discharging to a very low state <10% and not let the car sit still with charger plugged in at 100% for a long time.

I had the advice to charge my car around the 50% mark, ie from 20% to 80%. But it may be very academic and there is a 8 year warranty on the battery. However I do not know the terms and conditions around the warranty. In other words it may still be considered a workable battery even if it only holids less then X % of the original 100%. ( X = 70% or 80%????? )

 

[JimBob]

You can find a lot of material in the Porsche Engineering Magazine.

Here https://www.porscheengineering.com/peg/en/about/magazine/

 

[ciaranob]

..........
However I do not know the terms and conditions around the warranty. In other words it may still be considered a workable battery even if it only holids less then X % of the original 100%. ( X = 70% or 80%????? )

This is a big one for me that I was actually about to post a thread on but will keep it here. Forgive my laziness but I have not dug deep into the Porsche lit. to determine if the warranty states this specifically i.e. is there anything there that specifies after, 5, 6, 7, 8 yrs of use what an 'acceptable' max. range (battery capacity) should remain or be available and if below that what is the actual value that would meet the criteria for a full replacement? I will start looking but hopefully someone has already got info on this?

This is a OLD study from 2015 that to my mind is rather encouraging for any of us considering longer term ownership in respect fairly acceptable range loss over time albeit focused on Tesla batteries - you'd hope that the latest and greatest 93KW batteries used by Porsche might perform on the upper end of these distributions but have no data to support as yet:

https://steinbuch.wordpress.com/2015/01/24/tesla-model-s-battery-degradation-data/

PS: Obviously Taycan's have not been on the road long enough to have meaningful 'real world' data from consumers but I would assume the battery manufacturer and Porsche have more extensive data - given that just about every EV out there that offers similar battery packs also offer an 8 yr/100,000 mile warranty on their battery there equally has to be some std. outcomes of testing the degradation rate for these batteries.

 

[atebit]

IMHO, EV drivers shouldn’t need to be battery chemists. The car’s battery management should be smart enough to figure it out. The workflow should be: park car at home, plug it in. Let the car decide when it needs to charge. Otherwise, we’re back to the days of NiCad batteries & the PITA they were.

Joe Sixpack’s not gonna keep a .xlsx of his charge cycles & neither should you.

 

[JimBob]

This is from the Canadian warranty book on excessive loss of capacity. I think the US is the same.

A net capacity battery test is performed at an authorized Porsche service center. The battery is warranted for

• 100% of net battery capacity at the time of the initial vehicle's handover of initial registration. (This would be the 83.7 kWh capacity for the P+ battery)
• 80% of net battery capacity within a 3 year period or less than 50,000 km
• 70% of net battery capacity within 8 years or less than 130,000 km

Additional comments.
From the literature, the battery loses the largest fraction of capacity within the first few years.
Good reason to get the P+ battery.
There are some other terms and conditions for the battery warranty to be valid. Dealing with how the car is treated and driven.

 

[Scandinavian]

IMHO, EV drivers shouldn’t need to be battery chemists. The car’s battery management should be smart enough to figure it out. The workflow should be: park car at home, plug it in. Let the car decide when it needs to charge. Otherwise, we’re back to the days of NiCad batteries & the PITA they were.

Joe Sixpack’s not gonna keep a .xlsx of his charge cycles & neither should you.

Agree and I am confident that Porsche with all their expertise in Software have a World Class implementation of SW in the BMS. They have a great track record for SW in other areas.

NOT!

 

[ciaranob]

This is from the Canadian warranty book on excessive loss of capacity. I think the US is the same.

A net capacity battery test is performed at an authorized Porsche service center. The battery is warranted for

• 100% of net battery capacity at the time of the initial vehicle's handover of initial registration. (This would be the 83.7 kWh capacity for the P+ battery)
• 80% of net battery capacity within a 3 year period or less than 50,000 km
• 70% of net battery capacity within 8 years or less than 130,000 km

Additional comments.
From the literature, the battery loses the largest fraction of capacity within the first few years.
Good reason to get the P+ battery.
There are some other terms and conditions for the battery warranty to be valid. Dealing with how the car is treated and driven.

Yeah they def cover themselves with 70%! That would be a significant hit and the ‘average’ data from the Tesla batteries seem to suggest that a 10-15%. degradation might be more common at 8 yrs - but maybe wishful thinking on my part

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