Stretch out battery??

[DACSarasota]

Greetings!

Enjoying the heck out of my new Taycan! The concierge at my dealership advised me to stretch out my battery for the first 1500 to 2500 miles or so by charging fully to 100% and letting it go down to around 25%. Rinse and repeat.

Since this is contrary to standard advice to go to 85%, wanted to check if anyone has concerns with this.

Thanks!

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[kort]

Greetings!

Enjoying the heck out of my new Taycan! The concierge at my dealership advised me to stretch out my battery for the first 1500 to 2500 miles or so by charging fully to 100% and letting it go down to around 25%. Rinse and repeat.

Since this is contrary to standard advice to go to 85%, wanted to check if anyone has concerns with this.

Thanks!

I think his advise is to charge to 100% and drive the car, not let it sit at that high SOC, then run it down to a low level, again not letting it sit at a low level. it isn't bad advice but I question the need to do it.

 

[daveo4EV]

ummmm - I think this is dealer BS

expected battery life is measured in charging cycles over the useful life of the battery (3% to 98% roughly consider a “full” charge cycle) - every LiON battery (cell phone, laptop, power tool, EV) has a maximum number of charging cycles (1000-5000 cycles with exact specs vary by manufacturer and internal confidential design documents, time of day, moon phase, stock prices, number of otters sitting on a rock somewhere)

charge cycles that are NOT_ 3% to 98% have “less/fractional” impact against the full charge cycle “budget” - the exact amount of impact any fractional charging cycle has is difficult to quantify precisely - and hence the complexity and angst with regards to expected battery life…it’s an inexact science - we know the battery will last at least “X” cycles, but given usage/history we can not precisely predict that actual exact impact of any given charging cycle or fractional charging cycle on over all life…

_IF_ the Taycan has a theoretical 2750 full charge cycle expected life (my number not porsche’s - again hypothetically) - then the Dealer is recommending right out the gate that you “burn” some number of the full charge cycles in the batteries overall life expectancy…questionable advice in my opinion…and 100% un-necessary…dealer mythology and simply made up advice in my opinion - I doubt Porsche germany would endorse this approach and they would most likely scratch their heads and be confused as to what the dealer thinks is being accomplished…

that being said - 2-5 full charge cycles against 2750 life time cycles is 1 to 2% well below 1% of overall battery life expectancy so probably not your biggest worry.

* - thanks to @Hirschaj for the math check and proving I‘m human - math was wrong originally - impact is negligible was my main point - but my math was wrong - I’ve left my original math in strike-out on this post so you can all laugh and point at me…

 

[daveo4EV]

ummmm - I think this is dealer BS

expected battery life is measured in charging cycles over the useful life of the battery (3% to 98% roughly consider a “full” charge cycle) - every LiON battery has a maximum number of charging cycles (1000-5000 cycles with exact specs vary by manufacturer and internal confidential design documents, time of day, moon phase, stock prices, number of otters sitting on a rock somewhere)

charge cycles that are NOT_ 3% to 98% have “less/fractional” impact against the full charge cycle “budget” - the exact amount of impact any fractional charging cycle has is difficult to quantify precisely - and hence the complexity and angst with regards to expected battery life…it’s an inexact science - we know the battery will last at least “X” cycles, but given usage/history we can not precisely predict that actual exact impact of any given charging cycle or fractional charging cycle on over all life…

_IF_ the Taycan has a theoretical 2750 full charge cycle expected life (my number not porsche’s - again hypothetically) - then the Dealer is recommending right out the gate that you “burn” some number of the full charge cycles in the batteries overall life expectancy…questionable advice in my opinion…and 100% un-necessary…dealer mythology and simply made up advice in my opinion - I doubt Porsche germany would endorse this approach and they would most likely scratch their heads and be confused as to what the dealer thinks is being accomplished…

that being said - 2-5 full charge cycles against 2750 life time cycles is 1 to 2% of overall battery life expectancy so probably not your biggest worry.

what is KNOWN about LiON batteries is less is more

less charging = more battery life…(charge when necessary)
less full charging = more battery life…(don’t charge to 100%)
less full ‘drain’ = more battery life…(don’t run it down to 10% or less all the time)
less fast charge rate = more battery life…(why charge at 270 kW when 150 kW will do the job)

you should charge your EV battery when you need to - but no more than necessary…that is about the ONLY impact owners can have on their EV batteries…

less is more is about the _ONLY_ thing we actually do know impacts battery life - everything else is pure guess work.

 

[Fish Fingers]

Greetings!

Enjoying the heck out of my new Taycan! The concierge at my dealership advised me to stretch out my battery for the first 1500 to 2500 miles or so by charging fully to 100% and letting it go down to around 25%. Rinse and repeat.

Since this is contrary to standard advice to go to 85%, wanted to check if anyone has concerns with this.

Thanks!

I've never heard that mentioned by anyone on this forum before.

So either the concierge is right and 100s of owners on here are wrong and have been told the wrong thing by their dealers and Porsche guidance, or.......!

 

[Gubbjaevel]

That was what you did with the old NiCd batteries.... 20+ years ago....

Not applicable to our battery chemistry, afaik!

 

[Hirschaj]

that being said - 2-5 full charge cycles against 2750 life time cycles is 1 to 2% of overall battery life expectancy

Check that math my friend ?

 

[daveo4EV]

Daveo4v, a question here for you:

1. less full charging = more battery life…(don’t charge to 100%)
2. less full ‘drain’ = more battery life…(don’t run it down to 10% or less all the time)

Since the above will affect total charges during battery life, how does the utilization of 1 & 2 above, which will naturally reduce the number of charges affect battery life when comparing 1 & 2 above to the total number of charges. Do we know the battery degradation trade off or are we just assuming it is less degradation of the battery to charge cycle more times using less through put to the battery?

For example, if one charges 4X to 100% instead of 5X to 80%, the result is one extra charging cycle at 80% versus to 100%. Over a 1000 charging history to 80%, one will charge 200 times more than at 100%. Just curious.

I can’t answer that -and I have friends and co-workers who are battery engineers/scientist and they can’t answer that…to my knowledge

the problem with all this stuff is we as consumers/owners do not have full access to the battery - 0% shown to you and I is not ”true” zero percent at the LiON chemical/cell level, same for 100% - behind the scenes this is all being managed by Porsches/Teslas/GM’s/Ford/Rivian’s/Lucid’s battery-management-system/software

simply put we as owners are not charging to “true physical/chemical” 100% or getting down to “ture physical/chemical” 5% - and all the SWAG cycle math/model of LiON battery cells are about the “true” status of a given battery cell - but between you and I and the physical state of individual battery cells in your Taycan battery is a whole bunch of Porsche software - that is managing the cells/modules “behind our backs” to extend battery life and avoid warranty claims…Porsche’s internal software is measuring the impact, and it will adjust cell/module utilization to compensate based on it’s models of what Porsche wants to have happen to the battery over time…

Example:
let’s build a mythical 500 kWh LiOn battery…
but write some software that only allows utilization of 100 kWh to 400kWh (300 kWh ‘usable’ capacity)
this software will allow you to discharge the battery to 100 kWh (0% shown to the user)
and only charge to 400 kWh capacity (100% shown to the user)
now the user can charge from 0% to 100% all the time (100 kWh to 400 kWh)
but the actual impact to the physical LiON cells would be a lifetime of charging from true 20% to 80%
the SWAGs/Models tell us that would be nearly ideal for longevity on a LiON battery - and each 0-100% charge cycle would actually only be a 60% charge cycle in terms of “actual“ impact (cause my software is limiting you to 20-80% range utilization…

if the SWAG cycle math was linear (which it’s not) and my battery cells could sub-stain 3000 _FULL_ charge cycles - at daily 60% utilization that predicts my LiON battery will be good for 5000 charge cycles…

if you charge 200 times a year (5 days a week for 40 weeks) - cause weekends and vacations in daily usage

5000 ’full’ charge cycles = 25 year expected life - with those Battery-Management-System (BMS) parameters…

we lack access to Porsche’s LiON cell Chemical “models” - we don’t know how much they are holding “back” at the bottom and top end of true cell capacity, and Porsche has not documented the true expected number of full-cycle-count for their batteries, and we don’t know the SWAGs they are working from for their BMS…basically it’s all a mystery…

all we know is they warranty the battery for 8 years/100,000 miles and recommend only charging to 85% daily…and they added a feature to 2021 Taycans to optionally limit fast charging to 200 kW to “extend battery life”

we lack specific details as to how/why and what they expect to happen over time for their particular battery…

but we do know “less is more” - they have tipped their hand to that much…but specifics are elusive.

the impact on the battery by charging is based on SWAGs (Scientific Wild Ass Guess) - it’s based on good science, but that falls apart for precision when one enters the real world - it’s like asking what daily stock prices impact will be on overall 10 year trends…

science knows the “trend” of what happens to LiON batteries over time and why, but any particular charge/dis-charge cycle’s long term impact is nearly impossible to measure/predict…

if someone can answer this I’m all ears, but I doubt we have enough data - cause a lot of this depends on Porsche’s particular specs for cell chemistry/manufacture-process/porsche-software battery history…

I can speak to trends, but not particular specific impacts - and I believe a large number of people smarter and more informed/expert on this topic would agree…

I know/understand best practices - but am not knowledgeable enough to determine impact on any “micro” event vs. long term trends…and I believe that to be true even for a Porsche battery engineer, but I could be wrong about that.

 

[daveo4EV]

Check that math my friend ?

you are right I am wrong…

the math is off - but the sentiment remains true - not a big impact…

 

[Hirschaj]

you are right I am wrong…

the math is off - but the sentiment remains true - not a big impact…

Absolutely, the real numbers make the few charge cycles even less significant.

 

[Fish Fingers]

I can’t answer that -and I have friends and co-workers who are battery engineers/scientist and they can’t answer that…to my knowledge

the problem with all this stuff is we as consumers/owners do not have full access to the battery - 0% shown to you and I is not ”true” zero percent at the LiON chemical/cell level, same for 100% - behind the scenes this is all being managed by Porsches/Teslas/GM’s/Ford/Rivian’s/Lucid’s battery-management-system/software

simply put we as owners are not charging to “true physical/chemical” 100% or getting down to “ture physical/chemical” 5% - and all the SWAG cycle math/model of LiON battery cells are about the “true” status of a given battery cell - but between you and I and the physical state of individual battery cells in your Taycan battery is a whole bunch of Porsche software - that is managing the cells/modules “behind our backs” to extend battery life and avoid warranty claims…Porsche’s internal software is measuring the impact, and it will adjust cell/module utilization to compensate based on it’s models of what Porsche wants to have happen to the battery over time…


the impact on the battery by charging is based on SWAGs (Scientific Wild Ass Guess) - it’s based on good science, but that falls apart for precision when one enters the real world - it’s like asking what daily stock prices impact will be on overall 10 year trends…

science knows the “trend” of what happens to LiON batteries over time and why, but any particular charge/dis-charge cycle’s long term impact is nearly impossible to measure/predict…

if someone can answer this I’m all ears, but I doubt we have enough data - cause a lot of this depends on Porsche’s particular specs for cell chemistry/manufacture-process/porsche-software battery history…

I can speak to trends, but not particular specific impacts - and I believe a large number of people smarter and more informed/expert on this topic would agree…

I know/understand best practices - but am not knowledgeable enough to determine impact on any “micro” event vs. long term trends…and I believe that to be true even for a Porsche battery engineer, but I could be wrong about that.

I thought this post some time ago was really useful from member 'squiden' with hands on experience in a related field (satellite batteries)

https://www.taycanforum.com/forum/threads/charging-best-practices.7081/post-101651

 

[DACSarasota]

I knew Dave would chime in here with his brilliance. This is why I love this forum. Thank you.

 

[Gwaihir]

I can’t answer that -and I have friends and co-workers who are battery engineers/scientist and they can’t answer that…to my knowledge

the problem with all this stuff is we as consumers/owners do not have full access to the battery - 0% shown to you and I is not ”true” zero percent at the LiON chemical/cell level, same for 100% - behind the scenes this is all being managed by Porsches/Teslas/GM’s/Ford/Rivian’s/Lucid’s battery-management-system/software

simply put we as owners are not charging to “true physical/chemical” 100% or getting down to “ture physical/chemical” 5% - and all the SWAG cycle math/model of LiON battery cells are about the “true” status of a given battery cell - but between you and I and the physical state of individual battery cells in your Taycan battery is a whole bunch of Porsche software - that is managing the cells/modules “behind our backs” to extend battery life and avoid warranty claims…Porsche’s internal software is measuring the impact, and it will adjust cell/module utilization to compensate based on it’s models of what Porsche wants to have happen to the battery over time…


the impact on the battery by charging is based on SWAGs (Scientific Wild Ass Guess) - it’s based on good science, but that falls apart for precision when one enters the real world - it’s like asking what daily stock prices impact will be on overall 10 year trends…

science knows the “trend” of what happens to LiON batteries over time and why, but any particular charge/dis-charge cycle’s long term impact is nearly impossible to measure/predict…

if someone can answer this I’m all ears, but I doubt we have enough data - cause a lot of this depends on Porsche’s particular specs for cell chemistry/manufacture-process/porsche-software battery history…

I can speak to trends, but not particular specific impacts - and I believe a large number of people smarter and more informed/expert on this topic would agree…

I know/understand best practices - but am not knowledgeable enough to determine impact on any “micro” event vs. long term trends…and I believe that to be true even for a Porsche battery engineer, but I could be wrong about that.

All I know is my 2020 4S has done less than 5500 miles, only ever been charged on a home 7.4kW charger to 100% once and the rest of the time to 85%. Guess what? Porsche are replacing the battery pack! Go figure!!!

 

[Fish Fingers]

I knew Dave would chime in here with his brilliance. This is why I love this forum. Thank you.

Dave and W1NGE are very selfless with the amount of time they spend posting advice on this forum.

Even when it's repeated info for new members, they still do it.

I am sure I speak for many on here in thanking them. It doesnt go unappreciated.

 

[DerekS]

Do what the manual says not what the dealer says.

Mine told me "just charge to 100% all the time unless you plan on keeping the car more than 3 years."

Fortunately I already had EV experience so I knew not to do this.

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