Graph showing how charging rate deteriorates depending on battery charge level?

smoothound

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Hi folks - I am sure these potatoes have been boiled before - but I can't find it via forum search......

Is there a rule of thumb or graph to show how charging rate deteriorates depending on battery charge level? Assuming a 270kw charger.

Specifically I am interest to see how many KW to expect to be pulled if the battery is at say 50%- 80%

Many thanks
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Jhenson29

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Hi folks - I am sure these potatoes have been boiled before - but I can't find it via forum search......
Did you try outside of forum search?

E.g. google “taycan charging rates graph”?
 
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smoothound

smoothound

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Did you try outside of forum search?

E.g. google “taycan charging rates graph”?
Thanks - should have tried first - just did and lots of graphs on google.

Not sure of provenance etc but looks like around 120-150kw 50-70%....... then dropping quickly to around 50kw by 80% - and reducing thereafter.

seems reasonable - cheers
 


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Hi folks - I am sure these potatoes have been boiled before - but I can't find it via forum search......

Is there a rule of thumb or graph to show how charging rate deteriorates depending on battery charge level? Assuming a 270kw charger.

Specifically I am interest to see how many KW to expect to be pulled if the battery is at say 50%- 80%

Many thanks
Note that the graph (charging curve) depends on initial SOC. You will experience higher charging curves at lower initial SOC. I.e. plugging in at 10% will result in a higher charge rate at say 45% SOC than plugging in at 30%. On a 350kW charger the difference in this example is roughly 260kW vs. 150kW assuming the battery is preconditioned.
 

Jrkennedy37

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Commenting that I saw a much longer curve at 270kw than this chart shows. Yesterday at an EA DCFC I was seeing peak 270kw until almost 50% SoC (starting from 11%) and it stayed above 200kw until mid 60s, dropping from 150kw to under 100kw right at 80%.
 


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Commenting that I saw a much longer curve at 270kw than this chart shows. Yesterday at an EA DCFC I was seeing peak 270kw until almost 50% SoC (starting from 11%) and it stayed above 200kw until mid 60s, dropping from 150kw to under 100kw right at 80%.
Is this after the new update?
 

Jrkennedy37

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Is this after the new update?
I do have the update, yes. I never fast charged before the update so I cannot compare a before and after. I’m in a CT4 if it matters.

I found this charging curve chart elsewhere that is more in line with my experience:
Porsche Taycan Graph showing how charging rate deteriorates depending on battery charge level? EC26CD47-7C6D-4A22-80BD-124EA46CA8DF
 
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daveo4EV

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I do have the update, yes. I never fast charged before the update so I cannot compare a before and after. I’m in a CT4 if it matters.

I found this charging curve chart elsewhere that is more in line with my experience:
EC26CD47-7C6D-4A22-80BD-124EA46CA8DF.jpeg
NOTE: fast charging _IS_ very hard on the battery - it is also true that charging LiON batteries to 100% is also hard on them - combining fast-charger+100% chargingis therefore doubly hard on LiON batteries…

typically fast charging is during a road trip - as you get closer to 100% the charge rate tapers to improve battery stress/thermals/longevity - because of this taper it takes longer to charge the last 5% than it does the previous 25%…if you're away from home and waiting to get back on the road you now have time vs. reward calculations…

the reward in this case is more range…the time factor is obvious…

now 10% of a Taycan battery is about 8 kWh (give or take) - that makes 5% about 4 kWh

for sake of argument/simplicity let's say Taycan is about a 3 mile/kWh vehicle (sometimes beter sometimes worse)

8 kwh * 3 miles/kWh = 24 miles of range
4 kWh * 3 miles/kWh = 12 miles of range

now I've seen my Taycan take about 10-20 min of time to charge that last 10%

so you need ask yourself - how important is that last 15 miles of range that you're spending an extra 15 min waiting to "finish"…

for me personally I'm not normally cutting it that "thin" to reach my next planned stop (hotel, home or another charging stop) that 15 miles of range is make/break…

for me personally I'm basically ready to unplug at about 90% SOC +/- because over the years of driving EV's I've learned those last few percentages of SOC are simply not worth it - and the time investment is simply out of whack with the reward - this becomes especially true if youre charging session cost is time based vs. kWh based…

the Taycan charges soooooo fast to 85%+ SOC that normally that's more than sufficient to get you on your way and minimizes the time spend at your charging stop…and also should be more than sufficient range to get you to the next planned stop.

my $0.02
 

Jrkennedy37

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NOTE: fast charging _IS_ very hard on the battery - it is also true that charging LiON batteries to 100% is also hard on them - combining fast-charger+100% chargingis therefore doubly hard on LiON batteries…

typically fast charging is during a road trip - as you get closer to 100% the charge rate tapers to improve battery stress/thermals/longevity - because of this taper it takes longer to charge the last 5% than it does the previous 25%…if you're away from home and waiting to get back on the road you now have time vs. reward calculations…

the reward in this case is more range…the time factor is obvious…

now 10% of a Taycan battery is about 8 kWh (give or take) - that makes 5% about 4 kWh

for sake of argument/simplicity let's say Taycan is about a 3 mile/kWh vehicle (sometimes beter sometimes worse)

8 kwh * 3 miles/kWh = 24 miles of range
4 kWh * 3 miles/kWh = 12 miles of range

now I've seen my Taycan take about 10-20 min of time to charge that last 10%

so you need ask yourself - how important is that last 15 miles of range that you're spending an extra 15 min waiting to "finish"…

for me personally I'm not normally cutting it that "thin" to reach my next planned stop (hotel, home or another charging stop) that 15 miles of range is make/break…

for me personally I'm basically ready to unplug at about 90% SOC +/- because over the years of driving EV's I've learned those last few percentages of SOC are simply not worth it - and the time investment is simply out of whack with the reward - this becomes especially true if youre charging session cost is time based vs. kWh based…

the Taycan charges soooooo fast to 85%+ SOC that normally that's more than sufficient to get you on your way and minimizes the time spend at your charging stop…and also should be more than sufficient range to get you to the next planned stop.

my $0.02
I agree completely. I posted my first road trip report yesterday and similarly followed the charging planner which had me charging to 60-80% on all but one leg. Once the speed fell below 100kw (it plummets from around 150kw at 79% to under 100kw at 80%) it made little sense to keep charging vs moving on.

There was one 197 mile stretch that the charging planner recommended I charge to 90% - which took a full 30 minutes of charging - and even that was not necessary. I arrived at the next destination with 12% charge left.
 

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for me personally I'm basically ready to unplug at about 90% SOC +/- because over the years of driving EV's I've learned those last few percentages of SOC are simply not worth it - and the time investment is simply out of whack with the reward - this becomes especially true if youre charging session cost is time based vs. kWh based…

the Taycan charges soooooo fast to 85%+ SOC that normally that's more than sufficient to get you on your way and minimizes the time spend at your charging stop…and also should be more than sufficient range to get you to the next planned stop.
I agree completely. I posted my first road trip report yesterday and similarly followed the charging planner which had me charging to 60-80% on all but one leg. Once the speed fell below 100kw (it plummets from around 150kw at 79% to under 100kw at 80%) it made little sense to keep charging vs moving on.
Charging to 80-85% makes sense.
I'm planning a trip. I don't understand why the Porsche charging planner is recommending charging to 95% at every charging stop. Even when I specify charging stops that are only 100 miles or less apart, the charging planner recommends charging to 95%.
Why is the charging planner doing this?
 

daveo4EV

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all these charts are great and helpful planning tools

but there is an ideal taper curve (i.e. what can the Taycan do if everything goes "to plan") and then there is what actually happens during any particular charging session.

there are sooooooooooo many variables that you can never "plan" to achieve the optimal taper curve

as to what is happening during any particular charging session there is not enough information shown/displayed/available to properly diagnose as to why you are getting any particular charge rate for a given charging session

some (not all) of the variables that are invisible/out-side-your-control are:
  • battery temp
  • ambient temp
  • battery age
  • power grid limitations
  • charging station hardware faults
  • charging station software faults
  • load reductions being imposed by the power company based on overall grid load
  • shared load reduction due to other vehicles charging nearby
  • lack of sufficient onsite power storage to boost charging rate (depletions of local "booster batteries" due to previous charging sessions)
  • vehicle battery dynamics during the charging session - Taycan can reduce incoming load due to battery dynamics monitored during charging session
  • EV battery thermal management efficiency
  • charging station thermal management efficiency
  • load reduction due to commerce based considerations (are you paying for the fastest rate)
  • time of day
  • anticipated load management - charging networks monitor historical usage patterns based on time-of-day/week and will sometimes reduce load to keep local storage batteries "full" for predicted/up-coming peak charging loads…
  • etc…
basically there are many many many many reasons you may or may not achieve optimal charging rates when fast charging - as to why you are receiveing any particular charging rate for any given charging session you as the consumer do not have access to sufficient logs/data to determine where the system is constrained during any single session and why it's not charging faster

the _MOST_ common reasons for sub-optimal charging rates are:
  • battery thermals out of "ideal" for fast charging
  • ambient thermals out of "ideal" for fast charging
  • local site-level problems/faults/restrictions on the fast charging station hardware (unpublished typically)
sometimes I've been charging at stall #4 getting a pathetic charging rate (60 kW or less) and simply moving from stall #4 to stall #2 restored my faith in humanity and increased my rate! why? I have no idea and with out full session logs (from both the station and vehicle) there is no way to tell - but factually that's true.

a good friend/track-buddy recently has taken the plunge into EV land - he has fast charged it a lot - and calls me for "advice" while on the road - he pulled into EA baker's field once with his eTron SUV and plugged into an EA station - he called me in "horror" at a 18 kW charge rate @ battery SOC of 5% and was agast/confused/mad/frustrated it was anticipating like 2 hour stop - he asked me "why?" - I said I don't know - he asked if there was anything he could do - I asked him if he'd tried changing stalls - he said no but all the other stalls were full - I then suggested it wouldn't hurt to change charging cables (EA stations have two cables) - he said ok - and stopped the session and swapped cables (not stalls) - plugged into the other cable - boom - 157 kW charge rate!!! (eTron SUV is a great EV with the 2nd best charge rate) - why was this true? We will never know…but factually that happend.

for me if I can get a sustained rate of 125 kW or more and get to about 85% or better - that's about as good as it gets these days given all the variables - and if you're getting 150 kW or more - basically that's golden and honestly the Taycan battery isn't big enough to spend much more than 25 min charging if you're getting 150 kW charge rate or more…and I have no problem killing 20 min during fast charging stop - it's when it stretches to 45 min or longer that I start to notice "hey this is taking a long time"…

YMMV - my $0.02
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