Can we talk, for a moment, about profiles?

thenaimis

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There is a lot of talk about charging at home or at a station to 80-85% as opposed to 100%. Is there a simple reason for this:
1. Does it help maintain the condition of the battery?
2. Is it slower to charge the last 15-20%?
3. Does it proportionally cost more to charge the last 15-20%?
  1. Yes, though Porsche and others (not tesla) mitigate this by adding a "top buffer" limiting what the charge voltage is for displayed 100%
  2. Yes, the charging current drops off the closer the battery voltage gets to the charge voltage. This also means that on long trips where you're going from charger to charger, there's generally no benefit to charging significantly more than you need to reach the next charger. Extreme example: if you only need 60% state of charge to get to the next charger, you could spend an hour charging from, say 70%-100%, instead of just charging to 70% so you arrive at the next charger with a 10% SoC, where you'll be able to charge faster.
  3. Only if you're being billed by the minute (or some other time unit). If you're being billed by kWh, it doesn't matter.
 

svp6

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There is a lot of talk about charging at home or at a station to 80-85% as opposed to 100%. Is there a simple reason for this:
1. Does it help maintain the condition of the battery?
2. Is it slower to charge the last 15-20%?
3. Does it proportionally cost more to charge the last 15-20%?
To preserve battery life it is not advisable to charge to 100% all the time. Tesla recommends 90%, Taycan 85% as maximum daily levels. Of course you can charge to 100% whenever you plan for a long trip. That's why we keep talking about 80-85%.

Indeed last 15-20% take longer to charge, as the battery will do a lot of balancing towards the peak charge. It is only coincidental to the discussion though.
 

svp6

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Lots of unknowns with charging etc. I don’t have my car yet but I’ll probably create a you tube channel with short videos etc. Be something to keep me in the car!! Lol
Get your car pronto - lots of needs for how-to videos. So many things I read about in the manual and I cannot figure out how to work. Starting with the location-enabled homelink that remains elusive to me. Even more annoying is that you can only program the memory button to bring up the homelink screen, but not actually open the garage......
 

Dambo

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  1. Yes, though Porsche and others (not tesla) mitigate this by adding a "top buffer" limiting what the charge voltage is for displayed 100%
  2. Yes, the charging current drops off the closer the battery voltage gets to the charge voltage. This also means that on long trips where you're going from charger to charger, there's generally no benefit to charging significantly more than you need to reach the next charger. Extreme example: if you only need 60% state of charge to get to the next charger, you could spend an hour charging from, say 70%-100%, instead of just charging to 70% so you arrive at the next charger with a 10% SoC, where you'll be able to charge faster.
  3. Only if you're being billed by the minute (or some other time unit). If you're being billed by kWh, it doesn't matter.
Thank you - this is very helpful.
Therefore in a 4s with the standard performance battery, you would probably need to plan a recharge every 250km or so (based on charging to 80%)?
Do public recharge locations have a time/percentage charge limit to stop people loitering or does it just come down to charging ettique?
 


thenaimis

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Thank you - this is very helpful.
Therefore in a 4s with the standard performance battery, you would probably need to plan a recharge every 250km or so (based on charging to 80%)?
Do public recharge locations have a time/percentage charge limit to stop people loitering or does it just come down to charging ettique?
Some do. Some locations will have signs requesting that you don't spend more than some amount of time in a charging location. Others will charge idle fees if you stay connected to the charger after charging completes. Then there are locations where the chargers aren't maintained or there's ICE-ing or both. Lot of variation, but there are apps like plugshare and "a better route planner" to help deal with it all.
 

Scandinavian

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I don't. It's set to the default: optimized charging.
Then the car will charge to 80% and stop there. Optimised Charging requires the Porsche Home Energy Manager. If that is not present it does nothing more.

i tried the same and set minimum to 30% and wanted it to charge over night, but nothing happened. It was 30% in the morning.

Not a very user friendly implementation! Over engineered.
 

Dee

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To preserve battery life it is not advisable to charge to 100% all the time. Tesla recommends 90%, Taycan 85% as maximum daily levels. Of course you can charge to 100% whenever you plan for a long trip. That's why we keep talking about 80-85%.

Indeed last 15-20% take longer to charge, as the battery will do a lot of balancing towards the peak charge. It is only coincidental to the discussion though.
Not quite true.
That only goes for fast DC charging (>50kW)
Temperature is the only thing that matters when charging (your phone battery lasts around two years for that exact same reason: no forced cooling).
The cooling system can withdraw some heat out of the battery but there has to be a balance between heat production and heat removal, thermal balance.
So, in my case, I always charge to 100% at 3,7kW.
I did that with my BMW i3 all the time but I don't know if 100% was 100% if you know what I mean... :)

PS I didn't check yet what battery temp we're talking here when doing 3,7kW.
 


svp6

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Thank you - this is very helpful.
Therefore in a 4s with the standard performance battery, you would probably need to plan a recharge every 250km or so (based on charging to 80%)?
Do public recharge locations have a time/percentage charge limit to stop people loitering or does it just come down to charging ettique?
I think that is very conservative - but of course it will depend how fast you are travelling. If you go around 120 km/h your range 100% to 0 will be around 500 km in the summer. On the autobahn, at 130 km/h I have seen reports suggesting around 370 km range. Considering you should spend as little time as possible at the charger, you could go 80% to 10 %, which gives you 350 km at 120 km/h or indeed around 250 km at 130 km/h.
 

svp6

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Not quite true.
That only goes for fast DC charging (>50kW)
Temperature is the only thing that matters when charging (your phone battery lasts around two years for that exact same reason: no forced cooling).
The cooling system can withdraw some heat out of the battery but there has to be a balance between heat production and heat removal, thermal balance.
So, in my case, I always charge to 100% at 3,7kW.
I did that with my BMW i3 all the time but I don't know if 100% was 100% if you know what I mean... :)

PS I didn't check yet what battery temp we're talking here when doing 3,7kW.
Dee, I have not checked for the Taycan yet, but in my Tesla the top 10 % is slower to charge on AC too, not only on DC. The last 1% is particularly slow.
 

Gogs

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Dee, I have not checked for the Taycan yet, but in my Tesla the top 10 % is slower to charge on AC too, not only on DC. The last 1% is particularly slow.
Yip, normal battery chemistry. That’s why on either AC or DC the state of charge being low will result in more KW being fed into the battery. Near the end the chemistry is unstable and it can’t take high amounts of KW.
 

KensingtonPark

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Have to admit, I am confused by all of this 80% talk. I was under the impression that the Taycan by design does not allow owners to use a percentage of the battery already (5-10%). Doesn't that mean that the 100% we are charging to already is not a full percentage of the battery's capacity? My initial reaction to hearing about the 83.7 usable vs. 93.4 was a hope that we wouldn't have to worry about managing charging the way that is being discussed here.
 

Dee

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Yip, normal battery chemistry. That’s why on either AC or DC the state of charge being low will result in more KW being fed into the battery. Near the end the chemistry is unstable and it can’t take high amounts of KW.
That's NOT what I was talking about.
I'm talking about temperature and what it does to the condition of the battery.
Charging to 100% and whether or not that's good is another discussion.
 

kevinod

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Is anyone actually planning to keep their car long term?

My Turbo S will stay for 3 years and then get sent back to Porsche, so if the battery has degraded...ill let them sort it. If it becomes an issue that Im getting a lot less than I should be getting during the three years...ill send it to them to fix under warranty.

If they want you to keep a buffer, then they need to find a way to inform people of this...not expecting people to work it out between each other on forums. Surely they should let you charge to 100% and have a hidden buffer, if you are going on a long trip you can press a button to say you want to use the buffer and that will let the car charge the extra 5kwh for maximum range.

I wont be messing around charging mine to 80% and hoping to find fast chargers on my travels in the UK because our charging Infrastructure is quite frankly crap at the minute.
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