Charging to 100%?

Friedrich

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Ok this is ridiculous. There is a built in buffer that is not an accessible charge capacity, so apparent charge to 100% should only fill up to 88% of real battery capacity. Now Porsche also says that for regular daily use charge to 80% of apparent capacity?? So 80% of 88%??? This calculates to around 70%. If so I may be out. I was ready to settle for less range than a MS but not that much.
The buffer is not on the full load, but on the downside. Obviously there is no buffer on fulling loading the battery. But EVERY electric vehicle it is recommended that you stay keep the charge 20-80%, not above, not below, to preserve the battery. Of course with any EV you CAN load it to 100%, but why, your ICE vehicle is almost NEVER above 80%. You dont fill up your ICE everyday. But you can load it to 80% every night from home. So only load it to 100% ONLY when you plan on needing it, just as you fill your ICE before taking a long journey.
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svp6

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Some confusion in the posts here - I suspect because different manufacturers have chosen different pathways to battery management,

While I do not have any direct information of how Porsche's software works, it sure sounds like they follow the Tesla approach. On Tesla, there is a small buffer that cannot be used by the car under any circumstances - it is there to prevent permanent damage to the battery ("bricking"). When Tesla charges to "100%", 100% refers only to the available battery (i.e., total capacity minus reserved buffer). The recommendation is to daily charge up to 90% of the available use battery unless you plan a trip, when you can charge to 100%. Most people try to schedule that last charging to just before departure - avoiding to keep the battery at fully charged state for any significant time. With this strategy, degradation is fairly slow - hopefully it will be the same with Porsche. I suspect they chose 80% to be even more conservative.

The buffer is not created to be able to regenerate and store energy when 100% charged. I am convinced that when you charge to 100%, Porsche will use the standard brakes rather than engage any part of the regen system. Tesla does the same - which makes for a funny difference for a short while - it essentially loses the one-pedal driving until there is enough space on the battery to store energy from regenerative braking. The same happens when the battery is cold, and cannot accept large charges. From what the manufacturer says though, the Porsche driver will not feel any difference, as regenerative and physical braking are blended seamlessly.
 

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I have not seen the deep technical descriptions on how Porsche will manage the battery but I do agree with svp6 above about sensibly charging to 80% on a frequent basis. It would be interesting if we could get some deeper info on how Porsche is going to use the extra buffer they have built in in the battery?

I have seen some video on you tube were some company have reversed engineered a couple of EV’s, I think Tesla M3, BMW i3 and iPace?? There he stated that the Tesla with their cylindrical batteries as well as the heat management system they have, was far superior to the others. But still Tesla only recommends to charge the battery to 90% on an ongoing basis. 100% is fine if you will travel immeadetly with the car for a longer trip.

I think that the important issue is how fully charged the individual cells will be. Will a cell be charged to 100% while there is a buffer in the complete battery pack? Or will each cell be charged to only 88% as said while also using the buffer?
 

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Performance Battery Plus
Gross Battery Capacity: 93.4 kWh
Net Battery Capacity: 83.7 kWh
Buffer: 93.4 - 83.7 = 9.7 kWh = 10% of gross capacity
When you charge to "100%", you really charge to 90% of full capacity (Gross)
No worries:)
 

Friedrich

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Performance Battery Plus
Gross Battery Capacity: 93.4 kWh
Net Battery Capacity: 83.7 kWh
Buffer: 93.4 - 83.7 = 9.7 kWh = 10% of gross capacity
When you charge to "100%", you really charge to 90% of full capacity (Gross)
No worries:)
There would be a logical flaw here on capacity then......

If you are assuming you can only charge the battery to 83.7 kWh AND you can only use battery to the charge down of 10%, then you have 20% of the battery in reserve, meaning only 80% or 74,72kWh of the battery would be usable. Porsche has indicated that on 9.7 kWh are used for reserve, so logically, the would mean a percentage of the battery ( the 9.7kwh reserve) can't be used for complete charge down, and a percentage can't be for complete charging. Those two SEPARATE percentages (charge down reserve and full charge reserve) are unknowns, but for arguments sake, we can speculate that it is 5% on the charge up and 5% on the charge down.

BUT, Porsche RECOMMENDS to preserve the life of your batter that you never let you battery go below 20% and never charge above 20%
 


Singularity

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Interesting and important discussion! If it is easy to change this "charge until x%" behaviour from the settings, I will be following the recommendations for max longevity. I mean, it's not needed for normal work commute and city driving to have more than 80% charge ever. Then charge to the max for longer trips.
 

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I don't drive much on daily basis, so I charge my Tesla once a week to 90% except when I travel away on weekends. I probably do the same with the Taycan.
 
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BliXem

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I charge my tesla every day up to 90%. I use it daily, also for short routes. Musk did recommend this without damaging the battery. Still not sure what to do with the Taycan. 80% daily use, 90% for road trip about 200-600km.
 

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it’s pretty silly and I wouldn’t worry about it. You want to keep the charge between 20-80% of it’s true capacity, but there’s plenty of data from Model S owners showing minimal degradation after many years of 10-90%. Avoid charging at extreme temperatures. You won’t break it, though. You’d need to break the guidelines frequently over years to even notice a small change.

the battery chemistry is the same as the Model S, although the taycan has much better thermal management (the model 3 has denser batteries and better thermal management than the model S. The cheaper Tesla is better).
N
Exactly, most people will charge at home every day so no point in charging to more than 80%. If you start out on a road trip charge to 100% and do it every time on the way if it makes sense. 100% charge on Taycan is only 88% of the net capacity so no problem. The thing that will degrade the battery is frequent HP charging so better keep that as little as possible. On my frequent road trips in Europe I will of course use the Ionity 350 kW chargers on the long hauls but most of the time I will get by using Hotell AC charging or 50 kW charging points.
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