Possible to drive on empty / zero battery / charge? Any reserves?

[JimBob]

There are lots of articles on the performance of lithium ion batteries. One of the points is that the capacity of the battery can be reduced overtime by taking the charge too low, too many times. Refer to references on depth of discharge. I doubt continually allowing the battery to reach very low levels before charging is a good strategy.

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[JimBob]

The SOC of charge measurement on the Taycan under constant load appears to be linear to a very high degree but may not be at very low SOC. When it is no longer linear, forecasting becomes problematic and the errors get larger. As long as there is energy to power the car and its systems, it will give it to you. When the SOC drops too low to do this it shuts down. However there are ongoing reactions in the battery which will rebuild the voltage which can give you one last bit of distance. When this is over there are no more reactions to build any more useful voltage and you aren't going anywhere. The battery is not truly dead, just at a level too low to be useful. If you let it sit there for a long period time, it could become truly dead.

Addendum
There is a related question here. The buffer. Where is it and what is it doing? The information available out there is that a portion of the battery is not available to protect the battery during repeated cycles. The stress on the battery comes at very low states of charge and very high states of charge. Also for a battery to be useful it needs to be predictable. The SOC appears to be highly predictable. From observation basically a straight line. I did not get all the way down to 0 SOC but it was still linear at close to 0 SOC.

At 0 SOC the car is known to shut down. There are two ways for this to occur.
1. The battery truly has no charge. (Not likely)
2. Porsche capped the output to not allow the battery to discharge below a certain level. (Probably)

This could be tested by measuring the voltage directly across the battery at 0 SOC. Or ask a technician.

Is there a buffer at the top? Harder to say. It is recommended to not continuously charge the battery to 100% but to 85% which is a buffer, but we know about that one. It may be that the 100% reported to the user is not actually 100% but some lesser number.