So apparently, always charging to 100% is OK (?)

[Daniel]

Fast charging does degrade the battery, that is a fact. There is a rumored spare capacity in the Taycan batteries (it charges to lower SoC at first, will try to confirm one Porsche manages to build and deliver one for me). Why would they let you? Because you need it on long distance trips. Does it degrade the battery faster? Sure it does, as does using launch control mode. Does Porsche still warranty the battery even if you charge at 250KW and lanuch every day? Of course they do, but notice that they don't guarantee 100% of the original capacity. I have not found the actual percentage, but Tesla for example only warranties 70% of original capacity in 8 year or 100K miles. So if a 400 mile range Tesla degrade 280miles, it's still not covered under warranty (279 qualifies you for warranty coverage). I suspect Taycan is the same.


11KW is not fast charging. Minimum DC charging is 50KW, and the charging rate which starts to do damage is usually considered 1C (i.e. rate which would charge the battery in 1hr), so for a Taycan, ~97KW. As a side note, I've been charging one of my Model S at 80A and another at 48A for years, minimal degradation.


That is my plan once the Taycan gets here (current TYD estimate February 2023). For trips I plan to do 98% since that keeps regen enabled, unless it's winter then 100% on trips since regen is limited by low temps of the battery anyways.

Found in this forum:

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[artdept]

Would it not just simply dissipate as heat and the tech would simply say "no room at the inn" rather than lead to damage? Most people probably never switch regen off and if you live your life in Sport / Sport Plus then it is always on. I'm sure Porsche would have put appropriate protection in place if this was a real concern.

On a tesla. if you charge to 100 it will automatically disable regen until you have used up the proper range for regen to perform. i pop up appears on your screen. I feel confident the guys in germany figured this out as well. yes or no?

 

[W1NGE]

On a tesla. if you charge to 100 it will automatically disable regen until you have used up the proper range for regen to perform. i pop up appears on your screen. I feel confident the guys in germany figured this out as well. yes or no?

On a Taycan regen does nothing at 100% SOC. Same difference.

 

[Capt Mike]

in honor of your actions I'm going to change my charging % to 93% 89% because it's

1. arbitrary
2. not 100%
3. more than 85%
4. and a prime number

beware the next owner - they will now know I've done this to their battery when I trade the car in.

Edit: I was told there would be no math - my original choice of 93% is/was _NOT_ a prime number - the only primes below 100 and above 85 are 89 & 97 - so I've amended my posting.

Is this the moment when algebra will save our lives???

 

[mystermykee]

Found in this forum:

Does this mean that at year 3 or if your car has 37,500 miles and is below 80% net capacity, warranty will give you a new battery pack?

 

[daveo4EV]

Does this mean that at year 3 or if your car has 37,500 miles and is below 80% net capacity, warranty will give you a new battery pack?

no they will service the battery to restore at least 80% capacity - that may mean replacing the battery or just modules

 

[j.w.s]

This may or may not be useful to the forum members, but here goes:

Our batteries consist of 198 groups of cells, each group from around 3.1 volts discharged to around 4.2 volts fully charged. Each cell group voltage may become slightly different from the others over time. If the difference in voltage between cell groups gets too high (aka pack "out of balance") then there can be serious problems, especially at very high or very low states of charge.

For this reason, lithium battery management systems (BMSs) include a "balancing" function to keep the cell groups in the pack balanced - each at the same voltage within a millivolt or three. But for technical reasons balancing only works when the cells are nearing fully charged. Balancing cells that are only half full does not work well at all.

This leads to some *general* rules for Lithium battery packs that likely apply to our cars:

1) Charge to well above 95% periodically. The point at which balancing starts depends on the BMS programming, but starting to balance at 90-95% full would be typical.
2) When charging fully to do a balancing "top-up", charge "slowly". Balancing takes time, so blasting from 70% full to 100% full on a fast charger likely does not give the BMS enough time to fully balance. But charging at home, which is far slower than an EA station, is perfect.
3) Discharge moderately deeply, say to 10%, periodically, and then let the car sit for several hours with nothing running. Probably. Many fancy BMSs use this time to help calibrate their state of charge. Does the Porsche? I have no idea, but for now I will assume that it does and act accordingly.
4) If you want to get fancy and get the absolute longest battery life, avoid fast charging and avoid discharging fully if you haven't given the car time to balance "recently".

 

[Fish Fingers]

The point is the car is advertised and sold with a stated range at 100%. A petrol car is also sold with a stated range calculated by tank size. If an electric car should only be charged to 80%, then that should be the advertised range.

I think Porsche may be quite happy if you charge to 100% constantly.

Just like if you have an ICE car and start it from cold and immediately red line it.

The car won't stop you doing it, but it's probably best to avoid it. Especially if you are going to keep the car.

 

[Fish Fingers]

Is this the moment when algebra will save our lives???

Without checking, am I right in thinking we can only set the timer / profile to charge in 5% increments?

 

[daveo4EV]

Without checking, am I right in thinking we can only set the timer / profile to charge in 5% increments?

you are correct based on my quick test just now in the Porsche app.

 

[W1NGE]

Is this the moment when algebra will save our lives???

Good God no!

There's Jack Daniels for that!

 

[Tooney]

'''
For this reason, lithium battery management systems (BMSs) include a "balancing" function to keep the cell groups in the pack balanced - each at the same voltage within a millivolt or three. But for technical reasons balancing only works when the cells are nearing fully charged. Balancing cells that are only half full does not work well at all.

What is done physically to "balance" cell groups - charge them differently/independently, equalize their voltages some other way?

 

[j.w.s]

What is done physically to "balance" cell groups - charge them differently/independently, equalize their voltages some other way?

The BMS takes some juice from the single cell group with the highest voltage and shunts it to the single cell group with the lowest voltage. Then it waits a bit and repeats the cycle. Eventually all groups are brought to within the tolerance set in the BMS - anything from one to a few millivolts.

Imagine this as a separate little module with separate wires to each cell - and that is in fact how it is often implemented, separate from the charger, which stuffs electricity into the battery pack as a whole.

From a technical perspective, there are several different ways to shuffle electrons from one cell to another (https://en.wikipedia.org/wiki/Battery_balancing) but basically it's all about taking from the highest voltage and sending to the lowest voltage.

Importantly, the maximum balance current is very low, which is why fast charging doesn't leave enough time for much balancing.

 

[whitex]

Could you elaborate on the point about keeping it plugged in? Is that an EV manufacturer's recommendation? Thanks.

It is a Tesla recommendation, but it makes sense for all EV's which have a competent engineering team. If you keep the car plugged in, the onboard software has the option to use it or not to use it, whatever is best for the car. For example, when pre-heating, or topping off the 12V battery, it should use shore power rather than the HV battery, therefore reducing the wear on the HV battery. If you keep the car unplugged, you eliminate one of the power source options the car software has for battery management.

 

[daveo4EV]

Could you elaborate on the point about keeping it plugged in? Is that an EV manufacturer's recommendation? Thanks.

to expand on @whitex response (excellent BTW) - leaving an EV plugged in is not like leaving a powertool, phone, tablet, or laptop plugged in - EV's are not continously "charging" the main battery - it's much more of an on/off thing - leaving the EV "plugged" in is NOT trickle charging the battery continously - but it gives the vehicle the "option" to pull power when it wants it or determines it "needs" it…if it's not plugged in as @whitex states then the vehicle has no option but to employ the main battery to meet power needs…

leaving an EV plugged in just gives the vehicle options when it needs some power - it can be battery based or "shore power" based - and it should cause little if any additional "wear" on the battery - since power isn't flowing

again this is very very different that consumer devices which do in fact tend to trickle charge the batteries continuously when left plugged in.

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