AC charging past 80% energy waste ?!

[BigApple]

Wanted to see if anyone out there knows
On DC charging it is straight forward.
The closer you are when charging to 100% SoC the lesser you car will draw from the charging station. But how is it with AC charging ?
I ask to know if you actually waste AC energy when you charge your car past the 80% SoC. On DC it won’t waste as it is same current. How about AC ? Will the 40-50 amps still be drawn from the house power while the car gets less kWh charged ?
It seems there is less energy lost during DC charging while on AC it seems you loose more. Wondering if anyone knows how that behaves ? Thank you.
If there is a bigger AC energy waste by charging past the 80% would be helpful to know. I usually don’t, to prolong the Batterie life. But I think it would be helpful to know in case I needed 100% SoC.
Thank you.

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[SergeyIndy]

Yes, there is more energy loss past 80%. Using parking lot analogy, when parking lot is 80% full, electrons take more time and energy to find a spot. There is no point of charging past 80% unless you really need it for a long trip and you start using up that energy right away as best practice.

 

[craz8]

Technically, correct. However, the ~10kw max from AC doesn't get limited by the charging curve of the Macan until about 97% (it's hard to read on the charge curve charts). Until that point, the car can handle as much as you can send at ~10kw.

So in practice, there is no slowdown or extra losses until you're above 95%. The last few percent may take a little longer as the car backs off the power demand.

 

[Fluff]

At first I thought you meant that charging to 100% leads to energy waste, because of no or limited regen. Which is lost energy. Especially on my trip home from work, with fast highway but with roundabouts, so you go from fast, to fairly heavy braking, very early in my trip.

 

[dbsb3233]

This is the first time I've heard a suggestion of extra energy loss as the power draw slows down. The car's BMS simply tells the EVSE to deliver less power. It's not continuing to deliver max power and the car only accepts some of it, if that's what you're thinking.

There's always some power loss from wire and connector resistance (translates to heat), but I don't see how that would scale up as the power goes down?

 

[BigApple]

This is the first time I've heard a suggestion of extra energy loss as the power draw slows down. The car's BMS simply tells the EVSE to deliver less power. It's not continuing to deliver max power and the car only accepts some of it, if that's what you're thinking.

There's always some power loss from wire and connector resistance (translates to heat), but I don't see how that would scale up as the power goes down?

Yes that was my question. If the power draw from the house grid gets lesser as the porsche AC/dc converter draws less is what I was hoping for. Just wasn’t sure if that’s the case. Thank you for yours and everyone’s input.

 

[dbsb3233]

Yes, there is more energy loss past 80%.

Time loss, not energy loss. The car simply tells the EVSE to deliver less power, which means charging slows down and takes longer.

The car's BMS is always telling the charger (whether AC or DC) what the max power level to deliver at any second. Sometimes the car will accept the max power the charger/EVSE can deliver, other times less. For instance, you could have a 40A EVSE that is capable of delivering 9.6 kW, but an older EV that's only capable of accepting 7.6 kW. It has to tell the EVSE to deliver only 7.6, even from the very start.

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