hmmm - my lovely Taycan is limited to 220 miles range - [Edit] I think it's the tires…

[feye]

this is incorrect - I had everything I could "turned off" - I would routinely lose 1-3% overnight after charging finished before I got in the car every morning…and I had everything turned off that I could

this was true for my:
2014 Model S P85D
2017 Model X P100D
2018 Model 3 Performance

my experience is Tesla vampire drain is real, it's a thing and it does actually cost quite a bit over the life of the car

I had a co-worker that lived close enough to work that he walked most of the time - owned a Model S - drove it soooo little - that he spend more recharging vampire drain than he did actually driving the vehicle.

Glass roof with highly efficient solar cells embedded. I wish Porsche would offer this as an option...


Solar cells all over the body. In summer on a good day, parked outside for 12 hours, gives them up to 35km range. If I add this up in my climate, I might hardly ever have to charge the car...

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[Kingske]

7.7% for charging overhead. How do you estimate it?

These are the first 4 full charges I made with 11kW Porsche Charger. I have over 15% loss. Could be because of 3 phase slightly faster charging...

Unless the Taycan's usable battery capacity in reality is larger than the specified number? By the way, did you really let your battery go down to 0% before recharging that second time? Wow.

 

[feye]

based on the graph below I see no reason to assume the battery charge rate deviates from the observed 7.7% delta between the raw power input rate (9.6 kW) to the observed "in car" rate reported by the Porsche Charging User Interface (8.86 kW)…that's an overhead of 7.7% and is inline with my experience for EV charging since 2013.

Ah, now I understand. The problem is, that we don't know, what the 8.86 kW is showing. Is it after the inverter but before the battery internal resistance? Does it include cooling/heating the battery during charging?

 

[feye]

Unless the Taycan's usable battery capacity in reality is larger than the specified number? By the way, did you really let your battery go down to 0% before recharging that second time? Wow.

How else can I experience the turtle mode and see, what comes after? IMHO this is an essential experience driving an EV. Besides there is plenty of safety buffer. If not and the battery is toast, Porsche has a problem.

 

[JimBob]

This from a discussion at Physics Forums

Every battery has an internal resistance. You can think of an actual battery as a perfect battery in series with a resistor. As you charge the resistance converts some of your charging energy to heat. (note that watts = power = energy/time = Joules/sec). Say you're charging a 10V battery at a rate of 100 watts (stored energy per time). For a perfect battery that would require you apply 10V at 10 Amps. But if the battery has a 1 ohm resistance you'd actually need to apply 11V meaning you'll need to supply 110watts of power to get 100watts to the battery. The remaining 10 watts goes as waste heat. But that's not all! You again loose energy discharging the battery. But that's is a variable amount. If you drain the battery at low power for a long time you get better efficiency than if you drain it quickly at high power. That's why EV drivers with a lead foot dramatically shorten their vehicle range. Finally the chemical process releasing energy in the battery also occurs slowly when not in use and you loose energy over time with the battery just sitting. In effect there's also a very high short circuit resistance.

Source https://www.physicsforums.com/threads/power-consumed-during-battery-charging.570315/

There are more than just rectifier losses


This from Green Car Congress

Unlike conventionally fueled vehicles, electric vehicles experience a loss of energy during “refueling,” with an energy loss of about 16% from the wall power to the battery during charging.

And when you go from wall to the road

However, electric vehicles are otherwise highly efficient, delivering 60%-65% of the energy from the wall power to the road even before energy is reclaimed through regenerative braking.

 

[JimBob]

Then let's add the rest of the quote from GGC

When energy gains from regenerative braking are included, the amount of energy used for traveling down the road can rise to more than 80% in the EPA-combined city and highway driving cycle, according to the US Department of Energy (DOE).

By contrast, only 12-30% of the energy put into a conventional car is used to move the car down the road; the rest of the energy is lost to engine inefficiencies or used to power accessories. (Earlier post.)

Tesla's strategy is the first paragraph with its one pedal driving. Whereas Porsche is trading efficiency for driving pleasure.

And ICE is off in its own world plus stinking the place up.

 

[whitex]

Teslas don't do that unless you set cabin overheat to on and run Sentry mode. If you do those things, the car won't sleep and vampire drain can be bad. If the car is allowed to sleep, it'll be fine.

Oh, but they do. 8+ years of driving Tesla's, including ones which did not have cabin overheat or Sentry mode (early cars), they all have vampire drain. Tesla's design methodology is to have everything controlled via one main computer, which needs to be on for the car to stay alive (if you pull out the main MCU for example, battery cooling/warming will not kick on at all). The later cars (post march 2018) moved to a new, more power hungry MCU too, and Tesla didn't bother implementing sleep mode either, plus their software had moved to higher levels of abstraction which while speeding up development, do use more power (and memory, and CPU, etc). As long as Elon's hype works and people are buying them, there is no reason for Tesla to improve this (or other things). Perhaps if EPA added an overnight parking to their range test - Elon is sensitive to the range number.

 

[whitex]

@daveo4EV
I think you're right on the tires, but out of curiosity, is battery balancing a thing with Taycans?

I assume nobody hacked the Taycan BMS and made it public yet, like with Tesla where you can get the status of each individual cell via in-car CAN buses. With Teslas, especially the early ones, occasionally some of the battery cells would get out of balance (charged more or less than the others), which prevented the all the cells from charging completely, resulting in lower range on a seemingly full battery. The solution was to run the car down as close to 0% as you're comfortable (lower is better), then charge the car to 100% SoC. It would balance all cells and recalibrate Tesla range algorithms at the same time.

 

[Jhenson29]

Tesla's strategy is the first paragraph with its one pedal driving. Whereas Porsche is trading efficiency for driving pleasure.

Coasting is more efficient than recuperation.
And Porsche uses recup when braking anyway.

This isn’t saying Porsche is more efficient relative to Tesla. Just that I expect the coasting/ braking recup strategy to be more efficient than one pedal driving. So, Porsche would be less efficient if it implemented one pedal driving while Tesla could be more efficient if it didn’t.

See here where I explained it some (you can think of overrun recup as a lighter version of one-pedal driving)
https://www.taycanforum.com/forum/threads/recuperation-modes.5718/#post-79271

And see here where a forum member remarked about efficiency being better with overrun recup off (it’s a long post, check the very end of it where the table is, plus maybe a few comments after).
https://www.taycanforum.com/forum/t...-4s-after-6-months-ownership.6447/#post-91725

 

[JimBob]

It depends on the case as to which is more efficient.

In the particular case of highway driving, where your speed is relatively constant, coasting is the more efficient strategy. If your speed is varying, recuperation will be better. Tesla uses a very heavy degree of recuperation and Porsche uses a lighter one. I kind of like the strategy Audi uses, which lets the driver dial in the degree.

 

[Jhenson29]

@JimBob

It’s only better relative to friction braking.

But the Taycan uses recup when you press the brake pedal. So, I don’t understand your comment.

Can you elaborate on why releasing the accelerator for recup would be more efficient than pressing the brake pedal for recup?

 

[JimBob]

@JimBob

It’s only better relative to friction braking.

But the Taycan uses recup when you press the brake pedal. So, I don’t understand your comment.

Can you elaborate on why releasing the accelerator for recup would be more efficient than pressing the brake pedal for recup?

First the definitions from the manual.

1. Overrun recuperation starts as soon as you take
your foot off the accelerator pedal and slows
down the vehicle. You can configure the overrun
recuperation strength.

2. When you press the brake, braking recuperation
increases the amount of recuperated energy to a
maximum. A higher braking request is then
achieved using the vehicle's wheel brakes

First I think we both agree on this.

Coasting is neither of the above and is a more efficient strategy for highway cruising where speeds are relatively constant.

Braking recup is 2 above and applies to something like going hard into a corner, braking late and accelerating hard out. This one is emphasized by Porsche because of it performance heritage.

We are dealing with 1 above, overrun recup which Porsche doesn't use much of and Tesla does (one pedal driving). So is there is any case where this would be the more efficient strategy? Back to you on that.

 

[f1eng]

We are dealing with 1 above, overrun recup which Porsche doesn't use much of and Tesla does (one pedal driving). So is there is any case where this would be the more efficient strategy? Back to you on that.

PMFJI but basically if the motor was 100% efficient whilst being used as a generator recuperating and the battery charge/discharge was also 100% efficient then recuperation on lift off would be equally efficient as coasting.
Neither are, so coasting is more efficient than recuperating at any level.
If you are slowing down anyway doing it by programming in aggressive regen with throttle lift off will be the same efficiency as the same deceleration using regenration controlled by the brake pedal.

 

[JimBob]

I was looking for a slightly more technical article on one pedal driving as most of the stuff is pretty consumerist. So here is an interesting article from Eindhoven University of Technology.


Since 2011 the Eindhoven University of Technology (TU/e) is using an in-house developed battery electric vehicle based on a Volkswagen Lupo 3L for educational and research projects. The TU/e Lupo Electric Lightweight (EL) is able to recuperate kinetic energy by using regenerative braking. A brake pedal based regenerative braking strategy demands applying a combination of hydraulic and regenerative brake force. A proper control of this brake blending proves to be challenging. An advantage of an electric vehicle compared to an ICE car is that substantial amounts of deceleration can be achieved without applying the friction brakes. These observations have led to the concept of One Pedal Driving (OPD) where the accelerator pedal can also be used to perform regenerative braking. A similar concept is applied in for example the BMW i3 and Tesla Model S and is rated quite positively by drivers. Since kinetic energy cannot be recuperated with 100% efficiency, for some driving conditions the best thing to do is neither propel nor brake the vehicle and just let the car roll freely, which is known as coasting. During coasting minimal energy is used which improves the overall energy efficiency. To assess regenerative braking strategies that are currently applied in electric vehicles, a selection of vehicles has been investigated. These vehicles are subjectively evaluated by driving tests on public roads where special attention is paid to the regenerative braking and coasting characteristics. Before designing a suitable OPD algorithm, a list of requirements is composed. The overall motor performance limits are investigated and based on the OPD requirements a general accelerator pedal map is designed and implemented. Based on a limited number of driving tests, subjective and objective conclusions regarding energy efficiency and drivability are drawn. The tests with various drivers indicate a slightly improved driving efficiency. Furthermore, all drivers comments positively on using OPD as being very intuitively and are able to adapt to it quickly.

I bolded the conclusion which I thought was interesting. One pedal driving seems to have slightly improved driving efficiency but it's not setting the world on fire. Most of this looks like just driving technique and preferences. Of course this is just one article. I was trying to avoid Tesla articles and their sales pitches.

Conclusion based on limited data. Porsche's strategy makes a lot of sense.

 

[JimBob]

PMFJI but basically if the motor was 100% efficient whilst being used as a generator recuperating and the battery charge/discharge was also 100% efficient then recuperation on lift off would be equally efficient as coasting.
Neither are, so coasting is more efficient than recuperating at any level.
If you are slowing down anyway doing it by programming in aggressive regen with throttle lift off will be the same efficiency as the same deceleration using regenration controlled by the brake pedal.

Apparently not. See above. Your argument should be that OPD is only slightly more efficient. Not that it is less efficient.

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