Dear Porsche: Please let us set a DC fast charging limit in %

[Scandinavian]

there is a difference between euro L2 DC charging and L3 charging. I am willing to bet that you cannot set a time when using an L3 charger.

Correct! I can only set times when AC charging. At a SuperCharger I can only set the % SoC I would like. Not when I charge.

I can really not see any reason why I would plug in to a SuC and set a timer??

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[whitex]

It is not proven I mean not true. Charging from higher SOC generates significantly more heat, that is why charging speed is limited in the ratio of higher SOC.
Charging from lower SOC generates less heat so BMS allows higher charging speed.
Heat is the main issue of degradation, that is kept in balance by the BMS according to the above.

Why then does the battery pre-heat to higher than normal temperatures rather than pre-cool, if according to you, the less heat the higher the charge rate it can accept?

Charging 10-55% causes similar or less wear than 50-95% maybe little bit less as charging above 80-85% hurts the battery more if not pick up immediately.
Additionally the benefit of charging from lower SOC is less charging time.

There are different battery chemistries out there. Porsche suggests 80% for daily, Tesla suggest 90% for their older batteries and 100% for their latest LFP batteries. You are correct that DC charging faster means charging less time, but by that argument, AC charging takes the longest, do why does DC charging wear batteries more? If shorter was better, ultra fast DC would be the most optimum for wear, yet even Porsche has a battery friendly charging which elongates DC charging times by slowing it down.

It is in line with that, Porsche Charging Planner implements as low possible starting SOC as possible when planning the route.

I think you are making an assumption that the Charging Planner attempts to preserve your battery. Charging Planner implements as low as possible starting SOC to minimize charging times and therefore maximize trip speed, nothing to do with preserving the battery. If preserving the battery was the primary goal, Charging Planner would prioritize L2 charging over DC charging.

 

[whitex]

I can really not see any reason why I would plug in to a SuC and set a timer??

There are residential DC chargers (15-22KW) on the market today, for example the Ford home charger, which also supports bidirectional power (the car which supports this feature, such as the F150 Lightening, can power your home in case of an outage).

 

[whitex]

Totally agree with @j.w.s here--- better to provide the UX maximum granular control. It is always a better option for consumers.

Not all consumers, for example allowing full granular control would allow someone to set speed and max SoC, so if they wanted to use the supercharger as free parking, they could set the rate really low and take the spot up for hours without being charged idle fees, or pay much for electricity (imagine setting 1KW charge rate at a supercharger, you can park there all day for pennies). That would not be good for consumers waiting to use that charger now, would it?

Another great reason to have the ability to set DC charging top % is that you can quickly and easily see the time. I don't recall what the native nav does on Porsche, but in the AAOS/Google setup on the Volvo/Polestar, it would tell you "charge to 65% to make it to next stop" (as you arrived at a charger) -- so it'd be nice to set that slider so you can also visually see how many estimated minutes until you hit target --

That already exists. If using Taycan nav planner, it will give you the time estimate of when you will have sufficient charge to drive off to your next leg of the trip, it just doesn't stop charging when it gets there. I don't remember off the top of my head if it shows it in the car, app, or the DCFC screen, but I sure remember seeing it when traveling.

 

[Jhenson29]

Yes it is clear with me. I thought we are talking about to limit the charging power on DC I mean to set up max charging power 100kW or 80kw etc. similar as we are able to limit it on AC from 6A to 32A.

You can’t set AC charging power limits. Not in the car at least. If you’re setting one, it’s on the EVSE, not the car, and it’s not Taycan specific, It would work the same on any car (up to the car’s limit).

—edit—: I missed that this was for a Tesla.

 

[whitex]

You can’t set AC charging power limits. Not in the car at least. If you’re setting one, it’s on the EVSE, not the car, and it’s not Taycan specific, It would work the same on any car (up to the car’s limit).

Teslas do let you set AC charge rate. Personally while I played with it, never found a use for it other than a theoretical one charging the car from the whole house backup generator via a mobile EVSE which does not let me set the AC charge rate (Tesla mobile EVSEs don't have a rate setting).

 

[Jhenson29]

Teslas do let you set AC charge rate. Personally while I played with it, never found a use for it other than a theoretical one charging the car from the whole house backup generator via a mobile EVSE which does not let me set the AC charge rate (Tesla mobile EVSEs don't have a rate setting).

I see. I missed where he was talking about Tesla. My mistake.

 

[Scandinavian]

Teslas do let you set AC charge rate. Personally while I played with it, never found a use for it other than a theoretical one charging the car from the whole house backup generator via a mobile EVSE which does not let me set the AC charge rate (Tesla mobile EVSEs don't have a rate setting).

It can be useful if you are going to charge several EV’s over night. Unless the EVSE has automatic load balancing functions of course. I use it frequently in winter time when we need to charge the Taycan and the Tesla over Night. It could trip the fuse else with both the House Heat pump and pool pumps running as well as washing machines etc. We do have 36 kVA supply but we have exceeded this before.

Tesla does it in car while Porsche does it on the PMCC.

 

[whitex]

It can be useful if you are going to charge several EV’s over night. Unless the EVSE has automatic load balancing functions of course. I use it frequently in winter time when we need to charge the Taycan and the Tesla over Night. It could trip the fuse else with both the House Heat pump and pool pumps running as well as washing machines etc. We do have 36 kVA supply but we have exceeded this before.

Tesla does it in car while Porsche does it on the PMCC.

I can see the possible usecase of adjusting the current, just never ended up needing one. When I first got the Taycan, I was a little disappointed it didn't have a way to set the current, but then I thought to myself "I never actually needed it on a Tesla, so perhaps it's not needed". The one usecase would be mobile EVSE in makeshift conditions (generator, poor wiring, manual load sharing) and for that, as you mentioned, Porsche suggests throttling at the EVSE.

PS> Perhaps you should consider automatic load balancing. I have 3 Tesla 19.2KW EVSE's all auto-balancing 19.2KW total (so either 1 is running full rate, 2 are running 50% rate, or 3 are running 33% rate at the same time) installed in my garage, so even with Teslas, I never needed the manual adjustment. Today two of those are converted to J1772 to charge a Porsche and an Audi (each can use the full 19.2KW when charging alone) and the third one has the Tesla connector with an available J1772 adapter for any guest car usage. I've auto balanced a Porsche, Audi and a guest Tesla charging concurrently without any problems.

 

[Scandinavian]

PS> Perhaps you should consider automatic load balancing. I have 3 Tesla 19.2KW EVSE's all auto-balancing 19.2KW total (so either 1 is running full rate, 2 are running 50% rate, or 3 are running 33% rate at the same time) installed in my garage, so even with Teslas, I never needed the manual adjustment. Today two of those are converted to J1772 to charge a Porsche and an Audi (each can use the full 19.2KW when charging alone) and the third one has the Tesla connector with an available J1772 adapter for any guest car usage. I've auto balanced a Porsche, Audi and a guest Tesla charging concurrently without any problems.

Yes I have thought about this. But I have a well functioning PMCC and a 5 year old Tesla Wall Connector. on the drive way and the other in the garage which is 30 meters apart. As long as they work fine I see no reason to change any of them. But if any of them fails I certainly will look at that technology!

I use a Tesla UMC as an emergency back up in the Taycan. Great with the possibility to change plugs between Schuko, 3 pin CEE 16 amp plug As well as UK plug. Really useful. And a small compact package!

 

[arijaycomet]

That would not be good for consumers waiting to use that charger now, would it?

Perhaps something lost in translation here. I'd been under assumption the OP was talking about limited SOC at DC fast chargers, not speed of charging. Those are two very different things. I'd never suggest DC fast charging be throttled other than by the car for longevity, and we already have a setting for that IIRC that caps around 200kW max DC charging speed, for sake of battery health. So that is more than sufficient. I was suggestion a "SOC max" for DC fast charging, so that you could get alerted it was done at a certain SOC (read: not 100%) -- but your message infers something completely different than what I had "read/interpreted" was meant here. Oh well.... no need to continue to hash this subject. Peace!

 

[Jasper4S]

When you charge with DC you are on a public spot right? So why the need for a timer. Move the vehicle when you have enough juice, or when you need to go. Setting a timer will result in a idle vehicle blocking others to charge.

 

[j.w.s]

Imagine your battery charge level at say 40%, and you want to top up to 75% for the next leg of your journey. So you plug in to a 150kw or 350kw DC fast charger and head off to grab some lunch or do a bit of shopping.

Returning a bit later, the battery is at 95% - far higher than you intended. As commonly happens, the car was ready to go before you were.

It would be very useful - and just a software change - to let us set a charge limit when DC fast charging, just like we do when AC charging at home. Mercedes does it, Tesla does it, as do others. Dear Porsche: Please add this feature!!

Here's my bad scenario:

I roll up to a fast charge location. The car says that I am at 30%. I roughly calculate that I need between 65% and 75% charge to make it to my destination with enough juice remaining in the battery for emergencies. I estimate that I need maybe 10 minutes of charging at least, but no more than say 25 minutes or the SOC will be higher than I want - roughly estimated. I head to the cafe, where I pull out my phone every few minutes to check the charge level. As my wife and I are enjoing an espresso and some cake, she pointing out that I keep looking at my phone, I note that the battery level is now at 85%. I scramble a bit, telling the wife to hurry it up because the car battery is about to get more charged than I'd like. The wife gives me the not-good look and keeps sipping coffee. I keep looking at my phone, then at her, then the phone. We return to the car a little stressed, with the charge level now at 95%. I sort of enjoyed the coffee, but I spent too much time managing my battery level to really enjoy it.

Here's my dream scenario:

I roll up to a fast charge location. My trip planner says that I am at 30%, and need to charge to at least 71% to make it to my destination with my requested >20% charge remaining - rather predicsely calculated by the car with knowledge of speed limits, my driving style, terrain, weather, traffic, precipitation, etc. I set the charge limit to 90% and head over to the cafe.
Not too many minutes later, the app pings me that the car will reach the required 71% in five minutes, and my 90% limit in 20 minutes. We've got our coffee and a slice of cake, so we're not going to rush it, safe in the knowledge that the charge will stop at 90% if I run a bit late.
Soon the app pings me that it'll reach my 90% charge limit in 5 minutes. we're just about done with the snack, so good timing. We wrap it up, and start waling. The app pings me that the 90% limit has been reached while we're about two minutes away. But no rush and no stress, since the car stopped the charge for me. It's a busy station, so I'm going to get charged a buck or two in idle fees - no big deal.

For me, the SOC charge limit setting (and better app notifications) are tools that I want to use to make the charging experience more seamless, allowing me to spend less time thinking about my battery. In some cases, I might even trade a few dollars in idle fees for a slightly more relaxing stop - "happy wife, happy life", etc. No, I'm not going to clog up a fast charge station for 15 minutes on idle, so don't worry about that.

 

[Bognar67]

Why then does the battery pre-heat to higher than normal temperatures rather than pre-cool, if according to you, the less heat the higher the charge rate it can accept?

I did not say this alone.
There is optimum battery temperature (32-40C) for maximum charging speed. Below pre-heat above cooling.
Too many variables wrong way to pick up 1-2 factors and make a statement on them.

 

[whitex]

Here's my bad scenario:

I roll up to a fast charge location. The car says that I am at 30%. I roughly calculate that I need between 65% and 75% charge to make it to my destination with enough juice remaining in the battery for emergencies. I estimate that I need maybe 10 minutes of charging at least, but no more than say 25 minutes or the SOC will be higher than I want - roughly estimated. I head to the cafe, where I pull out my phone every few minutes to check the charge level. As my wife and I are enjoing an espresso and some cake, she pointing out that I keep looking at my phone, I note that the battery level is now at 85%. I scramble a bit, telling the wife to hurry it up because the car battery is about to get more charged than I'd like. The wife gives me the not-good look and keeps sipping coffee. I keep looking at my phone, then at her, then the phone. We return to the car a little stressed, with the charge level now at 95%. I sort of enjoyed the coffee, but I spent too much time managing my battery level to really enjoy it.

Here's my dream scenario:

I roll up to a fast charge location. My trip planner says that I am at 30%, and need to charge to at least 71% to make it to my destination with my requested >20% charge remaining - rather predicsely calculated by the car with knowledge of speed limits, my driving style, terrain, weather, traffic, precipitation, etc. I set the charge limit to 90% and head over to the cafe.
Not too many minutes later, the app pings me that the car will reach the required 71% in five minutes, and my 90% limit in 20 minutes. We've got our coffee and a slice of cake, so we're not going to rush it, safe in the knowledge that the charge will stop at 90% if I run a bit late.
Soon the app pings me that it'll reach my 90% charge limit in 5 minutes. we're just about done with the snack, so good timing. We wrap it up, and start waling. The app pings me that the 90% limit has been reached while we're about two minutes away. But no rush and no stress, since the car stopped the charge for me. It's a busy station, so I'm going to get charged a buck or two in idle fees - no big deal.

For me, the SOC charge limit setting (and better app notifications) are tools that I want to use to make the charging experience more seamless, allowing me to spend less time thinking about my battery. In some cases, I might even trade a few dollars in idle fees for a slightly more relaxing stop - "happy wife, happy life", etc. No, I'm not going to clog up a fast charge station for 15 minutes on idle, so don't worry about that.

Why did you pick different numbers for the bad vs. dream scenarios? Harder to compare. In your bad scenario, you say wanted between 65% and 75% and yet you didn't tell your wife you should be heading back until the car showed 85%! If we used the same numbers for your dream scenario, your car stops charging at 75% before you even order the coffee, then sits there blocking the DCFC while you leisurely enjoy your coffee, since you have no sense of urgency to check the app or move it.

Hint to fix your bad scenario: start wrapping it up at the cafe when you see the car hit 60-65% (depending how from it you are), don't wait until the app shows 85% - problem solved. If the app shows 85% as soon as you got to the cafe, let your wife order for you and move your car closer to the cafe.

I understand "happy wife, happy life" (though a more accurate phrasing would be "unhappy wife, unhappy life"), but imagine how you would have felt if someone inconvenienced you in order to make their wife happy. Say you get back to the charger and someone has parked their ICE car blocking you in, while they went to dinner at a nearby restaurant. Why block you in? Because it was the closest spot to the restaurant and it was raining, and they guy's wife didn't want to get too wet. They come out after their dinner and the guys shrugs his shoulders and winks at you saying "happy wife...".

Also, in your dream scenario, by making your wife happy, you might be making some other other guy's wife unhappy who has to wait to use the DC charger while you are idling.

PS> I get not always being able to return exactly when the car is at desired SoC, but I know when I travel that if I'm a few minutes behind, my car gets a higher SoC, so I "give those few minutes" back at the next charger.

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