Home charging software limitations

[JimBob]

Yes. I’ve done lots of testing on the operation numerous times to confirm consistency so I’m relatively confident in these calculations. Or at least the general logic behind them. Exact start times may deviate just slightly.

However, Porsche could also update it at anytime through a non-existent OTA. ?

And, of course, if anyone disagrees or has a correction, I’ll be happy to recheck if provided some settings and observed outcome.

I will run a test to confirm as I would really like to see this start and stop aspect of charging. If it does that, it removes most of the issues.

Will run the battery down to 40% then set a departure timer for several hours after my preferred times, record the readings and post back.

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[Jhenson29]

I have printed out your excellent work through of your settings. But before I try your solution can you confirm that charging ceases at the end of the cheaper window even if the target level of charge has not been reached.

Shigura, With that setup, my car has never charged outside of the charging window. HOWEVER, with our level 2 charger and our driving/charging pattern, we never run the battery down enough so that our 80% target could not be reached during the charging window. May try that however I'll bet that it would stop with the charging window having higher priority than the 80% target charge.

It will charge outside of the preferred times if the timer requires it. See my other graphs. It will start earlier than the preferred time if required and/or continue charging past if required and the timer is set later than the end of the preferred times.

You can check the expected operation of different setups yourself as well:

www.TaycanChargingCalculator.com

 

[DerekS]

www.TaycanChargingCalculator.com

This is a beautiful piece of work!

 

[Jhenson29]

Take for example the General profile, "Minimum charge" is the chosen label to describe "Maximum charge."

Many people make this mistake because they use it in isolation as a proxy for a target charge, but it is actually not labeled incorrectly. It is the minimum charge as labeled.

It is the minimum level of desired charge to reach immediately. Then, other settings, such as timers, can continue charging higher. Since other settings can cause the car to charge higher, it would not make sense to label this setting as a “maximum”.

 

[Jhenson29]

I will run a test to confirm as I would really like to see this start and stop aspect of charging. If it does that, it removes most of the issues.

It helps some, but I think most people would prefer to just set a maximum charge with an optional time window that it will not charge outside of if selected.

But I think the current setup provides features for certain use cases that conflict with that, which is possibly why they don’t have it.

But I also think they could leave the current system in place to serve its purpose and then have a separate “easy mode” which is only the settings and operation I described. I think that would make a lot of people happy.

“Easy mode” would be at the exclusion of the existing operation.

 

[Scandinavian]

This is a beautiful piece of work!

I agree, best explanations about it as well.
Thank You

 

[JimBob]

Did my test to compare it to your 10pm to 2am preferred times with the departure timer set for what looks like 7am. You have some charging outside of that time because the preferred time interval wasn't long enough to go from 25% to 80%.

The test confirms that if your preferred charging time contains enough time, even if the departure time is distant from that time, the car will fully charge during the preferred times and then just sit there until the departure time is reached at which point it will preheat/precool if selected. This is probably the most frequent case as most peoples best TOU rates are overnight. There should only be a small number of cases where the car will need to charge outside of the preferred times.

Target SOC 80%
Preferred Charging Time 7pm - 8am
Departure Timer 11am

Time​	SOC​	Status​
6:30pm	37%	waiting
10:00pm	37%	waiting
7:00am	73%	green
8:00am	80%	green
9:00am	81%	green
10:00am	81%	green
11:00am	81%	green

 

[gnop1950]

Whatever. I'm telling you what worked for me. Not interested in arguing.

I do pretty much the same thing. I have my home charging profile set to 0001-0630, min charge to 25%, max charge to 85% and it seems to work just fine and is always at 85% by 0630. I do have the 19.2 kW option and PWCC that supports that rate.

What would the behavior be if someone set a profile where it couldn't reach the max/target charge in the specified time window? Just stop charging at the specified time?

Edit: I think @JimBob may have answered that while I was typing.

 

[Archimedes]

Not sure why, but my car is much less complicated. I just plug it in whenever it needs a charge, and it charges to 85 percent. Then I drive it again.

 

[Jhenson29]

@JimBob it sounds like your test confirmed my graphs. At least for that case.

@gnop1950 if you have a timer target that can’t be reached within profile preferred times, it will charge outside of the preferred times. Either before, after, or both depending on setting. FYI, your setup would charge the same with or without the profile. You could use a timer by itself for the same result.

@Archimedes that’s what I do too and in that case it’s simple. The issue is for people with certain TOU cases.

 

[Archimedes]

@Archimedes that’s what I do too and in that case it’s simple. The issue is for people with certain TOU cases.

That's my point. I find it funny that people drop $150k on a car like this and they're worried about a few hours of charging at a higher rate. Life is too short to worry about things like that IMO.

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