Scheduled Departure

[pdk42]

I've just had 36.2.1 installed and have played with the scheduled departure a little. It seems a bit lame to me. Here is what the release note says:

Scheduled Departure
It's now easier to have your car comfortable and ready to drive with Schedule Departure. For any location (e.g. Home), plug in your car and select a time for when you want your car to be ready to drive. Once your specified time is set, the car will schedule charging to complete before peak electricity rates begin (6AM) to reduce energy costs and ensure consistent regenerative braking and performance. It also automatically starts climate control so the cabin is comfortable at the set departure time.

To enable Scheduled Departure for the current location, go to Charging > Schedule. Then select DEPART AT and set the departure time, choosing whether you'd like Scheduled Departure to apply ALL WEEK or only on the WEEKDAYS. If ALL WEEK is selected, you have the option to "Precondition Cabin on Weekdays Only" by selecting the checkbox.

Note: Scheduled Departure will not precondition your car if it has less than 20% battery remaining. This feature improves and replaces the setting previous called Smart Preconditioning.

So, a few points based just on this info:

1. Charging will stop at 6am, whatever time you set (aka hard coded !!!). What?

2. Assuming you set departure at 6am or earlier, you'll get cabin preconditioning + charge. You can't separate them.

3. In order to ensure charging completes just before 6am, I'm guessing that the car will throttle charging to a lower rate.

From using the feature, I've also gleaned this:

4. It doesn't seem you can have scheduled departure and scheduled start running at the same time. I was playing around last night at about 9:30 pm and set a scheduled departure time for 7am. As soon as I plugged the car in, it started charging immediately - even though I'd previously set a scheduled start at midnight.

5. It plays around with the max charge rate. When it started charging at 9:30pm, it was throttled at 12A - I guess that's the rate it needed from 9:30pm to 6:00am to get the car to 85% (the limit I'd set).

Now, there's an interesting question here. What is the strategy for the start time? It seems to me that it could either:

- Start immediately and restrict the charge rate to finish at the scheduled time.

- Start as late as possible, knowing the max charge rate available, so that it's done by the scheduled time.

The latter approach would need the car to "sample" the max rate available (maybe that's what it was doing at 9:30 when I was fiddling with it?). But that won't reliably work if (like me), your charger ramps up the charge over a few minutes, unless the car waits long enough. But how long is long enough?

All-in-all, I'm of the view that this new feature is at best very poorly explained with a confusing UI, but at worst is actually pretty badly thought out!

 

[Glan gluaisne]

The charge point has no control over the charge current, other than to signal to the car the maximum capacity of the supply and turn that supply on or off. All the ramping up and down of charge current is done by the car onboard charger; the charge point is just a fairly dumb on-off switch.

From what's been described it's the car software that seems to be flaky. In my view, what's needed is a simple option to set the charge start and finish time (so that region by region variations in off-peak times can be accommodated) . This needs to be separated out from any departure time functionality, as it may well be that many owners want the car to be charged at the off-peak rate, but don't want, or need, to set a departure time, as they haven't got any firm plans for car use the following day.

My pattern of use is such that I always want the car to have enough charge in the morning for a long trip (ageing relatives - never know when an urgent trip may be needed). I'm retired, so don't have a daily commute, and consequently don't need to set a departure time. If I want to precondition the car/cabin then this is something I want to be able to select quickly and easily from inside the house. My last two cars have had a precondition button on the fob, works well and is really simple - just press the button and the car heats or cools as needed.

 

[pgkevet]

I looked at it and though "Huh?" and just don't see how it can work unless you go to work at silly o'clock...

 

[thosirl]

It doesn't seem very clear alright. I set it last night, and didn't get any different result.

Complicating factor is that I'm using a Zappi, the car would have been on ECO+ when first plugged in, and switched to Timed Boost after midnight to 8am, to coincide with end of my cheaper night rate. What happened is that the car charged finished charging around 5am, and didn't do any sort of preconditioning.

 

[pdk42]

The charge point has no control over the charge current, other than to signal to the car the maximum capacity of the supply and turn that supply on or off. All the ramping up and down of charge current is done by the car onboard charger; the charge point is just a fairly dumb on-off switch.

That's not true. Smart chargers can (and do) have control of the charge current delivered. I have an EVBox Elvi and it definitely throttles the current (at 6A) for a short while at the start of charging. I can see that in the car, it displays 6A/6A (taking 6A of 6A available).

 

[Glan gluaisne]

That's not true. Smart chargers can (and do) have control of the charge current delivered. I have an EVBox Elvi and it definitely throttles the current (at 6A) for a short while at the start of charging. I can see that in the car, it displays 6A/6A (taking 6A of 6A available).

It is true. All that's in any charge point is a contactor, that can only turn the power on and off. There is no other physical power control circuitry within any AC charge point, the specification just doesn't allow for it.

All any AC charge point can do is signal to the car the current available from the supply, by changing the duty cycle of the control pilot 1 kHz signal and turn the supply on or off

All power control is done physically in the car, by the car onboard charger. That has the ability to vary charge current, either by command from the car systems, or in response to the control pilot duty cycle.

An AC charge point (of any flavour) is not a charger, it is just a source of switched AC power with a very simple signalling interface to the car.

.

 

[LukeT]

When I used it the other day and looked afterwards at my teslafi data to see what it had done, it appeared to do the following:
- stay not charging for a period
- with a much more than enough time to go, charge to 80% (it was set to 90%) then stop; mine stopped a few hours before scheduled departure
- then with less than an hour to go, start HVAC and, a little later, start charging again

I suspect the amount of time for each step was decided by the car based on speed of charger, temperature outside etc etc.

 

[pdk42]

It is true. All that's in any charge point is a contactor, that can only turn the power on and off. There is no other physical power control circuitry within any AC charge point, the specification just doesn't allow for it.

All any AC charge point can do is signal to the car the current available from the supply, by changing the duty cycle of the control pilot 1 kHz signal and turn the supply on or off

All power control is done physically in the car, by the car onboard charger. That has the ability to vary charge current, either by command from the car systems, or in response to the control pilot duty cycle.

An AC charge point (of any flavour) is not a charger, it is just a source of switched AC power with a very simple signalling interface to the car.

.

I understand that the charger can only turn the supply on or off, but what it can also do is advertise the max charge current available to the car via the data connection. That means it can declare the potential charge current to be less than the supply is capable of giving. That's what I mean by "throttle", since the net result is the charger tells the car there's less available than there really is and the car faithfully only pulls that load.

 

[Glan gluaisne]

I understand that the charger can only turn the supply on or off, but what it can also do is advertise the max charge current available to the car via the data connection. That means it can declare the potential charge current to be less than the supply is capable of giving. That's what I mean by "throttle", since the net result is the charger tells the car there's less available than there really is and the car faithfully only pulls that load.

That's right, the car onboard charger (OBC) is the only thing that can control the rate of charge, all the external charge point (which is not a "charger") can do is switch power on and off and alter the duty cycle of the control pilot to tell the car systems the maximum available current from the supply.

It is worth noting that an AC charge point is not a charger, it is just a pretty dumb AC power switch, much the same as any other outdoor AC outlet, with some safety interlocks to prevent a disconnected cable from being live and the ability to signal to the car the available maximum current by changing the CP duty cycle. The car OBC doesn't have to follow the signalled current from the charge point, it can charge at a lower rate if the car systems signal it to (hence the split display giving both figures on Teslas).

The only external chargers available are DC fast chargers, that do have the ability to control the current to the car, as they connect directly to the HV battery (via a contactor in the car).

 

[12Pack]

I'll just stick with the Stats app. Besides being able to adjust for a later departure, you also get the ability to not condition if the car is not plugged in - which I don't do when I am away and is a nice way to not pre-condition if you're not going to be using the car.

 

[LukeT]

I'll just stick with the Stats app. Besides being able to adjust for a later departure, you also get the ability to not condition if the car is not plugged in - which I don't do when I am away and is a nice way to not pre-condition if you're not going to be using the car.

From the release notes I believe scheduled departure requires the car to be plugged in anyway. I wouldn't see much point in it in an unplugged car.

 

[MrBadger]

So how much energy is this feature wasting?

I know electricity can seem cheap compared to petrol/diesel, but doesn't mean that it should be wasted. If petrol was dirt cheap, I doubt everyone would be driving around in huge inefficient ICE cars. We are long past that indulgence and I don't see why a different attitude is taken with EV's. They still have an impact on the environment.

 

[ACarneiro]

Seems like the BMW i3 has this a bit more refined.
You set a departure time for the car to be ready at and you also tell it what time is “cheap rates” and the car tries to fit as much of the charge into the cheap rate as possible aiming to just hit 100% at the set departure time.

It’s not rocket science!

 

[kuruma]

It also seems bonkers that you cannot adjust any aspect of this new feature from the app...

 

[Radders]

i'm totally confused on this, so before the update i just set to start charging approx 4hrs before i would usually leave.

so now if i set up departure time should i just let it start charging immediately and it will just limit charging so it completes and preconditions ready for departure?

In not too fussed when it charges as im not on any EV tariff (as i have elecrtic heat pump for heating house used during day) i just wanted it to finish about when i leave so the batteries are not cold for my morning journey.

 

[LukeT]

So how much energy is this feature wasting?

I know electricity can seem cheap compared to petrol/diesel, but doesn't mean that it should be wasted. If petrol was dirt cheap, I doubt everyone would be driving around in huge inefficient ICE cars. We are long past that indulgence and I don't see why a different attitude is taken with EV's. They still have an impact on the environment.

Fair point. If it's a lot then it is an issue. However I have no idea whether it is a lot. Would teslafi file all these kwh under the charge or some under something else, like "conditioning"? Either way, should be measurable to some extent.

 

[jimbo_hippo]

Fair point. If it's a lot then it is an issue. However I have no idea whether it is a lot. Would teslafi file all these kwh under the charge or some under something else, like "conditioning"? Either way, should be measurable to some extent.

Apols if I’m being a bit dumb but isn’t preconditioning when plugged in saving electricity which would be taken from the battery at the beginning of the drive which if you don’t do, it just uses more power and you end up charging it more at the next connection?

 

[Glan gluaisne]

Apols if I’m being a bit dumb but isn’t preconditioning when plugged in saving electricity which would be taken from the battery at the beginning of the drive which if you don’t do, it just uses more power and you end up charging it more at the next connection?

Yes and no. The BMW i3 wastes loads of electricity by forcing the car to precondition when you don't need it to. My use case may not be typical, but I always want the car to charge up overnight, during the E7 off-peak rate. I often don't need to drive the next morning, so don't want the car to precondition at all. I just need the car to have a "full tank", in case I get called away unexpectedly (aged relatives who live a long way away).

The i3 will not allow off-peak charging without setting a departure time, and when a departure time is set there is no way to prevent the car from wasting energy preconditioning, when that's most probably not needed.

If the Tesla system does the same, and forces the user to set a departure time in order to use off-peak charging, and also preconditions the car for that departure time, then it will also waste energy in the same way.

My fix has been to forget about using the deeply flawed off-peak charging option in the car and have the car always set to "charge immediately". I redesigned my charge point so that it includes a switchable option to select off-peak charging, which means I can reliably charge the car only during the off-peak periods when I want to, without wasting energy preconditioning the car when it's not needed.

 

[ACarneiro]

You can disable the preconditioning on the i3.
Pretty sure there is a “pre-warm car for departure” (or some such thing) option that you can disable.

 

[Glan gluaisne]

You can disable the preconditioning on the i3.
Pretty sure there is a “pre-warm car for departure” (or some such thing) option that you can disable.

No you can't, I've tried. No matter what you set the cabin stuff to be, the car will always precondition the battery pack etc ready for the set departure time. It uses "shore power" to do this if it's available, and will draw around 2 kW to 5 kW for around 15 to 20 minutes whilst it's doing it.