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Scheduled departure anomaly

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I charge my model 3 to 80%. I have a scheduled departure time of 8:30am. This morning I left a little late, at about 8:50. I came out, and as I was unplugging my car, noticed it was charged to only 77%. (BTW, the second i backed out onto the driveway, it immediately dropped to 76%).

Any thoughts on why I didn't have my full charge?

Thanks

charging photo.jpg
 
Scheduled departure, if I recall correctly, also enables climate control. If it's still in its not-properly-implemented state, it also assumes you're leaving at 6:00am if you set a later time.

There are cases where the car will use wall power for climate control, but not always (especially if just finished a charge, actually) and not completely (i.e. climate control power can exceed wall power, it isn't limited by wall power).

So my thought is perhaps the extra 20 minutes took about 3% for climate control, but likely involves some standby power usage for nearly 3 hours until you departed.

Technical: You have an SR+ if I recall. 3% is very roughly about 1.5kWh. I'll round to 3h from 6am (the time it aims to finish) to 9am (just after you left). That implies an average power draw of 500W over those 3 hours. Since it would probably be awake for those 3 hours, 300W of that average is just being awake and standby (which accounts for 0.9kWh). The other 0.6kWh is easily for whatever climate conditioning occurred aiming for 8:30am, and the extra 20 minutes. For example, if it was using climate control for 30 minutes total, that implies 1.2kW draw for whatever climate control was doing on average -- this is an entirely normal number.

tl;dr: Looks normal, probably partly climate control but mostly standby power after 6am.
 
Scheduled departure, if I recall correctly, also enables climate control. If it's still in its not-properly-implemented state, it also assumes you're leaving at 6:00am if you set a later time.

There are cases where the car will use wall power for climate control, but not always (especially if just finished a charge, actually) and not completely (i.e. climate control power can exceed wall power, it isn't limited by wall power).

So my thought is perhaps the extra 20 minutes took about 3% for climate control, but likely involves some standby power usage for nearly 3 hours until you departed.

Technical: You have an SR+ if I recall. 3% is very roughly about 1.5kWh. I'll round to 3h from 6am (the time it aims to finish) to 9am (just after you left). That implies an average power draw of 500W over those 3 hours. Since it would probably be awake for those 3 hours, 300W of that average is just being awake and standby (which accounts for 0.9kWh). The other 0.6kWh is easily for whatever climate conditioning occurred aiming for 8:30am, and the extra 20 minutes. For example, if it was using climate control for 30 minutes total, that implies 1.2kW draw for whatever climate control was doing on average -- this is an entirely normal number.

tl;dr: Looks normal, probably partly climate control but mostly standby power after 6am.


Camalaio thank you!

A couple of things. How could standby power drain the car when it was plugged in? My understanding has always been it hits the number and keeps you there. (For example, leaving the car plugged in while on vacation).

Please forgive me, as you well know, I don't understand all the wattage info. But this hasn't happened before. Plenty of times, I have left my house after the scheduled time I expected to leave. (Got delayed, got a phone call, etc.). Sometimes by an hour or so. In each case, the car was plugged in, and maintained the max charge. This was the first time I came out to find it short of where it was supposed to be.

The car has religiously been ready-to-go in the past....a few times I've come out to find it at 81% instead of 80. This is a new development.

BTW I see you live in B.C. I was there for the Olympics and so wowed by it I took my wife back a month later. Just beautiful!
 
Camalaio thank you!

A couple of things. How could standby power drain the car when it was plugged in? My understanding has always been it hits the number and keeps you there. (For example, leaving the car plugged in while on vacation).

Please forgive me, as you well know, I don't understand all the wattage info. But this hasn't happened before. Plenty of times, I have left my house after the scheduled time I expected to leave. (Got delayed, got a phone call, etc.). Sometimes by an hour or so. In each case, the car was plugged in, and maintained the max charge. This was the first time I came out to find it short of where it was supposed to be.

The car has religiously been ready-to-go in the past....a few times I've come out to find it at 81% instead of 80. This is a new development.

I failed to explain this properly, but the car does not actively maintain the exact charge the whole time while plugged in. It internally connects and disconnects from the charger to "top up" after it falls back down a bit, but otherwise doesn't work super hard to maintain exactly the percentage you set. This is especially confusing because a lot of historical posts on this forum falsely state that it does keep connected to wall power whenever plugged in. For what it's worth, this topping-up is how most Lithium Ion battery chargers work - they disconnect after charging, but will reconnect to top up after the charge falls by a certain amount. Being 3% off before topping up is a bit more than I'd expect, but I've seen 4% once. Truthfully I haven't concretely figured out when they decide to top it back up, other than knowing this is how it behaves

As for why it's always been 80/81% before, my guess is that it may have done one of these "top-ups" just before you got to the car, but this time it hadn't gotten around to that yet, so you saw it at the lower state.

Apologies for the wordiness. Succinct, I am not.

BTW I see you live in B.C. I was there for the Olympics and so wowed by it I took my wife back a month later. Just beautiful!

Nice :) if you're ever out this direction again I can always recommend things. But bring or borrow a CHAdeMO adapter, it's hard to get around the most beautiful parts on just the Supercharger network!
 
I failed to explain this properly, but the car does not actively maintain the exact charge the whole time while plugged in. It internally connects and disconnects from the charger to "top up" after it falls back down a bit, but otherwise doesn't work super hard to maintain exactly the percentage you set. This is especially confusing because a lot of historical posts on this forum falsely state that it does keep connected to wall power whenever plugged in. For what it's worth, this topping-up is how most Lithium Ion battery chargers work - they disconnect after charging, but will reconnect to top up after the charge falls by a certain amount. Being 3% off before topping up is a bit more than I'd expect, but I've seen 4% once. Truthfully I haven't concretely figured out when they decide to top it back up, other than knowing this is how it behaves

As for why it's always been 80/81% before, my guess is that it may have done one of these "top-ups" just before you got to the car, but this time it hadn't gotten around to that yet, so you saw it at the lower state.

Apologies for the wordiness. Succinct, I am not.



Nice :) if you're ever out this direction again I can always recommend things. But bring or borrow a CHAdeMO adapter, it's hard to get around the most beautiful parts on just the Supercharger network!

Your explanation makes sense---albeit worrying me a bit about exactly what you described---trying to second guess when that topping off procedure kicks in!

Thank you for your guidance on navigating B.C. I was just thoroughly blown away. Never got as far inland as the area where you live. During the month I was in Vancouver, made it out to Victoria once and of course, numerous times up to Whistler during the games. I just couldn't believe how beautiful the country was, and everyone was incredibly friendly. My wife had been watching the games, and just based on the bump shots during the coverage, said "I want to go THERE" when I got home!
 
Not only does the car not retain the percentage, but I bet there's a good chance if you plugged it in to charge that it wouldn't take it from 77 to 80. You might have to expand the bar to 90 and then stop charging at 80(If you needed the level to be precise).
For long trips I've dipped from 100 to 96 and when I tried to charge the car it refuses to top it off. I'm not exactly sure how that plays out at lower levels.
 
Not only does the car not retain the percentage, but I bet there's a good chance if you plugged it in to charge that it wouldn't take it from 77 to 80. You might have to expand the bar to 90 and then stop charging at 80(If you needed the level to be precise).
For long trips I've dipped from 100 to 96 and when I tried to charge the car it refuses to top it off. I'm not exactly sure how that plays out at lower levels.

Interesting. this is the first time this has happened. In the past, it's always been loyally sitting there at 80% (or sometimes 81) no matter what time I've come out.
 
Interesting. this is the first time this has happened. In the past, it's always been loyally sitting there at 80% (or sometimes 81) no matter what time I've come out.

How long was the car sitting there though?
I'm talking about a car being plugged in overnight that might have lost 1-2 miles of range. The car isn't going to start charging every time it dips a mile or a percent.