Unscheduled top ups

[beatle]

When I realized that the cooling pumps only ran for ~3 hours before shutting off after a charge over 75%, I started scheduling my charges to 90% at 3am. This tops up the car in most circumstances overnight, and the pumps are not running when I get up, so I don't have to listen to the whine.

That said, I noticed my car just topped itself up starting around 6:30am today. Charge had dropped to 87%. I figured it would simply schedule the charge for the upcoming evening, but instead it decided to charge right away, so when I went out to my garage to work on my bike, I had to listen to the pump whine again.

I wouldn't call this the end of the world, but I think it's interesting that the car will top itself up whenever it wants, regardless of your schedule. Since my car tops itself up every 27 hours or so, I rescheduled my charge to start at 8pm. This should give me a few more days of silence if the car sits in the garage for more than a day or two.

 

[DerbyDave]

Is your key in your pocket? Mine wakes up when I approach the car, and I hear all sorts of pumps and noises whenever I approach, plugged in or not. If it is plugged in, it will use the wall outlet for power and not the car battery. The wall outlet looks like it is charging, but it is really just powering the car. Check the charging screen, and you can see it is very low amperage when it is just powering the car.

 

[beatle]

No, but my car never sleeps anyway. This is just related to the cooling pumps that run aggressively after a charge. If I charge to 75% or if it has been longer than ~3 hours or so since the charge completed, the pumps do not run and the car is silent whether I get in or not.

 

[serendipitous]

I think I've noticed that when I use Scheduled Charging to start at, say, 2AM, it considers itself to have a blanket license to charge until noon the following day. If it charges, finishes at 6AM for example, and I increase the charge limit at 10AM, it will start charging immediately. If I change the slider at 1PM it says it'll start tomorrow morning.

Sounds like what you're experiencing, plus the other issue with your pack where it deliberately runs pumps to keep the battery below 85% or whatever target they've picked. It doesn't want to be left at 90, so it's draining itself down and then topping up.

 

[beatle]

The pumps aren't running to deplete the battery, though it can feel like that because we feel it's such a waste. In the earlier days of COVID while I wasn't driving the car, I left the charge at 50% and it still drained the same amount of power each day. Whenever the pack drops more than 3% below the desired SoC, it starts charging.

 

[DerbyDave]

I think I've noticed that when I use Scheduled Charging to start at, say, 2AM, it considers itself to have a blanket license to charge until noon the following day. If it charges, finishes at 6AM for example, and I increase the charge limit at 10AM, it will start charging immediately. If I change the slider at 1PM it says it'll start tomorrow morning.

Sounds like what you're experiencing, plus the other issue with your pack where it deliberately runs pumps to keep the battery below 85% or whatever target they've picked. It doesn't want to be left at 90, so it's draining itself down and then topping up.

Your example was loosely 8 hours from scheduled start charging time. Are you sure this isn't what's happening? From Manual:

When you set a scheduled charging time, Model S displays the set time to begin charging when you are parked at the scheduled location. If, at the scheduled time, Model S is not plugged in at the location, charging starts as soon as you plug it in, provided you plug it in within six hours of the scheduled time. If plugged in after six hours, charging does not start until the scheduled time on the next day. To override this setting, touch Start Charging or Stop Charging.

 

[serendipitous]

Your example was loosely 8 hours from scheduled start charging time. Are you sure this isn't what's happening? From Manual:

When you set a scheduled charging time, Model S displays the set time to begin charging when you are parked at the scheduled location. If, at the scheduled time, Model S is not plugged in at the location, charging starts as soon as you plug it in, provided you plug it in within six hours of the scheduled time. If plugged in after six hours, charging does not start until the scheduled time on the next day. To override this setting, touch Start Charging or Stop Charging.

That's probably the case. Either way it sounds like OP's issue, coupled with the fact that those 85kWh packs no longer like to sit at high SoC, so it drains itself and will top back up in that 6- or 8- or however-many- hour window.

 

[beatle]

Even with my car's aggressive phantom drain due to the car never sleeping, it still only recharges every ~27 hours or so, not 6-8.

 

[Fierofiend]

This seems to be normal, and is not a new behavior. I don't drive my S for days at a time sometimes, and even with a charge set below 75% it will reactivate charging once it has drained a few % below set point.

 

[beatle]

Yes, I was familiar with it topping off after a few percentage points were lost to phantom drain, but that was also before I'd turned on scheduled charging.

I wouldn't necessarily call this a bug, though the car does seem to prioritize getting back to the desired SoC over charging at a particular time.