High-voltage discharge while car is not used

My 2016 SEL got a new set of tires for Christmas so I had to reset the tire pressure monitor setting. About the same time this was done I started to notice a loss of range while the car was parked in the garage. The guess-o-meter dropped 5-10 miles a day. Power was off and there were no visible or audible signs of any activity. Re-charging times were normal, indicating that it really was a discharge and not a malfunction of the range indicator. The only thing I could think to do was to reset the factory settings, and to my relief this solved the problem. Not sure if it was caused by the tire pressure reset or if that was a coincidence.

Any ideas what might have caused this, or what was draining the high-voltage battery?

1. Was the car locked while sitting unused?
2. What do you mean "charging times were normal" - please give us some data?
3. How did you reset to factory settings?
4. What was the State of Charge (SoC) at the beginning and end of the dwell time?
5. What was the ambient temperature at the beginning and the end of the dwell time?
6. Were you communicating to the car via the cell phone app or via the web interface during the dwell time?


I find it hard to believe the HV battery was being drained. I have left my car sitting for weeks at a relatively constant ambient temperature and saw no change in SoC, and I have done this three or four times. If you locked the car, it goes into a deep sleep mode and uses essentially zero energy.

1. the car was not locked most of the time, just sitting in the garage and getting charged when necessary
2 and 4. I did not keep close track of numbers, but typically when the range got down to 30-40 miles I would plug in the level 2 charger and after a few hours it was up to 60-80, This was consistent with my experience at other times so I assumed that the battery was indeed discharged.
3. press car, select setup, then select factory settings at the bottom of the list. There are options to change specific settings or to reset all to the factory settings, but you have to confirm this choice to avoid blunders.
5. There were substantial temperature changes during the time when this was happening, and my estimated drop of 5-10 miles per day took account of this. When the temperature dropped overnight the charge dropped more, and vice versa. On a couple of occasions the temperature went up overnight but the charge still went down.
6. I do not use my phone or the internet. Everything I have reported is based on sitting in the car and pressing the screen or reading the gauges.

My experience for the past six years is the same as yours, aside from this notable exception. I have left the car for a couple of months sitting in the garage while I was away, with no concern about discharge of either battery. On those occasions I did not record the read-outs before and after, but I have done that on numerous occasions overnight or for a few days, with zero difference in the range except when there were significant temperature changes.

I do not understand how the car could use 7.5-8.5 kWh sitting turned off.

Have you ever replaced the 12 V battery?

You should probably lock the car in the future to be sure it goes into deep sleep. It would also be useful to get an OBD dongle to read the pack voltage.

Still using the original Varta AGM

It might be time to get a new 12 V battery, as maybe that may be leading to unusual draining. I was under the impression that the 12 V battery will not charge if the car is turned off, but now I'm not sure given your strange observations. You should at least check the health of the 12 V battery - I think there is a way you can see that through the center display.

f1geek said:

... You should probably lock the car in the future to be sure it goes into deep sleep. It would also be useful to get an OBD dongle to read the pack voltage.

Click to expand...

• Probably good plan because I hear some kind of coolant pump running frequently just sitting in car without power ON

• How to learn about the OBD reader? Is it obvious on menu of choices how to find SOC or HV volts?

I mostly use car scanner and have learned through playing with the software.

Nick said:

..
3. press car, select setup,...

Click to expand...

Hey I just thought of battery draining and this menu. Instead of SETUP, try looking in Energy Mgr. At top there's SETTINGS. In here, see if the box for CLIMATE...BATTERY is checked. I've seen this use 2 -3 kWh to heat in winter!

Was there any conclusion to this?
I'm seeing the same thing, last week the SOC dropped from 50% to 46% overnight, then this morning I've noticed it drop from 53% to 48%.
I run Home assistant so have history of the SOC via car-net.

See the drop at 6:54am over an hour before I went to work. Interestingly here I nipped out for lunch to the supermarket and gained 1%?????


Then this morning I lost 5% before going to work.

I have a few ideas:
1)Is it a pre-heater schedule software bug? Its turned off but the schedule time is 5:30.
2)Is it a battery temperature capacity correction by the BMS? Temp was reading 8°C this morning, dropping from mid teens yesterday.
3)As above, could it be the 12V battery on its way out and charging? Seems unlikely as the car was off and locked.

Any ideas or confirmation welcome.

Thanks
Jonathan

VR6 said:

Was there any conclusion to this?
I'm seeing the same thing, last week the SOC dropped from 50% to 46% overnight, then this morning I've noticed it drop from 53% to 48%.
I run Home assistant so have history of the SOC via car-net.
View attachment 212
See the drop at 6:54am over an hour before I went to work. Interestingly here I nipped out for lunch to the supermarket and gained 1%?????

View attachment 213
Then this morning I lost 5% before going to work.

I have a few ideas:
1)Is it a pre-heater schedule software bug? Its turned off but the schedule time is 5:30.
2)Is it a battery temperature capacity correction by the BMS? Temp was reading 8°C this morning, dropping from mid teens yesterday.
3)As above, could it be the 12V battery on its way out and charging? Seems unlikely as the car was off and locked.

Any ideas or confirmation welcome.

Thanks
Jonathan

Click to expand...

Probably temperature related. As pack cools, it may lose some SoC. I do not believe car charges 12V if not charging or turned on.

My car has been standing in the garage now for ~3 months. It was moved once when the garage was needed for something else. Battery is now at ~80% and it was not charged in between.

Fugazi said:

My car has been standing in the garage now for ~3 months. It was moved once when the garage was needed for something else. Battery is now at ~80% and it was not charged in between.

Click to expand...

That makes sense. I have seen similar behavior when ambient temps stay pretty steady. .

I'm also thinking it must be temperature, just before I set off home the SOC went up from 28% to 31%, a 5% increase, which is the same percentage it lost. It must be as day time and night time temperatures make the battery cross a threshold. Last week I seem to remember reading there was a 15°C BMS threshold, this must be the temperature at which we get a 5% SOC de-rating, which seems about right give ambient temperatures here at the minute.
It does make me wonder if there are other thresholds when it gets even colder where the battery is further de-rated. And what actual KWh capacity drops to in the depths of winter?

Update to last post. Needed the garage again today and moved the car out. High voltage still the same but now the car advised me to charge the low voltage battery.
And additional information, the temp has been pretty steady just above freezing point. 0-10 C.

Nick said:

My 2016 SEL got a new set of tires for Christmas so I had to reset the tire pressure monitor setting. About the same time this was done I started to notice a loss of range while the car was parked in the garage. The guess-o-meter dropped 5-10 miles a day. Power was off and there were no visible or audible signs of any activity. Re-charging times were normal, indicating that it really was a discharge and not a malfunction of the range indicator. The only thing I could think to do was to reset the factory settings, and to my relief this solved the problem. Not sure if it was caused by the tire pressure reset or if that was a coincidence.

Any ideas what might have caused this, or what was draining the high-voltage battery?

Click to expand...

I bought my 2015 used, and it has been doing the same for months, losing 5-10km of range the next morning in steady ambient temperature. But i noticed it seemed to have stopped losing range in the next morning recently, what I have done during the period was swapping my MIB2 to a MIB2.5 to enable using of a 9.2" screen (in fact swapping back and forth for a few times amid figuring out long-codings), and left it plugged for some 15 mins after charging to full each time. I have no idea what contributed to the change, I suspect it was either swapping of Headunits or coding them somehow did a deeper reset of the Battery Management System (than just pressing reset on the HU), or, leaving it plugged after charging somehow helps balanced the HV battery (as suggested by some users here)