10% battery loss almost left me stranded.

[SoCalNick]

I went on a road trip.

I left on a trip on Thursday night, SoCal area, with my ModelS, 100D.
I left at 8pm @84% and got to my first supercharger at 49% (1:16hrs, 90 miles)
I charged for 20 minutes, and was back to 77%.
I left at 945pm and got to the next supercharger at 28% (1:27hrs, 115 miles)
I charged for 28 minutes, and was back up to 74%.

Now, here I am, 11:45 at night, on the last leg of the trip.
I have 74%.
I drive 115 miles, and climb 5000 feet, and arrive at 1:20am with 16% charge.

Here is where I messed up.
There was a supercharger 20 miles before my destination.
It was late, I wanted to sleep.
I went straight to my destination - 16% will be fine, right?

The next day, Friday, my car sat and did nothing.
90F during the day, 40F during the night.
Even if I lose a few %age I should be fine.

Saturday morning (early) I get up and go to take the car to the Supercharger.
But my car is now at 6%, and it will take 7% to get to the superchager.

So, in less that 30 hours, my car lost 10% due to what?

Yes, I made it to the SuperCharger. (I turned off HVAC and headlights, and turned the screen down to minimum. I drove at 35mph.) No, there were NO other charging options available to me, it was either towing, or using a generator. No RV hookups or anything.

I parked the car at 930am that day, at 77% battery.
The following day at 140pm, I was still at 77% battery - Almost ZERO battery loss in another 30 hours.
I charged again, and at 5pm, I was at 81%, the following morning I was at 78%. 3% battery loss overnight is okay.

So, why did my car lose 10% in 30 hours.
Was it "battery conditioning" following a long drive.
Was it battery heating so the battery was not cold overnight.
I didn't change any settings in the car.
At less than 20%, sentry mode was not active anyway.

Obviously I will be careful not to leave the car under 20% again following such a trip, but I don't really think I did anything wrong??

 

[SDRick]

10% loss sounds high, could be several factors.
Was the no electricity (even 120V) at your destination?

 

[tontod]

I've seen similar behavior at low SoC. I left the car overnight around 15% SoC, checked on it 8-10 hrs later, around 10%, temps were in the 50s overnight. Barely made it to the SuC. I have left it overnight with higher SoC and have not seen such a dramatic loss. Tesla did a battery diagnostic, said it was fine.

 

[tontod]

I've seen similar behavior at low SoC. I left the car overnight around 15% SoC, checked on it 8-10 hrs later, around 10%, temps were in the 50s overnight. Barely made it to the SuC. I have left it overnight with higher SoC and have not seen such a dramatic loss. Tesla did a battery diagnostic, said it was fine.

I obviously dont make a habit of leaving it overnight with a low SoC, but like the OP that night I was tired and needed sleep.

 

[Zishan]

"Cabin overheat protection" on? I lost 10% in like 10 hours due to this....in hot ass Houston. Had to turn that off....

 

[Tam]

...I don't really think I did anything wrong??

I think I've read quite a lot about scenarios like yours, so it is best to charge before you rest and it is risky to rest before you charge.

The range after you rest should shrink down somewhat because your battery pack was all warmed up during the drive but now after the rest, it's not warm anymore.

Now you've learned its behavior during a low state of charge.

 

[ucmndd]

So, in less that 30 hours, my car lost 10% due to what?

Cold temperatures.

The car warns you about this when you park it with less than 20% battery under a certain ambient temp. As the battery cools, less energy is available for propulsion, particularly at low states of charge.