Faster Phantom Drain at Higher Battery Level

[npardo]

I have a 2014 AP1 Model S that I don't normally charge overnight. On rare occasions I will charge my car up to 95-100% and not drive it until the next day.

Whenever I have done this, I always lose significantly more charge overnight than I would at a lower charge level.

Example: last night at 10pm stored car with 251 miles (about 98% SOC). Today at 2pm when I went to drive the car, it had 235 miles. Or a drop of 1 mile of range per hour not driven.

If I were to store the car around 80% charged as I normally do, I would lose no more than 5-7 miles in the same time period.

The "phantom" drain is more than double the rate at the higher state of charge. I have all power saving options enabled and don't use third party apps.

I am wondering if this is a feature/as designed, since leaving the car at 100% charge for extended periods is bad for the battery, so I could totally see Tesla doing this to help extend the life of the battery by burning of that charge that isn't being used.

Anyone have thoughts or experienced the same thing?

 

[ucmndd]

Over ~80% your car’s battery coolant pumps are likely running non-stop, the result of “safety measures” Tesla has implemented in recent firmwares to reduce the likelihood of your 85kwh battery failing before the warranty runs out.

when charged to this high level do you notice a humming noise coming from the front passenger side? If so, this is your “problem”. There’s nothing you can do about it.

 

[ucmndd]

Also, you should really consider switching up your routine. Keeping your battery charged to near 100% for 8+ hours is asking for problems.

 

[beatle]

IME, the coolant pumps only run at full tilt for a few hours after charging above 76%.

I'm not sure at what point the battery starts to balance itself, but the balancing process consumes energy by bleeding off capacity from modules that have reached their maximum voltage while others continue to charge. If you have reached the point at which balancing starts, that could explain the high consumption at high SoCs.

Agree that for the best lifespan you should really keep the car at 90% or below unless you need that extra capacity, and even then I would recommend only bringing it up to 100% right before you aim to leave on your trip.

 

[strider]

Agree with @beatle. You are most likely seeing the pack balancing and as part of that process it adjusts the range to a more accurate (lower) number.

I think the OP is doing fine with their 80% charge. The occasional run to 100% even if it sits overnight is not going to make a material difference.

 

[npardo]

IME, the coolant pumps only run at full tilt for a few hours after charging above 76%.

I'm not sure at what point the battery starts to balance itself, but the balancing process consumes energy by bleeding off capacity from modules that have reached their maximum voltage while others continue to charge. If you have reached the point at which balancing starts, that could explain the high consumption at high SoCs.

Agree that for the best lifespan you should really keep the car at 90% or below unless you need that extra capacity, and even then I would recommend only bringing it up to 100% right before you aim to leave on your trip.

Pack balancing is an interesting thought. And yeah, I don't notice the coolant pumps running when I leave the car for the night. There is a lot of time for the pack to cool down between 90 and 100% charge since it crawls at a rate of like 1mph at the end.

A general, unrelated update on my cars efficiency:
On Monday, as mentioned, I charged the car to 256 miles. Between Monday and today, I have driven 40 miles and have lost a total of 100 miles of range in that time through a combination of phantom drain and inefficient 21 inch wheels.

It is actually laughable. When you compare the supercharger price per KW ($0.28) to the average gas price where I live ($3.00/gallon). My car has averaged 14mpg during that 40 miles. I feel like 90% of Tesla owners don't notice excessive drain because they leave their cars plugged in every night but this is actually a joke.

If I were to charge the car then immediately take it on a freeway drive, I'm sure the mpge would be closer to the 30's, and using the home electricity rate instead of the supercharging rate would probably boost that a little more, but golly.

 

[David_Cary]

How are you calculating MPG since there are no G's? Or are you calculating Miles per dollar? And then your throw in mpge which is totally different.
Your phantom drain is very high. I have a 2015 with 86k miles - bought new.
I lose 2 miles a day or so. I have never in any circumstance lost 1 mile per hour.
I also pay 10 cents a kwh and get right about EPA lifetime (normal rims). So I am somewhere around 3 cents a mile.
My vampire drain is about $20 a year.
I also hit 100% probably 20 times in my car's life and rarely for more than an hour.
You do realize you are accusing 90% of Tesla owner's of being dumb as rocks? I am sure the number is closer to 80%.