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Odd battery level behavior after charging

Skipdd

Supporting Member
Supporting Member
Dec 30, 2015
702
730
Silver Spring, MD
So, the rated range after I left the SuperCharger said 280. Drove back to hotel. Several hours later I went to the car and it was showing 297. I have never seen this before. Any ideas? Is this normal?

I am on a trip to Morgantown WVA. Arrived at Supercharger with about 60 miles of range left. Charged to 280. Drove back to hotel - showed 277. Then later as noted it showed 297.

Trying to understand what’s happening and if there might be an issue.

Thanks.
 

Tam

Well-Known Member
Nov 25, 2012
9,110
7,830
Visalia, CA
So, the rated range after I left the SuperCharger said 280. Drove back to hotel. Several hours later I went to the car and it was showing 297. I have never seen this before. Any ideas? Is this normal?

I am on a trip to Morgantown WVA. Arrived at Supercharger with about 60 miles of range left. Charged to 280. Drove back to hotel - showed 277. Then later as noted it showed 297.

Trying to understand what’s happening and if there might be an issue.

Thanks.

That's not an issue. It's expected.

Your BMS (battery management system) recalibrates the numbers to reflect updated numbers.

It's an indirect way to calculate the top and bottom capacity of your battery so it needs to experience what's the 100% is then what's the 0% is. However, either extreme is very bad for your battery. So Tesla just uses 90% as a typical daily charge for most owners to extrapolate what's your 100% and 0% numbers should be. When your car has a chance of near depletion as in this case of 60 miles, the BMS has a chance to recalibrate the numbers to a more accurate one.
 
  • Disagree
Reactions: Silicon Desert

Skipdd

Supporting Member
Supporting Member
Dec 30, 2015
702
730
Silver Spring, MD
That's not an issue. It's expected.

Your BMS (battery management system) recalibrates the numbers to reflect updated numbers.

It's an indirect way to calculate the top and bottom capacity of your battery so it needs to experience what's the 100% is then what's the 0% is. However, either extreme is very bad for your battery. So Tesla just uses 90% as a typical daily charge for most owners to extrapolate what's your 100% and 0% numbers should be. When your car has a chance of near depletion as in this case of 60 miles, the BMS has a chance to recalibrate the numbers to a more accurate one.
Makes sense, thanks.
 

AmpedRealtor

Well-Known Member
Jun 30, 2013
6,404
3,391
Phoenix, AZ
That's not an issue. It's expected.

Your BMS (battery management system) recalibrates the numbers to reflect updated numbers.

It's an indirect way to calculate the top and bottom capacity of your battery so it needs to experience what's the 100% is then what's the 0% is. However, either extreme is very bad for your battery. So Tesla just uses 90% as a typical daily charge for most owners to extrapolate what's your 100% and 0% numbers should be. When your car has a chance of near depletion as in this case of 60 miles, the BMS has a chance to recalibrate the numbers to a more accurate one.
Sorry, but no. Show me a single Model S that has regained 20 miles of range while sitting, idle, not being charged. Please show me a single one that fits your hypothesis. What you are saying occurs over long periods of time and only after depleting the battery to below 20% and charging it back up to 100% multiple times. None of that occurred here.
 
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Reactions: Silicon Desert

Skipdd

Supporting Member
Supporting Member
Dec 30, 2015
702
730
Silver Spring, MD
Sorry, but no. Show me a single Model S that has regained 20 miles of range while sitting, idle, not being charged. Please show me a single one that fits your hypothesis. What you are saying occurs over long periods of time and only after depleting the battery to below 20% and charging it back up to 100% multiple times. None of that occurred here.
So are you suggesting I should investigate further to make sure I don’t have a battery issue?
 

tldickerson

Member
Jul 2, 2014
55
29
So. Calif.
Skipdd, I wouldn't get worried. You might check later on if this happens again. I think that Amped Realtor is correct and just go on with your trip and don't worry.
 

Skipdd

Supporting Member
Supporting Member
Dec 30, 2015
702
730
Silver Spring, MD
Skipdd, I wouldn't get worried. You might check later on if this happens again. I think that Amped Realtor is correct and just go on with your trip and don't worry.
Thanks. Trip is over. And I did not see the same behavior when I charged on the way home. Separately I did notice another anomaly on this trip. The wattt/mile rate seemed to reset itself to zero after supercharging. I don’t think I’ve ever observed that before. I was traveling from near Baltimore to Morgantown WVA, and there Watt/mile rate was quite high once I got into the far western part of Maryland through the rest of the trip. Am sure that was because of the very steep hills. So it was very noticeable to see the energy rate drop way down after supercharging even when the terrain was the same. Seems to me that either the way the car measures energy has changed or I have an issue. For now I’m going with the former. I will need annual service in the next few months and will note it when I take the car in.
 

tldickerson

Member
Jul 2, 2014
55
29
So. Calif.
Skipdd, for your information. They have stopped doing annual service from what I've been told. I did that on my first Tesla after 2 years ownership and it wasn't cheap either. There's really not much they do except check the wiper fluid and tire pressure. Good luck with your car and future charging sessions.
 

Electric700

Active Member
May 21, 2013
1,729
385
Florida, United States
Instead of the annual service, I recommend you do a tire rotation every 5,000 to 7,000 miles and Tesla can take care of that. You should also do an alignment check / balancing every year too. They should be able to help you with those items and a full inspection along with a windshield wiper fluid refill. Every few years they should clean your cabin air filter too.
 

Skipdd

Supporting Member
Supporting Member
Dec 30, 2015
702
730
Silver Spring, MD
Skipdd, for your information. They have stopped doing annual service from what I've been told. I did that on my first Tesla after 2 years ownership and it wasn't cheap either. There's really not much they do except check the wiper fluid and tire pressure. Good luck with your car and future charging sessions.
I misspoke, when I said “annual service.” Thanks for noting - I’m aware they stopped that. My recollection was every 2 years, to check the batteries, and some of the other systems, change cabin filter. I know I can have brake service and alignment done elsewhere, but I will probably have them do it. Used to be they recommended brake service yearly - now it’s every couple. It’s been 2 years since the car was last serviced.
 

Skipdd

Supporting Member
Supporting Member
Dec 30, 2015
702
730
Silver Spring, MD
Instead of the annual service, I recommend you do a tire rotation every 5,000 to 7,000 miles and Tesla can take care of that. You should also do an alignment check / balancing every year too. They should be able to help you with those items and a full inspection along with a windshield wiper fluid refill. Every few years they should clean your cabin air filter too.
Thanks, that makes sense. As noted in another post its been 2 years. However, I have winter tires, and swap them out for all weather, so the tires get rotated 2x year. I used to have Tesla do that, but I needed to replace my tires this year and went to a discount spot that does lots of Teslas and bought Michelin A/S P4s. They did a great job and will be going back in the fall to replace my winter tires. Last time I had my car at Tesla (upgrade to MCU2) early fall 2020, I had them check alignment and they said it was good. Windshield wiper blades definitely need to be replaced.
 

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