# Forums

## Is it possible to find out how much the battery degraded?

Is there any way to find out how much the battery degraded? Using the estimated range isn't the correct solution, so how to find out?

How to tell what I'm doing is best for my car?

How to find out if I need to be concerned about my battery performance?
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My intent is to crowdsource simple instructions that will help people gauge their battery's health. Once that is settled I hope to use it as a 'do this first' for anyone who shares battery concerns on this forum.

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My take away from the replies:

There is no exact way to find out how much the battery has deteriorated. The answers from @TeslaTap.com and @stingray.don provide the most useful information, their replies are supported by other forum regulars such as @jallred, @derotam.

WW_spb | 16. Februar 2020

You just told us after 4 years you still get 310. So why all the questions?

WW_spb | 16. Februar 2020

I will run our Tesla until the day it has less than 100 miles on full charge. This will be good time to buy new Tesla. So 15 years from now.

stingray.don | 16. Februar 2020

Charge the car to 100% and drive a single trip without idle time down to nearly 0%. Extrapolate the remaining battery charge to determine the car’s total range. Multiply the miles by the wh/mi from the trip to and divide by 1000 to get the total kWh. Then compare that to the battery size (75 kWh for the LR). Note that the trip card displays kWh used but I believe it only displays to the nearest kWh, so it will be less precise.

vmulla | 16. Februar 2020

@stingray.don,
Thank you!

yudansha™ | 16. Februar 2020

WoWa, he was just speculating his car didn’t have any degradation based on number on the screen. It would be strange if his battery didn’t degrade at all after 50k miles/2 years.

andy | 16. Februar 2020

When my Leaf was serviced they did a check not the battery and printed a heath report - 100% at 15k miles. This is for a car with an air cooled battery that had been used a lot with CHAdeMO charges. I'd be gobsmacked if Tesla don't have a similar capability, Whether they would share the results is a different question.

@vmulla , my impression of you from this forum and your YouTube s that you are considerate and look after your car (and others) well. Would be really surprised if you are not already doing the best for your car. Your stats seem to back it up too.

One thought the has occurred on battery life - all modern batteries have a rated number of cycles. I am often away and leave my car in public places with no charging and sentry mode on. The resulting battery drain is noticeable in mileage terms, so I assume it must be contributing to the total number of battery cycles. I've thought about reducing the drain by switching off sentry etc., but have decided that I'd rather have the peace of mind of using the tools that come with the car.

WW_spb | 16. Februar 2020

My bad not 4 years 50k miles

vmulla | 16. Februar 2020

I'm seeing a consistent user experience with range and battery, but that does not tell the full story about degradation.

@Rikki-Tikki-Tavi,
I'm very very happy with my battery performance. I'm asking this question on behalf of others.

@andy,
My usage pattern is now a habit, it's hard to undo :)

teslamazing | 16. Februar 2020

Stats app ?

sheldon.mike1010 | 16. Februar 2020

In Apple store, there's "Battery Compare". I didn't like my results, but recommend the app if you're curious.

WW_spb | 16. Februar 2020

The question should be why so many people obsessed with battery degradation? Are they obsessed with phone battery degradation, laptop or vacuum robots ? Let Tesla monitor your battery and chill out. I have more trust in Tesla business ethics then any other car manufacturer.

WW_spb | 16. Februar 2020

Than*

yudansha™ | 16. Februar 2020

Battery is probably the most expensive part of Tesla.

WW_spb | 16. Februar 2020

Tanya. Once again. Let Tesla monitor your battery and chill out. They have all the tools to diagnose your battery vs you or Fish or 3rd party apps.

chase.chick | 16. Februar 2020

Actually it's super easy. Just set the limit (say 90%) and then complete charging. If you get in the car, and it says charging completed, and it's not at 90%, your battery has degraded.

teslamazing | 16. Februar 2020

Not that easy @chase

I sometimes get extra miles the morning after I supercharged the night before. Sometimes it’s a significant amount.

TeslaTap.com | 16. Februar 2020

Battery degradation is not something I worry about, but I do have one friend who seems to worry about everything. I guess it is just in some people's nature to worry about stuff they have little control over.

@andy - To explain cycles a bit better - the battery doesn't die after a number of cycles, it just has less capacity. Often 70% capacity is considered end of life, but the battery can still be used for years onward. The cells in our Tesla's have something like 500 to 1000 cycle life, although this has never been stated by Tesla. Now a cycle is rated at going from 100% charge to 0% charge and back to 100%. If you charge to 100% and discharge to 50%, that counts as a half-cycle. There are other factors that Tesla uses to extend life, but this is the simplified one-paragraph overview!

TeslaTap.com | 16. Februar 2020

Should be
"If you charge to 100% and discharge to 50% and back to 100%, that counts as a half-cycle.

teslamazing | 16. Februar 2020

OCD

stingray.don | 16. Februar 2020

"Actually it's super easy. Just set the limit (say 90%) and then complete charging. If you get in the car, and it says charging completed, and it's not at 90%, your battery has degraded."
____________________

The battery meter does not measure battery degradation. It will be affected by various factors outside of degradation. To measure degradation, you need to measure the total energy expended by the battery and compare the result to when the battery was new and under the same conditions.

vmulla | 16. Februar 2020

Thank you @stingray.don and @TeslaTap.com, they're truly helpful.

WW_spb | 16. Februar 2020

If capacity of understanding topic at hand is low, no amount of explanation will help. Example: Fish

stingray.don | 16. Februar 2020

vmulla | February 16, 2020

_______________________________

Completely agree. I just don't know how Tesla can provide accurate information on battery degradation on-the-fly.

M-A-B-MCMLXXX | 16. Februar 2020

To know how much energy your battery can hold, I'd recommend measuring how much you put in from a near-zero charge.

AWDTesla | 16. Februar 2020

"Rikki-Tikki-Tavi | February 16, 2020
If capacity of understanding topic at hand is low, no amount of explanation will help. Example: Fish"

vmulla | 16. Februar 2020

stingray.don | February 16, 2020
Charge the car to 100% and drive a single trip without idle time down to nearly 0%. Extrapolate the remaining battery charge to determine the car’s total range. Multiply the miles by the wh/mi from the trip to and divide by 1000 to get the total kWh. Then compare that to the battery size (75 kWh for the LR). Note that the trip card displays kWh used but I believe it only displays to the nearest kWh, so it will be less precise.
----

Let me try to make adjustments to make your recommendation more usable.

1)Charge the car to your daily maximum (typically this is 80/90%)
2) Start a fresh trip meter and drive a single trip without idle time. Make sure you deplete the battery as much as you can during this trip
3) Note the percentage of battery remaining at the end of the trip.
4) Note the energy expended for the trip
5) Using the battery percentages at the start and end of the trip extrapolate to determine the car’s total range.
6) Multiply the miles by the wh/mi from the trip to and divide by 1000 to get the total kWh.
7) Repeat #1-6 multiple times and take an average of the readings to arrive at an ESTIMATE of the current battery capacity.
8) Then compare the current battery capacity to the battery size (75 kWh for the LR).

I know that this is less precise than your original method, but my intent is to arrive at a manageable steps that owners can follow. I hope such instructions will help alleviate battery depreciation concerns.

Thanks

M-A-B-MCMLXXX | 16. Februar 2020

vmulla,

Why not just drain the battery and then fully charge, noting the amount of energy added?

FISHEV | 16. Februar 2020

Very easy to see battery degradation via the tools the car provides via 3rd party apps like StatsApp for Tesla and TeslaFi.com and Battery Health.

https://imgur.com/yI1pBb6

https://imgur.com/vQwhJlO

stingray.don | 16. Februar 2020

vmulla,

I agree with your summary. Just the closer you can get to measuring the full battery capacity the less error you will encounter from extrapolation. Ideally, you would measure the energy from 100% to depletion, but that might not be realistic and would be hard on the battery.

vmulla | 16. Februar 2020

@stingray.don, @TeslaTap.com (other too)
My intent is to crowdsource simple instructions that will help people gauge their battery's health. Once that is settled I hope to use it as a 'do this first' for anyone who shares battery concerns on this forum.

The challenge is simple, the estimated range on the screen is a misleading representation of the battery health, but it is also the most accessible representation to owners. There is no good that comes out of telling people to ignore the estimated range or belittling folks who ask a legitimate question about range. I would expect them to turn sour on Tesla with those answers. People pay extra money to get extra range, so I think it is absolutely OK for them to question if they're getting their money's worth. I hope that this set of instructions will guide people to understand and estimate their battery's health before prolonging these discussions on the forum.

If this is a wasted effort, that's Ok too...we tried.

derotam | 16. Februar 2020

@vmulla, "My intent is to crowdsource simple instructions"

Good luck with that / easy to set yourself up for failure

These threads will continue because there in no "good" way to accurately measure degradation. The most accurate way is to do what I and many people in the past have said, including stingray here... drive from 100% to 0% I. A single co sinuous drive and compare the power used to what you believe the battery capacity to be.

WW_spb | 16. Februar 2020

Or stop the obsession and trust Tesla to monitor the health of your battery. Very simple

M-A-B-MCMLXXX | 16. Februar 2020

Same question for derotam: why do it via depletion rather than charging? Is the intent to circumvent losses in the wall? They wouldn’t manifest in the car’s display, right? Also when comparing to a baseline, you’re comparing to something determined by charging (EPA procedure).

jfaubl | 16. Februar 2020

When people ask about degradation what they are really asking is am I normal? Has my car at x miles experienced more or less degradation than the average person at x miles.

AWDTesla | 16. Februar 2020

"jfaubl | February 16, 2020
When people ask about degradation what they are really asking is am I normal? Has my car at x miles experienced more or less degradation than the average person at x miles."

Well said, that's how I read it also. I've had a lot worst "degradation " than some here but I dont bother posting questions because it will be 16 pages of fanbois losing their shit.

FISHEV | 16. Februar 2020

"I've had a lot worst "degradation " than some here but I dont bother posting questions because it will be 16 pages of fanbois losing their shit."

I'm thinking your 16 pages of fanboi sturm und drang to 1 page of facts ratio might be a tad light.

vmulla | 16. Februar 2020

@derotam,
I know ;) I've seen you try over and over again. There's a restlessness within if I don't try :)

@Rikki-Tikki-Tavi,
If there was absolutely trust in Tesla this question wouldn't come up as much.

@jfaubl,
In my opinion it's not just if they're experiencing normal battery behavior, it's also a little bit of trying to find out if they're getting what they paid for.

walnotr | 17. Februar 2020

There is only one constant in any range calculation. That is mileage. Everything else is out of your control unless you are sitting on a dyno in a controlled environment with precise instruments. The only metric that matters is will you arrive at your destination and can the vehicle be recharged.

M-A-B-MCMLXXX | 17. Februar 2020

“ There is only one constant in any range calculation. That is mileage. Everything else is out of your control unless you are sitting on a dyno in a controlled environment with precise instruments.”

Right, but degradation isn’t about range, it about how much energy the batteries can hold over time.

hokiegir1 | 17. Februar 2020

I was thinking the same as @M-A-B-MCMLXXX....deplete however to as low as possible/comfortable and use some method to measure what the charge takes, whether it's OBD port, 3rd party app, direct API read, power meter on the charger, receipt from supercharging or whatever. You don't need to know what was expended -- only what goes in.

jallred | 17. Februar 2020

Since you can't directly measure instantaneous battery capacity everybody wants to measure degradation using some unrelated measure. Typically miles. But it is hard to find the standard mile done in the standard way.

It really is no different then charging the car to full and then running the heat at full blast and measuring the time until the battery is depleted. Then assume that a full running heater is 3kW.

Granted the error in the 3kW number is substantial, but probably not as substantial as the error in energy used to move the car up and down hills and at different speeds.

You must measure time to deplete across a constant load.

vmulla | 17. Februar 2020

@jallred,
But the car gives you the energy used since last charge, that's the number that was suggested (Wh/m and miles driven can be used too)

jallred | 17. Februar 2020

@vmulla

That number comes from the integration of current and voltage over that time period. There's no float in your gas tank here. It is measuring these values to calculate energy in and energy out. The measurements have error and error grows during integration.

It is like you are in charge of a big coffee urn. You don't know how much coffee is in their, but you estimate it by counting the amount you add and the amount every person takes out. Since the measurement of in and out has errors, the more that goes in and out the more you are unsure exactly how much is in there. Two things you know for sure, when it is empty and when it is full. But if the urn actually shrinks over time it is still hard to know how much is completely full.

I'm saying that if you take coffee out a very precise rate from a full urn, then you can get a better measure of how much the urn holds.

vmulla | 17. Februar 2020

@jallred,
Very nicely explained, thank you.
Now, back to the original concern - how to create a simple set of instructions for owners to estimate their battery degradation?
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The easy answer is that there is no way for an owner to estimate the degradation, so just enjoy the car as-is. But that's simply not going to be enough when people notice their estimated mileage drop.
--

I've edited @stingray.don's text to create these steps, please edit/change to make it better, I've added TeslaTap.com's excellent writeup as the last step :)

1) Charge the car to your daily maximum (typically this is 80/90%)
2) Reset the trip meter and drive a single trip without idle time. Make sure you deplete the battery as much as you can during this trip
3) Note the percentage of battery remaining at the end of the trip.
4) Note the energy expended for the trip
5) Using the battery percentages at the start and end of the trip extrapolate to determine the car’s total range.
6) Multiply the miles by the wh/mi from the trip to and divide by 1000 to get the total kWh.
7) Repeat #1-6 multiple times and take an average of the readings to arrive at an ESTIMATE of the current battery capacity.
8) Then compare the current battery capacity to the battery size (75 kWh for the LR).

WW_spb | 17. Februar 2020

Or even easier solution. Stop the obsession and trust your car smarts and Tesla to monitor health of your battery. That was easy, right?

WW_spb | 17. Februar 2020

Also most precise method

jallred | 17. Februar 2020

@vmulla,

I appreciate your noble cause and effort.

I have a question for you. Why do you think that Tesla does not provide a measure of degradation to the driver?

andy.connor.e | 17. Februar 2020

i would think you discharge to 0% and charge to 100% and see the kWh's you put into the battery.

vmulla | 17. Februar 2020

@Rikki-Tikki-Tavi,
You can say that over and over again and fill the forum with messages telling folks to forget it and trust Tesla - but that's really not helpful for anyone seeking to find out about true degradation, myself included.

Forum members often point out to Tesloop as an example and say the degradation is less than 6%...Umm ok, but how did you come up with that number? and how can I get such a degradation number? You can't reasonably say here, in this case, I'm giving you an example of how well the car's battery is doing, but at the same time say there's no way to really find out and we should just trust Tesla.

As confident as I am about my car's battery health, I have no clue what the degradation is. I go out of my way in my 50K mile review to avoid discussion about degradation and focus my narrative on day-to-day usable range on my car.

jallred | 17. Februar 2020

@andy,

Certainly the integration of energy into the battery has less error than the integration of energy out of the battery.
But even with energy in we have efficiency that varies with current, SOC, temperature. And we also have that there is some net energy out as well, computer control, cooling, heating, cabin air.