# Forums

## 75D Battery Degradation after 1 year, 25k mi

I received my Model S 75D at the end of June 2017, and have put 25K miles on it to date. I decided to check up on the condition of my battery recently, since I noticed a rather sharp drop in overall range over the past 6 months.

I just drove 123.4mi on what the MCU estimator considers to be 33.6kWh of energy - at an average of 272Wh/mi, which seems really good.

However, this was also going from 90% to what the car thinks is 36%. Doing the math on this (assuming linear discharge) my max range is 228-229mi. When I charge to 90%, the car estimates a range of 217-218mi (I always lose 10-20mi from the estimate going from 90% to 20-30%). Putting this against 100% at 259mi as advertised, this is about 12% less than it should be.

Should I be concerned, and how should I address this?

hirorir | 04/08/2018

Adding to the above, I understand that I should expect some amount of battery degradation, but 12% over a year is quite a bit, and it's showing no signs of stopping.

loc_nguyen | 04/08/2018

Wait... 218mi at 90% would give you 239.8 mi at 100%. So your drop off is 7.5%

Bruh, do you even math?

hirorir | 04/08/2018

That's assuming that the MCU estimated range is correct - which it's not. I'm using my trip meter.

hirorir | 04/08/2018

Also - if the drop from 90% to 36% is accurate (54% drop), usage of 33.6kWh of energy puts my "100%" capacity at 62.2kWh, which is 83% of a 75kWh pack.

Bighorn | 05/08/2018

Tons has been written on the subject and you’re trying to reinvent the wheel with bad assumptions including that the capacity was ever 75kWh for range.

SCCRENDO | 05/08/2018

@hirorir. For better accuracy you should fully charge your battery and run it down as far as possible to do the calculation. Calibration errors could have crept in. Ideally you should fully charge and run it down as low as possible three times in a row before doing the test to recalibrate. Many years ago some of us did this with the 85S. The rated mile range was 265 miles but many of us dropped down to the low 250s very rapidly and then the deterioration slowed. At 144000 miles (April 2013 car) my 100 % is around 245 miles. But originally we estimated that out of an 85kWh battery there was a 5kWh battery reserve below zero and a 6 kWh reserve for anti-bricking. So the battery only gave us 74 kWh. I never truly saw anything above 71 kWh. Our estimate was that the calculation for the 85S was 278 wH/m. I also have a Model 3 and the battery technology has improved. Tesla no longer states battery size and just sells the car as a specific battery rated mile range. Natural deterioration would be expected. Sudden unexpected drops are covered by warranty and Tesla will remanufacture the battery if this happens. I would try recalibrate the battery first but 238 miles should be a less than 5% drop over I believe the promised 249 rated miles. I think this would be appropriate at 25000 miles but feel free to call Tesla and let them check out your car.

thranx | 05/08/2018

75D July 2016 build with 27,000mi. At occasional 100% charge, stated range is consistently 254 miles. Brand-new, best I could get was 257 miles. No change in driving habits. Very pleased.

Much less drop-off than over the equivalent mileage with my 2013 S60. Reason...better battery tech?

avesraggiana | 05/08/2018

I don't know, the later day 60, 75 and 90 battery packs seem less "stable" than the earlier 85s, which seem to degrade much less, and much less quickly.

On the other hand, before my dad totaled my mum's X100D, the car had lost NOTHING in the way of rated range over the course of six months.

Anecdotally, this is what I'm gathering.

RedJ | 05/08/2018

I have a Dec2016 MS75D with 40k+ miles. At 90% my estimated range is 227-228. I think that 218 is a little low. It could be a simple calibration matter fixed by charging to 100 and down to near 0 (3 times apparently). If this doesn’t change the displayed range then you may want to check with service.

hirorir | 05/08/2018

Does anyone know if the trip-meter energy usage is accurate? I'm not worried about seeing a high/low number on my dash, I'm more concerned that the estimated rated mileage that my car is telling me that I should be getting is what I get.

If I run down the battery all under 288Wh/mi, the mileage estimates the car gives me should not drift by 10-20 miles. That's nearly a 7-8% estimated drift, considering that the computer is already compensating for battery degradation.

I will do a 100% to ~10% test with the car to see the actual mileage that I get. If I get under 210 miles I'll go bug the service center. I have to do a 25K checkup anyways.

Bighorn | 05/08/2018

You only achieve rated range if you match the efficiency figure of the EPA test which is likely between 270 and 280 Wh/m based on
https://electrek.co/2016/12/14/tesla-battery-capacity/
I found Jason's figures to be optimistic on the 85kWh battery--we saw slightly less than74 kWh available where he said 77.5 were available based on his research. So 70/259 yields 270 Wh/m. This will only work if you do it one session. Like I said above, you're making all the newbie errors in thinking and these errors and proper methods were figured out 4 years ago.

hirorir | 05/08/2018

@Bighorn I don't understand the point you're trying to make. I'm literally taking every possible combination of statistic that the car issues me, and they all underperform even if you take into consideration that 72.6kWh is the max capacity.

If the car tells me that I should get 218mi of range (at 90%) if I match the efficiency figures that the EPA issues (because the car tells me so), and I get say 205mi (actual, at 0%), I have an estimated 13mi worth of estimated "unaccounted for" energy. I'm also not sure if any other electrical component is factored in at all when calculating the Wh/mi.

murphyS90D | 06/08/2018

Heat or air conditioning will definitely reduce how far you can drive. Heat is a much bigger drain than A/C is.

tes-s | 06/08/2018

Normal.

There. I saved you a trip to the service center.

Bighorn | 06/08/2018

@loc
My calculator shows 218/0.9 to be 242.2 RM or 6.5% less than 259. Perfectly acceptable.

@op
Like I said, Jason’s theoretical data was optimistic vs real works results. Expecting much more than 70 kWh when new is unrealistic. Without an accurate number achieve and proper methods, you are bound to continue to generate bad data.

Bighorn | 06/08/2018

Works/world

TSLC | 06/08/2018

To further add some complexity, my recent build #nevercorked 75D has not once charged to 259 miles. It has been about 250 or and 100% SOC shows 243 these days, at one year old and 16K miles.

So roughly 3% based on personal observation, 6% based on stated manufacturer specs.

Put it on percentage and drive happy knowing you can still make it between chargers in almost all scenarios.

roninhuy | 06/08/2018

Over thinking. Its like trying to locate an electron in the electron cloud of an atom.

hirorir | 06/08/2018

This is going way off topic here. I'm not talking about my battery full charge going from a theoretical 100% at ~250mi to 240. I understand that not all batteries are made the same, that they degrade, and all that.

I'm wondering why the car estimates tells me that I can go 218mi on a 90% charge, but I drive 143mi (within 2 days) and the car tells me that I have 48mi left. Am I supposed to attribute 20 or so miles worth of energy to phantom drain? I don't sit and idle in my car with the AC on, and god forbid I turn on the heater during the summer in CA.

Extrapolating this data shows that I will never get above 220 actual miles on a single full charge (to 0), even if the car estimates otherwise. Maybe I'll go on a road trip to LA just to record what I can get from 100 to very low.

Bighorn | 06/08/2018

Tropopause | 06/08/2018

Drive one long, continuous leg from 90% (or 100%) down near 0%. See what you get. Don’t stop. Don’t do it over two days. Then you’ll know what you have... sort of.

ktslab | 06/08/2018

@Tropopause "Drive one long, continuous leg from 90% (or 100%) down near 0%."

Then you are strained by the side of the road, waiting for a flatbed. That is if not properly planned.

ktslab | 06/08/2018

strained = stranded.

tes-s | 06/08/2018

"I'm wondering why the car estimates tells me that I can go 218mi on a 90% charge, but I drive 143mi (within 2 days)"

The "within 2 days" is your problem. Do a measurement on a single trip for better calculations.

Better yet, read more and calculate less.

Bighorn | 06/08/2018

Reading comprehension ain’t a strong suit.

p.c.mcavoy | 06/08/2018

@hirorir - "Am I supposed to attribute 20 or so miles worth of energy to phantom drain? I don't sit and idle in my car with the AC on, and god forbid I turn on the heater during the summer in CA".

There are several things which can increase the phantom or vampire drain. A couple are leaving cabin overheat protection or leaving the app active on your phone, even if it's in the background. Both of these prevent the car from fully going to sleep, which significantly increases drain. 10 miles in a day, while on the higher side, is not out of the realm of possibility especially if you're doing either of these two things.

JayInJapan | 06/08/2018

If OP would only read the posts above. Key points have been repeated several times.

hirorir | 07/08/2018

Key points that aren't related to answering what the cause of the loss of estimated energy actually is.

Only @p.c.mcavoy has bothered to mention anything related to why the car would "estimate" a (roughly) 10% charge loss. Problem there is I have energy saving on, always connected off, cabin overheat protection off, range mode on, new 19" Goodyear wheels.

@Tropopause I'll run that test on a road trip next weekend.

I'll refrain from posting further on this forum since it's been fairly unhelpful with directly answering my questions, and turn my attention to Tesla directly. "Reading available information" has only netted me situations that are unapplicable to how I use the car.

p.c.mcavoy | 07/08/2018

@hirorir - you didn't comment on whether you leave the app, or any similar app (Stats for Tesla, TeslaFI, VisibleTesla, etc) running. That will prevent the car from going to sleep, even if you have energy saving on. Even leaving it open in the background on a phone will cause it to periodically ping the car, preventing it from going to sleep. That significantly increases my phantom or vampire drain.

avesraggiana | 08/08/2018

@hirorir. Yep. As I said in my post several posts earlier, 200 real world miles is about all you're going to squeeze out of a fully charged S75D.

The only way you're going to approach reaching 218 "real" miles at 90% is if you drive your S75D the way the EPA did, in the terrain and weather conditions they stipulated.

alexandrubv | 28/04/2019

I have a Nov.2016 S75D, with 53k mls. The battery doesn't charge more than 238mls, vs the advertised 259mls. A little under 8% drop, is that normal? Tesla tech advised me to try "recalibrate" by driving close to 10mls left of charge...Is that the solution, would it even work?Thx

Bill_75D | 29/04/2019

I have a December 2016 75D with 28,000 miles. I have repeatedly run the battery below 10% and then charged to 100% and get 235 rated miles every time. I used to get 250+ miles for the first 2 years, and then it dropped to 235 last fall. I mentioned it to Tesla at my 2 year service hoping to have them look into it. They apparently forgot, since there was no mention of a battery test on my receipt.

TeslaTap.com | 29/04/2019

Bill - if the drop was sudden, I'd suspect a shorted module - although I'd also expect diagnostics to know about it. Each of the 14 modules (16 in 85/90/100), contributes 7.1% of the total. If the 100% range drops by about 17 miles on your car from one day to the next, it points to a bad module in the pack. If it was a gradual loss over 6-12 months then it doesn't point to a module.

Bill_75D | 29/04/2019

@Tap - can they see a defective battery remotely, or do I need to get a service appointment?

TeslaTap.com | 29/04/2019

@Bill - I'd think they could see a defective module remotely, but don't know for sure. it shouldn't require a discharge/charge cycle.

Bighorn | 29/04/2019

They can do remote diagnostics