"Nearly harmless" is what concerns me, I feel like I shouldn't charge to 100 if there isn't a reason to, no?
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Battery health tracking SS
- Thread starter msinfo
- Start date
AlanSubie4Life
Efficiency Obsessed Member
Not really any more harmful than a 70% charge in this context. I said nearly harmless because anything above 55%-57% or whatever is a bit worse than below (and still really not a big deal). But for short periods it just doesn’t matter (nearly).
On a road trip, if a longer stop allows it, a 100% charge is definitely good.
I always just slide it to 100% on the road. Rarely get there of course and usually minimal benefit if Superchargers are plentiful - but it can help and that is the idea.
Not really any concern from an overnight 100% charge on the road. Only issue is lack of regen braking and usually that is not a concern since you get straight on the freeway.
For out purposes 100% not too important but still…. Anyway your car seems to have 279 at 100% - most likely, but not certain is all.
Last edited:
Thanks, I have heard some talk about causing micro cracking if you charge to 100%. Are you familiar with this? Any truth to that?
AlanSubie4Life
Efficiency Obsessed Member
@AAKEE can comment on mechanisms but it appears from the data that any such cracking resulting eventually in more loss of cyclable lithium happens above 60-65% as well.
Anyway the overall data doesn’t suggest it is a big deal. I am not suggesting always doing it if you don’t need to.
But anyway it just does not matter much overall.
Yes, I already did a few days ago.
( Post )
There is an issue with us non-researchers reading terms like *microcracking* and so on.
I know that in an earlier discussion anout charging to 100% someone refered to a research reports about this where he’s interpretation was that the battery totally failed from a few cracks in the SEI.
SEI usually starts to crack anyway when it gets to thick, so these cracks will be there anyway sooner or later.
So, if we forget about all very technical terms and only look about how the battery degrades from calendar aging and cyclic aging, we seem to have the least degradation from cycles around 35-55% for Tesla NCA cells.
And if we cycle them 100% to true 0% (where the cars stops by itself) we can to ~ 800-1000 such cycles before loosing 25-30%.
Thats 800 x 400 km for a LR car = 320K km or 200K miles. Despite *microcracking*
Any use with smaller cycles and not reaching the end points will degrade less, so we won’t wear them oit on cyclic sging anyhow.
18650 cells tested ~ 7-10 year back.
Below actual tesla model 3 cells.
50-100% cycles did ”cost” 20% for 2500 FCE cycles in Room temp (R50-100).
2500 FCE is 2500 x 400 km, thats 1 million km despite *microcracking*.
To sum it up: look what is happening to the cells and do not dig half deep into technical terms. —> If you are to dig anyway, dig deep and learn to understand what the terms means and how bad or not bad these terms are so you are not startled by a completely normal reaction in the battery cell.
AlanSubie4Life
Efficiency Obsessed Member
It’s miles or km, not minutes, and it does not matter much. Can select all three, can help if a particular choice allows for larger values for the numbers (better accuracy). Using km can help, but it depends on whether recent efficiency number is too low (it has a lower value in units of Wh/km).
Largest values for all three numbers is best.
Thanks. I will likely be taking a long road trip next week and will try to do a 100% charge (if you think it won't cause any long term issues) and post new pictures. Thanks for all of your help.
Thanks for all your help. I want to make sure I understand what you are saying. Often using wh/mi x range at 5, 15 and 30 miles yields different numbers. Are you suggesting whichever yields the largest number before dividing by SOC will be the most accurate?
All numbers ar rounded.
The larger the number, the less fault introduced by that number.
If the consumption is 100Wh/mile its a 0.5% fault margin, if the consumption is 200Wh/mile the fault margin is 0.25%
But using all three values from the same time make us detect rounding errors or at least a part of them.
I wasn't able to get to 100% charge yet, but here's another picture form a charge today.
I didn't get it to 100% on this trip, but here's another screen shot. Also, for what it's worth this car was built in 7/2023 and has 3,467 miles on it. When I change to miles from % the car shows 249.
AlanSubie4Life
Efficiency Obsessed Member
67.5kWh to 67.7kWh pack capacity (possibly the degradation threshold), assuming all pictures at a true 100% displayed charge level.
I assume your car still displayed 279 miles at 100%.
Anyway if so, that ~67.6kWh is the degradation threshold (with about 242Wh/mi constant). I would adjust your starting "when new" number in Tessie to 68kWh. That's probably about right.
You'll start to show rated mile loss when you drop below the threshold, so the first hint will be around 67.4kWh.
I hope this addresses your original question about your original capacity. We can say for sure it was above 67.6kWh or so. And given passage of time, it was probably around 68kWh. (@AAKEE could back calculate for you (haha), but we can't actually do that and get a final answer until you show rated range loss. Right now, he could give you a back calculated minimum initial capacity, but not your actual initial capacity.)
Last edited:
Thanks. Yes, it still showed 100%. Most days I only charge to 50%. It sounds like my battery is still in great shape!
rogbmw
Member
I will just throw this in the ring...so here goes. I just sold our 2013 Model S 85. 111,565 miles. I charged every night to 90% at 25 amps for 11+ years. My 90% charged range (real world) when new was 236 miles. When we sold it last week, my 90% charged range was 224 miles, for a real world battery degradation of 5.1%. I charged to 100% about every 3 months or so, to "balance" the pack (much discussion on this early on), or when I took a trip requiring a full charge. I plan on charging similarly with the new MYLR. Again, these are my actual numbers, and were "actual miles driven" numbers, not projected or estimated range numbers.
AlanSubie4Life
Efficiency Obsessed Member
I do not know how Tesla treated the top buffer for this generation of vehicle.
Keep in mind that rated-mile loss can miss the loss of the top “buffer.” In recent Teslas, it’s just a couple percent (depends on vehicle). But could be larger for the older generation vehicles.
I don’t keep track of that stuff and have not seen hard data on it.
Also probably slightly different battery chemistry though it probably makes little difference.
*In modern vehicles the buffer manifests as rated miles with expanded energy content, not a specific charge level above which the rated miles stay constant. Hope that makes sense.
rogbmw
Member
AlanSubie4Life
Efficiency Obsessed Member
Ah, I misunderstood what your post was saying (even though it did try to clarify).
Yeah, a really hard thing to judge since tires, etc, can have such an impact.
Rated miles on the dash are the energy content. All else being equal, that is what matters.
Last edited:
S85 2013 had 265 miles (426 km) EPA range.
Anyway, from research we know that degradation is foreseable and quite little variations.
A panasonic NCA battery that have been above 55% displayed SOC most of the time would loose ~ 15-17% or so from calendar aging in a medium climate.
This is a datapoints from S 85:
I added the starting point, as Scan my tesla was not up and running back then so we have no 0 km data.
The average today, slightly under 350 km implies 350/426 = 17.X % degradation.
Just as the earth is not flat, there are no extreme variations from the physics/chemics behind the battery.
If you live very cold and have the car out in the cold you could cut the normal degradation in half, but if not it will follow the normal degradation curve.
Similar threads
- Locked
