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What is more damaging to the battery?

M3tex

Member
Dec 3, 2019
21
10
Fort worth
I am going on a road trip and am wondering, which one is more damaging to the battery -- slow charging to 100% at home, or slow charging only to 90% but then supercharging extra 10% than otherwise? I understand that both charging to 100% as well as supercharging have negative effects on battery life, but which one is worse?
 
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Dr. J

Active Member
Aug 23, 2017
1,476
2,734
Fort Worth, Texas
I am going on a road trip and am wondering, which one is more damaging to the battery -- slow charging to 100% at home, or slow charging only to 90% but then supercharging extra 10% than otherwise? I understand that both charging to 100% as well as supercharging have negative effects on battery life, but which one is worse?
Nobody knows the answer to that. If 90% from home gets you to the Supercharger with at least 10% (or a larger, reasonable cushion) remaining, just do that. If it won't get you there with at least 10%, charge to 100% at home. Don't fret like I did when I got the car. ;) Use abetterrouteplanner.com for planning your trip, and the in-car navigation system to check periodically how much battery you will have on arrival. Adjust your speed accordingly.
 
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Kognos

Member
May 20, 2019
231
249
Portland, OR
Charging to 100% is only considered harmful if not consumed reasonably rapidly. It's only about long-term health as well -- there's no harm in and of itself charging to 100%. For road trips, that's precisely when you want to - time permitting - do this. I would always aim to charge to 80% on road trips but then take that as an alert that I needed to wander back to the car. Usually I was eating, or strolling, or something for fun.

It is also an urban myth that supercharging is harmful to the battery in and of itself. The battery will slurp as much charge as it reasonably can. It will slow or speed up based upon conditions - weather and temperature, battery capacity, etc. When you think about this from a "pull" perspective, it is less concerning than thinking the charger "pushes" and has the potential to damage. Not so.

There is a correlation / causation problem that usually exists with normal battery degradation and supercharging but I've seen no real science to back that up. The only real factor is don't let your battery rest at 90%+ for long term health. The rest is very subjective.

EDIT: I did some research. Heat is a battery killer in general, which is why there is a lot of fan activity when supercharging. I stand behind the general statement that it probably isn't supercharging in general that causes problems (for example, supercharging in colder climates probably won't get you 250kw pull but it probably also won't generate a lot of heat) - but also there may have been improvements in fans and batteries from the X and S.

It's hard in general to say that the supercharging caused a problem in Arizona vs the general hot climate, if you follow my logic. There's not a direct link or a lot of science, and I tend to believe - granted, on faith - that Tesla would allow your battery harm by simply using the tools it has to charge it. The manual directly states an optimal charge % but says nothing about the style of charge. Superchargers are perfectly fine.
 
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KenC

Active Member
Sep 4, 2018
3,969
3,660
Maine
I am going on a road trip and am wondering, which one is more damaging to the battery -- slow charging to 100% at home, or slow charging only to 90% but then supercharging extra 10% than otherwise? I understand that both charging to 100% as well as supercharging have negative effects on battery life, but which one is worse?
Run some simulations on your trip in ABRP, using different starting SOCs. As long as you're not too far from a Supercharger, you may find there's little advantage to starting with 90% or 100%. In fact, because the optimal charge strategy on a trip is to be in the lower 60% SOC, for faster charging, you may find that your simulations indicate that you can start at a much lower SOC. Counterintuitive, but you won't know until you test out some sims.
 

mswlogo

Well-Known Member
Aug 27, 2018
6,360
5,460
MA, NH
I think his point is that he'd be "Slow" charging to 100%. Meaning it could lurk at high charge for a while and that can be hard to time just right when it finishes that you leave. If you need the 100% you need to target it so it's done well ahead to be sure it's always done.

If he is only adding 10% at supercharge (and I assume he means not the last 10% but somewhere in the middle of his trip). I'd lean towards a short boost via supercharger would be better for the battery.

If it's gonna be a super hot day and stopping off on the highway for supercharge then maybe on those days home top off is better.

If this was just a few times it makes no difference. If this was a daily routine, I sure would try to avoid the Supercharge stop (hassle wise) if it had to be every commute, practice getting that 100% charge at home timed just right before you leave.
 

ElectricIAC

Devil’s Advocate
Dec 31, 2019
2,967
1,990
DFW
Having tested 100% before I can say with certainty that if the first part of your drive is surface streets: don’t. There’s not much advantage to charging past ~94% as your regen will be close to non existent. Now if you’re hopping on the highway immediately this may not be as much of an issue unless going into heavy traffic.
 

XLR82XS

D M C
Jul 26, 2019
3,166
1,978
SWFL | Vegas
It's hard in general to say that the supercharging caused a problem in Arizona vs the general hot climate, if you follow my logic. There's not a direct link or a lot of science, and I tend to believe - granted, on faith - that Tesla would allow your battery harm by simply using the tools it has to charge it. The manual directly states an optimal charge % but says nothing about the style of charge. Superchargers are perfectly fine.
Agreed. As I've stated here before I follow the manual when it comes to charging and only 100% for trips over 2 hours. I charge to 90% at home 220 line and drive at least 60 miles a day. 280 miles @ 90% SOC & 320-322 SOC @ 100% SOC.

I also read the optimal operating temperature for the battery is 80F. Most of the days here in S. Florida are 75-85F and I never hear the fans running unless I'm supercharging.
 

CertLive

Member
Dec 15, 2019
638
486
United Kindom
I am going to claim I know the answer! So the total charge is spread over the packs when you do charge it. However supercharging is more of a strain on the batteries than home charging at say 7kw-11kw. It all really depends on how much you rely on the supercharging network for daily commutes. If you are like me and you use it for short trips and the odd holiday then most of the charging is done at home so you will wear the cells less over time. If you supercharge daily well at some point and sooner than my scenario the software will start to slow this down to get you more life out of them. Charge as much as you like up to 90% but only push it past that if you really need the extra range and you don't mind losing most of your regeneration until you use some of this juice. But 20-80% is a fine bracket to keep it charged up to daily. I would say in 76.7% of usage cases you should expect many years of acceptable range. This info is based on current model 3 cars though not the older packs in the S and X.

If you are going on holiday I would say charge it as needed, forget any worries. The only situation where you would put max strain is supercharge 0-100% daily. Allow the software to do the rest.
 

DaveRZ

Member
Nov 19, 2019
193
277
Murrieta, CA
Just remember that the things you hear about being "BAD" for your battery typically aren't that bad, and really only are a problem if you continually do it.

I look at it this way: Drive the car however I need to for getting the job done. Its a car. Charge at home as much as possible to save $$ and give the battery they best fighting chance of a long life. Supercharging, charging to >90%, discharging to <10% only when needed. I have high confidence this will allow my battery to easily last the length of time I typically keep a car (6-8 years) and still have plenty of life left for the next owner.

Put another way, smoking causes lung cancer. Odds are if you smoke only 1 cigarette a day, you may never get it. Smoke a pack or more a day, you're far, far more likely. Regardless of what you do, its also up to chance. My father died of lung cancer at age 61 - he smoked for ~15 years in his youth. My grandfather smoked heavily for 75+ years and died just after his 100th birthday. Go figure.

In your case, I would just charge to 100% rather than stop at a supercharger. This is less about battery longevity and more about an unnecessary supercharger stop for 10% charge.

Drive the car, don't sweat the charging "rules" too much unless you have to break the rules daily, and don't smoke.
 

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