Tesla Battery Expert’s Recommendation For Maximum Battery Life – Video


What is the best charging plan if you want to keep your Tesla battery healthy for years and years?

There are many different theories out there, and until we have someone that has driven a Tesla for decades, it will be hard to know the right answer. The automaker suggests keeping your battery somewhere between 50 and 90 percent charged as often as possible. More specifically, the company says to charge daily to 90 percent and then use 100 percent for long trips. Tesla CEO Elon Musk has said before that charging to 80 percent is better than charging to 90.

See Also – GM Versus Tesla: Bolt EV And Model 3 Battery Packs Compared


Tesla’s “Mr. Lithium-Ion Battery”, Jeff Dahn, responded to Michael’s question in less than an hour.

Who might be the best person to ask this question and get an answer that you can trust? As Michael (Freedom101) pointed out on the Tesla Motors Club forum and the above YouTube video, “Mr. Lithium-Ion Battery”, Jeff Dahn is the man.

Dahn, Tesla Industrial Research Chair and Professor of Physics and Atmospheric Science at the University of Dalhousie in Nova Scotia, is one of the most renowned battery experts in the world. He has spent a majority of his career trying to answer this question. He told Michael:

“I would recommend charging to 70% normally. When you need a long trip, charge to 100%.”

So, it’s that simple? Just set it and forget it. (You can set up a limit using the car’s touchscreen or your Tesla mobile app)

We all have different driving habits, we live in different climates, and we commute different distances. Nonetheless, if you want to keep it simple, most of us know that we shouldn’t fully charge unless there’s no other option. Charging to 90 percent has been recommended often by many. Surely charging to 70 percent would be better, if 80 is better than 90.

Heck … if you don’t need the range, charge to 50 or 60 percent. Keep in mind, however, that you will begin to notice the affect on performance as you dip below 70 percent. Also, cycling around 50 percent is supposed to lead to the longest battery life.

Most people don’t have a daily round trip commute that requires some 100-150 miles, so this 70 percent method should fare pretty well for the masses.

Video via Freedom101 on YouTube:

IDEAL Tesla Battery Daily Charge Limit for your day-to-day driving as per Mr. Jeff Dahn.

Check out Jeff Dahn’s TEDx Talk below:

Making Batteries Better | Jeff Dahn | TEDxDalhousieU

Jeff Dahn has won countless award for his work on batteries.

His talk highlights some of his research experience. Dahn has received National and International awards including: International Battery Materials Association (IBA) Research Award (1995); Herz- berg Medal, Canadian Association of Physicists (awarded to a physicist under 40 years old for career achievement – 1996); Battery Division Research Award (The Electrochemical Society – 1996); Fellow of the Royal Society of Canada (2001); The Electrochemical Award [Canadian Section of the Electrochemical Society – awarded once every 4 years for career achievement] (2006); Medal for Excellence in Teaching (2009) from the Canadian Assoc. of Physicists and the “Technology Award” from the ECS Battery Division in 2011. This talk was given at a TEDx event using the TED conference format but independently organized by a local community.

Sources: Tesla Motors Club via Electrek

Categories: Battery Tech, Tesla, Videos

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30 Comments on "Tesla Battery Expert’s Recommendation For Maximum Battery Life – Video"

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Nothing new, we charge our S 60 (with software-limited 75 kWh battery) to indicated 80% (about 64% real SOC) whenever not in use, resulting in a typical range of around 260 km, which is way more than our daily needs and only charge up for road trips or when on free energy (but our indicated 100% are still just around 80% real SOC). Anyway, small cycles around 50% (real) SOC are best for battery life. 🙂

Perhaps if we charged a lithium battery to operate an electric razor, the 70% recommendation would be useful, although perhaps hard to determine. As for the Tesla automobile, the battery pack has been designed to accept a perfect level of charge and a perfect level of discharge.
Except in the event of a natural disaster in which Elon will dial in a deeper level of discharge to get you a greater distance out of town.

Not keeping at 100% seems to be the key, and keeping (parked) closer to 50% is probably better when the weather gets too hot.

But if you don’t charge to 100%, and depending on cell balancing method, it may seem like the capacity is degrading. For SparkEV, it seems the balancing occurs after 100% charge. After charging to full after months of only charging to ~90%, I have gained back much of what was “lost”.

I routinely charge my 2014 Spark EV to 100%, at least three or four times per week and almost daily in the winter. Most of my charging is on level 2, but about 10 – 20% of the time it is level 3. Typically, it doesn’t stay fully charged for very long as I generally unplug and drive away within 10 to 30 minutes of filling up. I also use up the battery to less than 10 miles of remaining range, about four or five times a month. After 38 months and ~35k miles, I haven’t noticed any battery degradation. If there has been any degradation, it is not apparent to me. I consistently get over 90 miles of range on days with good weather (the car is rated for 82 miles of range), and that is with high performance tires. I’ve lost more range from changing my tires than from charging to 100%. Before the tire change a couple of months ago, I was hitting 100+ miles on some days. Perhaps my charge and discharge habits will catch up with me in the long run, but so far, it hasn’t seemed to make a difference.

“Perhaps my charge and discharge habits will catch up with me in the long run”
— Yup.

70%? that is pretty close to the Volt’s 67% (Gen1) range or ~71% (Gen2) range of the Volt.

So, if one charges only to 70%, you can expect 6,000 charging cycles out of it like the Volt in a Tesla.

So a 250 miles Tesla with 70% charging (175 miles) will last 6,000 cycles (using the Volt battery claim) or 1,050,000 miles. Here comes the million miles Tesla.

Discharge also matters. Volt won’t let it go too low, but it is possible to go low with Tesla. Pulling a number out of my arse, maybe 25% is the low limit and 75% upper limit for 50% as best usable range.

As the miles pass, degraded battery will result in fewer possible miles. Depending on degradation profile, you can’t simply multiply today’s 70% (or 50%) range by cycle count. It’s not clear what the capacity will be after 6000 cycles. Some may consider 50% acceptable, others not.

Combining all these factors, 1M miles probably won’t be possible. But with care, I think 500K miles is possible.

For many EV’s, like my Ford Focus Electric, it is important to occasionally fully charge, as this is where cell balancing happens.

Maybe Tesla, when the user programs a lower limit than 100% still does cell balancing. I do not know.

On my car I usually only charge to 75%. About once a month I do a full charge.

I really wish more EV’s had a user programmable SoC limit!

Once a month is probably overkill for anything that’s not a LEAF. Many DIY builders who opt not to use a battery management system find that once every year or two is more than sufficient for water cooled (and gently treated air cooled) batteries; even for cars that see somewhat frequent use. Many a flame war has been started on DIY forums over this, but the evidence continues to point toward this being true. If the BMS indeed only balances at the top (there really is no other way except balancing at the bottom, which OEM’s will never do), the cells should stay very close to balanced for hundreds of cycles due to lithium battery’s inherent low internal resistance. I say “probably” above, because this doesn’t prohibit manufacturer’s from doing other funny business that may impact cell balance with the BMS, but I kind of doubt they do and the BMS only kicks in near 100% SOC. Given that, the only other way to get them out of whack is with a high temperature differential between cells, which won’t happen in water cooled packs. In a FFE (and every car except the LEAF), you should be able to go several… Read more »

Good info.

Cell balance is given over CAN, so I can check it easily, too.

Once a month is more than required to keep balance, but it is about the norm for when I need the extra range that a full charge is appropriate.

I have worked on PHEV’s in the past (HV battery engineer) at an unnamed OEM that had balance problems. It was made worse by users that never plugged them in. That wasn’t the root problem of the imbalance, but it didn’t help.

I am not sure why you single out the Leaf. I use 19 Leaf modules in my Vectrix scooter, and they seem like they never get out of balance without any sort of BMS.

“Once a month is probably overkill for anything that’s not a LEAF. Many DIY builders who opt not to use a battery management system find that once every year or two is more than sufficient for water cooled (and gently treated air cooled) batteries; even for cars that see somewhat frequent use. Many a flame war has been started on DIY forums over this, but the evidence continues to point toward this being true.”

Thank you for that excellent advice, Malevolence. You’re right to say this is a controversial subject, but the evidence seems to point to not getting any benefit from frequently charging to 100%; rather, that this unnecessarily ages the batteries.

I think it’s also rather questionable that charging to 100% actually balances the cells. A lot of knowledgeable people think all that does is recalibrate the BMS (Battery Management System), which may result in the car displaying more capacity available, but doesn’t provide any increase in the actual capacity.

I’ve had a FFE Ford Focus Electric in the Phoenix HEAT 3 years and charged to 100% all the time. I parked in the HOT Sun with no plug at work every day. I never lost any capacity.

FORD has a buffer so you don’t really get to 100% or 0 on the discharge. Most Automakers do that.

Only the Nissan LEAF doesn’t have battery cooling (thermal management) so they loss capacity of 5-15% a year. Gone forever. Lizard chemistry doesn’t seem any better.

Would love to see some data to see the actual consequences…Charge to 100% daily? How’s it look 100K miles, 200K miles, etc…

If I recall correctly, doesn’t Tesla limit DCFC charging? And didn’t the Tesla Loop Tesla regularly supercharge to 100% and have very little degradation?

Tesla does limit supercharging speed to protect the cells as they age and they discourage setting the battery charge limit at 100% (resetting after 3 days).

“And didn’t the Tesla Loop Tesla regularly supercharge to 100% and have very little degradation?”

First of all, that may be an exaggeration; a result of an overly enthusiastic user over-praising his car. That’s human nature, and observer bias happens so frequently that scientists have established the procedure of double-blind studies.

Second of all, one outlier data point, even if 100% true, doesn’t disprove the rule. It just shows that rules sometimes have exceptions.

If you think you can frequently Supercharge your Tesla car to 100% and not experience noticeable battery degradation over time… well, odds are that you’ll be disappointed.

The Tesloop people are an interesting case. They supercharged multiple times every day for several years, but they likely didn’t supercharge to 100% (takes too long). They did likely charge to 100% every night, but then they’d be up and driving in the morning so the car didn’t sit at 100% charge very long. And they only had 6% degradation after 200,000 miles in just over a year.

That included a battery pack reconditioning/replacement somewhere in the middle of that 200k miles.

Jim Chanos is still shorting Tesla and telling his subscribers to short Tesla. I don’t know how much money Jim lost on Tesla for himself and investors but I would think people should be shorting Jim Chanoa

” Keep in mind, however, that you will begin to notice the affect on performance as you dip below 70 percent.”

I don’t think so. According to R&T http://www.roadandtrack.com/new-cars/car-technology/videos/a32831/heres-exactly-how-much-a-tesla-slows-down-as-its-battery-gets-depleted/

Using Launch Control on a P100D they were able to measure a difference in 0-60 times:

Charge 060
10% 3.9s (launch control disabled at this state of charge)
25% 2.9s
50% 2.7s
75% 2.5s
100% 2.5s

So if you are using launch control and are at a drag stip, you might notice some 0.2 to 0.4 second loss of 0-60 times.

But if you are just driving around and using normal, even very quick, acceleration rates, just ’cause its fun. I submit you will not notice any change in your car’s performance even down to 10% state of charge.

Its called power limits.

“Heck … if you don’t need the range, charge to 50 or 60 percent.”

Charging to 50 percent for a car that’s actually going to be driven is very poor advice. Li-ion batteries are best stored at a 50% charge, but if you’re going to drive it, then the aim should be to even out how much it’s cycled above and below 50%. In other words, you would want to cycle it between 40% and 60%, or 30% and 70%, or 20% and 80%, as much as possible.

Charging only to 50% should be done only if you plan not to drive the car for some time; and then you should charge it up some before driving it again.

M3 - reserved -- Niro/Leaf 2.0 - TBD

We’ve charged our Fiat and Spark to 100% overnight via Level 2 charger for three years and daily cycles down to 10% on each of them.

No battery degradation so far on either. Just Lucky perhaps?

With Powerwall 2.0. It charges to 100% and deep cycles and they have the new battery size from the Gigafactory that’s going into the Model 3. for them too. Why is that different?

PowerWalls are designed to be deep cycled on a daily basis. EV battery packs are not.

PowerWalls may use a different battery chemistry, one which stands up to deep cycling better. Since it’s stationary storage, it doesn’t need to be lightweight, and the power requirement is much, much lower than what is needed in an EV. Batteries optimized for high lifespan by sacrificing power output would certainly make sense for the PowerWall.

Or perhaps Tesla builds in some reserve in the PowerWall, in the way that GM built in a reserve in the Volt battery pack. It may be that there is some degradation over time, but this capacity loss is hidden by the pack adjusting how much of the capacity can be cycled, to maintain the same usable capacity by eating into that reserve.

At any rate, don’t assume that Tesla engineered the PowerWall battery pack like they did the Model S/X battery pack. It’s quite likely that they are different in important ways.

Actually my comment applies to his NEXT video – where he spent C$5,000 for a Tesla HPC installation. I thought he was going for the full 80 amps, but I guess the electrician only ran a 60 amp circuit (48 amp charge rate at the car as indicated by the Tesla display), but hey it beats the 110 he was using before. He went from a what looked to be a Federal Pointe 100 amp panel (the equivalent Federal Pacific in the states – the ones that regularly caught fire in later years – the ones in the states with orange handles) – and the electrician installed a Schneider Homeline 200 ampere (Square-D) panel….Hey Its safer stuff than what he had. As far as Battery Longevity goes, I had a long chat Saturday with JIM, the head of the Ithaca NY Drive Electric event next Saturday. I asked him about his ‘Imported from California’ Toyota Rav4EV, but he said he is extremely disappointed in the battery, seeing his range went from 145 to 110 miles in only 45,000 miles, and he said he rarely charged the car up fully. I just made the guess that perhaps the relatively large vehicle… Read more »

Did some investigation: (for Canadian readers such as Djoni:)

The Troublesome Federal Pacific (FPE) panels that were discontinued in the states decades ago, however Schneider Electric is still manufacturing them under the ‘Federal Pioneer’ label.

One troublesome (sometimes doesn’t trip) is the 15 ampere NC015 or NC015P breaker.

There has been some discussion that the Canadian manufactured “FP” products may be more reliable than the old FPE stuff, but Canadian Authorities state there is no hard evidence either way, and that the basic “STAB-LOK” system used weakens over time EVEN ON THE BRAND NEW FEDERAL PIONEER stuff, and that in one case, a Toronto homeowner was required to duct-tape his breakers in place.

ANY FPE OR FP panel, regardless of country of origin, is strongly recommended to be replaced, even if the size of the electric service is unchanged (eg: 100 amp old to 100 amp new). Schneider has not responded to official inquiries regarding the FEDERAL PIONEER line, but officials recommend avoiding usage of it if at all possible.

I don’t understand, does Tesla not have any upper/lower limit buffers like the Volt?

Agree with Mr. Dahn, BUT if you charge your EV to 70% there is more probability that you discharge your battery pack completely while try to reach some point, that is can instantly kill the battery pack! Some EV still do not have any protection again the “Instant Death”. Even Tesla did not have it (till 2015 or 2016?). Now Tesla has it after cases leaving a Tesla unattended for few months. The fact of the Tesla GOOD care of this problem: Some Tesla S got additional 10 kWh in Florida @ the time of harakane.

Sorry for auto correction on my mobile phone — protection ‘against’ the “Instant Death”. To reach destination at any price is the human behavior, moreover it is unavoidable in any emergency. That would definitely kill unprotected EV pack! I drive my Leaf from 2011. Ready to trade it in for Tesla M3 in 2018