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Battery life

I use my car a lot. About 30,000 miles per year. Can anyone tell me what the battery life expectancy is? If I have, say 100,000 miles on the battery, what kind of range will the battery have left? 90% of my travels are under 225 miles and that's why I ordered a S with the biggest battery. But, if the battery is rated at 265 miles and at 100,000 miles it only has, say 70% capacity left, that puts the range at about 185 miles. That just won't work for me. Also, does anyone know what Tesla's policy is on battery replacement. Will they replace the battery if it's under 80% capacity? 70%? 60%? or what? Thanks.

Since I have a short commute (15 miles round trip) I asked specifically about the need to "leave the car plugged in so it could *wake up* and draw automatically when needed" as was mentioned above. My plan for regular commuting is to charge at work a few times a week to keep the rated range between 190 and 237 (my full standard charge). I was told by a delivery specialist the recommendation in the manual was geared to those that might leave the car for prolonged periods of inactivity at an airport, etc. I was told there would be no adverse effect on longevity to charge sporadically in this fashion, but I've received conflicting information from the ownership experience team.

I think this issue needs to be clarified by Tesla because these batteries have clearly been engineered for special functionality not found in routine lithium cells. If there are nuances to maximizing longevity given the unique nature of the batteries, they need to be explained more fully to owners.


Batteries wear out because of stress which in turn are caused by factors such as voltage, temperature and degree of use. 165 miles a day (5 days a week?) is a lot. I would expect conservatively a life of 10 years or more to 70% of initial range (70% X 240 miles 168 miles) in may temperature Southern California marine environment.


What I meant was to reach full range say an hour before leave on a regular commute. Higher voltage storage is harder on a battery the lower voltage


I've heard conflicting views on this battery charging issue as well. My original understanding was that it's best to charge the car whenever it's not in use and that range-charging as well as draining the battery close to zero would reduce battery life. However, last week I heard from a service advisor that it's a good idea to let the battery drain down and range charge 2-4 times per month to ensure that all of the cells are getting even use. Which approach is best?

battery cycle life – The number of cycles, to a specified depth of discharge, that a cell or battery can undergo before failing to meet its specified capacity or efficiency performance criteria.

So not so clear as "full discharge" or "deep" discharge required for "cycle". Believe to some degree depends on battery in question. For example its my understanding that Chevy Volt will maintain 30% State Of Charge (SOC) to improve battery life. In other words 30% of battery capacity is held in reserve and operator does not have access.

As stated in my earlier posting I am not sure the Panasonic Study I posted referred to cell Tesla uses but information I came across from various sources seemed to support that it does. I saw no source that supported the Tesla battery having Manganese (MN) in its composition. They also refer to the Tesla battery as (NCA) if I recall correctly which believe points to Nickle, Cadmium, and Aluminum (no manganese). That said I am not Tesla Engineer so can't say conclusively and have to rely on information from internet.

1)Research I've done with respect to Lithium-Ion indicates that you can extend the life of battery if you do not fully deplete the battery. So one way to extend battery would be to purchase Tesla Battery Pack with more capacity than you would day to day typically. In other words maintain a higher nominal daily State Of Charge (SOC).

2) Research also points to extending Lithium-Ion Battery Life by not "over charging" cell (dramatically shortens life) and further benefit is had by not fully charging battery cell. Numbers are not at hand so this is ball park numbers but example is each cell charged to 3.77V rather than 4.20V etc. Believe Tesla "Extended or Full(?) Range" charge likely uses a "Max or near max Voltage" charge/cell (if used frequently will shorten battery life) or is it "normal range" charge likely under charges cells to prolong battery life.

Battery University Site:
Good source probably for "generally applicable" information.
1) How to prolong battery

2) How to charge battery

Correction NCA refers to Nickle, Cobalt, and Aluminum.
Large part of battery composition and I think weight is Cobalt (as I understand it).

Believe Composition is: LiNiCoAlO2

Battery University Link on various Lithium-Ion Battery Types

Basis: My conclusion that Tesla Model S uses
Nickle Cobalt-Aluminum (NCA) Battery and "not"
Nickle Manganese-Cobalt (NMC) battery came from Tesla Motor Club Link below

But as always subject to error of internet!

Excerpt from Tesla Motor Club
The cells Panasonic (Matsushita) produces for the "retail market" uses NCA (under the new marketing name of NNP, it was previously marketed as NCA). And Tesla uses a "retail market" cell, specifically, the NCR18650A (the only 3100mAh 18650 battery that Panasonic makes). Tesla is not using some special formulation by Panasonic (I have not seen any evidence presented that they are, but there's plenty of evidence pointing to Tesla using specifically the NCR18650A, they even had a press release that said as much announcing Tesla was using Panasonic 3.1Ah batteries made at 300 mil. units per year AKA the NCR18650A).

Link shows Panasonic and Tesla Management holding cell that Model S will use

Link referenced:

Sounds like new acronym might be NNP
Here is link to Panasonic document

From Tesla:

Article above seems to imply Roadster rather than Model S but previous link, with same photo, seemed to imply Model S.

Link to Panasonic embedded in above

This doesn't seem to show same 3000 cycle study. So who knows?

Tesla Configuration Guy just said expect 70% of original capacity after 8 years or so. That is more what I've seen in the battery industry generally for end of life capacity.

I appreciate all the discussion on this topic.

From reading the previous posts, it appears that (if you have time) charging on a standard 120V outlet is better for the battery than charging on a NEMA 240V outlet.

Is this correct?

So if I'm "topping off" and there will be hours before driving, should I lower the amps coming in? And if so, to what level, how do I make that calculation? Thanks in advance.

2 points;
TM guarantees 70% after 10 yrs -- but expects the battery will do twice as well (100% margin allowed). I.e., 85%.

And, wonder, there is no nickle in the battery. Lotsa nickel, though! ;)

Brian H, May I please ask you for the written source of your comment that "TM guarantees 70% after 10 yrs?"

There are no guarantees on battery capacity in the battery warranty language, which I'm sure you will recall generated a bit of an uproar on the forums after the battery warranty was released.

I'd be most grateful for the source of a written battery capacity guarantee from Tesla.

Can we get any of the early Model S owners to comment about any changes they've seen so far in battery life?

With the onboard software, Tesla can provide a lot of help in managing battery life and optimally charging the car.

For example, if slower recharging is better to maintain capacity, the charging software could be told to do full recharges overnight, during a specific timeframe - and lower the recharging rate to achieve maximum charge, but at the lowest rate.

Another option would be to do what newer laptops do - and have a threshold that must be crossed before the battery will charge. I have a tablet and laptop that won't charge until the battery is below 95% in capacity. If the car is only driven a short distance in a single day (30 miles?) - then it might be better for the battery not to charge at all that night - and defer charging until more of the battery has been depleted - if the number of times the battery is fully charged affects lifetime.

As more vehicles are on the road - and Tesla continues to collect more data from operating vehicles - they will hopefully use that data to continue to refine their recharging recommendations - and the onboard software - and help all of use maximize the long-term capacity of our batteries.

@bp - if any Model S owners can see any change at all in at most 3 months, then there is something seriously wrong. My 14-month-old LEAF has no measurable change in the battery after 10k miles.

Also, I think the "standard" charge setting does exactly what you describe, as it keeps you from fully charging the battery anyway.

Yes, the documentation of early promises is sketchy. Early statements are not (yet) followed through on in writing, though the Tesla Facts page comes reasonably close. Various LiIon battery specialists have described and laid out LiIon lifetimes, with the caveat that temperature control (particularly prevention of overheating) is a dominant variable.

The unlimited miles/8-yr warranty on the 85kWh batteries corresponds to the figure above, as "70%" is the industry standard for end-of-life, though that would be still 60kWh, and degradation slows down after that point, according to the experts. So TM is promising the 85kWh battery will not fall below 70% in 8 yrs, no matter how far you drive with it! As long as they adhere to standard "end of life" determination. But no one has seen the fine print yet, of course.

(Interesting side note, is that an Alaskan Roadster owner reported about 40,000 miles so far with less than 5 or 6 miles of range loss, which is around 2%, in about 4 yrs of ownership. Cooling seems to help! Conversely, some AZ Leaf owners were reported to be suffering the consequences of inadequate (thin, hot?) air cooling, with severe range losses.
The owners' estimate their reduced battery capacity is at least 30 percent [some were seeing 50%], even though they claim they are driving in strict accordance with Nissan's owner's manual. They also showed CBS 5 News their dealership service records, which show high marks for properly driving and charging their Nissan Leafs.

According to Nissan, that 30 percent battery capacity loss shouldn't happen until after about seven years on the road.)

Note that Nissan was using 70% as its standard after 7 yrs, even with its much weaker cooling system. Industry standard?

The phrase "industry standard for end of life" was referring to the LiIon battery industry generally, not narrowly automotive. It's early days, and Ownership says they're not likely to put anything that firm in writing until they've had longer track record to work from. But they do rate the battery tech and advances as their #1 strength and are committed and confident in that regard.

typo: "had a longer track ..."

Considering..."So TM is promising the 85kWh battery will not fall below 70% in 8 yrs, no matter how far you drive with it! As long as they adhere to standard "end of life" determination." may not be applicable to high mileage drivers; the service/warranty requirement is 12,500 mile or annual, whichever comes first, between "visits". An 8-yr 85kWh owner who drives 20K per year would not necessarily have a capacity level warranted, just a "no manufacturing defects" promise. It will be possibly/likely a matter of some contention in many cases what is "normal" and what is a "defect".

Per the warranty - "The Battery, like all lithium-ion batteries, will experience gradual energy or power loss with time and use. Loss of Battery energy or power over time or due to or resulting from Battery usage, is NOT covered under this New Vehicle Limited Warranty. See your owner documentation for important information on how to maximize the life and capacity of the Battery."

Sounds like Tesla is off the hook even if your battery is at 70% capacity in 4 years instead of 8, Tesla would not cover it under warranty. Brian H. makes a good point about what is normal and what is a defect. Severe loss of battery capacity (outside the "norm") should be considered a defect.

I had some questions for Tesla about battery life and cold weather operation as well as regarding my car sitting outside during the day, while at the office. Here is the official response:

I wanted to send you an email that we have received from HQ regarding your question about the loss of range when the car is parked outside during the cold weather.

Model S does not irreversibly lose energy when it’s cold outside.

In cold conditions, the accessible battery energy is correspondingly low, resulting in an underestimated range number. However, the liquid thermal control system immediately starts warming every cell in the battery, so accessible energy grows exponentially as the battery reaches nominal temperature.

This is evident by looking at the battery graph, which approximates battery state of charge. After a standard mode charge in both warm and cool temperatures, the customer will notice the battery graph looks identical (e.g. approximately 90% full).

A future software update will better estimate range based on where the battery will be after it heats up, whereas current firmware calculates range based on current temperature.

Cars left in cold ambient temperatures do not inherently lose range. Reduced range predictions shown on the instrument panel and touchscreen reflect range assuming the battery will remain at cold ambient temperatures. As the car is driven or preconditioned, battery temperature rises and driving range is more accurately predicted. As always, Model S should be plugged in when not in use, especially in cold weather.

I hope that your question was addressed appropriately, please feel free to add feedback should you have any more questions.

Best Regards,

That's the end

It should be noted that while plugged in the Battery Heating / Cooling system/s will attempt to keep pack temps nominal and seemingly leaving the car plugged in whenever possible may be the best bet for longevity by minimizing temperature extremes. I would assume that Tesla has matched the charging algorithms of their charger/s to the specific needs of the pack. Might be why the charger is on board the car?? They surely would not include an on board charger that would charge the pack in a manner that would damage it.

I plan on following the owners manual / charging instructions and will plug my model s in whenever possible and for sure every night when I return home no matter how much or little distance I travel during the day.


I too will follow the Manual and keep it plugged in when possible in the cold, even if its a 110v.

Probably people in cool climates will get greater lifetime range. One dude in Alaska has lost 2% in 3+ yrs. and 40K miles on his Roadster, and TM claims major improvements in battery quality and management since the Roadster.

I will pass 100000 miles at about 3.25 years so I will keep you posted from the Chicago area


This page states 1.66% loss yearly
So a 60kwh will go from 200 to 168 range after 9 1/2 years at 65mph, with ideal driving conditions.

Even if not plugged in at night, the pack will continue to normalize temperature extremes
protecting itself, albeit at the expense of range. Unless you need the range, no need to plug in all night per delivery specialist. My concept of the car sipping small amounts of juice all night to protect itself is apparently incorrect.

you can "force" that by restricting the amperage, or using a 120V (few miles added, but keeps the battery warm and ready to go, with regen). As long as you don't fill it before leaving.

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