The original degradation curves showed ~3% the first year, then 1% every year after with normal use. Batteries seem to be following this formula pretty closely.
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Tesla's Battery lifespan
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yes and yes. Just to make it easy for the OP, most of the common shibboleths about li-ion were created during the early days when li-ion technology was young, when nano-technology was unknown, when industrial quality control was far weaker' cell production was far less automated and Battery Management Systems were in their infancy.
It is true to say that, other things remaining equal, li-ions are happiest when having shallow cycles, moderate temperature, slow charge/discharge etc. However, all things are not remaining equal.
Elon, EB and lots of other people have had pronouncements on the subject encouraging moderation in all things. Then, the same Elon discovers inconel can safely allow discharges far faster than they had been, thus, Ludicrous. It is notable that Tesla makes the 8 year warranty regardless of how many launches on makes, whether one charges to 100% every day and runs to near zero. They advise against such treatment, but do not void the warranty because of it.
The bottom line of all this is that the Tesla cells, packs and BMS allow us to use them and charge them pretty much as we want to. All the evidence suggests very robust abilities.
Finally, I might as was well admit how I treat my own P85DL, which at 28,000 miles has the same capacity as it did when I bought it. I never drop below 20% (well, almost never, I have from time to time dropped to 18%). On a daily basis I stay between 40% and 60%. I rarely charge above 90%. On the rare occasion when I do go to 100% I immediately drive as soon as the charge has completed. As with almost all valuable things in life, moderation never harms, but immoderation can do so.
So, I'm debating the necessary and definitive statements rather than the desirability of moderation when convenient.
EV-lutioin
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There was a great graph posted to another thread that showed battery degradation over time. If anyone has access to that graph, can they post it? As I recall from the graph Tesla batteries are quite slow to degrade after the initial 10% loss.
There are several of them. The very active Belgian Tesla community has one of the most detailed:
MaxRange Tesla Battery Survey
Another one that is really interesting is PlugIn America. Theirs includes Tesla, Rav4, Leaf and Tesla Roadster. Many of us, including me, contribute to this one.
Battery Survey « Plug In America
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You're probably safe charging to 90% most of the time. I leave mine set to 90% and it sits in the garage for days at a time plugged in. Because I work from home I can go several days in a row without leaving home. The car is perfectly happy like this. It loses about 1 mile of range a day when in this state and it will recharge itself after about 3 days if left plugged in. When I leave the house I have between 266 and 269 miles rated range.
As i said in my first post in this thread, I have yet to see any degradation in 6 months of this.
kmanauto who has a pre-refresh 90D and has a YouTube channel has been seeing some degradation over the last year, but he superchargers a lot. It's possible he just got a battery pack with one or more cells that weren't quite right.
Thank you for the information.
Degradation is not my main concern, as I said the distances that I drive are short. my worry is about the lifetime
like how does the battery die? does it just keep degrading or does it suddenly die?
Generally, the degradation curves are the best indications of expected calendar life. As said above nobody knows precisely because the ultimate failures have been so few during the last decade. Several posts, threads and other reports have been made about failure rates of 2011/2012 Nissan Leafs and also of battery pack chageouts in early Model S, although none of those seem to have related to the battery itself.
As it stands today the best estimates I have read in relevant journals suggest a >20 year typical life span for today's li-ion batteries, including Tesla.
Although nobody has yet mentioned these issues, there are two relevant points:
1. Changing a Tesla battery pack takes only a couple of hours, most of the time being devoted to recalibration and testing. The actual battery pack changeout takes a few minutes. For illustration, installing the Ludicrous upgrade required removing the battery pack and changing several components. That process took a half day.
2. Battery prices are dropping at ~5-6% per year. Thus the cost of pack replacement a decade or more out will not be a huge cost, even if it happens.
So, battery lifetime need not be a worry for a Tesla owner, with or without careful and prudent battery treatment.
Oops, forgot.
Li-ion cell failure modes typically have pretty predictable patterns, but most of the data comes from cellular telephones, tablets, laptops and other such devices rather than cars. That is mostly because cars have much higher quality control, more robust BMS and much tighter production tolerances.
The typical pattern is a pretty stable fully charged voltage during service life, with a fairly steep drop in fully charged voltage at the end of life. Normally that allows substantial advance warning of failure. Some of the 2011-2012 Nissan Leafs that were operated in very cold and/or very hot weather and operated at very low SOC regularly did exhibit those failure patterns. The Plug in America Leaf charts do show that early pattern.
Sorry I did not reply to that last question.
Li-ion cell failure modes typically have pretty predictable patterns, but most of the data comes from cellular telephones, tablets, laptops and other such devices rather than cars. That is mostly because cars have much higher quality control, more robust BMS and much tighter production tolerances.
The typical pattern is a pretty stable fully charged voltage during service life, with a fairly steep drop in fully charged voltage at the end of life. Normally that allows substantial advance warning of failure. Some of the 2011-2012 Nissan Leafs that were operated in very cold and/or very hot weather and operated at very low SOC regularly did exhibit those failure patterns. The Plug in America Leaf charts do show that early pattern.
Sorry I did not reply to that last question.
Degradation is part of the process of dying. There have been some people who had battery failures, but it wasn't the cells that tended to go out, it was usually some other part of the pack and Tesla replaced the entire pack. Tesla probably did that so they could study the failure and improve reliability. They did the same thing with drive units that began making noise.
When battery packs start going out of warranty, it will just be a matter of replacing the bad parts when parts in a battery pack go out.
As for the Li-ion cells themselves they tend to die by holding less and less of a charge over time until it isn't worth it to keep the battery anymore. That's usually what happens to cell phone and laptop batteries. People replace them when they go flat too quickly.
Li-ion batteries can also die suddenly by catching fire, but when that happens it's an engineering defect that allowed the battery to get into thermal runaway in the first place. Samsung is the latest company to be bitten by bad battery management design, but Tesla has never had a case of a battery catching fire in any condition other than a pretty serious accident that probably would have caused a fire with an ICE car too.
I've never heard of a Li-ion battery just quitting with no degradation symptoms or catching fire, but it probably has happened. It's rare if it does happen.
Typically batteries degrade a little at the start, then if managed well (like Tesla does) they have a long period of holding the same level of charge consistently, then degradation kicks in again and the battery holds less and less of a charge until it isn't very useful anymore. In other words, you usually have a lot of warning before the cells quit entirely.
Not exectly off topic, I hope, but related, is the entire subject of vehicle fires:
Two quick comments, definitely not disagreements:
1. In the Tesla cases, so far all of them [that had publicly available data] , individual damaged cells have experienced thermal runaway aka fire, but thermal runaway has NOT propagated to adjacent cells even within the same module. In the rare cases available to assess that seem otherwise there have been external electrical sources that had failed fault protection.
2. There are about 90 motor vehicle fires in the US for every billion miles driven.
NFPA report - Vehicle fire trends and patterns
Tesla, as of April, 2016 reported about two billion miles driven by Tesla.There have been a grand total of six incidents in which a Model S had fire, three of those happening in 2013. If one compares, so far Tesla has 3 fires per billion miles. It is good to know that after the first accidents tesla reengineered the undercarriage to minimise risk of foreign object damage. Two of the fires happened while charging, and Tesla has consequently strengthened charge control parameters. (In addition that data was also incorporated in the newest protocols for CCS).
The summary here is that Tesla battery life is long and stable, but it is also engineered to be very, very safe, vastly safer than fire risk in an ICE.
If I remember right, I believe the two fires that happened while a car was charging, they never determined the starting point of the fire. In the first case, which was in a garage in Canada I believe there was some evidence the fire started in the wiring of the garage. In the second case (the one at a supercharger in Norway on Jan 1) it was probably in the car somewhere, but it may have started in something being carried in the car.
I believe there were a few more than 6 fires though. There were the three in 2013, one caused by an accident that ripped the car in half and embedded half the car 6 feet up in the wall of a building (joy rider hit a parked car on a city street doing 100 mph in Los Angeles). There were two cars that went over cliffs in California and I think one started a small fire, but in both cases the car was utterly destroyed by the crash. In one case the California Highway Patrol ordered a dump truck rather than a tow truck because there wasn't enough left of the car to tow away. This year there were two fires due to accidents, one was the guy who plowed into a tree in the Netherlands at something like 180 kph and the crash in Indianapolis also at very high speed. In both of those crashes the impact ripped apart the battery pack and some cells burned when they shorted with wreckage. There is video of the cells burning in the Indianapolis crash where the cells are going off like fire crackers.
I think the total may be up to 8 now, but that's still very low. How many videos have we seen of ICEs catching fire in gas stations alone?
In any case, the number of fires in Teslas is much, much lower than the average rate for ICEs. The entire Tesla fleet is younger than the average age of a car on US roads (11 years) so that contributes a little to the safety record, but I also think the case that EVs are safer from fire is pretty strong.
There was this fire which was not due to damage.
Tesla Model S catches on fire during a test drive in France
Tesla Model S catches on fire during a test drive in France
Just to reconcile our numbers, I did not have either the Netherlands nor Indianapolis cases. It is interesting that in the Tesla instance we can document each case. Unlike most ICE fires, the Tesla ones all have involved pretty outrageous driver behavior (for that matter every Tesla fatality has involved pretty outrageous behavior). In addition, except for driving into stationary objects at terminal velocity there have not even been injuries in Tesla fires, a major contrast to ICE fires.
There is very strong evidence for that one, I agree, but we also must allow that the typical ICE fire involved an older vehicle with fuel line problems somewhere.
OT, I hasten to add, not always older; my only personal ICE fire was with a brand new Maserati. I drove it from delivery to Park Avenue and 56th St in NYC to pick up a colleague, just as I stopped the car burst into flames. There apparently had been shipping damage that the importer/dealer missed. I got a replacement one later the same day, no new taxes because the paperwork on this one had not yet been submitted.
Yes, I missed that one too. Has there been any further information about this one? I have found nothing.
There was also the crash in the rotary in Mexico. As I recall, the driver tried to take the rotary at >100 MPH, hit a concrete barrier, went airborne into/through a tree, and caught fire. The occupants got out and walked/ran away.
That one slipped my mind. That one was caused by a technician error:
Model S Fire In France Blamed On Bad Electrical Connection, According To Tesla
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