Tesla reveals 5 year CALENDER life for battery pack!

[paco3791]

[ed: It is important to note here that the battery cell chemistry that is used in the Roadster also has a calendar life. The expected calendar life is five years.]The above quote is an editors comment added to the latest blog post over at teslamotors.com. From my point of view this is huge news and something I had never heard before. I am very curious to know what the actual degradation curve for the batteries is over, as Tesla puts it, calender time.

Is this 80% after five years?! or less that 80% capacity?!

What about after that? is it linear?

Does this apply evenly to both performance and range?!

Unless someone else has heard this before, I think this is kind of a sneaky way to slip in this information. Interested to hear what everyone else knows about this issue.

[SByer]

It's been mentioned a number of times. One of the Tesla blog entries on batteries from quite a while ago mentioned it.

It's a known property of lithium ion batteries, just that most batteries tend to lose capacity due to cycling much faster than by calendar time, so you generally never really notice. And yes, it's an 80% thing - they'll be down to 80% of current capacity after 5 years if you've been really gentle on them cycle-wise.

[Albern]

Hey paco3791,

Those aspects of the Tesla ESS's cycle and calendar life have been discussed:

Tesla Motors - think (http://www.teslamotors.com/blog2/?p=39) (check out the last few paragraphs on the calendar life).

I too was temporarily shocked as you rarely hear anyone speak of the ESS's calendar life.

[Cobos]

This is a known quality for Li-ion batteries.This is why buying "new" batteries for your 4 year old laptop is usually not a very pleasant experience since in many cases those batteries has been stored at a supplier's shelf for a few years and thus they are not as good as they "should" be. It does indeed suck though as it's pretty obvious the battery will loose capacity regardless of what you do...

Cobos

[paco3791]

Interesting, Thanks for the feedback everyone.

I would still be somewhat concerned about his issue if I was a Roadster owner. If your planning on treating this vehicle as a "special occasions only" type car, I can see how there might be a bit of a rude awakening when 10 years down the road you've lost significant performance but only have 30K miles on the OD. how will the ESS have changed in 10 years? will you even be able to get replacement parts without upgrading other parts of the car? What kind of investment would it take to get back to "like new" performance? Some of these questions are brand new to this type of vehicle, since this type of issue is not really a concern for well taken care of ICE cars.

In looking at the Tesla blog referenced above (thanks Albern, had forgotten that one), they try and sell this issue as comparable to losses in an ICE car but I find that difficult to follow. For an ICE car I would guess that the loses gradually flatten out to a reasonable platue, especially if the car is reasonably well tended. But, what this calender life stuff tells me is that a roadster will never be a collectors car, at least with original equipment. Even if you baby it, at some point it just won't be practical to drive. Now where is that point? is it 10 years? 15? I don't know but I'm guessing in 2020 you might see some grips about this. Of course I also don't know what a new pack will cost in 10-15 years but I'm guessing it still won't be cheap.

Of course I also realize that this a problem with any EV and Tesla is doing the best anyone has yet done. It's just a bit jarring to think about.

[BBHighway]

Battery technology still needs work. The NiMH used in the (latter) EV1s don't suffer the calendar life issue much, but don't have as much energy density, and so provide less range. They also have patent issues. Still, they are used in the Toyota Prius and other hybrids.

Nickel-Cadmium have severe memory effect problems, less energy density, and contain hazardous materials making disposal/recycling difficult.

The Lithium Cobalt batteries used in the Tesla are expensive and have calendar life degradation, but provide superior energy density. As such, they are good fit for a high-end product like the Tesla Roadster. Not so good for a Chevy Volt, Plug-in Prius, or even for a low-end EV.

Lithium Phosphate have long calendar life, can be made to recharge very quickly, in as little as 10 minutes or so. But they only have about half the energy density of the Lithium Cobalt, so a Roadster would only go about 110 miles. They are also very expensive.

Traditional lead-acid batteries are cheap, but have very low energy density, and the lead is considered a hazardous substance.

Hopefully, in five years when the Tesla Roadster batteries need replacing, there will be new ones that have even more energy, longer calendar life, and cost less. Lots of people are working on it, the physics say it is possible, so I think chances are good. But nobody knows for sure.

[WarpedOne]

Paco, you are waaaaay overreacting.

Face it, Tesla Roadster is an exotic car and as such has some exotic needs.

For better perspective take a look at Ferarris and then come back all shocked about its 5000km service intervals and 50.000km engine lifetime.

If you want an economy car ... sorry sir, The Roadster ain't for you.

[paco3791]

WarpedOne.

I know I know. but, in part, you brought up exactly the point I was trying to make. All of the intervals you've listed are distance based. where as for the Tesla they are Time based on top of distance concerns. So If you baby a Ferrari and get it serviced regularly and only drive it say 50K km over ten years you might expect performance to stay relatively constant. But for a Tesla no matter what you do or how many times you take it to the dealer, not only will you have to replace the "engine" (read Ess) after the 50K km over 10 years but you might also be down to say 50-60% performance (range and accel).

Not saying that any car doesn't have it's drawbacks, just that this one's are new and different and not all owners may anticipate how it will all fall out since they are used to the degradation curves of ICE's. and this is a potential problem beyond this high end unit, and may have an even larger impact on the long term ownership of cars like whitestar.

[Cobos]

Paco: I see how this feels very strange and wierd, and especially for the Roadster with such an expensive battery pack compared to lead-acid batteries which has so limited cycle life and lower price that you just exchange the whole or parts of the pack regularily for a much lower one-time cost.
But this is actually one of the reasons why Thinks "battery-insurance" idea and PBP's battery swap idea makes a lot of sense. You pay a monthly fee and the entire problem is gone.

Cobos

[WarpedOne]

Paco:
>> All of the intervals you've listed are distance based.

Yes, but there are also time limits on ICE cars. X-year waranty, 3 - 5 year tire lifetime, max 2 year interval for engine oil changes, standard lead-battery also ages (I don't know the lifetime right now), etc.

The Roadster is different enough from most other cars that owners will at least somewhat inform themselves about what exactly they've just bought. You don't expect someone will drive it to gas pump and try to fill it up just because they are used doing that, do you?

The ESS is a consumable part of the vehicle and should be viewed as such. An expensive consumable though :)

[TEG]

Yeah, I knew about this Li-Ion shortcoming from the early days. It sucks. Ironically some companies would try to engineer in calendar lifespan to ensure future revenue possibilities (e.g.: if your product lasts forever you don't get so much repeat business). We live in a society where more and more products are considered disposable. Many cars are engineered only to last through the warranty period and not much beyond.

Another reason to hope that EEstor turns out to be the real deal.

[tonybelding]

The above quote is an editors comment added to the latest blog post over at teslamotors.com. From my point of view this is huge news and something I had never heard before.

As others have already noted, this is something Tesla have been telling us about ever since the Roadster was first unveiled.



I am very curious to know what the actual degradation curve for the batteries is over, as Tesla puts it, calender time.

It depends. It's a combination of age and use, and it also depends on how much degradation of range you can personally tolerate. The comments I've heard from Tesla suggest that many people might get eight or nine years out of a battery, and they expect few should need replacement before five years.

Bottom line: Don't buy one without expecting a battery replacement at some time during its life span.

So how much will they cost? Some have estimated the cost at around $20,000 at today's li-ion cell prices. Tesla estimated that if li-ion prices follow their past trends, then the replacement cost should be more like $12,000 when the first cars start coming due for their replacements. But there's no way to be sure -- if electric cars are the hot ticket five years from now, and companies are struggling to catch up with demand for batteries, then it might be higher.

Of course, the batteries may also be improved by then.

[Brent]

Keep in mind, too, that GM is actively pursuing better battery chemistries for the Volt, as the cycle life requirements are substantially more demanding. Perhaps something new and wonderful might come out of it.

[Brent]

[N]ot only will you have to replace the "engine" (read Ess) after the 50K km over 10 years but you might also be down to say 50-60% performance (range and accel).

I'm not sure this is quite right. Range will suffer, but it's not clear to me that acceleration will fall off too.

From what I've read, the battery won't simply fail; it will gradually require more frequent charges, until at some point it becomes annoying to charge it so frequently. My guess is that a substantial number of owners will be happy enough driving range "compromised" vehicles. They'll get enough range for day-to-day purposes like commuting and running errands.

[insndrvr]

The other thing to remember is that in those 5-10 years, there aren't very many things that will need servicing on the roadster. So for people who are used to shelling out money every year to maintain their high end ICE cars will be saving money in the short term to then give it back in the long term. So it could be looked at like an advantage, you could invest the money you would have spent on the upkeep of a high end ICE car and make money on your money over the next 5-10 years and then buy a new battery when it's needed.

I think it will take a while to convince people that an EV will cost enough less in yearly maintenance that it will be worth it to spend more up front. This is more related to something along the lines of the Bluestar and the average car buyer. Telling them that spending extra now to save money later may not sit well for some people.

[donauker]

One big savings that needs to be added in to the equation.

Fuel Costs:

Current 2 seat ICE roadster with less performance. 50,000 miles @ 17 mpg @ $3.45 gal. = $10,147

Tesla Roadster 50,000 miles @ 325 wHr/mile = 16,250 kWh @ $.06 off peak = $975

Savings at current costs = $9,172

If both gas and electric double in cost over 5 years time fuel savings alone will amount to $13,758

No money sent to terrorist supporting foreign regimes: Priceless!

[paco3791]

insndvr,

your point about bluestar is what might be the real concern here, if there is one. I would say that this will also come in to play for whitestar (and bluestar), much more than for the roadster since it is such an upmarket vehicle and buyers will be more tolerant of "quirks". Also as you move down market buyers will become less informed about the base technology and its potential disadvantages.

That being said I don't know if this will be as much of an issue for the REEV whitestar and GM Volt. They will have to use different cell chems because of the application and that may limit the impact of this particular problem. We'll just have to see what other issue pop up with those vehicles.

[BrianMRolfe]

I agree, the battery life limitation is notable simply because the practical ramifications are unknown. I actually believe this will end up being more relevant for Roadster owners than for future owners of the whitestar sedan or potential bluestar. The reason for this is that the Roadster is an "instant classic" and for that reason a collectible. The very long term usability of the car is a component of its value to the collectors who will purchase it.

IMHO, as Tesla moves down market, the cars will increasingly become commodities and the buyer an individual who is not looking to own the car past three to five years.

The major car dealers today do not support their business on selling cars that last decades, but on individuals who want the latest model. Building cars that last for decades does effect resale value but this, in my opinion, is a secondary consideration (relevant, but secondary).

I think the EV market is too young to worry about resale value effecting sales. It will take years to satisfy the initial market demand and by that time the world of battery technology will have changed to the point that current predictions are somewhat futile.

[paco3791]

IMHO, as Tesla moves down market, the cars will increasingly become commodities and the buyer an individual who is not looking to own the car past three to five years.I can't say I disagree with you on this statement Brian. Especially for the target market of a 50-70k sport sedan.

But speaking for myself, if I am going to invest that kind of ching in a car, I am damn sure going to drive it for more than 3 years. In fact a reasonable loan on a vehicle of that price for a person of my not totally unreasonable financial means is probably a minimum of five years! I would like to drive the car for at least, say 7-8 years, to get more out of the substantial investment made up front. For a full EV what does that kind of time frame mean for range and performance? Assuming a reasonable/average charge-discharge cycle what kind of "total mileage" can I expect to get out of the battery pack, and in what time frame?

I am very seriously considering a whitestar purchase and these are important questions. Hopefully there will be more info on these issues before I have to make a decision on plunking down $5-10-20K (or more) to get on a whitestar wait list.

[Albern]

I am very seriously considering a whitestar purchase and these are important questions. Hopefully there will be more info on these issues before I have to make a decision on plunking down $5-10-20K (or more) to get on a whitestar wait list.

I actually decided to not get a new car this year and wait for the Whitestar (pending its final details). I'm glad you brought the battery calendar issue on the forum as I would store my cars for 4 months out of the year during the winter. Hopefully the series hybrid / REEV version of the sedan will be able to combat such concerns but at the expense of more frequent visits to the gas station.

Early indications show that the REEV would be ~$50,000 while the full BEV would be upwards of about $70,000 - Tesla Gets $40M, Says We'll See Sedan This Year | Autopia from Wired.com (http://blog.wired.com/cars/2008/02/tesla-motors-ge.html).

[BrianMRolfe]

But speaking for myself, if I am going to invest that kind of ching in a car, I am damn sure going to drive it for more than 3 years. In fact a reasonable loan on a vehicle of that price for a person of my not totally unreasonable financial means is probably a minimum of five years! I would like to drive the car for at least, say 7-8 years, to get more out of the substantial investment made up front.

You make an excellent point.

Currently it appears Tesla is offering assurances of 100,000 miles/5 yrs (whichever comes first) on the Roadster. As you point out you have every intention of keeping the whitestar longer than five years. If you were to reach that milestone today, your options would be to buy another ESS at an estimated $20,000 (guessing from earlier blog posts) or keep the current ESS (which will be at 80% capacity and falling).

My only point is that you aren't going to have to make that decision today. You will have to anticipate the options in 2009/10 when you consider whether or not to purchase the whitestar. You will have to actually make that decision around 2014/15 when the whitestar ESS reaches the end of its "shelf-life". There is a very good possibility that the options available then will be quite different than what can be anticipated today.

I also 'anticipate' that your Tesla sales representative will have a well-considered response to your concerns. :)

[Cobos]

And as has been said after the calender life of the pack has been reached it will continue to loose capacity as you add months and more miles on the pack. What actual state it will be in compared to your purchase date is still unknown. It might be about 80% of the range or it might be 90% or it might be 30%. I would guess at the 60-80% mark. Regardless the car should still be driveable and you would only need to change the ESS if you wanted to.

Looking at the Think purchase model you would after I beleive 3 years get an option of getting your battery replaced and still pay the same mobility-pack monthly fee, OR keep your lower performing battery and pay a substantially lower mobility-pack fee. So they also expect the old batteries to last for some time after they are passed their prime.

Cobos

[Cobos]

Moved post to Video section

Cobos

[Joseph]

I don't know if this has been talked about, but on the handy FAQ section of Tesla Motors they say,

"Our testing and modeling indicate that a typical Tesla Roadster owner who drives 50,000 miles over five years should have about 70 percent of initial performance levels available."

This gives us some more details about the life of the battery. My first concern about this was whether this loss of "initial performance" includes the range and power output, or just range. I talked to ProEV (google them), who have a Kokam lithium-polymer battery race car. They said that power output shouldn't be affected, only range. IMO, this makes it less of a deal breaker. The car will "only" go ~160 miles after five years of driving but it will still be super fast.

[AGR]

Since the Roadster is constantly compared to "exotics" and "super cars" which are usually toys not used for commuting the battery pack will last or should last several years.

If the Roadster is used as a commuter car doing 12 to 18,000 miles per year...the customer would not want to own the battery pack.

What is a used electric car with a "worn out" battery pack worth? What is the depreciation on the car? What is the depreciation on the battery pack? What is a used Ferrari F430 with a worn out motor worth?

Once the initial sales to the high profile customers are done, the typical customer will look at a "walk away" lease on a Roadster or a Sedan the lease term will be within the parameters of the warranty, and life expectancy of the battery pack.

Let Tesla remarket the car with a used battery pack, or let Tesla install a new battery pack, or reconditioned battery pack in their reconditioning process.

[malcolm]

Here in the UK, replacing the ESS after 100,000 miles is already starting to look like an economical choice.

If petrol here stays fixed at its present £1:20 per (Imperial) gallon - HA! and the electricity night rate stays at 5p per kWh, then 100,000 miles of motoring will cost about £15,500 in petrol for any ICE car getting an average of 35mp(I)g. Electricity for the Roadster will cost about £1,500 for 100,000 miles (assuming you always charge at the fastest rate possible).

So I could afford to pay anything up to £14,000 (about $27,800) for a replacement ESS!

Of course, comparing the Roadster to a 35mpg car is silly. Mileage and maintenance of comparable ICE sports cars is even worse - so the sums are even better for the Roadster after 100,000 miles!