How Long Will Your Electric Car Battery Last? Science Is On The Case

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2004-2009 Toyota Prius battery pack, second generation

2004-2009 Toyota Prius battery pack, second generation

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We all know that battery packs are the biggest Achilles Heel of the electric car, which is why automakers like Nissan and General Motors are working hard to improve the energy density, cost and lifespan of electric vehicle batteries. 

But once you've designed a new battery pack, how do you prove its lifespan without waiting year and years?

You’d think that some complex math, along with some basic scientific theory would answer the problem, but life is rarely as predictable as a science lab. 

Instead, physicists, chemists, battery firms and automakers are working together to build sophisticated equipment that can give electric car battery packs a lifetime of testing in a few weeks. 

In turn, the test equipment could aid the development of cheaper, more energy-dense battery packs for electric cars that would easily outlive the life of any electric car.

Enter Dalhousie University professor Jeff Dahn and his research team. 

Tesla Motors - Model S lithium-ion battery pack in environmental test chamber

Tesla Motors - Model S lithium-ion battery pack in environmental test chamber

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Working with the Natural Science and Engineering Research Council of Canada, the Canada Foundation for Innovation, and a list of private-sector partners that include 3M Canada and Manga E-Car Systems, Dahn and his team are embarking on a five-year project designed to take the guesswork out of predicting battery life. 

Funded to the tune of nearly $4.1 million, the 25-strong team will examine how efficiently battery packs store and deliver electrical charges over time using tests that better replicate the real-world duty cycle of electric car and electrical grid-storage battery packs. 

In order to do this, the researchers will build new equipment that they claim will give battery packs a lifetime of use in just a few weeks, producing accurate battery degradation data that can then be used to better predict electric car battery life. 

What’s the result for electric car owners? Lower costs. 

We'll explain.

If more accurate data exists to predict battery life, automakers should be able to improve on-board battery management systems to more accurately anticipate battery degradation.

With a more accurate way to predict battery life, engineers can then work on producing cheaper and higher-density battery packs free from the worry of unknown pack-life.

Advanced Battery Pack

Advanced Battery Pack

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There’s a big benefit for those leasing or considering making a used electric car purchase.  

At the moment, leasing companies tend to give electric cars very low residual values after a few years, caused in part by uncertainty around battery life.  

As a consequence, lease payments may be higher to ensure the leasing companies are not out of pocket at the end of the lease. 

If more accurate battery life-evaluations can be given, perhaps with the aid of testing hardware designed to be used by garage mechanics at service time, leasing companies can amortize the higher purchase cost of an electric car over a longer period.

In turn, those buying a used electric car will be able to better evaluate the true lifespan of its battery pack before handing over any money. 

Cheaper, more predictable electric cars? That has to be a good thing.


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Comments (10)
  1. Today most of the auto companies focus on State of Health SOH, state of charge, temperature & currents. Effort is need measure State of Life, SOL. SOH is like a trip to your doctor's office;they measure your temperature, pulse & blood pressure at that very moment in time. You could walk out & drop dead. This SOL technology is important; with batteries it matters the time history. Constant cycling a battery pack is one measure even with varying the temperature. A battery pack left discharged for long times, can hurt the batteries & reduce their life, so do temperatures, rates of charge & discharge. To test a pack in a week and predict life will be a challenge, but we need it now. Must test at pack & not the cell level; need mfg variations

  2. I think there is difference between developing equipment to perform accelerated life testing of battery packs and developing equipment to measure the life remaining in a used pack. Are they doing both of these things or just the accelerated life testing?

  3. Good article Nikki. I would like to add my experience of two hybrids the first(Gen 1 Honda Insight) bought when it was three yrs old in 2003 and the second ( 2nd gen Prius) replaced it in 2008.Both these cars have been flawless throughout ownership and the batteries have shown no discernable difference during ownership. As stated elsewhere the Prius has been abused with extended periods of idleness each year without any ill affects it seems.Even the 12v batteries have outlived the norm. It remains to be seen if an EV which has much greater demands on the system will fair as well though.

  4. Forgot to mention the Prius an 04 is now eight years old.

  5. I think driving habits in these cars will vary widely, as well as operating conditions. I notice when the battery powered cars are compared to others this replacement cost is never considered. This is not an OWNER issue. It is a manufacturer warranty issue.

  6. There is a line of thinking that part of the higher price of EVs is a factor for the possibility of needing warranty repair of the battery. So the lack of reliability of batteries packs may be passed on to consumers in the form of higher car prices. At that point, it does become a little bit of an OWNER concern.

  7. There is also a huge difference between a single owner of a 6 year old car going on to the market to try to sell a used battery for second life at reduced capacity and a manufacturer doing this at bulk level. Manu's or lease companies will be able to do considerably different (better) deals as these very expensive LiON battery's are still going to be very useful for grid balancing or other uses when they hit 80% capacity and car owners are looking to take them out.

    We all know that EV power trains are going to be way more reliable than the corresponding ICE car engines.

  8. That is why Volt works. Even if the battery goes down in peformance, it is still a decent hybrid...

  9. Predicting battery life more accurately would NOT be expected to produce a better battery. Batteries are subjected to wildly varying experiences during their lifespan, making predictions probably impossible (unless batteries exist that are immune , lifespan-wise, to those differing experiences, a very unlikely event). And certainly there is no reason to assume that just because I can predict how long an A123 li ion battery lasts I will be in any better position to build a better one. And the name of the game, while lifespan is important, is battery costs, initial and replacement. If batteries cost 1/10th what they do now (as several companies have promised in the near future), then lifespan becomes a far less important factor.

  10. Well, cost is related to the lifespan. If it cost $200 and need replacement everey 3 month, it still won't be acceptable. But if it costs $15,000 but last 25 years, then it is a good deal.

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