Lithium Ion Batteries Can’t Stand the Heat

By · June 22, 2012

Lithium ion batteries are truly fair weather friends – just like people, they fare best in a comfortable climate. Lately, we at Pike Research have been delving deep into how environmental factors, such as temperature, affect battery performance and the rates at which vehicles are charged or discharged. Our discussions with automotive companies and battery pack assembly companies have revealed numerous approaches for optimizing performance and extending a battery’s life – comparable to the many ways people dress to beat extreme heat.

According to our research, lithium ion batteries perform optimally, and will last longer, if they are kept at temperatures between -10°C and +30°C. This range is consistent with findings by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE).

In very cold temperatures, batteries don’t achieve their full rated power until the battery cells warm up. According to Ford engineers V. Anand Sankaran and Bob Taenaka, this short-term effect has greater implications for battery electric vehicles (BEVs) than for plug-in hybrids (PHEVs). A PHEV can rely on its gas engine for power during warm up, but BEVs don’t have that other power source.

As the accompanying EERE graphic shows, batteries exposed to hotter average temperatures lose their ability to store energy; the hotter the temperature the faster they lose their storing ability. So BEV owners in Phoenix will likely be looking to replace their batteries faster than owners living where the thermometer doesn’t often reach 110°F.

To combat the extreme temperature effect and keep batteries within their optimal temperature range, automakers use thermal management systems relying on either air or liquid cooling. As the EERE data shows, liquid cooling is generally more likely to preserve a battery’s capacity than air cooling, though performance variations will occur depending on how well a battery management system was designed to control temperature. According to Ford, the liquids used in cooling systems can retain a temperature for a long time, which contributed to Ford’s decision to use liquid cooling on the Ford Focus EV. Ford has also used air cooling on its hybrid Escape and Fusion, as have Nissan and other BEV manufacturers on their vehicles.

In addition to external heat potentially shortening the usable life of a battery, operating batteries at high charge and discharge rates can have another negative impact. That is particularly true for fast DC charging a battery pack at a rate of 50 kW for as little as 30 minutes (the expected time to charge a BEV 80%). If done every day, that would generate enough heat to reduce the battery’s capacity. BEVs that offer fast charging were designed with this fact in mind, so their battery management systems can force an EV charging system to slow down, thus protecting the batteries well before the pack is fully charged.

The interaction of batteries and fast charging is one of the many EV topics that Pike Research will explore at the Plug-In 2012 conference, the premier North American EV industry event, on July 23, 2012, in San Antonio. I’ll be representing Pike Research at the conference where Ford and many of the leading companies will be discussing business models, technology challenges, and EV rollout strategies.

Comments

· Zarwin (not verified) · 5 years ago

Since that graphic is so hard to see, being horribly crushed down, here is the direct link to the presentation referenced in the article:

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/thermoelectrics_app_20...

· · 5 years ago

Outside of the unfortunate title this article carries (which will invite unwarranted criticism of lithium cell technology from anti-EV zealots in general,) there's a lot of good information presented here.

I didn't realize it until I moved to the warm desert climate from the cold northeast some 30 years ago, but automotive battery (12V lead acid) manufacturers design different batteries for different regions. Thick lead plates, for instance, that would be common for a long life cell in colder climates is something you won't find in a heavy duty unit designed to long life in a high heat climate.

Stands to reason that lithium cells will be formulated with slight variations in design for the disparate climates where the vehicles they'll be installed in will spend most of their lives.

I'm wondering: which particular lithium formulation makes the best low resistance cells?

Now, if we can only convince OEMs that heated steering wheels simply don't make sense for every car slated to be sold in Arizona!

· · 5 years ago

"just like people, they fare best in a comfortable climate"
Fortunately, humans have spent a lot of the past 10,000 years or so learning how to make themselves comfortable in sub-optimal climates.
This, then restricts EV usage to places where people have learned to live comfortably.

· · 5 years ago

This article has a great catchy title if you are trying to scare off potential buyers of EV's. What about, "How batteries and high heat interact" or something like that? Sensationalist titles will be used by the "other" side. It is way too early to say how things will go in high heat areas really. The suggestion of potential problems makes it a reality for some.

· Lad (not verified) · 5 years ago

I invite the writer to visit The A123 web site for an update on his thinking about batteries. They have just announced their chemistry will not be affected by high or low temps and doesn't require heating or cooling...the title should say "Some Li batteries..."

· David Martin (not verified) · 5 years ago

No mention of the fact that different battery chemistries perform very differently, both at high and low temperature and in cycle life under fast charging.
The effects, for instance, of switching to lithium titanate are far more than whether you are using air or liquid cooling on manganese spinel.

· · 5 years ago

I'm surprised Any Chu from A123, who is a registered participant here, hasn't logged a comment regrading their new & improved LiFePO4s.

Unfortunately, as the Plug in Cars article from a couple of weeks ago points out, these new batteries seem destined to be used in anything and everything that ISN'T related to consumer EVs . . .

http://www.plugincars.com/battery-maker-a123-systems-pivots-away-electri...

· Chris O (not verified) · 5 years ago

Pike Research....isn't that the same guys who predicted that battery cost would be at $523 per kilowatt hour by 2017 just a few months ago while recent studies indicate battery cost dropping much faster than that to just $250 by 2015, which is in fact more in line with the $400/KWH that Tesla charges right now for battery capacity retail?
I think nobody should take anything Pike research says about EVs too seriously. Their main objective seems to be spreading anti plug-in FUD as demonstrated by the title of this article.

· · 5 years ago

Reminds me of this article from last Oct. http://batteryuniversity.com/learn/article/discharging_at_high_and_low_t...

Making sweeping generalities regarding lithium ion batteries I find rather silly. The performance of lithium ion batteries varies dramatically with construction, chemistry, format, etc.

Here's an interesting PR
http://ir.a123systems.com/releasedetail.cfm?ReleaseID=682278

· · 5 years ago

The modern electric car was invented back in 1998 by honda, it was their first hydrogen fuelcell car prototype

· Andy Chu (not verified) · 5 years ago

A lot could be said about the issue of calendar life and this probably merits an A123 blog post on its own. One comment I'd make regarding fast DC charging a battery pack: it's not just the heat or temperature that will reduce the battery’s capacity. The statement in the article implies that if you could only cool the battery properly during fast charging, you wouldn't have reduced life. In fact, other mechanisms can also reduce life during fast charging, such as from lithium plating or structural damage to the active material particles.

Calendar life will vary based on chemistry, cell and system design, and other factors. Without having hundreds of individuals conversations, discussing the details of any given situation, it's impossible to avoid generalities. The key is just to recognize that they are rules of thumb. Actual results will vary. =)

· · 5 years ago

Could you comment, Andy, on the new EXT batteries that A123 will be producing soon? Specifically: it's been reported here (link in my above post to another recent Plug In Cars story) that there will be less of an emphasis on supplying EXT cells to EV manufacturers but, rather, marketing them mostly towards telecommunications and military applications. I think a lot of us here would be disappointed if these new batteries of yours wouldn't find their way into next generation EVs.

· Spec (not verified) · 5 years ago

So . . . is this what Nissan and Arizona Leaf owners are learning the hard way?

· · 5 years ago

I suppose the operative word here, Spec, is "leaning." Better to possibly fail, learn and improve than sit back, complain that it will never work and accomplish nothing.

· Andy Chu (not verified) · 5 years ago

The Nanophosphate EXT technology will be finding their way into next-generation passenger vehicles. Although we focused on the micro hybrid market during the launch, reducing or eliminating active thermal management is an area that we think could be very attractive for EVs.

· · 5 years ago

@Benjamin Nead,
I think that A123's biggest hurdle for supporting EVs will be finding a manufacturer that will buy enough of their batteries. Nissan seems to be interested in their current Asian supply options. Tesla wants to stick with commodity form factors.
This leaves GM and Toyota as the only ones mass producing EVs and theirs are both PHEVs with relatively small batteries.
I hope that other auto manufacturers start making EVs in large quantities so there's a real battery market for A123 to support. Otherwise, it is smart for them to diversify outside the EV business if that's where battery customers are.

· · 5 years ago

Glad to hear that, Andy. I did catch a web news lately that the upcoming Chevy Spark is slated to have EXT cells installed. Good luck with that and let's hope GM will allow this car to be available nationally (not just a lease-only California compliance item.)

I own, incidentally, a small 4.6Ah / 13.2V pack comprising of 8 A123 26650 cells . . .

http://www.rce168.com.tw/welcome/main/20

The builders of these packs design them as drop-in replacements for 12V motorcycle ICE starter batteries. I couldn't resist the eye-catching packaging, the A123 cells contained within and I was additionally sold on the promise of their top notch BMS.

RCE makes rather extraordinary claims - which I tend to doubt - that they're the only authorized A123 reseller in China. But I do think they put together very nice packs. Retail pricing is also all over the map. They sell on eBay (where I got this one) and either practically give them away or charge far more than anyone else putting together packs with a similar cell count.

While I've not subjected it to much stress, I will end up using it as a field battery for my model airplane hobby. It did get put to use some months ago in the home burglar alarm, when the main panel's NiMH pack failed and it took several days to go find a replacement. After that incident, my wife stopped being mad at me for buying this thing. :-)

· · 5 years ago

They forgot to say that they can't stand the cold too and here in canada it's cold for 6 months a year.

· · 5 years ago

And also i won't buy any battery only car if it don't come with a small gasoline electrical generator because when it's cold the battery have to be back-up by a generator to attain the optimal temperature. Then the volt seam right but the generator is oversized and the whole car is too costly but they are near an optimal car if they can drop the price to 25 000$ approx.

· Mark (not verified) · 5 years ago

What I take away from the first chart is that even in worst case Phoenix, an EV will still retain 75 percent of its relative capacity after 12 years. And then the battery will begin its second life as home or cell tower back up power. This seems like good news to me.

· · 5 years ago

@Mark, The problem with that chart is that it is NOT proving true for the LEAF in Phoenix. Many LEAFs there are down to 85% capacity in just 10 months to one year and some are already approaching 80%. What is needed for hot climates is thermal management or a battery chemistry that is less sensitive to heat.

Anyone buying a LEAF in a hot weather state would be well advised to lease the car. Or pick another EV that does have a thermally managed battery pack and hope that it is effective.

· · 5 years ago

@dgpcolorado - So the Leaf and i are going to be more prone to battery degradation from heat than the Tesla, Focus, or other EVs that use water cooled batteries? Is that what you mean by thermal management?

Because I know there is some air cooling on the i - not sure about the Leaf.

· · 5 years ago

@Dan, Probably not. The LEAF battery seems to be holding up well in mild climates. The rapid capacity losses are happening in places like Phoenix, Dallas (hot summer last year), Tucson, and Palm Springs. Places that can get really hot for an extended period of time. (The warranty says the battery should not be exposed to 120ºF for more than 24 hours.) Places that get a routine seven bars on the temp gauge for an extended period of time. For people in Seattle, San Francisco, Toronto, Norway (or high up in the Colorado mountains like me) it isn't an issue to be concerned about. Since you live in Pennsylvania, according to your profile, my guess is that you won't be affected by this extreme heat issue.

The issue with Thermal Management Systems (TMS) is how they work. Do they actively cool the battery pack—meaning running AC to chill the battery coolant—while the car is parked and plugged-in? How about while it is not plugged-in? Or are they just for heating the pack in winter to keep range up in the cold? I believe that the Volt will actually cool the battery while unplugged down to a certain charge level (Volt owners can correct me if I am wrong about that). Does the FFE or Model S do that? I have no idea. If not, it won't help much to protect the battery pack from extreme heat unless they are using a battery chemistry that is less sensitive to heat than the LEAF.

There are reports of new battery chemistries that are less sensitive to heat than Li-Mn. If those prove viable that might eventually be the best solution for EVs in Phoenix.

· · 5 years ago

I'll have to check with some of the 15 or 20 Leaf owners I know here in Tucson, but I have yet to here any of them complaining to me of excessive battery capacity loss on their vehicles. As with Volt battery fire stories from this past spring, I tend to think this one has been over-hyped and blown out of proportion. Perhaps we should have an "Urban EV Legends" tab on this site to keep track of this stuff

We're having another hot one down here this summer but that has translated to daytime highs of around 105 F and nighttime lows in the 75 to 80 F range. It might be above 100 for only a few hours per day. Phoenix is slightly worse in this respect, where just about 110 is the current daytime high . . . and, again, that isn't a 24/7 temperature constant.

Agree, though, that long term high temperature damage to various types of lithium batteries is something that should be carefully researched and tabulated. We're still in the early years of widespread commercial EV adoption. We'd be naive to think that first generation vehicles weren't going to have areas that were going to need improvement. The early adopters (you know, those "interlopers" who who are getting the big federal tax break) are the ones who are helping us find out.

· Dan Hollands (not verified) · 5 years ago

FFE definitely cools the battery. In extreme cases the manual says the air condition may be diverted from the driver to cool the battery. It obviously does this while driving. Not sure what happens if it is turned off and not plugged in

· · 5 years ago

@Benjamin Nead, if you think the LEAF battery capacity loss in very hot areas is an urban legend you are profoundly mistaken. The LEAF has a battery capacity gauge and at least 19 LEAF owners in the mynissanleaf.com forum have reported the loss of the first bar and 2 have reported the loss of two bars. All of them are located in very hot climate areas, most in Phoenix. At least one Tucson owner has used a Gidmeter to determine that he was down in capacity and expected to lose a capacity bar in the near future.

Based on the original LEAF service manual the first capacity bar represents 15% and the subsequent ones about 6%. (However, the table was left out of later revisions of the service manual.)

· · 5 years ago

@dgpcolorado,
If the only evidence is a few posts on an open forum, I'd definitely call it a candidate for urban legend. I'm not saying it isn't true but I'd hardly say anyone has shown me any solid evidence.
What the heck is a Gidmeter by the way? It sounds from some searching the all-knowing, all-valid internet, it appears to be something some shade-tree mechanics (or should I say shade-tree-computer-geeks) hacked together to try to read the Leaf's diagnostic port. They really don't seem to know what it is reading, they're just making guesses.

· · 5 years ago

@ex-EV1 driver, Well, you won't get any solid evidence if you don't bother to look for it. I have been monitoring the 90+ page threads on the subject at MNL for quite some time and the loss of capacity bars in very hot climate zones is hardly some sort made up nonsense or just few anecdotal outliers. Some of the people reporting the drop in capacity have long posting histories and considerable credibility.

Yes a Gidmeter reads battery watt-hours from the LEAF's data port. The data are quite consistent with the drop in capacity bars and predictive. You may choose not to believe it but there are some very bright EE LEAF owners working on understanding the car. To dismiss them as "shade-tree-computer-geeks" is a remarkable bit of arrogance from you.

I am troubled by the notion that this heat problem should be swept under the rug and posters at this forum should just wave their pompoms and cheer "GO EVS!" Seems a bit short-sighted to me. And it is not as if I don't have some skin in the game: I plunked down my money to buy a LEAF, despite my meager income and no EV infrastructure whatsoever in the area where I live. I am also in the process of tripling my solar panels so that my LEAF and household electricity use will be fully "sunpowered". But that doesn't mean I am wearing blinders when looking at issues that confront EVs.

· · 5 years ago

@dgpcolorado,
Sorry if I came down so hard but I tire of folks thinking that Internet information is definitive.
I, too, am concerned about Nissan's election not to cool their batteries and have posted many times to this affect. Short-sightedness seems to be Nissan's main flaws, including their sadly slow L2 charging rate, short range, and what may be a battery cooling deficiency. I just hope that the whole plug-in vehicle market doesn't take too much of a hit because of the perception damage done by poor execution.

· · 5 years ago

I didn't mean to write off the phenomenon of hot climate battery capacity depletion as purely urban legend, dgp. But this sort of news will undoubtedly be blown out of proportion and used nefariously by those who simply want to see EVs fail on all counts. Yes, it's a serious issue and for none more so than Leaf owners.

Perhaps it would be valuable to know the total number of Leafs that are in the hotter climates and what percentage of these have shown this sort of permanent depletion. Studying those, how many follow a trend of being regularly parked in direct sunlight on particularly hot days? Were any of these cars quick charged regularly? What might these affected car owners be doing differently with their Leafs when compared to identical, unaffected Leafs parked down the street? These are the sorts of statistics that are worth examining in detail.

One of my Leaf owner friends, Jerry Asher, who has already put 10s of thousands of both long distance highway and in-town miles on his car, should be able to give us some insight. He's due back in town later today and I'll ask him then how his batteries are doing.

Side note: I have lots of household devices that use NiMH and lithium batteries and I've gotten to know a bit about the related technology of the charging equipment. Memory effect is well known in the realm of NiMH AA and AAA cells and there are somewhat sophisticated chargers designed to recondition such batteries that are no longer holding a charge as well as when the batteries were new. By all accounts, they work quite well . . .

http://www.thomasdistributing.com/Maha-Powerex-MH-C9000-AA--AAA-Battery-...

Likewise, with the tiny lithium packs used in model airplanes and cars, tools are available to partially discharge the cells in a controlled and consistent fashion, when it is known that the batteries won't be used for several months at a time. This, apparently, leads to longer cell life and the little field box devices sold for this have been reported to do it quite well . . .

http://www.hobbyking.com/hobbyking/store/__10328__Hobby_King_Battery_Med...

Perhaps a larger version of the above lithium "battery doctor" could be employed at dealerships to periodically partially discharge the Leaf's pack and then recharge each cell comprehensively (ie: more precisely than possible through the single J-1772 port) to full or near-full capacity. If it works for the little stuff, it's certainly worth trying on the big stuff. Just a thought . . .

· Toby Palisbo (not verified) · 5 years ago

Solar power is such an excellent method of creating energy. I read somewhere that the sun produces enough energy in 45 minutes to power the whole worlds energy supply for 1 year. I hope more people find out about the incredible benefits of renewable energy and are motivated to change over while we still have time. I'm hoping to change our house over soon too(and will be so happy to know my electricity use isn't polluting the Planet. Toby Palisbo

· Natalia Jenkins (not verified) · 5 years ago

I had never heard that lithium batteries can't stand the heat. But it seems smart for manufacturers to use cooling systems for the batteries. Many electronic devices using some type of cooling system to keep the temperature balanced.

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