Ford Says Li-On Batteries to Outshine Very Reliable Nickel-Metal

By · December 12, 2012

Ford Battery Testing

The lithium-ion reliability performance is based on lab data, but it's likely to prove true in the real world. (Ford graphic)

Probably the biggest worry people have about electric cars is projected battery life—it’s a top purchase consideration. The fear is this: A few years down the road, their pack will fail and the dealer will be holding out his hand for $20,000. First of all, this isn’t likely to happen because most EV batteries are warranted for eight years or 100,000 miles (it’s 10 years and 150,000 miles in California emission states).

Low Failure Rates

And it’s also not likely to happen because batteries in hybrids and electrics have proven incredibly durable. A Consumer Reports test of 2001 and 2002 Toyota Priuses with 200,000 miles found spot-on performance, including from their battery packs. Obviously, we don’t have much long-term data on lithium-ion batteries yet, but Ford says it’s figured out how to simulate that—with a rigorous protocol called the Key Life Test that mimics 15 years of wear in just 10 months.

The company has performed real-world testing on nickel-metal packs—some new, others with high mileage—and used lab data to extrapolate how much better lithium batteries would perform under the same conditions. As the chart above shows, lithium should degrade at a much slower rate, perhaps 20 percent better.

Great Expectations for Li-Ion

“We’re very confident that lithium-ion is going to greatly exceed the capability of nickel-metal-hydride,” says Kevin Layton, Ford’s director of electrified power engineering. “And in our testing, nickel-metal cells and packs [taken from such cars as the Ford Escape Hybrid]—some with more than 250,000 miles on them—have performed flawlessly.” California’s Escape taxis have collectively almost 100 million miles on them. Ford has put 50 million hybrid battery cells on the market, and only six have failed.

Anand Sankaran, a Ford technical leader for energy storage and hybrid systems, said the company takes batteries, as well as individual cells, and “accelerates their failure modes.” That means subjecting them to 140 degrees Fahrenheit in Phoenix, and minus-40 degrees in Manitoba, as well as water immersion tests and other challenges.

Big Benefits

Li-ion has obvious benefits over NiMH, including 25 to 30 percent size reduction with three times the power output per cell. Some companies are sticking with nickel-metal for hybrids and li-ion for battery electrics, but the trend is plainly in lithium’s favor. Durability is still the critical question, so we’re awaiting the first hard data on that. Projections like Ford’s are interesting, but what’s really going to matter is what happens in the field.


· Whiny Person (not verified) · 3 years ago

I would like to propose that we all stop using the term "lithium ion battery" because I think it's going to lead to a lot of confusion for consumers. There are a load of different chemistries and Ford happened to test the one they use in their hybrids. Their battery pack uses some state of charge windows and I don't know what they are. Whatever they are they are working well.

"your mileage may vary". ......And now we should also teach people: "your battery chemistry will vary".


· Modern Marvel Fan (not verified) · 3 years ago

Not all Li battery are created equal. That is very true.

However, even the "lowest" peformance Li-ion is better than the best NI-MH in terms of power density, energy density and energy/mass.

· Whiny Person (not verified) · 3 years ago

Yes true. :-)

This article is about cycle life though. Recently We have had the problems with the Nissan Leaf. I just think that journalists should say what the chemistry is in each electric car and talk about it's properties. If "lithium ion battery" is this one type of battery and there is a problem with the battery in one of the new cars then it will hurt all the cars and the reputation of EVs. It shouldn't do though because they are all using different chemistries.

The Chevy spark may have a battery that could last for 2 vehicles (slight exaggeration), but the Leaf maybe doesn't (OK not necessarily true but I'm making a point stay with me). The public aren't told about this though.

I think everyone is smart enough to be told about the different chemistries.

· · 3 years ago

@Whiny Person,
Unfortunately the differences between battery pack suitability goes well beyond just the fundamental chemistry. Performance is also dependent on interconnect wiring, pack cooling, as well as many different internal design characteristics.
A lot of things can make batteries look bad. Just look at what the Leaf did for hot weather tolerance of Li-ion batteries.

· · 3 years ago

I can't make heads or tails of this graph which has numbers with no units on the x-axis and nothing at all on the y-axis.

· · 3 years ago

In the hunger for good news on the EV front, there seems to be a lot missing from articles like this:
1- did these tests involve the use of an active thermal management system?
2- besides just temperature, were the batteries subject to quick-charging? Besides increased energy density (i.e. range), the ability to quick-charge appears essential if EVs are ever to take hold.

@ex-EV1 driver - Got time for another tutorial on "interconnect wiring" and other "internal design characteristics"?

· Jesse Gurr (not verified) · 3 years ago

If that graphic was available when the article was first published then it isn't there now. I found the press release from ford at:

They have a different picture than what you have included. Here is the link:

There is also this:

Mildly interesting stuff here about battery evolution. I was surprised to learn that the NiMH cells used in the escape are slightly different than the ones used in the Fusion.

· Ernie (not verified) · 3 years ago

Okay, so first, it would be nice to see what the axes are labelled.

Second, it's not like Nissan hasn't already done this. About three years ago.

Third, and most importantly, the article failed to mention *how* it's extremely unlikely that you'll ever need to shell out $20,000 for a new battery pack when the old one goes kaput. And that reason is that car battery packs are not like laptop battery packs. Well, they are kind of, but it's all about how they're sold. Both laptop and large-capacity car batteries are made up of individual cells. But laptop batteries are *only* ever sold as complete packs, while car batteries can have those cells replaced for various reasons. The reason that any battery pack fails isn't because the whole thing fails all at once - it's always because individual cells fail. Unless something really catastrophic happens, like half of the pack getting destroyed in a collision.

· · 3 years ago

@Ernie - This may be true in theory but I am wondering if it is in practice:
"'s extremely unlikely that you'll ever need to shell out $20,000 for a new battery pack when the old one goes kaput. "
Others have suggested that the new cells would be drawn down first, presumably resulting in their rapid degradation to the state of the older cells. I'm wondering if the car's battery could ever be restored to a 'new car' capacity without replacing all the cells.

· · 3 years ago


"Okay, so first, it would be nice to see what the axes are labelled.

Second, it's not like Nissan hasn't already done this. About three years ago."

Are you saying Nissan also published a graph that make no sense at all? About three years ago?

· · 3 years ago

I've been working around batteries for various applications for over 20 years but I don't claim to understand what makes one better than another. I have come to the conclusion, however, that battery designers also really have limited causal knowledge about what makes one battery design more suitable than another. The only way I know of to know if a battery will work is to test the whole battery pack with realistic loads. GM and any serious EV manufacturer will have huge rooms of testers, charging and discharging them at loads that they expect the car to put on them during normal driving.
Clearly, this means one needs to destroy a few packs under different conditions. I'd guess that Nissan failed to test a pack's life at 120F ambient and full charge/discharge cycles or they wouldn't have tried to sell them in Phoenix without cooling.
I do know a few interesting things about batteries that I'll share:
1) Li-ion charging is apparently an endothermic reaction, meaning that the batteries actually get cooler as they charge.
2) The basic laws of electronics apply to batteries as well and if one doesn't put in large enough conductors, the current going through them will get hot and surpass the benefit of endothermic cooling of the actual Li-ion chemistry.

· · 3 years ago

"1) Li-ion charging is apparently an endothermic reaction, meaning that the batteries actually get cooler as they charge."

Here is an interesting article on the subject. They become heavily exothermic at the end of the discharge cycle.

· · 3 years ago

The link I see above (to a pdf) does not work, at least for the current Firefox I use.

Have any info. about whether problems with Boeing 787 battery systems mean anything for EV cars?
(They have different voltages, current, & needs, and vastly different operating environments, but some similarities, right?)
I am watching to see if useful conclusions are announced.

· · 3 years ago

Methinks that the various BEVs out there LACKING the very serious battery environment controls that Chevrolet has incorporated in the Volt, will be be needing early changeouts.

Air cooling or no cooling -- or heating -- is NOT going to get it In the diverse condtions EVs must face.

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