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Ford’s Key Life Battery test for Li-ion batteries simulates 10 years, 150K miles in 10 months, under different conditions

Leveraging some 20 years of experience and data reaching back to its early work with hybrids and the Ranger EV, Ford has developed a battery model and life validation protocol it now uses to predict how lithium-ion batteries are likely to perform under 10 years and 150,000 miles of use (40-season equivalent key life tests). The Key Life Test (KLT) takes about 10 months to complete.

Ford had earlier developed a NiMH battery model for use in KLTs, as detailed in a 2010 paper by a Ford team (Yang et al.) published in the International Journal of Energy Research. A detailed core model incorporating critical degradation mechanisms of battery components under various usage profiles is key to the testing. The Li-ion KLT test allows engineers to simulate many factors affecting the Li-ion batteries, including location of a battery within a vehicle; the temperatures they might have to endure; and various kinds of acceleration and stopping that different drivers would apply.

Other battery tests include simulating hot and sunny Phoenix weather by subjecting batteries to greater than 140 °F (60 °C) temperatures, extreme cold conditions in Manitoba, Canada with -40 °F (-40 °C) tests, and by driving vehicles equipped with the batteries through ditches filled with water to ensure there are no issues.

Battery reliability ranks as the single-most important purchase consideration by potential hybrid customers, topping 17 other factors such as fuel economy and number of safety features, according to a recent Ford-commissioned survey. The Key Life Test aims at delivering higher-quality and even more reliable batteries, said Kevin Layden, director of Ford Electrification Programs.

Ford began working with hybrid vehicle technology in the late 1980s. The company offered a limited release of the Ranger EV in 1998, the Escape Hybrid in 2004 and the Fusion Hybrid in 2009. Ford draws on the data it collected from these previous-generation efforts, especially the higher volume production hybrids.

For example, 50 million battery cells have been produced since 2004 in previous-generation production Ford hybrid vehicles such as the Escape Hybrid and Fusion Hybrid. Some of these have been put to use in taxi fleets in such cities as San Francisco and New York, with some taxi vehicles attaining more than 250,000 miles individually and taxi fleets in California alone attaining a total of nearly 100 million miles.

Of all Ford production hybrid vehicles produced to date, only six battery cells have failed of the 50 million that were put into use, the company said.

We can’t do an apples-to-apples comparison between the nickel-metal-hydride and lithium-ion batteries, but we can evaluate much of the data collected to see how hybrid vehicles are driven, the kinds of conditions they face and the demands that are placed on them. Knowing all of that helps us benchmark our tests and ensure the lithium-ion batteries are meeting or exceeding expectations.

—Mazen Hammoud, chief engineer, Electrified Powertrain Systems

Ford is investing $135 million in the design, engineering and production of key components—including doubling its battery testing capabilities—for the five electrified vehicles the company will have in its portfolio by the end of the year: Fusion Hybrid, Fusion Energi plug-in hybrid, C-MAX Hybrid, C-MAX Energi plug-in hybrid and Focus Electric.

Ford also now has more than 1,000 engineers working on vehicle electrification, which is headquartered at its 285,000-square-foot Advanced Electrification Center in Dearborn.

Ford says it has reduced the cost of its current hybrid system by 30% compared with previous-generation technology and vehicles are coming to market 25% faster.


  • Yang, X. G., Taenaka, B., Miller, T. and Snyder, K. (2010), Modeling validation of key life test for hybrid electric vehicle batteries. Int. J. Energy Res., 34: 171–181. doi: 10.1002/er.1657


Kit P

My conclusion has not changed. Hauling batteries around is a stupid idea except for the one to start the ICE.

“some taxi vehicles attaining more than 250,000 ”

Is that it is that is all they are going to tell us. Ford like to brag about how there vanilla 5 passenger car by comparing to the US average. You can tell about about how good something by the facts they present or do not present in this case.

Ford did not present any facts to suggest that batteries are a better way for consumers to meet their transportation needs.

I work in the power industry. Our record in the US is very good especially nuclear. A few counties come come close. For example when I worked in Spain and I hear the same about Japan, power companies do not support running the washing machine and dryer at the same time. What if everybody came home from work and did a few loads of wash while cooking dinner while turning the heat up or cooling down? In the US, this is not a problem.

The problem I have with Detroit is that building a quality car for American families was not 'Job one' for half my adult life.


"..only six battery cells have failed of the 50 million that were put into use.."

One wonders how many million of the last 50 million ICE engines have failed during 150,000 miles.


I know this story is supposed to impress me with Ford's futuristic forethought, but really I am just surprised they didn't do this ten years ago. The car companies are really slow on the uptake. I suppose the brainwash they have the public controlled under takes time to remanipulate.


The ICE on my new Mercedes failed (vapor lock etc) about 40 times in the first 12 months before I got rid of it? I never came near a Mercedes since. However, my wife Camry did not fail (while in use) in the first 13.5 years i.e. before the (second) timing belt broke down while she was driving on a city street, i.e. after only 82,000 Km. The first timing belt was changed at 110,000 Km. Her Camry will be due for a third timing belt in 2018/2019 or so. By that time it will be almost 20 years old. No wonder that the Camry has been the number one selling car for the last 9 years or so.

Bob Wallace

This is good news. It means that new battery design can get to market faster.

We see so much encouraging battery tech on these pages but so little improvement in what is being installed.

Speeding up the testing process and making them "real world" is a great move. It will mean that we can dismiss ICEVs as 'last century' transportation even sooner.


If the average ICE engine lasted 150,000 miles at 50 mph, the mean-time-between-failures(MTBF) would be 3,000 hours.

This article describes the Ford method of simulating 150,000 miles on EV Li-ion batteries.

"..only six battery cells have failed of the 50 million that were put into use.." calculates to 1 failed cell per 8,333,333 cells.

If a Ford battery uses a hundred Li-ion cells, the MTBF is 83,333 hours.

So, the battery is ~28 times more reliable(MTBF) than ICE. Even if a one-moving-part motor/electronics has a similar MTBF, this still leaves a EV power train 14 times more reliable than ICE.

With these numbers, it really doesn't matter if some think "Hauling batteries around is a stupid idea except for the one to start the ICE."

Ford marketing FIVE new electric drive models is clear enough.


The reason "they didn't do this ten years ago" (nor did ANYONE else) is because there was no EV market 10 years ago. And because of battery costs, there is not much of one now.

And these are "PR pseudo-facts". All car makers do similar BS with ICE powered cars.

And "new Mercedes failed about 40 times in the first 12 months" is not typical of ICE cars (except Mercedes).


The problem with thinking why didnt we do this 10 or 20 or 30 years ago is just what we didnt have 10-20-30 years ago.. or what we had that was total junk compared to todays stuff.


The reason we didn't have EVs decade(s) is examined at

Suppose we had microprocessors, NiMH, and Li-ion batteries in the 1990s(we did) instead of corrupt, soon-to-be-bankrupt-and-taxpayer-bailed-out automakers.

Suppose all firms had immediately started improving and extending their own versions of the 1997 Prius and RAV4 EV since 1997.

The US should already have a complete EV charging infrastructure and significant EV saturation.

The people saying EVs don't work are the same ones driving in the 'fewer than 40 miles a day' EV statistics.


The people who said EVs didn't make sense in the 1090s were the 30 or 40 automakers in the world, ALL of them.

They said it with their actions, not just with empty words.

Toyota started making the Prius in the late 1990s and has made great strides, but since EVs of all kinds first entered the U.S. market, they have saved maybe 35 million barrels of oil (.03% of total US usage), and most all of that RECENTLY.

That is the PEOPLE saying it with their ACTIONS.

EVs will (none too) soon make a difference.

Bob Wallace

Take a look at this graph of crude oil prices from 1869 to 2009. Perhaps it will help folks understand why EVs were not actively pursued in the 1990s.

And think about the heyday of the SUV. Cheap oi. Big inefficient vehicles. Little interest in EVs and other ways to avoid high fuel prices.

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