Now this would be a huge jump in battery technology!

I sure hope Envia's claims come true. It announced it has produced a cell with energy density of 400 wH/kg and is priced at $125 per kWh. That would mean 300 mile range car in a car costing $20k. Better energy density and cost than anything out there today. This 2X+ improvement in batteries would really accelerate the electric car market. Read the article here.

Replacing my Chevy Volt Battery in 2020

Today's Chevy Volt Battery

I sure hope my Chevy Volt battery lasts for years and years. I keep my cars for a long time -- my 2012 Chevy Volt replaced a 20-year-old Toyota Camry. How long will the battery last? GM performed simulations that led them to conclude the battery will last many years past the 8-year warranty period. Just like my Camry lasted more than a decade after all its warranties expired. In terms of range, an article stated you would lose 10-30% of your range in 8 years.

For this exercise, lets assume you want to replace your Chevy Volt battery in 8 years (the length of the warranty). Since we are in 2012, that means it will be 2020 when I'm in the market for a replacement battery pack.

What will batteries be like in 2020? There are millions and millions of investment dollars around the globe racing to make the best car battery. What will the range, cost, size, and charge time be in 2020? To simply, I limited myself to three scenarios. I can come up with many more, but three is a nice number. The first scenario is, in 2020, I purchase some type of improved Lithium-Ion based battery. The technology is essentially the same, but improved on a linear scale from now until 2020. The second scenario is all this worldwide investment results in a battery breakthrough in energy density and cost, like the Lithium-Air battery IBM research and others are trying to create. The third scenario is that Steven Chu, the US Secretary of Energy, is great at predicting the future. We will use his predictions from a recent speech at the Detroit Economic Club.

For each scenario, I focus on 2 key factors:

1.             The energy density of the battery, which is what determines the range you can drive per charge

2.             The cost of the replacement battery pack

By 2020, we will definitely see improvement. The central question is: how much improvement will we see? Let's get to the scenarios.

Scenario One -- the linear progression of Lithium-Ion 

Many industry experts estimate that Lithium-Ion battery improvements will continue at the current pace. That pace is about a 7% improvement per year in energy density. According to Wikipedia, today's Volt has a 16 KW-hr battery that weighs 435 lbs (197 kg). So the pack-level energy density is currently:

16,000 wHrs

------------------     =     81.2 wH/kg

 197 kg   

Taking the 81.2 wH/kg figure and improving it 7% per year, you get 140 wH/kg in 2020. With a Volt you can drive 40 miles with 81.2 wH/kg so, with all else being equal, you should be able to go about 69 miles in 2020. Using the equation:

x miles              140 wH/kg

------------    =    -----------------

40 miles            81.2 wH/kg

Solving for x, you get 69 miles.

How much will the pack cost? Again, there are so many predictions out there. An article in AutoBlogGreen has GM stating the pack costs between $8000 and $9,500. I'm going to use $9,000 for a good round number. At $9,000, the battery pack has a cost of $563 per kWh ($9,000/16 kWh). The article above states GM "hopes" to hit a cost of $300 per kWh by 2015. That is quite aggressive. I'm being less aggressive and assuming that the battery pack cost goes down 5% per year, which will get to an energy density of $374 per kWh in 2020.

With these calculations, if you buy a 16 kWh battery pack, it will cost you $5,984 in 2020 (16 kWh x $374/kWh). If you select a battery with the Volt's 40 miles per charge, the battery pack will cost you $3,520.

The bottom line of scenario one is 69 miles per charge for $5,984 and 40 miles per charge for $3,520.

Scenario Two -- The Lithium-Air Breakthrough 

According to an article in the New Scientist:

IBM thinks it has a solution with a promising new lithium-air (Li-air) battery. According to the technology giant, a typical Li-air battery cell has a theoretical energy density more than 1,000 times greater than today's industry-standard Li-ion battery cell. Even better, Li-air batteries are one-fifth the size and they offer a lifespan at least five times as long.

These are significant claims. The kind of breakthrough everyone is hoping for to enable the electrification of mainstream vehicles, and therefore, reduce global warming pollution plus reduce the US dependency on foreign oil. So what does this mean for our exercise? The article states a theoretical energy density of more than 1,000 times better than Li-ion batteries. The key word here is "theoretical". So I arbitrarily cut it in half. That means, very roughly, if a Chevy Volt can go 40 miles with current technology, you could go 20,000 miles (40 miles x 500) on a charge. Of course, this 20,000 mile figure assumes you have the same size battery pack. My guess is you would, at most, put a 1,000 mile battery in the car. Going over that kind of range isn't really necessary since people don’t drive that much in one day.

I have no information on the potential cost of this battery. I don't know what to do here. So I will leave it with question marks in the summary table below.

Scenario Three -- Steven Chu is right

Chu, in a speech at the Detroit Economic Club, said that a plug-in hybrid-electric vehicle battery that can provide 40 miles of all-electric range will cost $3,600 in 2015, down from $12,000 in 2008. “That battery's cost will fall to just $1,500 by the end of the decade,” Chu added. "The advanced battery competition is a race the United States can and should win," said Chu.

So this means for $1,500 I can replace my Chevy Volt battery pack and go 40 miles per charge. It cost me more than $1,500 to pay for a tune-up and other maintenance after 8 years in an ICE car.

Summing it all up

A summary of all scenarios is in the table below. The breakthrough scenario looks quite compelling. I hope it comes to fruition! The Steven Chu prediction looks quite exciting too. The only one that looks expensive is the linear progression. Only time will tell what the future holds.

In this analysis, I did not account for the cost to install a new battery pack. But that may be more than offset with how much the old battery could be sold for on the open market. There is talk about using it for Energy Grid Storage. Sorry to complicate things here at the end. Let's get back to the summary below: 

Scenario                        Pack Cost          Miles per charge

One -- linear                    $5,984                        68

One -- linear                    $3,520                        40

Two -- breakthrough          $??                      1,000

Three -- Chu                   $1,500                         40

Thanks for sticking with me through these estimates. I don't know what to budget for my replacement battery pack. Maybe I can hold out until the breakthrough battery comes with 1,000 miles of range on a single charge. Then I could remove my ICE generator and cut down the Volts weight. Why would I need a generator if the car can go 1,000 miles on a single charge?

Let’s check back with each other in 2020 and see how this all turns out.