By Mike Witteman
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 with 175,000 miles.
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. My old Camry lasted more than a decade after all its warranties expired, so hopefully my Volt and battery will last far beyond my 8-yr warranty period.
Given the Volt only uses about 10 kWh of the battery’s 16 kWh capacity, it is conservatively designed to last a long time. We know from the Toyota Prius design, which only uses 50% of its battery’s capacity, that using only part of the battery’s capacity allows it to last a lot longer. Given the Toyota experience, the Volt battery should last for many years. Additionally, I imagine GM may “unlock” more of the battery capacity with a future software update, enabling the Volt to keep the same driving range over time by using more of the battery.
For this exercise, lets assume I want to replace the Chevy Volt battery in 8 years (the length of the warranty). Since I purchased my Volt 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? Globally, there are billions of investment dollars racing to invent the best car battery. What will the range, cost, size, and charge time be in 2020? To simply, I limited myself to four scenarios. I can come up with many more, but four 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. We’ll call this scenario: Linear Lithium-Ion.
The second scenario is all this investment results in a true battery breakthrough, like the Aluminum-air battery. A company named Phinergy mounted such a battery in a subcompact demonstration car that provided 1,000 miles of range. It should be noted the battery does require refills of distilled water every 200 miles. But that would be much cheaper than gas! Without the pollution too! As more evidence of this scenario, Tesla submitted a patent to use a similar battery. We’ll call this scenario: Aluminum-air Breakthrough.
The third scenario is based on what Steven Chu, the former US Secretary of Energy, predicted. We will use his predictions from a speech at the Detroit Economic Club. We’ll call this scenario: Steven Chu’s Prediction.
The four scenario is based on a what the startup Envia Systems claims it will produce soon. I picked them because they have 3rd party tests demonstrating their claims.
For each scenario, I focus on 2 key factors:
1. The range of the battery, based on its energy density.
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 #1 — Linear 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. We’ve seen this play out with small improvements in the 2013 Chevy Volt battery (going from EPA range ratings from 35 miles 38 miles). The Nissan Leaf Lithium-Ion battery also had a similar growth in range. 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:
—————— = 81.2 wH/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 (I usually get around 40 in real-world driving) 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 #2 — Aluminum-air Breakthrough
In my previous analysis of the future of Chevy Volt battery options, I used the IBM announcements around a new Lithium-air battery. 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.
For this version of the analysis, I believe a more likely possibility is an Aluminum-air breakthrough. The demonstration by Phinergy feels compelling. They showed 1,000 miles of range in a demonstration car — however it needs distilled water every 200 miles. The Phinergy CEO, Aviv Tzidon, told Bloomberg
TV that they signed a contract with a global automaker to deliver the battery in production volumes, starting in 2017. So if they stay on schedule, it will be ready by 2020.
This is 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? Phinergy demonstrated 1,000 miles of range, so we will go with that for range.
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 #3 — Steven Chu’s Prediction
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.
Scenario #4 — Envia Systems
is a startup claiming to have a 400 Wh/kg battery in the works. I find their battery quite interesting because GM Ventures, the investment arm of GM, invested in them. Plus Envia has put their prototype to the test at a 3rd party lab, under the sponsorship of ARPA-E, and published the results. Envia claims “When commercialized, this 400 Wh/kg battery is expected to slash the price of a 300-mile range electric vehicle by cutting the cost of the battery pack by more than 50%.”
For this analysis, the Envia battery weighs in at 300 miles of electrical range and we’ll say it costs 50% less than the current $9,000 Chevy Volt battery.
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, so does the Envia Systems solution. 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/charge $/Mile
#1 Linear Li-Ion $5,984 69 $86.7
#1 Linear Li-Ion $3,520 40 $88.0
#2 Aluminum-air $?? 1,000 $??
#3 Chu’s Prediction $1,500 40 $37.5
#4 Envia Systems $4,500 300 $15.0
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.
This entry was posted on Wednesday, April 24th, 2013 at 5:55 am and is filed under General. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.