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| 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
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.
Nice article. Ultra-caps, Zinc-air, and solid state batteries are also potential game changes by 2020, who knows. I read an article where GM said "40 miles is the right number for EREV" and that if batteries improve, they would reduce the cost and stick to the 40 miles electric range. Of course by 2020, the person that said that may not work there any more. Did you see this chart (http://goo.gl/aAUYu) it has price predictions for 2015 and 2020 from 5 major groups. Their estimates place your cost between $3600 to $8000 in 2020. Not as good as $1500. But these are just predictions, it is impossible to know what black swans are around the corner.
ReplyDeletePatrick, Thanks for pointing me to the article. Very interesting. There is a wide range of predictions. I hope we get to the low-end as fast as possible.
Deletegreat article. Like you we gave up our 1991 Honda Civic for a 2011 Volt. Big upgrade! Even the linear battery improvement path is not all that bad considering how much we would have had to spend keeping an internal combustion engine car running all that time.
ReplyDeleteThere are reports that GM has listed a replacement battery for the Volt at $3000, which is quite reasonable. Hopefully, in time it will get even more reasonable. Great article thanks for all the work and info.
ReplyDeleteObviously both scenarios are best case. What's more likely to happen is that prices will remain flat for current battery capacity even though size and density are reduced and a premium will be charged for enhanced batteries to give you a longer range. Also given the length of patents being 20 years, all new replacement batteries in the foreseeable future will only be sold by the auto maker unless they have been reconditioned by a third party. (Kinda like a transmission rebuild in cost and grief). 20 to 25 years out aftermarket batteries will be available, but with technology moving so quickly it's entirely likely no one will be making batteries for 20 year old cars.
ReplyDeleteI hear these people on TV ads saying they haven't bought gas for "blah blah" weeks. Gasoline engines will gum up after 60 days, that's why you have to drain a lawn mower at the end of the year.
ReplyDeleteDid GM actually test a battery for 8 years?? I find that hard to believe that the same battery material has been used and a vehicle driven in real life scenarios for 8 years before they started selling them.
Batteries always have a minute amount of leakage (on their surface) when they are left sitting, that's why you'll eventually see corrosion from a battery, even those left in that armor-like plastic that they come in. The point is, once again, did GM perform the maintenance required for 8 years, or did they just periodically clean the surface and/or connections? I'm not at all familiar with maintenance of an EV.
Timbo44b, Thanks for your comment. Let me mention a few things in response:
Delete- GM has gone to great links to manage the "stale gas" issue. First, the tank is pressurized which keeps the gas pure longer. Second, if the generator/engine isn't run for 6 weeks, it automatically goes into maintenance mode and burns some gas, and in the meantime, lubricates the generator. During my first 5,000 miles I only used one 9 gallon tank of gas.
- GM has done simulated testing for way more than 8 years and actual testing must be up to 3 years by now (I think they got their 1st batteries from LG in 2009). The Lithium-Ion battery is maintenance free, like the ones in your laptop and cell phone. I think the corrosion issue comes up much more with lead-acid batteries.