Electric car quest: Batteries

(Part 3 in a series on choosing an electric car)

Battery Issues

Thanks to electric vehicles (EV), a new phobia is entering the lexicon: range anxiety.  Do I have enough juice to make it home?

There is a lot of confusion and ambiguity about how far you can actually go on battery power with your EV before you drain the charge.  Both Chevrolet and Nissan are hedging their estimates, giving a standard number (about 40 and 100 miles for the Volt and Leaf, respectively) that depends heavily on many variables.  In truth, the range as driven may be significantly less than that, which makes the gasoline backup generator on the Volt an especially attractive comfort feature.

Battery life / range while driving in real life is reduced by the following:

  • Cold temperatures decrease battery output (it’s chemistry, folks; reaction speed depends on temperature)
  • Extremely hot temperatures
  • Running the heater
  • Running the air conditioner
  • Aggressive driving (rapid acceleration and braking)

Except for the first two, items in this list generally apply to gasoline-powered internal combustion engines too.  But the variability in “mileage” is much greater for EV’s than for ordinary cars–leading to range anxiety. Until rapid charging stations become as widely available as gas stations, this is a problem that EV drivers will have to deal with.

Costs

Buying electricity is much different from buying gasoline.  Electricity is much, much cheaper for a comparable amount of power.  “Filling your tank” on an EV should only cost a couple of dollars, quite possibly less than the price of a single gallon of gasoline.

However, if you own an electric vehicle, you’ll want to install a special 240 volt charging station in your home (using the outlets your home has for major appliances like a clothes washter/dryer), because charging through a normal 120V outlet will take forever.  This installation could set you back a couple of thousand dollars, so add that to your budget for a new EV.

If your utility prices your electricity by time of day (peak vs off-peak usage), you’re in luck if you charge your car overnight, when prices are lowest.  Try that at the gas pump!

Current limits of the technology

Early adopters of EV technology–that is, anybody buying one in 2010, 2011, or 2012–should realize that they are taking a risk on batteries.  Current battery technology has a lot of room for improvement.  Problems to be overcome:

  • Batteries are large (take up a great deal of space inside the car)
  • Batteries are heavy (take a lot of energy to push around)
  • Batteries charge slowly (hours) and generally have less range capacity than a gas tank
  • Batteries are expensive and have an unknown life span

This last point, about the expected lifetime of a battery, is one of the great unknowns about buying an EV.  The current crop of batteries are expected to last at least 5 years, probably longer, but nobody really knows the true life span nor how expensive it will be to replace a battery in the future.  Be aware that this is a potential financial liability. I hear that Chevy and Nissan are offering an 8 year/100,000 mile guarantee on their batteries, which would be a good way to protect the buyer.  A Chevy dealer I spoke to mentioned they might also replace the battery if a better model is released in the first years of ownership.  Ask before you buy!

Charging Times:  How long you must plug in to “fill the tank”

Chevy Volt battery (T-shaped unit shown above in the center of the car):

  • 16kWh lithium-ion unit
  • Charging time:  10-12 hours at 120V (regular outlet); 4 hours at 240V

Nissan Leaf battery:

  • 24 kWh lithium-ion
  • Charging time: 7 hours at 240V

Tesla Model S battery:

  • Lithium-ion batteries, capacity varies with model purchase (but all greater than Volt or Leaf)
  • Charging time: 4 hours at 240V.  Model S will also have quick charge option, battery full in 45 minutes on 440V power.  Because you probably don’t have this at home, the point of quick charge is to have a car capable of using a quick-recharge infrastructure (i.e., electric stations) that currently do not exist but might exist in the future.

Model S Flat Battery Pack

U.S. Department of Energy website on EVs and other alternative fuel vehicles

Series of electric car quest posts:

Chevy Volt vs Nissan Leaf; the hot electric cars of Tesla Motors: Model S vs RoadsterEV BatteriesMSRP, incentives & leasesChevy Volt test drive

Also: A scientist from The Nature Conservancy discusses how “green” is the battery?

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2 Responses to Electric car quest: Batteries

  1. Ramon H Leigh says:

    A fairly balanced article, albeit with some issues worth noting : EVs like the Tesla, Volt and others have temperature controlled battery packs which does many things. It prevents the battteries from losing power due to low temps, which the article incorrectly claimed as a general characterisitc of EVs. It is a characteristic of SOME (such as the leaf, which doesn’t condition its battery pack). Conditioned batteries, alway maintained in a 72 degree environment
    (except when more power is desired, at which point the Tesla ups the temps
    a few degrees) means that its pretty easy to anticipate future lifespan, despite the claims of the article that “no one knows.” Believe me, LG is virtually certain
    about the minimum lifespan of its large format cells. And Tesla knows more about battery performance in a vehicle than any company on the planet, based on years of constant monitoring of the 1500 roadsters they have on the road
    which have logged more than 9 million miles. And a few cells of the Tesla’s 5900 not working won’t be detectable except by the car’s monitoring system.
    I notice it was a dealer who claimed that Chevy might replace the Volt battery packs if a better one came along. Don’t believe anything any dealer says and this claim is totally absurd and provides proof positive that this dealer hasn’t a clue as to the cost of the Volt battery pack (over $13K). And if batteries were so cheap that Chevy might replace existing packs, the Volt would at that time be a totally obsolete vehicle, since nothing but electrics would be sold.
    In term of home charging, a lot depends upon the EV’s driving range as to whether it makes sense to install a 240 charger (which can be done by anyone who has even minimal knowledge of electricty for less than $600, complete).
    If the driving range equals any of those available for the Tesla Model S
    (160, 230, 300 miles) then it is highly unlikely that anything other than a 120 Volt source is required, since the car can charge all night long. A 120 Volt source can fill the battery with 8 to 9 miles of range per hour. The Tesla Model S with its 300 mile rage will become the first electric in history to be totally competitive with a gas powered vehicle. A recharge time of less than 45 minutes for every 4 to 5 hours of driving means that even those on long trips are not unduly inconvenienced. And around town, the Model S is even less of an inconvenience, since the owner never has to drive to a gas station. The status of electrics right now is that a car like the Model S, which can out-perform high end sports sedans, like the E Class and 528, is actually more cost effective , both in terms of initial cost ($69K for the Model S with
    Fed tax break) and enormoously more csot efficient in terms of absolutely everything else – aintenance, fuel, resale value, lifespan of the machanicals,
    etc. One thing’s for sure – when that battery pack loses over 20% of its power out in 10 years or so, and the owner decides to restore it to like new condition, those batteries are 1) going to be available and 2) cost a whole lot less than they did when he bought the car.

    • Amy says:

      Thanks, Ramon, I’m getting more excited about owning an EV! And the Chevy dealer who casually tossed out that bit about replacing the batteries–it was pretty clear he had no idea what he was talking about. I’ll have more to say about that in my post about test driving a Volt.

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