Electric Vehicle Battery Basics

As we prepared for our trip out, we asked our member-owners and friends what they wanted to know most about electric vehicles. Charging questions definitely overwhelmed us, but questions about batteries were right behind.

We spent quite a bit of time learning about batteries, so we thought we would share what we learned with you.

What types of batteries do electric vehicles use?
Automobile manufacturers have identified three types of rechargeable batteries that are considered suitable for use in electric cars: lead-acid; nickel metal hydride; and lithium ion.

  1. Lead-acid batteries are the oldest form of rechargeable battery still in use. They’ve been used in all types of cars and usually contain a mild solution of sulfuric acid in an open container. The major advantage of lead-acid batteries is that, after having been used for so many years, they are well understood and cheap to produce.
  2. Nickel metal hydride (NiMH) batteries have been used widely for about twenty years. They have a high energy density and don’t contain any toxic metals, so they’re easier to recycle.
  3. Lithium-ion (Li-ion) batteries, which have been actively used for about ten years, have a very high energy density and are less likely than most batteries to lose their charge when not being used. These batteries are the preferred and most common battery used in electric vehicles. Because of their light weight and low maintenance requirements, lithium-ion batteries are widely used in laptop computers. Some experts believe that lithium-ion batteries are close to perfect when it comes to designing a rechargeable battery, and the best candidate for powering electric cars. A variation on lithium-ion batteries, called lithium-ion polymer (Li-poly) batteries, may also prove valuable to the future of EVs. These batteries have the potential of costing less to build than lithium-ion batteries. At present, lithium-ion polymer batteries are inconveniently expensive, but that is quickly changing. High profile companies are seeking ways to manufacture these batteries with much higher volume and lower cost.

Are electric vehicle batteries safe?
EVs must undergo the same rigorous safety testing and meet the same safety standards required for conventional vehicles sold in the United States, as well as EV-specific standards for limiting chemical spillage from batteries, securing batteries during a crash and isolating the chassis from the high-voltage system to prevent electric shock. In addition, EVs tend to have a lower center of gravity than conventional vehicles, making them less likely to roll over and often improving ride quality.

How often do you have to replace the battery?
Not for many years. GM, Tesla and Nissan, among other manufacturers, offer warranties covering up to eight years or 100,000 miles of driving on the lithium-ion batteries in their vehicles.

How much does a new battery for an electric vehicle cost?
Electric car batteries are typically compared by looking at the at the cost per kWh, the total cost of the battery over the total electric capacity. According to CleanTechnia, the average cost of a Lithium-ion battery today is about $209 per kWh. (For reference, the battery in the Tesla we are driving is 75 kWh.) While batteries continue to be a large proportion of the overall cost of a new electric vehicle, that ratio is changing. Recent battery technology developments, as well as consumer demand, is driving the price of batteries down substantially.

Where do the batteries end up at the end of their useful life?
Vehicle batteries have an excellent recycling record that will get even better with plug-in vehicles. Every car in the world has a lead-acid battery. Even with its low value as scrap, the national recycling rate for lead-acid batteries is about 98 percent. Plug-in vehicles mostly use lithium ion, which is much more valuable than lead. It’s illegal to dispose of these batteries in a landfill and their inherent value will help ensure that they are recycled.

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