The Basic Knowledge Needed on Electric Car Batteries

CARbattery
CARbattery

The electric car development is now at a dizzying pace, with a great number of vehicles rolling off assembly lines from many car manufacturers. Central to this particular market that will most probably overrun fossil fuel driven vehicles, is the battery.

There are many questions regarding the battery, such as replacement and usable life, recyclability, proper use and charging, maintenance and upkeep, and even up to the supply available of its primary components.

The current standard in use is the lithium ion battery. Now these kinds of batteries power many electronic consumer products, from mobile phones to laptop computers. These are also the power packs in use for the first wave of electric cars. In essence, the electric vehicle battery pack is an array of lithium ion batteries rechargeable after each use.

"If I want to buy an electric vehicle, I would want to know how many miles can I drive under REAL driving conditions, how long will my battery last and how long will the battery take to charge," said Venkat Srinivasan, a staff scientist at the Lawrence Berkeley National Lab who writes a popular battery blog.

The newest electric cars to hit the market, the hybrid Chevy Volt and the all-electric Nissan Leaf, have plug-in features to recharge their battery packs. Both though, have a battery usability lifetime of 100,000 miles or eight years. While this may put electric car purchasers’ minds at ease, the actual battery life and performance depends on many factors.

Srivinasan added, “Don’t keep continuously fully charging and discharging the batteries. Also, pressing on the accelerator too much also draws power from the battery at a high rate and can cause (battery) degradation.”

Another expert in the field, Sunil M. Chhaya, from the Electric Power Research Institute, also observed that batteries age faster if the battery’s temperature is higher than normal. The think-tank has postulated that heat management within the battery’s structure is the greatest factor that affects the battery’s service life and reliability. It is precisely for this reason that electric car maker Tesla utilizes a liquid cooling system to extend the battery life for its vehicles.

Chhaya adds that batteries perform optimally when the ambient temperature is between 20 to 45 degrees Celsius (or 68 to 113 degrees Fahrenheit). If the battery’s temperature goes beyond that, there is a need for a thermal management system to cool down the battery. This can be done through efficient inflows or outflows from the battery pack using a well-designed thermal system.

Another factor is the weather. A cold battery produces a higher resistance to the flow of the electrical current. This means that the same amount of power at the wheels would produce larger amounts of heat in the battery due to internal power loss. This process localizes the heat in the battery pack area, increasing the batteries temperature thus making the battery more prone to aging and inefficiency.

This peculiarity would severely affect the range of electric vehicles in colder climes, as the car’s heater would require at least 25% percent of the battery’s charge to keep the temperature of the passengers.

Another misleading concept is the “fast charge” batteries that use higher voltages to shorten charging times. There are trade-offs to the use of these kinds of batteries is the easy degradation of the battery thus shortening its battery life. This was advised by Mark Wagner, VP for Government Relations at Johnson’s Controls, a lithium ion battery manufacturer based in Holland, Mich. He adds,  "The vast majority of the vehicles will be charged up overnight at lower voltages, but if you charge very quickly, there can be mechanical stress on the battery."

Despite expert advice, the consumer still manages the charging times for the battery as the consumers rarely follow directions on battery charging and use. Mike Omotoso, Analyst at J.D. Power and Associates observes, "If you think of your cell phone or laptop, you're supposed to charge the battery fully for 24 hours before using it the first time. But of course most of us are anxious to use something new right away, so we charge it for a couple of hours and then start using it. Then we complain that the battery life isn't as long as advertised."