Battery Cooling System Electric Vehicle
Batteries have to be babied. That’s because batteries simply perform better when they don’t have to deal with extreme heat or cold. When it comes to batteries for electric vehicles, so-called thermal management systems that ensure batteries operate within a certain temperature range, will be crucial to helping electric cars drive greater distances for a longer period of time.
However there is a debate raging, over whether automakers should turn to air or liquid to regulate battery temperature, and the choice has provided fodder for some green car makers to toot their own horns or slam competitors.
Tesla Motors (s TSLA) CEO Elon Musk has derided Nissan’s battery pack, which uses an air cooling system, as “primitive” compared with the sophistication of even Tesla’s first prototype, which uses liquid cooling. As a result, the LEAF pack will have temperatures “all over the place, ” claimed Musk, causing it to suffer “huge degradation” in cold environments and basically “shut off” in hot environments. General Motors (s GM) for its Volt and Ford’s (s F) line of hybrids and EVs, have also opted to use liquid for battery temperature regulation. Coda Automotive, meanwhile, uses an air cooling system for its Coda Sedan.
According to Matt Keyser, a senior engineer with the National Renewable Energy Laboratory who focuses on battery thermal management systems, there are advantages to both technologies. Air cooling systems can be less complicated and lower cost, while liquid systems will generally take up less space and let you “drive the battery a little harder, ” Keyser explained. Liquid cooling allows the battery to handle a larger “pulse” of power (i.e. more kilowatts, which in electric cars are like horse power).
Of course, there are trade-offs, too. Among the weaknesses of a liquid cooling system are the potential for fluid to leak (which can cause an electrical short), said Keyser. Maintenance and repair can also be costlier and more complicated for liquid-cooled systems, which require more components and may weigh more than air systems. The battery pack can be “totally isolated” from liquid by an aluminum shell, however, which ensures that fluid (a 50-50 mix of water and glycol in the Tesla Roadster system) doesn’t “get to the battery itself, ” said Keyser.