What may seem like a foregone conclusion is still a hot topic for scientists and engineers: all batteries in electric vehicles must be able to withstand extreme temperatures. Five experts and more than a hundred representatives from the industry sat together and tried to analyze this key issue during PHEV’09, an international conference and trade show which ended yesterday in Montreal.
Loaded with all sorts of stats, the latest study on battery performance in extreme temperature conditions has proven at least one thing: in order for lithium-ion batteries to achieve optimum effectiveness, they have to operate inside a temperature range of 20 to 30 degrees Celsius. Anything higher or lower will not only affect battery capacity and durability but also available power.
Perhaps the most convincing data was provided by Environment Canada’s Martha Christenson, co-writer of a study and analysis on hybrid electric vehicle performance in Canadian conditions. Using a Toyota Prius featuring the Hy-motion system that supplies an additional 5 kWh of electricity, researchers conducted various tests in accordance with all the latest environmental standards and based on specific scenarios, including low- and high-speed, city and highway driving.
The deciding factor turned out to be -- you guessed it -- Mother Nature. Batteries were evaluated at temperatures of 22 degrees Celsius, minus 7 degrees and minus 18 degrees. As expected, the hotter it was, the farther the Prius travelled. That’s because the hybrid system does not have to rely on the gasoline engine to move the vehicle as much as when temperatures are cooler.
The same conclusion is drawn by the Americans. Richard Carson of the Idaho National Laboratory wound up with similar results after a long series of tests not only in Nordic temperatures but also in more exotic climates like Arizona.
"The only legitimate conclusion for now is that temperature has a greater impact on plug-in hybrids and electric vehicles. But while their performance is affected, they’re still more efficient than comparable gasoline-only models," Mr. Carson explained while adding that short-term solutions are far from convincing.
The military solution
Car makers are actively searching for ways to address the battery temperature issue. However, the answer may come from an unexpected source. The U.S. Air Force also uses lithium-ion batteries, most notably in fighter jets.
Using such batteries for military aircraft is fairly new, but it does allow extended operation in the event of generator failure. Overall, the range is ten times longer, but since fighter jets often reach high altitudes where temperature drops to minus 40 degrees, the batteries never achieve their full potential.
"We’ve tried different methods and we ultimately managed to develop batteries with a built-in internal heating system," said Steve Carkner, director of Panacis Inc., which specializes in innovative designs and technologies. "Thanks to some sort of heating blanket around the battery, we’re able to reach and maintain optimum operating temperatures. There is no mechanical thermostat involved; it’s all computerized. Problem is, it remains a low-scale, high-cost technology."
"We certainly believe that it could spread across the industry, but we’re still a long way from mass production," he then added.
Bottom line
So, is temperature really that catastrophic for batteries? Absolutely not. It’s a major issue as far as performance is concerned, no doubt about that, but not to the extent of compromising the virtues and viability of electric-powered vehicles. "Our work has only just begun," Richard Carson concluded.
photo:General Motors
Loaded with all sorts of stats, the latest study on battery performance in extreme temperature conditions has proven at least one thing: in order for lithium-ion batteries to achieve optimum effectiveness, they have to operate inside a temperature range of 20 to 30 degrees Celsius. Anything higher or lower will not only affect battery capacity and durability but also available power.
Perhaps the most convincing data was provided by Environment Canada’s Martha Christenson, co-writer of a study and analysis on hybrid electric vehicle performance in Canadian conditions. Using a Toyota Prius featuring the Hy-motion system that supplies an additional 5 kWh of electricity, researchers conducted various tests in accordance with all the latest environmental standards and based on specific scenarios, including low- and high-speed, city and highway driving.
The deciding factor turned out to be -- you guessed it -- Mother Nature. Batteries were evaluated at temperatures of 22 degrees Celsius, minus 7 degrees and minus 18 degrees. As expected, the hotter it was, the farther the Prius travelled. That’s because the hybrid system does not have to rely on the gasoline engine to move the vehicle as much as when temperatures are cooler.
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The same conclusion is drawn by the Americans. Richard Carson of the Idaho National Laboratory wound up with similar results after a long series of tests not only in Nordic temperatures but also in more exotic climates like Arizona.
"The only legitimate conclusion for now is that temperature has a greater impact on plug-in hybrids and electric vehicles. But while their performance is affected, they’re still more efficient than comparable gasoline-only models," Mr. Carson explained while adding that short-term solutions are far from convincing.
The military solution
Car makers are actively searching for ways to address the battery temperature issue. However, the answer may come from an unexpected source. The U.S. Air Force also uses lithium-ion batteries, most notably in fighter jets.
Using such batteries for military aircraft is fairly new, but it does allow extended operation in the event of generator failure. Overall, the range is ten times longer, but since fighter jets often reach high altitudes where temperature drops to minus 40 degrees, the batteries never achieve their full potential.
"We’ve tried different methods and we ultimately managed to develop batteries with a built-in internal heating system," said Steve Carkner, director of Panacis Inc., which specializes in innovative designs and technologies. "Thanks to some sort of heating blanket around the battery, we’re able to reach and maintain optimum operating temperatures. There is no mechanical thermostat involved; it’s all computerized. Problem is, it remains a low-scale, high-cost technology."
"We certainly believe that it could spread across the industry, but we’re still a long way from mass production," he then added.
Bottom line
So, is temperature really that catastrophic for batteries? Absolutely not. It’s a major issue as far as performance is concerned, no doubt about that, but not to the extent of compromising the virtues and viability of electric-powered vehicles. "Our work has only just begun," Richard Carson concluded.
photo:General Motors