It seems appropriate at this time of year to talk about cold weather and trucks. I am prompted to do so both because of a recent Phillips & Temro white paper on the subject and because of ongoing talk about what happens to the efficiency of batteries in battery electric vehicles when temperatures dip.
The Phillips & Temro white paper, while covering both gasoline and diesel engines, suggests that vehicle owners stop idling their engines in cold weather. The company says idling “causes damage to the engine, increases fuel consumption and pollutes the environment.”
Kevin Otto, NACFE team member, TMC Silver Spark Plug and former engineer at Cummins, says engines are more inefficient throughout their warm-up cycle and they warm up faster under load, so the faster you can warm the engine up, the better. Idling is not the fastest way to warm an engine.
Battery capacity decreases dramatically as the temperature gets below 32°F, therefore making less power available to turn the starter, he explains. Phillips & Temro suggests block or coolant heaters to keep temperatures several degrees above ambient temperatures. Otto cautions that they have to be sized properly and positioned in the cooling system in a way that encourages passive coolant circulation. See NACFE’s Confidence Report on Idle Reduction for more information on block heaters.
As for battery electric vehicles, battery life is dependent on a number of operational factors. The U.S. National Renewable Energy Laboratory (NREL) says that major factors include environment temperatures, depth of discharge, recharging cycles and charging levels. It is, in fact, true that cold weather affects vehicle efficiency — by as much as 40%. While this certainly is a negative for this technology, there are ways to mitigate the problem.
According to the NACFE, Guidance Report Medium-Duty Electric Trucks — Cost of Ownership, “Battery management systems actively monitor the batteries, charging, discharging and thermal profiles. Battery thermal management systems also have been found to contribute to extending battery life by maintaining the batteries in a narrower set of environmental conditions than the vehicle might see.”
One other important thing to remember is that battery technology is evolving rapidly and at some point, the cold weather efficiency of batteries could be improved. But even if it is not, fleets deploying battery electric vehicles simply need to remember to factor in the decreased efficiency when temperatures drop and ensure that they account for that when making routing decisions.
