During this time of year, one of the most important factors in the reduction of range in electric buses is the cold weather.
Even though there is a lot of empirical evidence that this is true, we rarely can find some hard evidence that helps us understand the effects of cold weather on the battery of electric buses and how to optimize their performance.
Cold Climates and Electric Bus Batteries
The new study published by the CTE sheds some light on the matter and backs it up with hard data.
This study compares both battery-electric and fuel cell electric buses’ fuel economy, in relation to different temperature trends.
The results of the analysis showed that the loss in range during a temperature change from 50-60 degrees Fahrenheit (10-15 degrees Celsius) to 22-32 degrees Fahrenheit (-5 to 0 degrees Celsius) was greater for battery-electric buses (37.8 % decrease) than for fuel cell electric buses (23.1% decrease).
Even though this study was funded under a National Fuel Cell Bus Program grant provided by the Federal Transit Administration, the information seems valid and trustworthy. Their intention is not to recommend one technology over another, but rather, give planning insights to transit agencies for replacing existing fleets.
According to Andrew Thomas, Director of the Midwest Hydrogen Center of Excellence (MHCoE), “Hydrogen fuel cell buses appear to offer cold weather ranges that will be most compatible with traditional route planning”.
The Center for Transportation and the Environment (CTE), is a nonprofit organization whose mission is to improve the health of our climate and communities. They strive to bring people together developing commercialize clean, efficient, and sustainable transportation technologies. The Study Team collected data from eight transit agencies: four that deployed fuel cells and four that deployed battery-electric buses.
Testing Electric Buses in Finland
Another interesting project to understand bus performance in winter and improve the performance in sub-zero temperatures was carried out at Veolia bus depot in Espoo. Veolia is part of the project where different bus manufacturer’s vehicles are tested in freezing conditions. In this eBus project, bus companies are cooperating with manufacturers and researchers to develop more winter-hardy electric buses.
Ebus technical specialist Sami Ojamo says “the cold has proven surprisingly challenging for electric vehicles. A bus that runs in minus five degrees, for instance, may not work at minus fifteen.” He also notes, improvements in keeping the battery warm during use and while charging, as well as better bus heating, have contributed toward better performance.
With this information in mind, let’s take a look at some of the best practices for increasing your electric vehicle range.
Increasing Electric Bus Range in Cold Weather
Managing batteries in cold temperatures can be difficult as just a few degrees can make a huge difference in the duration they can be used for. However, by following a few simple tips you can extend the range of your battery even in cold weather.
Here are a few tips:
- Use indoor parking facilities when possible
If an indoor parking facility is available, try to park there, to keep your battery warmer. A super-chilled battery won’t perform well or charge as much as a warmer one. If it is not possible to park in an indoor facility try to find a spot in direct sunlight during the day. Not only will this help to increase the range it can also help to minimize battery degradation.
2. Minimize the use of cabin heating
The number one cause of battery drain in winter is using the HVAC system, according to a study by AAA. HVAC use decreases range by as much as 30%. Preheating the cabin and keeping on your jacket while driving is a great way to increase range. Passengers riding should not be affected too much since they will have their coats on from being outside anyway.
3. Drive conservatively
Regardless of the type of weather, one factor that always affects the range is how your electric buses are driven. Harsh acceleration or braking, as well as driving at high speeds, all drain the battery. By looking ahead while driving and predicting when you need to brake next, your EVs regenerative system can be put to work, recovering energy and storing it back into the battery.
Note: In extreme cold, the regenerative braking system will be less effective since cold batteries can not accept as much energy as warm batteries can. However, even during winter, this will greatly help your battery degradation.
By being aware of these changes to your electric buses during this time of year, you can take precautions to minimize these effects on the battery of your vehicle.