Battery management key to maximize winter use of electric vehicles

Although the list of winter maintenance requirements for electric trucks and vans is quite short compared to their internal combustion counterparts, experts agree that powertrain battery management should rank high.

With more than two million miles of commercial electric vehicle experience, including traversing the harsh Colorado winters, Lightning eMotors CEO and co-founder Tim Reeser said the biggest lesson to take away t mind is how to combat reduced range in freezing temperatures.

Reeser said he’s seen up to 30% less range when winter hits, as the chemical reactions within the battery are slowed down.

“We now have enough data on this to be confident that we know the answer and that 30% is a good number,” he said.

According to the Department of Energy, the range can drop by up to 41% at 20 degrees Fahrenheit. About two-thirds of the energy consumption was attributed to cabin heating.

Simply put, cold weather slows battery performance according to Ford. “Temperatures below 40°F slow the electrolytic fluid, which limits the amount of energy available for discharge and the rate at which the vehicle can charge. When temperatures are low, you may notice a reduction in battery life, which is normal,says Ford on a webpage aimed at improving the range of electric vehicles in winter.

Range can also be reduced when electric vehicles require extra power to traverse snowy roads, Reeser said.

Proper battery management can help reduce range depletion in colder temperatures, which includes keeping electric vehicles plugged in when not in use so the vehicle’s thermal management system can keep the battery warmer.

“Whenever possible, just keep it plugged in,” Reeser said. “Because when plugged in, the battery management system manages to manage battery thermals.”

[Related: Mack, Volvo ink charging infrastructure deal with Pilot]

Voltage consumption can be adapted according to the needs of the fleet, such as charging to an optimal level shortly before departure and preheating the cabin for driver comfort.

Ford recommends parking electric vehicles in a garage to reduce the impact of freezing weather outside.FordThermal battery management experts at Modine, which has been regulating powertrain temperatures since 1916 (Henry Ford turned to them for the Model T), say there is a small window for optimal thermal battery management. .

“A battery should be maintained, depending on the manufacturer, but usually between 25 and 35 degrees Celsius (77 to 95 degrees Fahrenheit), so there is a narrow and ideal window for the battery to really maximize and minimize charge time” , said Gina. Bonini, vice president and general manager of advanced thermal systems at Modine.

“The battery thermal management system is a key addition to this battery to maintain this ideal temperature range,” continued Bonini.

Modine’s Battery Thermal Management System (BTMS) works to maintain an ideal battery temperature by circulating ethylene glycol around the battery. Ethylene glycol, more commonly known as coolant, can be heated or cooled depending on the temperature of the pack.

“In cold environments, our BTMS, for example, has a heating loop,” Bonini said. “On the battery there will be a battery plate or other structure to transfer heat to and from the battery cells in a coolant. We then heat this coolant with our battery heating loop to increase the temperature of the battery.

Navistar Electric Vehicle Field Services Manager Kyle Maki said battery thermal management is left to the truck, not drivers or fleet managers.

“Our BTMS makes it easy for the operator and fleet managers,” Maki said. “As long as the ignition key is turned ‘on’ or the vehicle is plugged into the charging station, the BTMS will work as intended. Our engineering team did not want to force our operators to activate switches, but that the system manages itself.

Once an EV is on the road, its powertrain battery generates heat “which then needs to be removed to keep the battery from getting too hot,” Bonini added.

Reeser said the cooling systems of Lightning electric vehicles are comparable to those of internal combustion engine (ICE) models.

“We use exactly the same coolant. In fact, we’re using the same radiator, the same heat exchanger that comes stock in many of these vehicles, so it’s handled in exactly the same way,” Reeser said. “That’s where fleets really like it because you don’t treat it any different than your ICE vehicle. You reduce it by the same amount, so usually it’s 50% water, 50% glycol and that’s what you use.

Training in new technologies

Maintaining ideal battery range in cold weather often comes down to overall vehicle management. Ford spokesman Eddie Fernandez cited cold weather advice given to e-Transit owners.

“AAA tested the range effects of a temperature of 20°F (-7°C) on several popular electric vehicles and found that the temperature alone could reduce range by 10-12%, while the Using air conditioning in the vehicle could amplify the loss of range by 41%,” Fernandez said.

Air conditioning habits inside an electric vehicle, especially in winter, play an important role in battery management, Reeser said. Some fleets may have to train drivers not to leave an electric truck or van on with the heater on while delivering packages for example.

“You have some apps that have less of a chance of that slowdown than others, but some of them are a training opportunity and some of them are also an opportunity to talk about things that weren’t historically standard in utility vehicles,” Reeser said.

Turning off the cabin heater and turning on the heated seats and heated steering wheel when you’re on the road on a cold day can help preserve battery life.

“We spend a lot of time looking at the heated seats in these vehicles because when you move to a heated seat, the driver is now more comfortable turning off the heat when out of the vehicle,” Reeser said.

Fleets may need to adapt to longer charge times in freezing weather. Electrify America points to an Idaho National Laboratory study that found EV batteries experienced a 36% drop in power consumption when charging at 32 degrees Fahrenheit.

“When temperatures are low, the EV software reduces its charging power, and for good reason: to avoid stressing the battery,” Electrify America says in its tips for charging EVs in cold weather.

Drivers and fleet managers should also be aware that regenerative braking will not work as well in colder temperatures.

“If the battery is very cold and it hasn’t been preconditioned, you’re limited on how well your regenerative braking works because you’re limited on how much energy you can absorb and put into the battery because we will protect the battery and limit the battery [when it’s outside of its optimum temperature range]“, said Reeser.

Some similarities with ICE

In addition to sharing a similar powertrain temperature management system, some electric trucks share the same air brake system, which requires the same approach to winter management, such as bleeding moisture and checking to ensure good performance of the air dryer.

“We recommend the same air brake system winterization procedures as our diesel products,” Maki said. “In addition, we recommend emptying the air tanks before long periods of parking to allow moisture to escape from the system.”

Vehicle contact with corrosive de-icers and sand is treated similarly.

“Navistar encourages customers to perform the same washing procedure they are used to, including defrosting,” Maki said. “We train our customers not to spray directly into the modules and to avoid close contact with all high voltage cables and modules.”

The focus on EV winter management, Maki said, remains battery thermal management.

“While gel fuel issues are not a concern, we will train our customers on how to properly maintain their batteries using our battery thermal management system,” he said.

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