Tips for Hot Weather Long-Distance Trip in Nissan LEAF

By · August 02, 2013

Leaf and QC Station />

With the availability of DC quick charging stations on the rise, the number of electric car owners thinking about a summer road trip in a Nissan LEAF is also growing. According to Nissan, you can quick-charge your LEAF multiple times in a single day without damaging the car's lithium-ion battery pack. But with temperatures hitting triple digits in many part of the United States, battery heat could have a real impact on charging times. What follows are lessons learned from a 270-mile trip in a 2011 Nissan LEAF across the UK in 85-degree heat—recharging and driving almost continually for eight hours.

In most circumstances, a DC quick charge can bring a LEAF battery pack from nearly empty—to nearly full—in about 30 minutes. That compares to a 240-volt charge that can take at least a few hours to complete.

Warmer with Every Quick Charge

If you’re in a drive-and-charge cycle where your car is either quick charging or being driven, the battery pack temperature will gradually get warmer with every quick charge. Because the LEAF has no active thermal management—perceived by many as a critical oversight by Nissan—and instead relies on forced air cooling to keep itself cool, it might take several hours for the battery pack temperature to return to normal levels, even if your car is parked in a cool spot.

In our experience, five quick-charges in an eight hour period raised the car’s battery temperature to more than 120 degrees Fahrenheit. Despite the outside temperature dropping to 75 degrees by the time we parked that evening, the battery pack temperature did not drop below 80 degrees for 12 hours.

Warmer with Extreme States of Charge

During our day-long drive in hot weather, we noticed the battery pack warmed up more quickly during the first few minutes of rapid charging, when the battery pack's state of charge (SOC) was below 20 percent. A similar quick rise in temperature was observed when the battery pack was more than 80 percent full.

In other words, due to the basic battery chemistry, the high flow of current during a quick charge, when the battery has either a high or low state of charge, produces more heat. It's not nearly as significant when the SOC is at a moderate level—or during standard charging (regardless of SOC).

Avoid Quick Charging Beyond 80 Percent

Because rapid charging your LEAF beyond an 80 percent state of charge will heat up a pack, the car’s on-board battery management system will dramatically reduce the charging current. That protects the safety of the pack, but slows down the charging process, and increases the time you need to add the same number of miles.

With outside temperatures around 85 Fahrenheit, and our battery pack already hovering near 118 degrees, getting the last electrons to top up the battery took almost 30 minutes. In colder weather, it usually takes about 10 minutes.

LEAF Battery Monitor App />

By avoiding quick charging beyond 80 percent, you’ll not only save time in an electric pit stop, but also help preserve your car’s battery health. If you absolutely need to quick charge beyond 80 percent to make it to your next destination, we recommend allocating extra charging time and some cool-down time for your car as well.

Occasional Prolonged Charge-and-Use Cycles Are Okay

We didn't conduct formal battery tests in a lab—we're not engineers—but we can report that a few days after making the epic trip, our LEAF returned to normal battery temperatures. There was no discernible impact on battery health or performance.

It appears that long-distance trips with multiple quick charges in a single day are possible in hot weather in the LEAF. But just like driving in colder weather, which reduces range, driving in hot weather requires a little extra planning to consider the potential extra time needed for charging.

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