Chevy Tweaks 2020 Bolt’s Battery Chemistry to Add Range
GM changed the cell chemistry while leaving the battery pack unchanged to add 21 miles of range, but a soggy test drive took back the added miles.
In late 2016, the Chevrolet Bolt became a breakthrough vehicle for long-range EV affordability. At the time, no other electric car came close to offering the Bolt’s 238 mi (383 km) of driving range at a base price of about $37,000. But since then, General Motors saw the Bolt’s lead surpassed by the Tesla Model 3, by far the best-selling EV in recent years. The base Model 3 nearly matches the Bolt’s price, while offering the same range, high-tech features and faster charging. In 2018, the Hyundai Kona Electric was rated for 258 miles (415 km) of range, claiming long-range supremacy among EVs selling for below $40,000.
Facing competition, two years ago General Motors started a conversation with LG Chem, the Bolt’s battery supplier, about what could be done. The automaker challenged the South Korean battery-maker to find a way to increase the range of the Bolt’s 60-kwh battery, aiming for a 10% bump. LG Chem proposed several options, according to YoungNam Kim, a battery cell technical specialist for GM. “They said the easiest way would be to make a brand-new cell for GM,” Kim said. But GM’s vehicle engineering team didn’t want to alter the battery pack or its packaging in the vehicle.
Better living through chemistry
After more than a year of discussions in which both LG Chem and General Motors conducted tests of new chemistries, the teams settled on a new recipe. Chevrolet announced on Aug. 22, 2019, that the 2020 Bolt had earned an official EPA range of 259 mi (416.8 km). The 2020 Bolt, which will arrive in dealerships later this year, will have 66 kilowatt-hours of usable battery capacity.
On the eve of the first media drive of the 2020 Bolt, Kim held up two battery cells, one from the outgoing 2019 Bolt and the new-and-improved version. They looked nearly identical. “The length of the cells is exactly the same. The width and thickness are slightly different,” Kim said, noting there are about 100 layers of anode, cathode and separator.
Robert Mantinan, engineering manager, explained, “It has the same number of cells, the same enclosure, the same format and the same layout.” General Motors declined to disclose the new battery recipe for the 2020 Bolt pack, other than that it remains a blend of nickel, cobalt and manganese. GM also said that the cells have additional active material in the anode and cathode.
In recent years, automakers producing electric vehicles have been trying to increase the percentage of nickel in its formulas, a strategy to improve energy density. At the same time, reducing the amount of cobalt reduces cost and mitigates price volatility. Also, human rights organizations have raised ethical concerns about the use of child labor to extract cobalt in the Democratic Republic of Congo and other regions. Cobalt and manganese help maintain cell stability and long cycle life, extending the reliability and longevity of EVs.
GM also used new methods for battery lab testing, allowing the company to lower the battery’s resistance during DC quick charging. “We optimized our charging algorithms,” Mantinan said. The Bolt can now add 100 miles (160.9 km) of range in the first 30 minutes of charging if the battery is nearly depleted when starting a charging session, and the ambient temperatures are mild.
Your mileage may vary
The 2020 Bolt’s extra 21 mi (34 km) of range and its ability to quickly add miles via a DC fast charger proved critical during our recent 240-mile (386-km) test drive. To test the range, Chevrolet set a winding course for journalists to travel from Tacoma, Wash. to Portland, Ore. A day earlier, engineers from GM successfully completed the route. But that was under sunny skies and 70°F (21°C) weather. By the next day, the weather turned, and we experienced long periods of pelting rain. The temperature had dropped to about 45°F (7°C), prompting use of the cabin heater. According to the Bolt’s dashboard indicator, the use of climate settings reduced range by about 8%.
By the time we traveled 153 mi (246 km) to Astoria, Ore., we had used 47 kwh of energy. The dashboard’s estimated remaining range was 59 mi (94.9 km), not enough to complete the remaining 90 miles (144.8 km) to Portland. Among the group of about 10 vehicles on the media drive, one light-footed driver arrived in Astoria with 100 mi (160.9 km) of remaining range. The most aggressive journalist had drained the battery down to its last 15 mi (24 km) of estimated range.
The hard rain and wet road conditions diminished the efficiency, requiring that we make an electric pitstop at the Electrify America DC fast-charging location in Kelso, Ore. Electrify America, a subsidiary of Volkswagen, is among the first public EV stations capable of charging at between 150 and 350 kW. The faster rates are usable by several new and upcoming EVs, including the Audi E-tron. However, the Bolt’s limit is 55 kW.
The location in Kelso features four charging pedestals with two chargers each. About half of the chargers experienced technical difficulties, such as credit-card readers failing to connect and charging sessions not initiating for inexplicable reasons. That was disconcerting because we had used 60 kilowatt-hours of juice to reach the Three Rivers Mall location. The dashboard range indicator read, “Low Range” and “Charge Vehicle Soon.”
Fortunately, with Chevrolet’s help, we were able to charge at 53 kW. The session lasted 23 minutes, adding 20.1 kilowatt-hours of energy, approximately the promised rate of 100 miles added in 30 minutes. The juice cost $6.00. We easily completed the remaining 43 mi (69.2 km) to Portland.
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