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Engineers Develop Electric Car Battery That Can Heat Itself During Winter (popularmechanics.com)
Engineers at Penn State have created a battery that can self-heat, allowing for rapid charging regardless of the outside cold. The battery can reportedly provide a 15-minute rapid charge at all temperatures, even when the cold is as low as minus 45 degrees Fahrenheit. Popular Mechanics reports: Batteries have both positive and negative terminals. The scientists placed thin nickel foil with one end attached to the negative terminal and the other end creating a third terminal. When a temperature sensor attached to a battery detects that the battery is below room temperature, it then sends electrons flowing through the nickel foil. This heats the battery up until it's above room temperature again. When the sensor detects that the battery is above room temperature, that's the sign that charging that can begin again. Electric current flows into the battery, rapidly charging in a more efficient state. After 4,500 cycles of testing, the new battery only showed a 20 percent capacity loss, which could provide approximately 280,000 miles of driving and a lifetime of 12.5 years. This is compared to a conventional battery that "showed a 20 percent capacity loss after only 50 charges," reports Popular Mechanics. Penn State released a press statement with more details.
Short circuit a battery, and it heats?
A group of Tesla owners on the Dutch-Belgium Tesla Forum are gathering data from over 350 Tesla vehicles across the world and frequently updating it in a public Google file. We have previously reported on the data, but they have since added many more vehicles and those vehicles have been driving a lot more – completing more battery cycles. The data clearly shows that for the first 50,000 miles (100,000 km), most Tesla battery packs will lose about 5% of their capacity, but after the 50,000-mile mark, the capacity levels off and it looks like it could be difficult to make a pack degrade by another 5%.
https://electrek.co/2018/04/14/tesla-battery-degradation-data/
The trend line currently suggests that the average battery pack could cycle through over 300,000 km (186,000) before coming close to 90% capacity.
EVs work fine in the cold, but it does reduce their range. A friend of mine used the same cells that Tesla uses to power a light for his dog sled in the Iditarod, and it worked flawlessly at 40 below.
Some cars do worse in the winter than others. My Tesla may lose a third of its range in extreme cold while my Leaf loses more than half. Whether this makes a particular EV impractical for you depends on the car and your needs.