What Happens to Car Batteries at Extreme Temperatures?
Both hot and cold weather cause excessive wear and tear on your car's battery. When the air temperature reaches 77 degrees Fahrenheit, the battery's capacity maxes out. For every additional 15 degrees in air temperature, the battery's ability to deliver amps decreases by 50 percent.
Cold weather also decreases battery capacity. For most lead-acid batteries, capacity decreases by 20 percent when temperatures drop to freezing. For every 15 degrees below freezing, the battery's ability to deliver cold cranking amps decreases by another 10 percent.