Behind the Forecast: Winter’s impact on our car batteries

Listen to Science Behind the Forecast with Meteorologist Tawana Andrew every Friday on 89.3 WFPL at 7:45 a.m.
Listen to Science Behind the Forecast with Meteorologist Tawana Andrew every Friday on 89.3 WFPL at 7:45 a.m.
Published: Feb. 3, 2023 at 9:53 AM EST
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LOUISVILLE, Ky. (WAVE) - Summer heat’s impact on our vehicles may last into the winter months.

Heat is more detrimental to our car batteries than cold. Batteries Plus explained that “in most cases, extreme heat all but kills the battery and then the added stress of the freezing temperatures finishes it off.”

The heat disrupts a battery’s chemistry by causing internal corrosion and drying out the electrolytes needed to carry energy. Electrolytes are substances that conduct electricity when dissolved in water. Heat can evaporate battery fluid, impacting its ability to hold a charge. Evaporated battery fluid could lead to structural damage and eventually acid leads that corrode battery terminals.

Experts state that batteries already weak due to extreme heat are more vulnerable when exposed to sudden cold snaps; this could drain the battery by up to 60%.

After the summer heat wreaks havoc, the cold weather slows down a battery’s chemical reactions. According to Firestone, a car battery loses 35% of its strength at 32°F and 60% at 0°F. Our car batteries gradually discharge energy over time; extreme cold can increase that discharge rate.

Winter also down the chemical processes inside a battery. Engine oil is thicker in the cold, requiring more energy to get it where it’s needed. Fans, defrosters, and viscous oil all require extra power, which further stresses the battery.

A fully charged battery won’t freeze until -76°F, but a fully discharged battery could start to freeze around 32°F.

AAA estimates that those living in Kentucky and Indiana may need to replace their batteries every 45 to 54 months (3.75 to 4.5 years).

Tire pressures typically decrease one PSI for every 10-degree drop in outside temperature, AAA...
Tire pressures typically decrease one PSI for every 10-degree drop in outside temperature, AAA says.(AAA)