Why do batteries work poorly in very cold weather?

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Cross-section diagram of an alkaline-manganese dioxide battery showing labeled internal components, including the steel-plated covers, cathode, anode gel, current collector, separator, steel can, and brass rivet. — battery Cutaway view of an alkaline–manganese dioxide power cell.

Batteries perform poorly in cold weather primarily because low temperatures reduce the voltage of the cell and slow down the internal diffusion rates of the chemicals required to generate current.1

For a battery to function, ions must move through the electrolyte at a speed sufficient to meet the device's electrical demand. When the temperature drops below a reference point, such as 21 °C (70 °F), these internal chemical reactions and ion movements become sluggish, limiting the rate at which current can be drawn.1

If the temperature falls below the freezing point of the electrolyte, the battery may produce very little useful current. Furthermore, extreme cold can cause the internal dimensions of the cell to change, potentially leading to permanent damage and diminished performance even after the battery warms up.1