Electrolyte Freezing

The freezing point of electrolyte depends on its specific gravity. Since freezing may ruin a battery, protect it against freezing by keeping it in a charged condition. As long as the green dot shows in the built-in hydrometer, the battery will not freeze unless the temperature drops below -32°C (-25°F). A fully charged battery will not freeze unless the temperature drops below -54°C (-65°F).