Frozen batteries, while rare, can be a frustrating problem for the heavy-duty commercial trucking industry, and can even become dangerous. When a vehicle battery freezes, it will fail to start.
According to Charley Gipe, Purkeys Technical Service Representative, the combination of sulfuric acid and water inside a battery, called electrolytes, normally has a freezing point far below zero. However, as the battery discharges, sulfuric acid is combined with the battery’s plates, leaving water behind. These increasing amounts of water in the battery are what make uncharged batteries able to freeze in temperatures as high as 20° Fahrenheit.
“If you think a battery is frozen, the last thing you want to do is attempt to charge or jumpstart that battery,” Gipe said.
Inside and outside of batteries, water expands as it freezes. This expansion inside of a vehicle battery can cause damage to its internal structure, cracking the battery’s casing or even stretching and fraying wiring. Jumpstarting batteries with this kind of damage can cause sparks, possibly triggering an explosion. If the sides of a battery are cracked or bulging, or no liquid can be heard inside when moved, attempting to use the battery can be extremely dangerous.
Keeping fleet batteries at a high state of charge is the best way to prevent freezing. According to Gipe, a fully-charged battery can have a freezing point as low as -70° Fahrenheit. “As long as the battery is fully charged, it’s not going to freeze,” Gipe said.