Group 31 Battery Specs

by Harry Havemeyer

The Battery Council International (BCI) is the nonprofit trade association of the battery industry. The BCI has established a standardized coding system for battery sizes to make classifying simpler. The Group 31 size pertains to heavy-duty commercial-grade batteries.


The Group 31 designation pertains to size only and does not inherently convey any information on the power of the battery itself, although the size can dictate power generation. Group 31 batteries measure 13 inches long, 6 13/18 inch in width and 9 7/16 inch in height.

Unit of Electrical Charge

Group 31 batteries are not assigned a specific ampere rating by their BCI size classification, but they do tend to fall into the range of 95 to 125 ampere hours.


Group 31 batteries are 12-volt batteries with six specific cells.


Heavy-duty, commercial-grade Group 31 batteries are commonly used in ambulances, firetrucks and other heavy motorized vehicles that require a long-lasting, reliable battery to start the ignition.

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