In fact, each car has one group size, and one group size alone, that works for it. Indication If looking to find the group number measurement of a marine battery, it can be found on the top of the battery, printed on a specifications label that will have other measurements on it as well. Group 27 batteries are an extremely popular BCI group size. Purchase your Batteries at BatteryWeb.com. A car's battery tray will vary in size depending on the manufacturer, but most are designed to accommodate batteries of a specific group size.. While the BCI does not determine the Amp Hours (AH) rating for the batteries, there is a correlation between case size and AH rating. You need to find the right size, or you open yourself up to a world of annoyance, aggravation, and possibly serious internal damage. Rectangular in shape, with recessed top post terminals, the OPTIMA H6 YELLOWTOP is 10.94 inches long, 7.48 inches tall and 6.89 inches wide, weighing in at just over 54 pounds. Battery Group Size This refers to the battery size that will best fit the physical dimensions, terminal locations and type required for your vehicle. I often hear people say they are going to increase the size of their batteries by replacing their Group 24 batteries with Group 27s. I purchased the $50 version, and has been cranking the engine & working fine all winter. The second way is to look directly on your battery (See Figure below). Presumably you got a reduced price b/c of the C version. Contact BCI, 401 N. Michigan ave, Chicago IL 60611-4267, (312) 644-6610 for more information. Width and length measurements are generally to the widest point, including protruding flanges, except for hold-down flanges at the bottom of the battery. Group Size Definition. Unfortunately they are under a misconception that group size and battery capacity are related. The battery group size of both a group 27 battery can differ depending on manufacturing processes—not just in dimension either, but considerably also in performance markers like CCA or the RC. Generally speaking these batteries will range between 85 amp hour (Ah) and 100Ah, 600 cold cranking amps (CCA) and 1050 CCA and 150 reserve capacity (RC) and 195 RC. It is important that your car battery fits snugly and securely in its battery tray. What is a H6 battery? Group 31 batteries measure 13 inches long, 6 13/18 inch in width and 9 7/16 inch in height. Smaller group indicates a generally larger battery, whereas larger group indicates a generally smaller battery. Rectangular in shape, with recessed top post terminals, the OPTIMA H6 YELLOWTOP is 10.94 inches long, 7.48 inches tall and 6.89 inches wide, weighing in at just over 54 pounds. Consult a replacement guide … Although some vehicles may accommodate a battery from more than one group size, it is important that you use a battery approved for use in your vehicle. But, if we are to answer based on dimensions, will arguably not be so different unless you are going for a leap in size (like a group 31 size battery). Battery specifications are generally present in the manual and are easy to get. Group numbers denote the dimensions that will mirror the physical characteristics of your present vehicle battery. For example, if a battery is rated at 40 amp-hours, the battery can provide 40 amps continuously for one hour, or one amp for 40 hours.