Battery BCI groups

Battery BCI groups

Most batteries are refered to as an “group XY battery”, there is a number like 24 of 27 at the spot of the XY. This only tells something about the dimensions of the battery and has nothing to do with Ah (Amp-hour) rating or CCA (Cold Crank Amps, applies to starter batteries). The capacity usually rises when the battery gets bigger so there is some logic.

 Deep cycle 12V batteries


Battery BCI Group Size (LxWxH) Capacity (Average)
Group 24 11.3″ x 6.8″ x 8.9″ 80Ah – 90Ah
Group 27 12.1″ x 6.8″ x 8.9″ 90Ah – 100Ah
Group 31 12.9″ x 6.8″ x 9.2″ 125Ah – 150Ah
Group 4D 20.5″ x 8.5″ x 10.0″ 200Ah – 250Ah

Other popula groups like for example 25, 34, 35 etc are all starter batteries used in cars.

Deep cycle 6V batteries

deepcycle-6v-gc2 deepcycle-6v-l16

Battery BCI Group Size (LxWxH) Capacity (Average)
Group GC2 10.4″ x 7.1″ x 10.9″ 200Ah – 225Ah
Group L16 11.7″ x 7.0″ x 15.8″ 340Ah – 400Ah