BCI Battery Groups

Marine batteries come in various sizes, having different capacities, voltages and performances in general.

Depending on the size, batteries are categorized in various size groups. Of course, there are always 'special' size batteries, so pay attention when buying new batteries.

Battery Dimensions By Group Size

Following tables show industry standard group sizes according to their external dimensions. Battery compartments are usually made for a certain battery standard, so knowing both values is important - larger battery can't fit into smaller compartment, while smaller can, but must be additionally fixed to avoid any damage to the boat or battery.

Most popular battery group sizes:

Following BCI battery group size chart lists most common battery sizes.

Note: we have really tried to verify information provided in this table, but there are no warranties of any kind.

BCI Group Size	L (mm)	W (mm)	H (mm)	L (inches)	W (inches)	H (inches)	Amazon Search
21	208	173	222	8 3/16	6 13/16	8 3/4	Group 21 Battery
21R	208	173	222	8 3/16	6 13/16	8 3/4	Group 21R Battery
22F	241	175	211	9 1/2	6 7/8	8 5/16	Group 22F Battery
22HF	241	175	229	9 1/2	6 7/8	9	Group 22HF Battery
22NF	240	140	227	9 7/16	5 1/2	8 15/16	Group 22NF Battery
22R	229	175	211	9	6 7/8	8 5/16	Group 22R Battery
24	260	173	225	10 1/4	6 13/16	8 7/8	Group 24 Battery
24F	273	173	229	10 3/4	6 13/16	9	Group 24F Battery
24H	260	173	238	10 1/4	6 13/16	9 3/8	Group 24H Battery
24R	260	173	229	10 1/4	6 13/16	9	Group 24R Battery
24T	260	173	248	10 1/4	6 13/16	9 3/4	Group 24T Battery
25	230	175	225	9 1/16	6 7/8	8 7/8	Group 25 Battery
26	208	173	197	8 3/16	6 13/16	7 3/4	Group 26 Battery
26R	208	173	197	8 3/16	6 13/16	7 3/4	Group 26R Battery
27	306	173	225	12 1/16	6 13/16	8 7/8	Group 27 Battery
27F	318	173	227	12 1/2	6 13/16	8 15/16	Group 27F Battery
27H	298	173	235	11 3/4	6 13/16	9 1/4	Group 27H Battery
29NF	330	140	227	13	5 1/2	8 15/16	Group 29NF Battery
33	338	173	238	13 5/16	6 13/16	9 3/8	Group 33 Battery
34	260	173	200	10 1/4	6 13/16	7 7/8	Group 34 Battery
34R	260	173	200	10 1/4	6 13/16	7 7/8	Group 34R Battery
35	230	175	225	9 1/16	6 7/8	8 7/8	Group 35 Battery
36R	263	183	206	10 3/8	7 1/4	8 1/8	Group 36R Battery
40R	277	175	175	10 15/16	6 7/8	6 7/8	Group 40R Battery
41	293	175	175	11 3/16	6 7/8	6 7/8	Group 41 Battery
42	243	173	173	9 5/16	6 13/16	6 13/16	Group 42 Battery
43	334	175	205	13 1/8	6 7/8	8 1/16	Group 43 Battery
45	240	140	227	9 7/16	5 1/2	8 15/16	Group 45 Battery
46	273	173	229	10 3/4	6 13/16	9	Group 46 Battery
47	246	175	190	9 11/16	6 7/8	7 1/2	Group 47 Battery
48	306	175	192	12 1/16	6 7/8	7 9/16	Group 48 Battery
49	381	175	192	15	6 7/8	7 3/16	Group 49 Battery
50	343	127	254	13 1/2	5	10	Group 50 Battery
51	238	129	223	9 3/8	5 1/16	8 13/16	Group 51 Battery
51R	238	129	223	9 3/8	5 1/16	8 13/16	Group 51R Battery
52	186	147	210	7 5/16	5 13/16	8 1/4	Group 52 Battery
53	330	119	210	13	4 11/16	8 1/4	Group 53 Battery
54	186	154	212	7 5/16	6 1/16	8 3/8	Group 54 Battery
55	218	154	212	8 5/8	6 1/16	8 3/8	Group 55 Battery
56	254	154	212	10	6 1/16	8 3/8	Group 56 Battery
57	205	183	177	8 1/16	7 3/16	6 15/16	Group 57 Battery
58	255	183	177	10 1/16	7 3/16	6 15/16	Group 58 Battery
58R	255	183	177	10 1/16	7 3/16	6 15/16	Group 58R Battery
59	255	193	196	10 1/16	7 5/8	7 3/4	Group 59 Battery
60	332	160	225	13 1/16	6 5/16	8 7/8	Group 60 Battery
61	192	162	225	7 9/16	6 3/8	8 7/8	Group 61 Battery
62	225	162	225	8 7/8	6 3/8	8 7/8	Group 62 Battery
63	258	162	225	10 3/16	6 3/8	8 7/8	Group 63 Battery
64	296	162	225	11 11/16	6 3/8	8 7/8	Group 64 Battery
65	306	190	192	12 1/16	7 1/2	7 9/16	Group 65 Battery
70	208	179	196	8 3/16	7 1/16	7 11/16	Group 70 Battery
71	208	179	216	8 3/16	7 1/16	8 1/2	Group 71 Battery
72	230	179	210	9 1/16	7 1/16	8 1/4	Group 72 Battery
73	230	179	216	9 1/16	7 1/16	8 1/2	Group 73 Battery
74	260	184	222	10 1/4	7 1/4	8 3/4	Group 74 Battery
75	230	179	196	9 1/16	7 1/16	7 11/16	Group 75 Battery
76	334	179	216	13 1/8	7 1/16	8 1/2	Group 76 Battery
78	260	179	196	10 1/4	7 1/16	7 11/16	Group 78 Battery
85	230	173	203	9 1/16	6 13/16	8	Group 85 Battery
86	230	173	203	9 1/16	6 13/16	8	Group 86 Battery
90	246	175	175	9 11/16	6 7/8	6 7/8	Group 90 Battery
91	280	175	175	11	6 7/8	6 7/8	Group 91 Battery
92	317	175	175	12 1/2	6 7/8	6 7/8	Group 92 Battery
93	354	175	175	15	6 7/8	6 7/8	Group 93 Battery
95R	394	175	190	15 9/16	6 7/8	7 1/2	Group 95R Battery
96R	242	173	175	9 9/16	6 13/16	6 7/8	Group 96R Battery
97R	252	175	190	9 15/16	6 7/8	7 1/2	Group 97R Battery
98R	283	175	190	11 3/16	6 7/8	7 1/2	Group 98R Battery
Passenger Car and Light Commercial 6 V Batteries (3 Cells)
1	232	181	238	9 1/8	7 1/8	9 3/8	Group 1 Battery
2	264	181	238	10 3/8	7 1/8	9 3/8	Group 2 Battery
2E	492	105	232	19 7/16	4 1/8	9 1/8	Group 2E Battery
2N	254	141	227	10	5 9/16	8 15/16	Group 2N Battery
17HF	187	175	229	7 3/8	6 7/8	9	Group 17HF Battery
Heavy Duty Commercial 12 V Batteries (6 Cells)
4D	527	222	250	20 3/4	8 3/4	9 7/8	Group 4D Battery
6D	527	254	260	20 3/4	10	10 1/4	Group 6D Battery
8D	527	283	250	20 3/4	11 1/8	9 7/8	Group 8D Battery
28	261	173	240	10 5/16	6 13/16	9 7/16	Group 28 Battery
29H	334	171	232	13 1/8	6 3/4	9 1/8	Group 29H Battery
30H	343	173	235	13 1/2	6 13/16	9 1/4	Group 30H Battery
31	330	173	240	13	6 13/16	9 7/16	Group 31 Battery
Electric Vehicle 6 V Batteries (3 Cells)
GC2	264	183	270	10 3/8	7 3/16	10 5/8	Group GC2 Battery
GC2H	264	183	295	10 3/8	7 3/16	11 5/8	Group GC2H Battery

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Many BCI battery groups differ by only fraction of an inch and they can be used interchangeably, if and only if the new battery fits the 'old' battery tray/box, and features equal or better charging/discharging characteristics compared to the old battery.