Common Battery Case Sizes By BCI Group Numbers | BatteryStuff

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Battery Store > Knowledge Base > Tools > BCI Battery Group Size Chart BCI Battery Group Size Chart Steve DeGeyter — Updated April 4, 2025 12:54 pm Share Post Share Pin Copy Link

Are you looking for a marine, RV, automotive, or solar PV battery? You may have heard common terms like a "group 24 battery" or "type 27 marine battery." Then our battery group size chart below may come in handy to help you find the right deep cycle battery. These numbers are referring to the Battery Council International, or BCI, Group Number of the battery. These numbers define the physical dimensions of the battery case. This is important as some applications call for specific case sizes.

While the BCI does not determine the Amp Hours (AH) rating for the batteries, there is a correlation between case size and AH rating. For deep cycle batteries, the larger the case size the more capacity the battery will usually have. For more information about Amp Hours, find out how it relates to battery capacity. To calculate how much reserve power you need, and thus which battery to use, check out our Calculator for Sizing a 12 Volt Battery to a Load.

Battery Group Size Chart for 12 Volt Deep Cycle RV & Marine batteries

BCI GROUP NUMBER	APPROXIMATE DIMENSIONS IN INCHES			Amp Hours (AH)	THUMBNAIL
	Length	Width	Height
U1 CSB Battery #: EVH12390 (AGM) CSB Battery #: GP12340 (AGM) MK Battery #: 8GU1 (GEL) MK Battery #: MU-1 SLD G (GEL)	7.71"	5.18"	6.89"	31 - 39
22NF Universal Battery #: UB12550-45825 (AGM) MK Battery #: 8A22NF (AGM) MK Battery #: 8G22NF (GEL) Univesal Battery #: UB22NFGEL (GEL)	9.01"	5.43"	9.00"	55
24 MK Battery #: 8A24 (AGM) Universal Battery #: UB12750-45821 (AGM) MK Battery #:8G24 (GEL) Universal Battery #:UB24GEL-D5872 (GEL)	11.13"	6.60"	9.25"	80
27 Universal Battery #: UB12900-45826 (AGM) MK Battery #: 8A27 (AGM) Universal Battery #: UB27 (GEL) MK Battery #: 8G27 (GEL)	12.00"	6.63"	9.06"	90
30H Universal Battery #: UB121100-D5751 Universal Battery #: UB30H (GEL)	13"	6.8"	9.5"	110
31 MK Battery #: 8A31DT (AGM) MK Battery #: E31 SLD G (GEL)	12.9"	6.75"	9.27"	125
4D Universal Battery #: UB4D-45965 (AGM) MK Battery #: 8A4DLTP (GEL) Universal Battery #: UB-4D-40701 (GEL) MK Battery #: 8G4DLTP (GEL)	20.5"	8.13"	10"	200
8D MK Battery #: 8A8DLTP (AGM) Universal Battery #: UB8D-45964 (AGM) Universal Battery #: UB-8D-40702 (GEL) MK Battery #: 8G8DLTP (GEL)	20.75"	11"	11"	245

Battery Group Size Chart for 6v Deep Cycle batteries

BCI GROUP NUMBER	APPROXIMATE DIMENSIONS IN INCHES			Amp Hours (AH)	THUMBNAIL
	Length	Width	Height
GC2 Universal Battery #: UBGC2 (AGM) MK Battery #: 8AGC2 (AGM) MK Battery #: 8GGC2 (GEL)	10.38"	7.13"	10.88"	225
L16 Lifeline Battery #: GPL-L16T (AGM) Universal Battery #: UB63800-40870 (AGM)	11.64"	6.95"	15.73"	400

Battery Group Size Chart for 2v Deep Cycle batteries

BCI GROUP NUMBER	APPROXIMATE DIMENSIONS IN INCHES			Amp Hours (AH)	THUMBNAIL
	Length	Width	Height
L16 Lifeline Battery #: GPL-L16T-2V (AGM)	10.38"	7.13"	10.88"	225

Battery Group Size Chart for 12v Starting batteries

BCI GROUP NUMBER	APPROXIMATE DIMENSIONS IN INCHES			Amp Hours (AH)	CCA	THUMBNAIL
	Length	Width	Height
25 BatteryStuff Part #: OPT-25	9.94"	6.81"	7.63"	44	720
34 BatteryStuff Part #: OPT-34	10"	6.88"	7.63"	50	800
34M BatteryStuff Part #: OPT-34M	10"	6.88"	7.94"	50	800
34R BatteryStuff Part #: OPT-34R	10"	6.88"	7.63"	50	800
34/78 BatteryStuff Part #: OPT-34/78	10"	6.88"	7.63"	50	800
35 BatteryStuff Part #: OPT-35	9.31"	6.82"	7.82"	44	720
75/25 BatteryStuff Part #: OPT-75/25	9.31"	6.82"	7.82"	44	720

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