BCI Group 27 Batteries

BCI Group 27 batteries are medium to large in size batteries, commonly used in automotive, marine, and industrial applications where BCI Group 31 batteries are slightly too large and BCI Group are too small to be able to provide enough power or store enough energy.

BCI Group 27 batteries are used in both cyclic and standby/float applications with Sealed Lead-Acid (SLA) Absorbent Glass Mat (AGM) batteries being the most common. For applications where lightweight design and a large number of charging/discharging cycles are required, Lithium Iron Phosphate (LiFePO4) batteries are becoming more and more popular.

Published: June 2, 2020. vmaxtanks mr 127 w400

BCI Group 27 Battery Dimensions

BCI Group 27 features several sub-sizes given in the following comparison table:

BCI Group Size L (mm) W (mm) H (mm) L (inches) W (inches) H (inches)
27 306 173 225 12 1/16 6 13/16 8 7/8
27F 318 173 227 12 1/2 6 13/16 8 15/16
27H 298 173 235 11 3/4 6 13/16 9 1/4

When trying to find a suitable battery model for your needs, always check the actual size of your battery compartment and the actual size of the battery - in most cases, knowing the battery BCI group is enough but better safe than sorry.

Also, some manufacturers label their batteries as 'group 27 batteries', but actual size is '27F' (slightly longer than '27') or even '27H' (slightly taller than '27').

Note: some manufacturers label their group 27 batteries as '27M' batteries to emphasize that their batteries are intended for marine applications.

BCI Group 27 AGM batteries are either dual-purpose or deep-cycle batteries - thanks to their size, even dual-purpose batteries are able to crank large marine and industrial diesel engines, negating the need for specialized cranking/starting Group 27 batteries.

Nominal (20h) capacity of the Group 27 AGM batteries ranges from 90 to 110 Ah, except for Optima group 27 batteries that feature a capacity of 'only' 66 Ah thanks to their spiral-wound cells ensuring great vibration resistance, high discharge currents, good deep-cycle characteristics while keeping the weight at an acceptable level.

Dual-purpose AGM group 27 batteries feature CCA ratings in the 800-930 Amps range and MCA ratings in the 1000-1080 Amps - even some deep cycle AGM batteries may be used as cranking batteries for smaller engines since they are able to provide 660 CCA Amps and 800 - 1170 MCA Amps.

Reserve Capacity of the Group 27 AGM batteries range from 170-220 minutes, except for lighter Optima batteries that feature RC values of 140 minutes.

renogy rbt100lfp12s g1 w250Lithium Group 27 batteries are not that common, but they offer many advantages over SLA AGM batteries, including a much larger number of charging/discharging cycles (10-15x increase), lighter weight (2-3x), more constant capacity leading to increase in weight ratio when being discharged with stronger currents (3-5x), faster recharging and similar.

On the other hand, the initial price of the lithium batteries is higher, but they save money in the long run.

Lithium batteries in general, even Lithium Iron Phosphate (LiFePO4) should be charged only with chargers and charge controllers intended for lithium batteries - note that some smart AGM battery chargers already feature special charging mode intended for lithium batteries, allowing such chargers to be used for charging even the lithium batteries with Battery Management Systems (BMS).

Note: If the lithium battery doesn't feature good BMS, I wouldn't use it in my car, truck, RV, boat, etc. Again, better safe than sorry.

Group 24 vs Group 27 vs Group 31 Deep Cycle Battery

BCI Battery groups 24, 27, and 31 are some of the most popular battery groups, differing in size and thus their capacity, CCA/MCA, and other ratings.

Physical dimensions of these groups are given in the following list:

- Group 24: 10.25 x 6.8125 x 8.875 inches (260 x 173 x 225 mm),

- Group 27: 12.0625 x 6.8125 x 8.875 inches (306 x 173 x 225 mm),

- Group 31: 13 x 6.8125 x 9.4375 inches (330 x 173 x 240 mm).

As the size and the volume of the batteries go up, so do their Amps, Ah, and other values.

Most Popular Group 27 Batteries

The following comparison chart lists some of the most popular BCI Group 27 batteries and their most important features:

Model Battery Type Chemistry Capacity (Ah) CCA MCA RC Weight Review
Banshee LFP-27M Dual Purpose LiFePO4 70 900 - ~165 18.8 lbs; 8.6 kg -
GreenLiFE GL80-80AH Deep Cycle LiFePO4 80 - - ~190 28 lbs; 12.8 kg -
Mighty Max ML100-12 Deep Cycle AGM 100 - - - 63.9 lbs; 29 kg -
NorthStar NSB-AGM27 Dual Purpose AGM 92 930 1080 195 68 lbs; 31 kg -
NorthStar NSB-AGM27F Dual Purpose AGM 92 930 1080 195 68 lbs; 31 kg -
NorthStar NSB-AGM27M Dual Purpose AGM 92 930 1080 195 68 lbs; 31 kg -
Optima 8027-127 D27M BlueTop Dual Purpose AGM 66 800 1000 140 54 lbs; 24.5 kg -
Optima 8037-127 D27F YellowTop Dual Purpose AGM 66 830 1025 140 53.2 lbs; 24.1 kg -
Powermall LFP12100-AGM Deep Cycle AGM 100 - - - 58 lbs; 26.3 kg -
PowerStar 12V 100Ah Group 27 Deep Cycle AGM 104 - - 180+ 66.1 lbs; 30.0 kg -
Renogy RBT100LFP12S-G1 Deep Cycle LiFePO4 100 - - ~240 26 lbs; 11.8 kg -
UPG UB121000 Deep Cycle AGM 100 - - 170 64 lbs; 29 kg UPG UB121000
VMAXTANKS MR127-100 Deep Cycle AGM 100 - 800 200 68 lbs; 31 kg -
VMAXTANKS SLR100 Deep Cycle AGM 100 - - 220 68 lbs; 31 kg -
VMAXTANKS XTR27-110 Deep Cycle AGM 110 660 880 220 68 lbs; 31 kg -
XS Power XP2500 Deep Cycle AGM 100 - - 185 67 lbs; 30.4 kg -
XS Power D2700 Deep Cycle AGM 100 - 1170 185 67 lbs; 30.4 kg -

optima d27f yellowtop w250Note: Amazon affiliate links ('Model' column) open in the new windows, so feel free to check them for the most up-to-date offers and prices.

Which Group 27 battery is 'the best'? When considering which battery is actually 'the best', there are few more things to consider, not just capacity, CCA/MCA, RC and similar:

- best general-purpose, budget-friendly batteries: Mighty Max ML100-12 and UPG UB121000,

- best dual-purpose battery: NorthStar NSB-AGM27, NSB-AGM27F, or NSB-AGM27M

- best lightweight dual-purpose battery: Optima D27M or Optima D27F,

- best all-round battery, with a budget in mind: VMAXTANKS MR127-100,

- best all-round battery: VMAXTANKS XTR27-110 and NorthStar for slightly stronger currents,

- best solar/wind/off-the-grid battery: VMAXTANKS SLR100.

As one can see, when trying to find 'the best' battery, one must consider personal needs, requirements, and also, preferences.

Lithium batteries are expensive, but for the deep-cycle applications they offer many benefits - GreenLIFE and Renogy group 27 LiFePO4 batteries are popular lithium batteries with their own specific features, so again, choose the battery that best suits Your need.

Banshee LFP-27M is a dual-purpose lithium battery - don't call me a dinosaur, but I still prefer good AGM as cranking battery and lithium battery for deep cycle applications.

And whatever you do, stay safe.