BCI Group 27 Batteries

BCI Group 27 Batteries are a group of mid-size batteries often used in as starting, dual-purpose and deep cycle batteries in one and two battery systems, commonly found in automotive, industrial, and marine applications.

While Sealed Lead Acid (SLA) Absorbent Glass Mat (AGM) batteries still dominate this group, Lithium Iron Phosphate (LiFePO4) group 27 batteries are gaining on the momentum despite their initial higher cost.

upg ub121000 1

BCI Group 27 Batteries - Dimensions, Features, and Specifications

Physical dimensions of the BCI Group 27 batteries (L x W x H) are 12.0625 x 6.8125 x 8.875 inches (306 x 173 x 225 mm) with the positive terminal on the left side of the battery.

However, BCI battery group 27 also has sub-models, including group 27, group 27F, and group 27H.

These groups vary slightly in their actual size, as given in the following comparison chart:

BCI Group Size L (mm) W (mm) H (mm) L (inches) W (inches) H (inches)
27 306 173 225 12.0625 6.8125 8.875
27F 318 173 227 12.5 6.8125 8.9375
27H 298 173 235 11.75 6.8125 9.25

Also, these batteries feature different terminal types, battery type depending on the intended use, battery chemistry, etc.

Note: when ordering new group 27 battery (or any other battery!), be sure to check the actual size of the battery, terminal types and orientation, as well as other parameters, like CCA, MCA, RC, chemistry, etc.

The most popular starting, dual-purpose, and deep cycle group 27 batteries are given in the following comparison chart:

Model Battery Type Chemistry Capacity CCA MCA RC Weight (lbs/kg)
Review
Banshee LiFeP04 Dual Purpose LiFePO4 70 900 - 160+ (?) 18.8 lbs; 8.5 kg -
Banshee 27M Starting Enhanced Flooded 77 800 1000 140 (37 lbs; 16.8 kg?) -
GreenLiFE GL80-80AH Deep Cycle LiFePO4 80 - - ~180 28 lbs; 12.8 kg -
Mighty Max ML100-12 Deep Cycle AGM 100 - - 180 @22.5A 63.9 lbs; 29 kg -
NorthStar NSB-AGM27 Dual Purpose AGM 92 930 1080 195 68 lbs; 31 kg -
Optima 8027-127 D27M Dual Purpose AGM 66 800 1000 140 54 lbs; 24.5 kg -
Optima 8037-127 D27F Dual Purpose AGM 66 830 1025 140 54 lbs; 24.5 kg -
UPG UB121000 Deep Cycle AGM 100 - - 170 64 lbs; 29 kg -
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 -

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

The most common group 27 batteries are AGM dual-purpose and deep cycle AGM batteries.

These non-spillable batteries vary in size, weight, and capacity - most of them feature flat plates, but Optima group 27 batteries feature spiral wound plates and have lower nominal capacity, weight, and Reserve Capacity (RC) value, but they feature excellent starting characteristics and easily support 300+ charging/recharging cycles.

optima d27f

Flooded/wet lead-acid batteries are being phased out by AGM and Gel-cell lead-acid batteries and various lithium-ion batteries, but 'Enhanced Flooded' batteries are still doing rather well, offering good performances at a lower weight than the AGM and Gel-Cell batteries.

Personally, if You need group 27 battery (or batteries) and classic non-spillable, maintenance-free AGM batteries are too heavy for Your applications, consider Lithium Iron Phosphate (LiFePO4) group 27 batteries - they do cost more initially, but deep-cycle group 27 batteries support 5-10x more charging/recharging cycles, they don't suffer from capacity loss when being discharged using stronger currents, etc.

greenlife gl80

Also, never, but really never charge lithium-ion battery with the 'intelligent' battery charger intended for AGM/Gel/Wet lead-acid batteries without 'Lithium-Ion Battery' charging mode.

Deep cycle AGM group 27 batteries feature 100 - 110 Ah nominal capacity, 170 - 220 min RC, and weigh around 64 - 68 pounds (29 - 31 kg). Although they should not be used as starting batteries, some models are able to provide 800-880 MCA Amps.

Since Group 27 batteries are in high demand for various applications, it is not uncommon that some companies manufacture several models of group 27 batteries. For example, VMAXTANKS manufacture:

- VMAXTANKS SLR100: a true deep-cycle battery, intended for solar, wind, and other similar off-the-grid applications that don't require the battery to provide large currents. Also,

- VMAXTANKS MR127-100: a deep-cycle battery for various applications, including industrial/automotive/marine applications that occasionally require the battery to provide larger currents.

vmaxtanks mr 127

- VMAXTANKS XTR27-110: another battery by VMAXTANKS that is labeled as a deep cycle battery, but it is very close to a true dual-purpose battery. This model is capable of cranking even the larger gas and diesel engines, but if possible, it should be used as a deep cycle battery and for powering loads that require a couple of hundred Amps from time to time - pumps, winches, and similar.

Dual-purpose AGM group 27 batteries are able to provide 800-930 CCA Amps and 1000-1080 MCA Amps and are able to crank rather large diesel and gas engines.

Their nominal capacity and RC values vary mostly due to the differences in internal construction (flat plates, spiral wound plates). Also, their weight varies from 54 pounds (Optima) to 68 pounds (NorthStar).

northstar nsb agm27

When choosing your next group 27 battery (or any other battery) always choose according to your own needs and requirements.

How to Charge Group 27 Batteries

If the battery (or batteries) are connected to the electric system of the vehicle, boat, or similar application that features an onboard built-in battery charger, let that charger charge the battery as before (assuming it is doing its task properly).

If the battery is being charged with a dedicated battery charger, use an intelligent battery charger that features several charging modes.

For AGM/Gel-Cell/Wet lead-acid batteries, an intelligent battery charger with temperature compensation, battery type selector, and charging modes that also include analysis, desulphation, equalization, and maintenance is highly recommended.

Such battery chargers may be even used for charging of the lithium batteries ONLY if they have a dedicated lithium-battery charging mode - otherwise, lead-acid charging modes (like desulphation) may damage the lithium-ion battery, or at least cause lithium-ion battery's Battery Management System (BMS) to shut-off the battery.

Since AGM group 27 batteries feature a nominal capacity in the 66 - 110 Ah range, a good 15 Amps AGM battery charger is ideal for charging of these batteries.

For example, if 100 Ah battery is being discharged down to 50% DoD, 15 Amps charger will recharge such battery in well under 4 hours.

Also, a good 25 Amps charger can do such a job in slightly more than 2 hours, but not all group 27 batteries can accept such charging current safely.


Group 27 Batteries as Inverter Batteries

Group 27 batteries are commonly used as inverter batteries for providing power in off-the-grid situations.

Actual runtime depends on the load and the battery.

For example, if UPG UB121000 battery is connected to 500 W pure sine inverter (with an efficiency of 85%), which is loaded at 100%, the battery must provide:

P(W) = 500 W / 0.85 = 588 watts

New, fully charged UPG UB121000 battery is able to provide 584 watts for one hour without the voltage dropping below 10.8 volts.

Although one hour doesn't sound much, one must note that 500W in the off-the-grid applications is a lot of power.

For example, if the same battery and power inverter are used to power 32-inch TV (LED ~41 watts, OLED ~57 watts, LCD ~70 watts), in the worst-case scenario (LCD ~70 watts), the battery must provide:

P(W) = 70 W / 0.85 = 82 watts.

New, fully charged UPG UB121000 battery is able to provide 82 watts for at least 13 hours without the voltage dropping below 10.5 volts. And if more energy-efficient TV technologies are used, this runtime can be even much longer.

 500 watts pure sine power inverters are very often used in the off-the-grid applications and in emergencies - they offer an excellent balance between the price and performances. However, they are not able to power larger home appliances and tools.


Long Story Short: BCI Group 27 batteries differ not only in the capacity, CCA/MCA, and RC values but also in the price, warranty terms, weight, terminal types, and orientation, etc.

Model Battery Type Chemistry Capacity CCA MCA RC Weight (lbs/kg)
Review
Banshee LiFeP04 Dual Purpose LiFePO4 70 900 - 160+ (?) 18.8 lbs; 8.5 kg -
Banshee 27M Starting Enhanced Flooded 77 800 1000 140 (37 lbs; 16.8 kg?) -
GreenLiFE GL80-80AH Deep Cycle LiFePO4 80 - - ~180 28 lbs; 12.8 kg -
Mighty Max ML100-12 Deep Cycle AGM 100 - - 180 @22.5A 63.9 lbs; 29 kg -
NorthStar NSB-AGM27 Dual Purpose AGM 92 930 1080 195 68 lbs; 31 kg -
Optima 8027-127 D27M Dual Purpose AGM 66 800 1000 140 54 lbs; 24.5 kg -
Optima 8037-127 D27F Dual Purpose AGM 66 830 1025 140 54 lbs; 24.5 kg -
UPG UB121000 Deep Cycle AGM 100 - - 170 64 lbs; 29 kg -
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 -

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

When choosing your next BCI Group 27 battery, be sure to choose according to your own needs and requirements, especially if you are considering different group 27 battery sub-model.