Group 27 Batteries - Dimensions, Features, and Recommendations

Group 27 batteries are rather large and powerful batteries, featuring 20h capacity in 66-110 Ah range, providing 600-1000 CCA, 140-220 minutes RC, etc. Their weight depends on the internal construction and it ranges between 54 and 70 pounds (24.5 - 32 kg).

Group 27 batteries' physical dimensions depend on the exact battery group because there are three different, although very similar battery groups: Group 27, Group 27F, and Group 27H, although they are often labeled as Group 27 Batteries.

Group 27 batteries are very common in automotive, marine, off-the-grid, RVs, and similar applications, making them one of the most popular battery groups.

Updated: April 29, 2021.

Actual Group 27 Battery Dimensions

As said before, there are three sub-groups of group 27 batteries, and their actual dimensions are given in the following table:

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

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

The real-life difference among these batteries is very small, but sometimes even a few millimeters can decide if the battery can (or cannot) fit the battery compartment/tray.

When labeling their batteries, most manufacturers provide both actual dimensions (inches, millimeters) and BCI Group Size, so before buying a new battery, check the actual dimensions of your battery compartment - better safe than sorry :)

Most Popular Group 27 Batteries

The following table lists the most popular group 27 batteries, with their most important features:

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

NorthStar manufactures three batteries in this group (NSB-AGM27, NSB-AGM27F and NSB-AGM27M), Optima Batteries manufactures two batteries in this group (D27M BlueTop and D27F YellowTop), while VMAXTANKS also manufactures three batteries (MR127-100, SLR100, XTR-110).

There are other group 27 batteries on the market, but these are the most popular ones.

As one can see, almost all the batteries in the table are AGM (Absorbent Glass Mat) SLA (Sealed Lead Acid), spill-proof batteries, being able to operate in virtually any position. Lithium group 27 batteries (mostly LiFePO4) are not so common due to their price, but they feature a good 20h capacity, a much larger number of charging/discharging cycles, and are much lighter than AGM SLA batteries.

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GreenLiFE Battery GL80-80AH is a 12V lithium-ion group 27 battery, designed to be used as a drop-in replacement for lead-acid batteries and its main flaw is its price - at least at first look.

Like other LiFePO₄ drop-in-replacements, the GreenLiFE GL80-80AH battery costs some 3x more than similar AGM batteries, but it is designed to withstand 3000-5000 charging/discharging cycles - and that is much more than AGM SLA batteries can withstand.

Also, GreenLiFE GL80-80AH battery is much lighter (more than double) than similar group 27 AGM batteries, and comes with built-in Battery Protection System (BTS) featuring:

- Automatic Low Voltage Disconnect,

- Automatic Short Circuit Protection,

- Automatic Over Voltage Protection,

- Automatic Reverse Polarity Protection,

- Internal Cell Thermal Safety Fuse,

- Automatic Internal Cell Balancing,

- Automatic Fault Recovery, etc.

For more info about this initially pricey battery, check GreenLiFE GL80-80AH Amazon link (link opens in the new window).

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NorthStar Group 27 batteries are dual-purpose AGM SLA batteries.

NorthStar NSB-AGM27, NSB-AGM27F, and NSB-AGM27M batteries feature 930 Amps CCA (Cold Cranking Amps) rating - new, fully charged batteries are able to provide 930 Amps for 30 seconds with the voltage NOT dropping below 7.2V at 0°F (-18°C). And that is very cold weather!

Also, they feature 1080 Amps CA/MCA (Cranking Amps/Marine Cranking Amps) rating - new, fully charged batteries are able to provide 1080 Amps for 30 seconds with the voltage NOT dropping below 7.2V at 32°F (0°C).

Reserve Capacity is rated at 195 minutes - new, fully charged batteries are able to provide 25 Amps for 195 minutes without the voltage dropping below 10.5 volts (1.75 volts per cell).

According to their manufacturer, NorthStar NSB-AGM27, NSB-AGM27F and NSB-AGM27M batteries are able to withstand:

- over 900 cycles to 50% Depth of Discharge (DoD), or to 50% State of Charge (SoC),

- over 400 cycles to 80% Depth of Discharge (DoD), or to 20% State of Charge (SoC).

Such number of charging/discharging cycles make NorthStar batteries one of the most resilient AGM SLA batteries on the market - just don't compare them with LiFePO4 batteries.

For more information about these batteries, check our NorthStar AGM BCI Group 27 Batteries - NSB-AGM27, NSB-AGM27F and NSB-AGM27M Batteries article, and for most up-to-date offers and prices, follow NorthStar NSB-AGM27 Amazon link (link opens in the new window).

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Optima Group 27 batteries feature spiral-wound cells and are lighter than other AGM SLA batteries.

They also feature the smallest 20h capacity of 66 Ah (66 Ah vs. 92-110 Ah).

However, both D27M BlueTop and D27F YellowTop are very popular batteries due to their balanced design, vibration resilience and durability.

Also, they feature 1000 MCA Amps value which is ~18.5 Amps pet pound (~40.8 Amps per kg), while NorthStar NSB-AGM27 features 1080 MCA Amps (~15.9 Amps per pounds, ~34.8 Amps per kg).

Optima D27M BlueTop is intended for marine applications, while Optima D27 YellowTop is intended for automotive applications.

For more information about these batteries, check our Optima Batteries D27M BlueTop and D27F YellowTop Starting and Deep Cycle Batteries article, and for most up-to-date offers and prices, follow Optima D27M BlueTop and Optima D27F YellowTop Amazon links (links open in the new windows).

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VMAXTANKS manufactures three batteries in this size:

- MR127-100 is a general AGM SLA group 27 battery, with good deep discharge features. Also, it can be used as starting battery, at least for smaller engines (MCA value of 800 Amps).

- SLR100 is a solar AGM SLA group 27 battery, optimized for low current applications - it should NOT be used as starting battery. Although both MR127-100 and SLR100 feature the same 20h capacity (100 Ah), SLR100 features a better RC value (220 vs 200 minutes).

- XTR27-100 is a high-performance AGM SLA group 27 battery. It features 110 Ah 20h capacity, 220 minutes RC, and 880 MCA amps.

For more information about these batteries feel free to check our VMAXTANKS MR127-100 AGM Deep Cycle Battery article, and for the most up-to-date offers and prices, check VMAXTANKS MR127-100, VMAXTANKS SLR100, and VMAXTANKS XTR27-110 Amazon links (links open in the new windows).

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Long Story Short: Group 27 batteries are capable of providing really strong currents that can cause damage, injuries, or worse. So, whatever you do be sure to know what are you doing, or let certified professionals do it for you.

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

When looking for proper battery group 27 replacement, check the actual size of the old battery and the battery compartment, check its capacity, CCA/MCA currents, RC values, and everything that may be important. The new battery should be at least equal (or better) in performance with the old battery and charged properly with the chargers on your disposal.