Firefly Oasis Group 31 BatteryFirefly logo

Microcell foam technology - the wave of the future.

Carbon foam, developed by scientists at Firefly International Energy in the United States, is a material that's revolutioninizing the battery industry. Compared to lead plates (one of the main components of most conventional batteries), Firefly's patented technology delivers:

–  Longer service life
–  Faster recharge
–  Greater energy capacity
–  Deeper discharge capability
–  Better performance under extreme conditions

The unique design of Firefly's batteries resists sulfation and corrosion (two of the primary causes of failure in lead-acid batteries), while dramatically increasing the surface area within the battery, resulting in greater energy capacity, faster recharges, and deeper discharge capability.

In an independent PSOC (Partial State Of Charge) testing of AGM batteries done by Rodd Collins of Compass Marine for Practical Sailor, the Firefly AGM was the only AGM to regain FULL capacity after 30 PSOC (one month) of cycle testing.

For a full description of the testing procedure, see:

For the test results summary, see:

Click on the following graph to see how Firefly performed after 30 cycles of "abuse" during Rodd's testing.


While these batteries have proven their resilience over the past 8 years in multiple land-based applications, the first well-documented field test in the marine environment was done in the summer of 2014 by Nigel Calder.

As a marine systems guru and author of the Boatowner's Mechanical and Electrical Manual, Nigel Calder's opinion is respected by boaters the world over. Here is what he had to say about the Firefly Oasis:

"In preliminary testing I worked the Firefly batteries hard in a real-world (onboard, while cruising off the west coast of Scotland) partial state of charge operation. The goal was to minimize engine run times and optimize electrical system performance in an 'off-the-grid' situation with limited recharging opportunities. The kind of operating regime I followed spells death for most lead-acid batteries. In contrast, after two months of intensive cycling, the Firefly batteries tested out with 100% of the capacity with which they started. These are encouraging results which, if substantiated over longer periods of time, represent a 'game changer' in terms of lead-acid technology and boat electrical systems design. I look forward to collecting more data."  - Nigel Calder

Then Nigel stored the batteries over Fall/Winter after discharging them to 38% state-of-charge and here are his results with his Spring commissioning:

After discharging the 24v series/parallel Firefly pack to 38% SoC last August I left the batteries disconnected all winter (over 8 months). When I got here I did a normal recharge with the 4 batteries in 24v series/parallel mode. I held the absorption voltage overnight (i.e. no specialized voltage/current; just an extended timer on the absorption for a mild overcharge without equalization voltages), ran the batteries in boat use for several hours with a float charge, then did a C20 capacity test. I got right at 110 Ah per block at the C20 rate, so this looks really good. I recharged with a voltage limit of 28.8v (14.4v/block) and a current limit of 0.25C. The 4 batteries maintained an amazingly consistent voltage on discharge and recharge. All-in-all, this is very positive. - Nigel Calder

Oasis Group 31 Battery Key Features:

•  Superior reserve capacity. Packs more power and energy
•  Low self-discharge characteristics and unprecidented ability to recover after a long period of inactivity/non-use
•  Sturdy brass terminals for increased conductivity and corrosion resistance
•  Sealed valve regulated maintenance free design
•  Absorbesnt Glass Mat separators prevent spilling of acid and resist damage from vibration
•  Substantially higher cycle life - over twice that of conventional batteries
•  Unparalleled ability to operate under Partial State of Charge (PSOC) without any loss of capacity and performance

Electrical Specifications:

Capacity at 20 hour rate 116 Amp/Hour
Reserve Minutes @ 25 amps 225
Maximum Charge Voltage 14.4v
Shelf life at 25 C / 77 F 2 years 
Cold Cranking Amps (CCA) 600
Internal resistance 3.8 mΩ
Battery Type Valve Regulated Lead Acid (VRLA)
Separator Type Absorbed Glass Mat (AGM)
Maximum Charge Current 250 amps at 25°C


Height 238.25 mm (9.4")
Width 170.18 mm (6.7")
Length 339 mm (13.37")
Weight 34 kg (75 lbs)
Terminal 3/8 - 16 UNC
Volume 13.77 L (840.25 cu in)

Download Firefly User's Manual

Limited Warranty is 3 or 6 years, depending on application (RV/marine is 6 years). Read the complete warranty.

Download specs-brochure with all this information. See more at Firefly International Energy's web site.

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Firefly Oasis Group 31 PSOC marine battery

  • Product Code: FF12D1-Gp31
  • Availability: Pre-Order
  • $486.00

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