Battle Born GC2 vs Group 27/31 100Ah: Which Case Fits?
Battle Born sells its 12V 100Ah LiFePO4 battery in two shapes: a GC2 golf-cart size and a group 27/31 marine size. The insides are similar, so the choice comes down to where the battery will go. This guide compares the two using our product listings and helps you decide. It also covers the 75Ah group 24 and 270Ah GC3 models. Check product pages for current specs and stock.
Side by side
| Battle Born 100Ah GC2 | Battle Born 100Ah 27/31 | Battle Born 75Ah group 24 | Battle Born 270Ah GC3 | |
|---|---|---|---|---|
| Voltage | 12V | 12V | 12V | 12V |
| Capacity | 100Ah | 100Ah | 75Ah | 270Ah |
| Case | GC2 | Group 27/31 | Group 24 | GC3 |
| Weight | 31 lb | 31 lb | 27 lb | 80.8 lb |
| Listed cycle life | 3,000–5,000 | 3,000–5,000 | 3,000–5,000 | 3,000–5,000 |
| Usable depth of discharge | 100% | 100% | 100% | 100% |
| Charging voltage | 14.2–14.6V | 14.2–14.6V | 14.2–14.6V | 14.2–14.6V |
| Internal resistance | 7 mΩ | 7 mΩ | 10 mΩ | 5 mΩ |
| Listed lead-acid equivalent | 200Ah | 200Ah | 150Ah | 540Ah |
Bluetooth and heating vary by variation on most of these models, so check the product page for the version you’re ordering.
The real difference: shape
The GC2 is the footprint of a 6V golf-cart battery: roughly square and fairly tall. The group 27/31 is longer and lower, like a standard marine deep-cycle battery. Measure your battery box or tray and choose the one that fits.
- Choose the GC2 if your boat has golf-cart battery trays, such as a house bank built around 6V Trojan T-105s, or a tall, narrow space.
- Choose the 27/31 if your boat has standard group 27 or 31 boxes, which is most trolling and house setups on bass boats, center consoles and pontoons.
Replacing a pair of 6V golf-cart batteries
A common upgrade is replacing two 6V golf-cart batteries with lithium. One 12V GC2 battery fits in the space of one 6V battery, but capacity matters. A pair of T-105s gives a 12V bank of 225Ah, with about 112Ah usable at 50%. One Battle Born GC2 gives 100Ah, nearly all of it usable. So:
- One GC2 roughly matches the usable energy of a T-105 pair and frees up half the space.
- Two GC2s in parallel give about 200Ah usable, nearly double the old bank, in the same two trays, at 62 pounds versus 124 pounds.
Replacing group 27 or 31 lead-acid
A typical group 27 deep-cycle lead-acid battery weighs 50–60 pounds and offers about half its rated capacity for good life. The Battle Born 100Ah 27/31 weighs 31 pounds and lists 100% usable depth of discharge, which is why Battle Born lists it as equivalent to 200Ah of lead-acid. For trolling motors, one battery per 12V in the bank is typical: two for 24V, three for 36V. Battle Born lists a maximum series voltage of 48V.
When the 75Ah or 270Ah makes sense
- 75Ah group 24: for small boats with group 24 boxes, kayak trolling setups and electronics batteries where weight and space are tight. At 27 pounds, it’s lighter than the 100Ah.
- 270Ah GC3: for big house banks. At 80.8 pounds, one battery provides 270Ah, comparable to a large bank of lead-acid batteries. It needs a GC3-size space and a sturdy mount.
Battle Born’s 24V 50Ah
For 24V trolling motors in tight spaces, Battle Born’s 24V 50Ah fits a group 27/31 box at 31 pounds. It has half the amp-hours of two 100Ah batteries in series but uses one case instead of two, which suits lighter-use 24V setups.
Charging
Set chargers to a LiFePO4 profile within Battle Born’s listed 14.2–14.6V range. For charging from an outboard alternator, a DC-DC charger is often recommended. Battle Born lists self-discharge of 2–3% per month, so a battery stored fully charged will still have plenty of charge after a winter. Check it every month or two anyway.
Cold weather
Heating varies by variation on these models. If you’ll charge below freezing, choose a heated version where offered, or charge in a warm space.
Fusing and protection
Battle Born sells a marine-rated MRBF terminal fuse and a fuse block, which mount on the battery’s positive post. Fusing at the battery protects the cables if there’s a short. Choose the fuse rating based on your cable size and the load, following your trolling motor or inverter maker’s guidance.
Warranty
The smaller Battle Born base models in our store list a 5-year warranty, but our listings for these larger models don’t show warranty terms. Check Battle Born’s terms for the model you choose.
Which should you buy?
| Your boat | Best choice |
|---|---|
| Golf-cart trays, house bank | 100Ah GC2 (one or two) |
| Group 27 or 31 boxes, trolling or house | 100Ah 27/31 |
| Group 24 box, small boat | 75Ah group 24 |
| Large house bank, lots of space | 270Ah GC3 |
| 24V trolling, one compartment | 24V 50Ah |
More reading
For comparisons with other lithium brands, see Battle Born vs EPOCH, EPOCH vs Dakota Lithium and Dakota Lithium DL dual-purpose. If you’re considering staying with lead-acid golf-cart batteries, read Trojan T-105 vs T-125 vs T-145. The hubs at marine battery comparisons and marine battery brands compared cover more, and how to choose a trolling motor battery helps with trolling setups.
Products mentioned
- Battle Born 100Ah GC2
- Battle Born 100Ah group 27/31
- Battle Born 75Ah group 24
- Battle Born 270Ah GC3
- Battle Born marine-rated MRBF fuse
Frequently asked questions
Is the Battle Born GC2 different inside from the 27/31?
Our listings show the same 100Ah capacity, 31-pound weight, cycle life and resistance. The main difference is case shape.
Can one Battle Born GC2 replace two 6V golf-cart batteries?
It roughly matches the usable energy of a T-105 pair. Two GC2s in parallel nearly double it.
How many Battle Born batteries for a 36V trolling motor?
Three 12V batteries in series. Battle Born lists a 48V maximum series voltage.
Does Battle Born make a heated battery?
Heating varies by variation on these models. Check the product page for the version you’re ordering.
What charging voltage does Battle Born use?
Battle Born lists 14.2–14.6V for its 12V batteries.