Lithium Batteries in Standard Group-Size Cases

One of the best things about modern LiFePO4 batteries is that most of them come in familiar BCI group sizes. That means you can usually drop a lithium battery into the same tray or box your lead-acid battery used. But the capacity inside each size is very different. This guide shows what you can expect from each lithium group size, using in-stock models from our store. Check product pages for exact dimensions and current specs.

Why group size still matters with lithium

Group size describes the case, not the battery’s ratings. With lead-acid, capacity is closely tied to size, because bigger cases hold more plates. With lithium, the cells are much more energy-dense, so the same case holds two to four times the usable energy. You choose the size for fit and the model for capacity.

Group 24 lithium

Model	Capacity	Weight	Notes
EPOCH 12V 100Ah Eco	100Ah	21 lb	No Bluetooth or heating, 6-year warranty
EPOCH 12V 105Ah Essential	105Ah	22.1 lb	Bluetooth, heated, 11-year warranty
Battle Born 75Ah	75Ah	27 lb	3,000–5,000 cycles
Dakota DL+ 60Ah	60Ah	16.5 lb	Dual purpose, 1,000 CCA
Dakota DL+ 135Ah Heated	135Ah	27.2 lb	Dual purpose, 1,000 CCA, heated, IP65
Interstate Li24M	60Ah	Not listed	60-month warranty
Interstate Li24MDP	100Ah	Not listed	Dual purpose

A group 24 lithium battery can match or beat the usable energy of a group 27 or 31 lead-acid battery, at about half the weight.

Group 27 lithium

Model	Voltage	Capacity	Weight
Battle Born 100Ah (27/31)	12V	100Ah	31 lb
Interstate Li27M	12V	100Ah	Not listed
EPOCH 24V 60Ah Pro	24V	60Ah	30 lb
Battle Born 24V 50Ah (27/31)	24V	50Ah	31 lb

Group 27 is where you’ll find single-case 24V trolling batteries that replace two lead-acid batteries.

Group 31 lithium

Model	Voltage	Capacity	Weight
EPOCH 12V 172Ah dual purpose	12V	172Ah	40 lb
EPOCH 12V 300Ah Essential	12V	300Ah	58 lb
EPOCH 12V 314Ah Eco	12V	314Ah	57 lb
EPOCH 12V 334Ah Essential	12V	334Ah	60 lb
EPOCH 36V 50Ah Essential	36V	50Ah	35 lb
Interstate Li31M 24V	24V	60Ah	Not listed
Interstate Li31M 36V	36V	50Ah	Not listed

Group 31 is the most flexible lithium size: high-capacity 12V house batteries, dual-purpose batteries, and native 24V and 36V trolling batteries.

GC2 and GC3 lithium

Battle Born’s 100Ah GC2 (31 lb) and 270Ah GC3 (80.8 lb) are 12V batteries in golf-cart cases. They drop into trays built for 6V golf-cart batteries. See GC2 golf-cart batteries.

8D-size lithium

EPOCH’s 12V 460Ah, 24V 230Ah and 48V 100Ah batteries use an 8D footprint, at 84–98 pounds. One can replace several lead-acid 8Ds. EPOCH’s 12V 300Ah Pro dual-purpose battery also uses an 8D footprint. See 4D and 8D marine batteries.

Batteries without a group size

Some lithium batteries don’t follow a BCI size at all. Small batteries like the Battle Born 10–30Ah and Dakota 10Ah mini are compact packs for kayaks, electronics and portable power. Some 36V models, like the EPOCH 36V 100Ah and Lithium Rhino kits, don’t list a group size in our store. Check the maker’s dimensions and measure carefully for these.

Fit tips when switching to lithium

1. Check exact dimensions. A lithium “group 24” can be slightly taller or shorter than your old battery.
2. Check terminals. Lithium batteries often have threaded M8 female terminals or bolts instead of posts. Your cable ends may need new ring lugs.
3. Secure it. A lighter battery is more likely to shift if it’s loose. Use the tray, a strap and spacers as needed. EPOCH and Dakota sell model-specific trays.
4. Fuse it. Install a fuse close to the positive terminal.
5. Update chargers. Switch every charger to a LiFePO4 profile.

How much capacity do you need?

Size the battery for your loads, then find a case that fits:

• Add up your loads in amps and multiply by hours to get daily amp-hours.
• Add 20–30% margin.
• Choose a lithium battery with at least that much capacity.

For example, a trolling motor averaging 20A for 5 hours needs about 100Ah, plus margin, so 120Ah or more. At 12V, that’s a group 24 135Ah or a group 31 battery. At 24V, the same motor might draw half the current, so a 24V 60Ah would be tight and a 24V 100Ah would be comfortable.

Weight savings by size

Size	Lead-acid (typical)	Lithium (examples)
Group 24	47–54 lb	16.5–27.2 lb
Group 27	55–66 lb	30–31 lb
Group 31	67–69 lb	31–60 lb
8D	161 lb	81–98 lb

The heavier lithium batteries in each row hold many times the energy of the lead-acid battery.

Consolidating a bank

Because lithium packs so much into each case, many owners use fewer batteries after switching. Three group 27 lead-acid batteries for a 36V trolling motor can become one 36V lithium battery in a group 31-size case. Two group 31 house batteries can become one 12V 300Ah lithium battery. Plan what you’ll do with the freed space, and make sure the remaining wiring is shortened and secured.

More reading

Compare sizes in group 24 vs 27 vs 31 and see the group 24 guide. Learn what 24M, 27M and 31M mean, and measure your battery compartment before ordering. The full chart is in BCI battery group sizes explained. For battery types, read cranking vs dual-purpose vs deep-cycle, and the marine battery buying guide covers the rest.

Products mentioned

• EPOCH 12V 105Ah (group 24)
• Battle Born 100Ah (group 27/31)
• EPOCH 12V 334Ah (group 31)
• Dakota DL+ 12V 135Ah (group 24)
• Shop all lithium batteries.

Frequently asked questions

Do lithium batteries come in standard group sizes?

Most marine lithium batteries do, including group 24, 27, 31, GC2 and 8D.

Will a lithium group 24 fit my lead-acid group 24 tray?

Usually, but check exact dimensions and terminal type on the listing.

What’s the biggest 12V lithium in a group 31 case?

In our store, the EPOCH 12V 334Ah Essential, at 60 pounds.

Can I replace a group 27 lead-acid with a group 24 lithium?

Often yes, if you secure it with a spacer or the right tray.

Are lithium terminals different?

Often. Many use M8 bolts or threaded inserts. Check that your cable lugs fit.