ECO Battery 12V 120Ah Lithium for Boats: What to Know

July 9, 2026 · Marine Battery Source

ECO Battery’s 12V 120Ah lithium battery packs several features into one group 31 case: internal heating for cold-weather charging, Bluetooth monitoring, an IP67 rating and CAN and NMEA 2000 communications. This guide explains what those features mean on a boat, where the battery fits and what to consider if it’s not available. Specs come from our product listings, which are based on manufacturer information.

The ECO Battery 12V 120Ah at a glance

Spec	Listing
Voltage	12V
Capacity	120Ah
Chemistry	LiFePO4
Case	Group 31
Weight	29 lb
Heating	Internal heating for low-temperature charging
Bluetooth	Yes, app
Communications	CAN / NMEA 2000
Ingress protection	IP67
Peak current	800A
Warranty	Limited lifetime

Availability

At the time of writing, the ECO Battery 12V 120Ah is listed as out of stock in our store. You can check the ECO Battery brand page for updates, or compare the alternatives below.

Key takeaways: ECO Battery 12V 120Ah Lithium for Boats: What to Know

What the features mean

Internal heating

LiFePO4 batteries shouldn’t be charged below about freezing. A heated battery warms its cells before accepting charge, so you can charge on cold mornings or in an unheated garage. That matters for boaters in northern states and anyone who stores the boat in winter with a maintainer. See heated lithium batteries and cold charging.

Bluetooth

Shows state of charge, voltage, current and temperature on your phone. With lithium’s flat voltage curve, this is the easiest way to track remaining capacity.

CAN / NMEA 2000

NMEA 2000 is the network standard many marine electronics use. A battery that communicates over it can, with compatible equipment, show battery data on a chartplotter display. Check your electronics’ compatibility and the battery’s documentation for setup.

IP67

Rated for dust and temporary immersion under test conditions. Helpful in wet compartments, but keep the battery above bilge water and protect the terminals.

800A peak

High peak current capability. ECO Battery’s listing doesn’t present this model as a cranking battery, so check the manufacturer’s guidance before using it to start an engine.

Where it fits on a boat

House bank: electronics, livewells, lights and a small fridge on a center console or cruiser.
12V trolling motor: a single 120Ah battery for kayaks and small boats with a 12V motor.
Series banks: check ECO Battery’s guidance on series connections before building 24V or 36V banks.
Cold-climate boats: heating allows early and late season charging.

Alternatives with similar features

If the ECO Battery 120Ah isn’t available, these in-stock batteries offer comparable capabilities:

EPOCH 12V 105Ah Essential: group 24, Bluetooth, heating, 11-year listed warranty.
Dakota Lithium DL 12V 135Ah heated: group 24, heated, 1000 CCA dual-purpose, IP65.
EPOCH 12V 300Ah Essential: for larger house banks, Bluetooth and heating.

Compare more in the EPOCH marine battery guide and the Lithium Rhino conversion kits guide for 24V and 36V trolling banks.

Who benefits most from these features

Northern anglers. Spring and fall fishing often means charging overnight in an unheated garage or at a cold dock. Without heating, a LiFePO4 battery may refuse to charge until it warms, leaving you with a partly charged battery at dawn. With heating, the battery warms itself and takes the charge.

Boaters with networked electronics. If your chartplotter and engine data already run on NMEA 2000, a battery that reports over the same network puts state of charge on the display you already watch, instead of a separate phone app.

Boats with wet compartments. Small boats, kayaks and skiffs often have hatches that take water. An IP67 rating gives more margin, though good mounting and drainage still matter.

Owners who don’t want to replace batteries often. A limited lifetime warranty can be attractive; read the terms to understand what’s covered and for how long.

Questions to ask before choosing a 120Ah group 31 battery

Does it fit your tray and hold-down? Group 31 is a common size, but measure.
Is 120Ah enough? Add up your loads in amp-hours per day and leave a reserve.
Do you need starting power? If so, a dual-purpose battery may be a better fit.
Does your charger have a LiFePO4 profile?
Will you connect it to NMEA 2000? Check what cables and settings are needed.

Sizing a 120Ah battery for your day

A quick way to check whether 120Ah is enough: list each load, its current draw and how many hours it runs, then multiply and add. A chartplotter at 3A for 8 hours uses 24Ah; a livewell pump at 4A for 5 hours uses 20Ah; LED lights at 1A for 4 hours use 4Ah. That’s 48Ah, comfortably within 120Ah with a large reserve. A 12V trolling motor averaging 15A for 6 hours uses 90Ah, which fits but leaves less margin.

Charging

Use a LiFePO4-compatible charger. For alternator charging, a DC-DC charger protects the alternator and charges correctly. With heating, the battery manages cold-weather charging itself, but the charger still needs a lithium profile.

Installation tips

Secure the battery with a tray and strap sized for group 31.
Fuse the positive close to the battery.
Route NMEA 2000 connections according to your network’s requirements.
Keep terminals protected and dry.

ECO Battery vs lead-acid

Compared with a group 31 AGM, the ECO Battery 120Ah weighs much less, delivers more usable capacity and can charge in the cold. An AGM costs less upfront and is a proven starting battery. If you’re staying with lead-acid, see the Trojan marine batteries guide and the Interstate marine batteries guide.

Frequently asked questions

Does the ECO Battery 12V 120Ah have heating?

Yes. It’s listed with internal heating for low-temperature charging.

Can it connect to my chartplotter?

It lists CAN / NMEA 2000 communications. Check your electronics’ compatibility.

Is the ECO Battery waterproof?

It’s listed as IP67. Still mount it above bilge water and protect the terminals.

Is the ECO Battery 120Ah in stock?

It’s currently listed as out of stock. Check the brand page or consider similar heated, Bluetooth lithium batteries.

Can I use it to start my engine?

Check ECO Battery’s guidance. Our listing doesn’t present it as a cranking battery.