Can I really use a 12V 300Ah lithium battery for both engine starting and deep-cycle use?

Yes. The Epoch 12V 300Ah Group 8D LiFePO4 battery is designed for both engine starting and deep-cycle power applications. It delivers up to 1,000A of peak discharge for 5 seconds and 800A for 10 seconds, providing the power needed to start compatible marine engines. Epoch specifically notes compatibility with Mercury 250 hp motors when the electrical system is properly matched. In addition to starting power, the battery provides 300Ah of capacity for electronics, trolling motors, lighting, and other onboard equipment. Always verify compatibility with your engine and charging system before installation.

Do I need separate starting and house batteries with a 12V 300Ah lithium battery?

In many compatible marine systems, no. A 12V 300Ah dual-purpose lithium battery combines engine-starting power and deep-cycle energy storage in a single unit. It can power fish finders, bilge pumps, lighting, marine audio, refrigeration, and other 12V accessories while still providing the cranking power needed to start compatible marine engines. Always verify compatibility with your electrical system before installation.

Will this fit in my current Group 8D marine battery tray?

Yes, this battery is designed around a Group 8D marine battery footprint. Epoch lists the dimensions as 19.70 in L × 10.5 in W × 9.75 in H (500 × 267 × 248 mm), and it must be mounted upright. If you currently run a Group 8D lead-acid or AGM battery, this lithium upgrade is intended to fit the same class of tray, but you should still verify tray dimensions, hold-downs, lid clearance, terminal access, and cable reach before ordering.

How much weight will I save on my boat?

The Epoch 12V 300Ah Group 8D lithium battery weighs 81 lbs. Many traditional Group 8D lead-acid or AGM batteries weigh roughly 130 to 160 lbs, so it is about 49 to 79 lbs lighter. Less stern weight can help improve boat balance, hole shot, draft, and fuel efficiency depending on the vessel.

Can I wire these batteries together for even more power?

Yes. Epoch lists this Pro Series model as supporting up to 16 batteries in parallel for expanded 12V capacity and up to 4 batteries in series for 24V, 36V, or 48V systems. With batteries in series, up to 4 strings may be paralleled (4S4P maximum: 51.2V, 1,200Ah, 61.44kWh). Use matched batteries of the same model, age, capacity, and state of charge, check that their voltages are within 0.5V before connecting, and follow Epoch’s series/parallel, communication, fusing, and charger guidance.

Is this battery safe to mount in a wet boat bilge?

No. Its IP67 enclosure is dust-tight and protected against temporary immersion to 1 m for 30 minutes, but the manual says not to install it where standing water can collect around the case or terminals, such as a bilge, and not to submerge or pressure-wash it. Mount it upright in a clean, dry, ventilated compartment, secured with its bracket, with a DC-rated main fuse close to the positive terminal.

Is there a way to see how much battery life I have left while on the water?

Yes. Bluetooth monitoring is built in, so you can use the free Epoch Pro app on an iOS or Android device to view battery information such as state of charge, voltage, current, temperature, and battery status. The Pro Series also supports over-the-air firmware updates through the app.

Does this battery work with Victron systems?

Through the Pro Series communications box. The battery has CAN Link in and Link out ports for networking a bank; for Victron systems or NMEA 2000 networks, Epoch offers the Pro Series communications box. Contact Epoch for configuration support.

Does it have cold-weather charging support?

Yes. It has internal heating. When a charger is connected in cold weather, the heater warms the battery to 10°C (50°F) and then switches to charging, so it charges down to -20°C (-4°F); leave the charger connected and allow up to 60 minutes. It discharges down to -20°C (-4°F).

What charger should I use?

Use a lithium-compatible charger, inverter charger, converter, solar charge controller, or DC-to-DC charger programmed for LiFePO4 batteries. The Epoch 12V 50A Lithium Battery Charger is compatible. Epoch’s recommended settings are 14.2V bulk/absorption (14.2V–14.6V range), 13.8V float (13.4V–13.8V range; float off is preferred where the charger allows), equalization disabled, temperature compensation disabled, and up to 150A charge current (300A maximum from all sources combined). 15.4V is a listed maximum, not a charger target. For alternator charging, use a DC-to-DC charger or lithium-ready regulation where the engine maker allows it.

What makes a 12V 300Ah lithium battery different from a standard deep-cycle battery?

This battery stores 3,840Wh (nominal; plan on about 3,072Wh) and is rated for 6,000+ cycles at 0.2C and 80% depth of discharge, to 80% of initial capacity at 25°C. It also handles engine cranking (1,000A for up to 5 seconds) and weighs 81 lb, against 130–160 lb for a lead-acid 8D.

What applications are best for a 12V 300Ah lithium battery?

This dual-purpose battery is built for marine engine starting plus deep-cycle house power: electronics, sonar, pumps, refrigeration and lighting on dual-purpose boats, RV, van and overland 12V systems, 3,000W-class inverter systems within 300A, solar, off-grid, cabin and backup power, and 24V to 48V banks. At 500W it runs about 6.1 hours, and at 1,000W about 3.1 hours. Its large energy capacity supports extended runtimes for appliances, electronics, and essential equipment. The battery’s lightweight LiFePO4 design, long cycle life, and reliable performance make it a practical choice for demanding energy needs.

by Epoch Batteries

Epoch Batteries 12V 300Ah Cranking & Deep Cycle Lithium Battery (Dual Purpose)

SKU: DP12300H

$1,599.00 - $1,599.00

$1,599.00

$1,599.00 - $1,599.00

$1,599.00

Availability:

in stock

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11-Year Limited Warranty

Off Grid Stores is an authorized retailer of Epoch Batteries products. Because of this, we pass on Epoch Batteries's manufacturer warranty to you.

Product Highlights

LiFePO4 Chemistry
Peak Discharge of 1,000A @ 5s, 800A @ 10s
Max Charge Current of 300A (Continuous)
Max Discharge Current of 300A (Continuous)
Victron Comms - CANBUS entire string of batteries to Victron Ecosystem
HEATED - Internal heating allows for charging in sub-zero conditions
BLUETOOTH - iOS and Android Apps
BLUETOOTH - Over the air Firmware update via the app
External Battery Gauge - Touch Screen (Optional - Coming soon)
Communications Box for more Inverter, NMEA2k compatibility (Optional - Coming soon)
IP67 Rated, Dust and WATERPROOF
Over current and short circuit protection
High & low temperature disconnects
Max (4) in Series up to 48V
Max (16) in Parallel
6000+ Cycle life & Maintenance-free
11 Year Manufacturer Warranty

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Description

Epoch Batteries 12V 300Ah Cranking & Deep Cycle Lithium Battery (Dual Purpose)

Marine cranking and deep-cycle lithium power

Epoch 12V 300Ah Group 8D Marine Cranking & Deep Cycle Lithium Battery

A dual purpose marine battery built to start compatible outboards and power your house loads from one high-capacity Group 8D marine lithium battery.

The Epoch 12V 300Ah marine lithium battery is a true dual purpose marine battery engineered for boaters and RV owners who need both cranking power and deep-cycle runtime. With 1,000A peak cranking current for up to 5 seconds, 300Ah (3.84kWh nominal), an IP67 dust-tight enclosure rated for temporary immersion, Bluetooth monitoring in the Epoch Pro app, CAN Link ports, internal heating, and an 81 lb BCI Group 8D case, it can replace separate lead-acid starting and house batteries in compatible systems.

300Ah

Capacity

3.84kWh

Stored energy

1,000A

Peak cranking

300A

Continuous output

IP67

Immersion-rated

81 lbs

Weight

Built to go further

11-year limited warranty 3 yrs free replacement

Pro Series High-output platform

Bluetooth app Real-time monitoring

CAN networking Link in / Link out ports

IP67 rating Dust-tight, temporary immersion

6,000+ cycles Long service life

The Ultimate Dual-Purpose Powerhouse for Boats & RVs

Start your engine, run your electronics, and simplify your 12V power system.

Standard lithium deep-cycle batteries are not designed for the intense surge demand of a starter motor. This Epoch Pro Series battery is different. Its high-output BMS is engineered for compatible cranking applications while still delivering a massive 300Ah of deep-cycle storage for house loads, marine accessories, RV systems, and off-grid power.

Instead of maintaining one battery for starting and another bank for house loads, this single Group 8D marine lithium battery can simplify wiring, reduce maintenance, save weight, and provide the confidence needed for long days on the water.

High-Surge Engine Cranking

Start compatible outboards with up to 1,000A peak output.

The Epoch Pro Series BMS delivers 1,000A for up to 5 seconds and 800A for up to 10 seconds for engine cranking and short start-up surges (tested above 60% state of charge at 25°C). It is rated by peak current and duration rather than CCA, so check the engine maker's battery requirements. Epoch specifically calls out compatibility with Mercury 250 hp motors and other leading outboard brands when the complete electrical system is properly matched.

300Ah Deep Cycle Capacity for House Loads

Run electronics and accessories without constant voltage drop.

Once the engine is off, 3.84kWh (nominal; plan runtime on about 3,072Wh) of LiFePO4 energy, within 300A continuous (150A recommended), can power multiple displays, sonar, radar, marine audio, pumps, livewells, lighting, refrigeration, and other onboard loads while maintaining the stable voltage curve lithium batteries are known for.

Ditch the Dead Weight: A Lighter Group 8D Upgrade

Replace heavy Group 8D lead-acid power with a lighter, smarter lithium platform.

Save about 49–79 lb

Traditional Group 8D lead-acid and AGM batteries often weigh around 130–160 lbs. The Epoch 12V 300Ah lithium battery weighs 81 lb (36.7 kg). It needs no watering or acid service; inspect it routinely.

Exact physical fitment

The Group 8D footprint measures 19.70 in L × 10.5 in W × 9.75 in H (500 × 267 × 248 mm). It is not a drop-in replacement for every lead-acid installation: always confirm your tray, cable clearance, terminal orientation, hold-downs, and lid clearance. Mount it upright; never on its side or upside down.

Rugged Marine Tech & Unmatched Protection

Immersion-rated, heated, connected, and built for serious systems.

IP67 Dust-Tight & Cold-Weather Heated

The IP67-rated enclosure is dust-tight and protected against temporary immersion to 1 m for 30 minutes; it is not rated for submersion, water jets or pressure washing, so install it where standing water cannot collect (not in a bilge). With a charger connected in cold weather, the internal heater warms the battery to 10°C (50°F) before charging, so it charges down to -20°C (-4°F).

Smart App Monitoring & CAN Networking

The free Epoch Pro app shows state of charge, voltage, current, temperature and status alerts, and installs firmware updates over the air. CAN Link in and Link out ports network a bank; for Victron systems or NMEA 2000 networks, Epoch offers the Pro Series communications box.

Compatible marine and RV applications

Cranking, house power, RV, solar, and off-grid 12V power.

✓ 12V outboard starting battery applications where motor, alternator, wiring, and charging requirements match.
✓ Dual purpose marine battery systems combining engine starting and house power.
✓ Mercury 250 hp applications specifically called out by Epoch, plus other leading outboard brands when properly matched.
✓ Marine house battery replacement for electronics, fish finders, livewell pumps, bilge pumps, audio, refrigeration, and lighting.
✓ Group 8D lead-acid replacements where the tray, hold-down, cable clearance, charging system and engine requirements are compatible.
✓ RVs, vans, overland rigs, and 12V house-power systems needing a 300Ah deep cycle lithium bank.
✓ Solar charge controller, inverter charger, alternator/DC-to-DC, and off-grid 12V systems.
✓ 12V parallel banks up to 16 batteries (4,800Ah, 61.44kWh).
✓ Series systems up to 4 batteries for 24V, 36V, or 48V builds using matched batteries and Epoch guidance; with batteries in series, up to 4 strings in parallel (4S4P maximum).

Battery features

Pro Series lithium performance with cranking power, deep-cycle runtime, and smart communications.

Dual-purpose marine batteryDesigned for compatible outboard cranking and long-duration deep-cycle energy storage.

1,000A peak dischargeProvides up to 1,000A for 5 seconds and 800A for 10 seconds for high-surge starting loads.

300Ah deep-cycle lithium capacityStores 3.84kWh for fish finders, livewells, pumps, lights, audio, refrigeration, and RV house loads.

300A continuous BMSSupports high current charging and discharging for serious 12V power systems (150A recommended).

IP67 enclosureDust-tight and protected against temporary immersion to 1 m for 30 minutes; not for submersion.

Integrated heatingWith a charger connected, warms the battery to 10°C (50°F) before charging, down to -20°C (-4°F).

Bluetooth monitoringThe free Epoch Pro app for iOS and Android, with over-the-air firmware updates.

CAN networkingLink in / Link out ports; Victron and NMEA 2000 through the Pro Series communications box.

Group 8D footprintDesigned around a 19.70 in × 10.5 in × 9.75 in format for compatible Group 8D trays.

81 lb lightweight upgradeCuts significant weight compared with many traditional 130–160 lb Group 8D lead-acid or AGM batteries.

Series and parallel expansionSupports up to 4 in series and up to 16 in parallel when installed to Epoch specifications (4S4P maximum).

6,000+ cycle lifeRated at 0.2C, 80% DoD, to 80% of initial capacity at 25°C. No watering or acid service; inspect it routinely.

Compatible chargers and accessories

Recommended add-ons for charging, monitoring, and advanced integration.

Epoch 12V 50A battery chargerCompatible high-output charger for this Pro Series battery.

Pro Series 5 in touchscreen displayOptional display accessory for easier battery visibility.

Pro Series communications boxConnects the battery to Victron systems or NMEA 2000 networks.

Lithium charging equipmentUse compatible inverter chargers, converters, solar charge controllers, and DC-to-DC chargers programmed to Epoch settings.

Specifications:

Epoch Batteries 12V 300Ah Lithium Battery

General
Brand	Epoch Batteries
Model / SKU	DP12300H
Series	Pro Series
Battery type	Dual-purpose cranking and deep-cycle LiFePO4 battery
Battery group size	BCI Group 8D footprint
Chemistry	LiFePO4 / lithium iron phosphate
Cell configuration	4S3P
Bluetooth	Yes — free Epoch Pro app (iOS and Android), over-the-air firmware updates
Communications	CAN (Link in / Link out ports); Victron and NMEA 2000 through the Pro Series communications box
Internal heating	Yes — internal heating film; warms the battery to 10°C before charging (charger connected)
Cycle life	6,000+ cycles
Voltage and Capacity
Nominal voltage	12.8V
Nominal capacity	300Ah
Nominal energy	3.84kWh / 3840Wh
Operating voltage range	10.0V – 15.4V
Maximum charge voltage	15.4V listed maximum (not a charger target)
Internal resistance	<30mΩ
Current and Cranking Performance
Max continuous discharge	300A
Max continuous charge current	300A (all sources combined)
Recommended charge current	150A
Recommended discharge current	150A
Cranking peak current	1,000A for up to 5 seconds; 800A for up to 10 seconds (cranking and start-up surges; tested above 60% SOC at 25°C)
Short-circuit protection	1200A / 500µs
Series and Parallel Expansion
Series connections	Maximum 4 batteries in series, up to 48V
Parallel connections	Maximum 16 batteries in parallel
Bank design note	Use matched batteries of the same model, age, capacity, and state of charge
Temperature
Charge temperature range	-4°F to 131°F, with heating
Discharge temperature range	-4°F to 140°F
Recommended storage temperature	32°F to 95°F
Low-temperature charge protection	Heater warms the battery to 10°C before charging
Dimensions and Weight
Length	19.7 in
Width	10.5 in
Height	9.75 in
Weight	81 lbs
Mechanical and Protection
Enclosure protection	IP67 (IEC 60529) — dust-tight, temporary immersion; not for submersion
Terminal type	M8 bolt
Terminal torque	8–10 N·m (71–89 in-lb)
Optional accessories	Pro Series 5 in touchscreen display and Pro Series communications box
Recommended Charging Settings
Bulk / absorption voltage	14.2V recommended (14.2V – 14.6V range)
Float voltage	13.8V recommended (13.4V – 13.8V range); float off preferred where the charger allows
Equalization	Disabled
Temperature compensation	0mV/°C (disabled)
Recommended charge rate	Up to 150A (50% of the battery or battery-bank capacity)
Battery charge temperature range	-4°F to 131°F, with heating
Battery discharge temperature range	-4°F to 140°F
Compliance
Certifications	UL 1973 (certificate of compliance available), CE, RoHS; transport UN 38.3
Enclosure rating	IP67 (IEC 60529)

Product Documents:

Epoch Batteries 12V 300Ah Cranking & Deep Cycle Lithium Battery (Dual Purpose) User Manual

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Epoch Batteries 12V 300Ah Cranking & Deep Cycle Lithium Battery (Dual Purpose) Specification Sheet

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Epoch Batteries 12V 300Ah Cranking & Deep Cycle Lithium Battery (Dual Purpose) Data Sheet

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Epoch Batteries 12V 300Ah Cranking & Deep Cycle Lithium Battery (Dual Purpose) Certification Of Compliance

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90%

(1336)

(95)

(25)

(9)

(27)

1465

Very heavy for a 4D - suggests a lot of plates - more plates the better. Batteries were packaged in an original Renogy box which had foam damage protection. Batteries arrived promptly and are working well.

Amazing product, at a better price, with even better Customer Service. I honestly wish I could leave 6 stars.

Easy connection and fully charged in a short time.

Jackery products are top! Off grid store has the best prices over the factory price. Order was delivered fast! Thanks!

I have bought 10 sets of these. I used 2 sets to support 2-590watt bifacial and 1 460 watt panel. These are setup vertically. I have them running in serial for a total of of 4 sets. Two of them run to my Anker Solix F3800 plus which allow me to get almost the max of 3200watts. I have 2 F3800 plus with a total of 10 bp3800 batteries for a total of 46,080 wh of storage. I mounted them on 15' aluminum rails. I connected the rails to boards and mounted them with 5" caster wheels which allow me to easily move them to the direction of the sun. This allows me on most days to outproduce my 27 360watt solar panels on my roof. The other 2 sets I each have two 460 watts panels. 1 set I have running to 2 chest freezers and a fridge in the basement. I have 4,000 wh of battery storage. The other set mostly runs my PC gaming area. I have 6,000 wh battery storage.
I have a total of 3.5mwh of battery storage with my electric company.

11-Year Limited Warranty

Epoch Batteries 12V 300Ah Cranking & Deep Cycle Lithium Battery (Dual Purpose)

Epoch 12V 300Ah Group 8D Marine Cranking & Deep Cycle Lithium Battery

Built to go further

The Ultimate Dual-Purpose Powerhouse for Boats & RVs

High-Surge Engine Cranking

300Ah Deep Cycle Capacity for House Loads

Ditch the Dead Weight: A Lighter Group 8D Upgrade

Save about 49–79 lb

Exact physical fitment

Rugged Marine Tech & Unmatched Protection

IP67 Dust-Tight & Cold-Weather Heated

Smart App Monitoring & CAN Networking

Compatible marine and RV applications

Battery features

Compatible chargers and accessories

Specifications:

Customer Reviews

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11-Year Limited Warranty

Epoch Batteries 12V 300Ah Cranking & Deep Cycle Lithium Battery (Dual Purpose)

Epoch 12V 300Ah Group 8D Marine Cranking & Deep Cycle Lithium Battery

Built to go further

The Ultimate Dual-Purpose Powerhouse for Boats & RVs

High-Surge Engine Cranking

300Ah Deep Cycle Capacity for House Loads

Ditch the Dead Weight: A Lighter Group 8D Upgrade

Save about 49–79 lb

Exact physical fitment

Rugged Marine Tech & Unmatched Protection

IP67 Dust-Tight & Cold-Weather Heated

Smart App Monitoring & CAN Networking

Compatible marine and RV applications

Battery features

Compatible chargers and accessories

Specifications:

Customer Reviews

Let customers speak for us