The Epoch 12V 172Ah is a 12V 172Ah LiFePO4 lithium iron phosphate battery built for marine use. It combines engine-cranking capability with deep-cycle house power in a single Group 31 battery eliminating the need for separate starting and house batteries on your boat.
With a 1,000A peak discharge for 5 seconds, this battery delivers reliable cranking power for outboard motors up to 250hp, while the 200A continuous discharge rating handles fish finders, chartplotters, VHF radios, live wells, bilge pumps, and other onboard electronics throughout the day.
The IP65-rated enclosure provides full protection against water jets and dust built to handle the spray, splash, and humidity of a marine environment. Built-in Bluetooth lets you monitor state of charge, voltage, current, and cell health directly from your phone using the Epoch iOS and Android app, without needing an external battery monitor.
At 40 lbs, the Epoch 12V 172Ah weighs significantly less than a comparable Group 31 AGM battery (typically 55–75 lbs), reducing hull weight and improving fuel efficiency and handling. The LiFePO4 chemistry delivers 4,000+ charge cycles at 80% depth of discharge significantly longer service life than lead-acid or AGM alternatives.
The internal Battery Management System (BMS) provides automatic protection against overcharge, over-discharge, short circuit, overcurrent, and high/low temperature disconnects. No maintenance is required.
As a dual purpose battery, the Epoch 12V 172Ah is commonly used in marine applications to start outboard motors up to 250hp and power onboard electronics from a single battery. The deep cycle capability also makes it suitable for RV house banks where it can start a generator and sustain house loads, as well as off-grid and backup power systems that require both reliable starting power and sustained energy storage.
Backed by an 11-year manufacturer warranty. Register within 90 days of purchase for full coverage. For full details read Warranty Tab
ELECTRICAL SPECIFICATIONS
| Nominal Voltage |
12.8V |
| Nominal Capacity |
172Ah |
| Energy Stored |
2.20 kWh |
| Cell Configuration |
4S1P Prismatic LiFePO4 |
| Max Charge Voltage |
15.0V |
| Operating Voltage Range |
10.0V – 14.6V |
| Parallel Connections |
Max 4 in Parallel, Plug & Play |
| Cycle Life |
4,000+ cycles @ 80% DoD |
| Bluetooth |
Yes iOS and Android |
| Self-Heating |
No |
| Low-Temperature Charge Protection |
Yes (BMS automatic cutoff) |
DISCHARGE SPECIFICATIONS
| Max Continuous Discharge |
200A |
| Peak Discharge (5 seconds) |
1,000A |
| Discharge Temperature Range |
-20°C to 60°C (-4°F to 140°F) |
CHARGE SPECIFICATIONS
| Max Continuous Charge Current |
200A |
| Bulk / Absorption Voltage |
14.2V – 14.6V |
| Absorption End Condition |
Stop when current ≤ C/20 or 15 min max |
| Float Voltage |
13.4V – 13.8V (disabled preferred) |
| Re-Bulk Voltage |
13.2V |
| Equalization |
14.4V / Disabled |
| Temperature Compensation |
0mV/°C Disabled |
| Recommended Charge Rate |
50% of bank capacity |
| BMS High Voltage Cutoff |
14.6V |
| Charge Temperature Range |
0°C to 55°C (32°F to 131°F) |
TEMPERATURE SPECIFICATIONS
| Discharge Temperature |
-20°C to 60°C (-4°F to 140°F) |
| Charge Temperature |
-5°C to 55°C (23°F to 131°F) |
| Recommended Storage Temperature |
0°C to 35°C (32°F to 95°F) |
MECHANICAL SPECIFICATIONS
| Group Size |
Group 31 |
| Dimensions (L x W x H) |
12.91" x 6.22" x 8.46" |
| Weight |
40 lbs |
| Case Material |
ABS & PC Blend UL94-V0 Flame Rated |
| Enclosure Protection |
IP65 Dust and Waterproof |
| Cell Type |
Prismatic LiFePO4 |
| Terminal Type |
M8 Female |
COMPLIANCE & CERTIFICATIONS
| Certifications |
UL 1642, UL 9540A, IEC 62619:2022, CE, RoHS |
| Shipping Classification |
UN 38.3, Class 9 |
| Warranty |
11-Year Limited Manufacturer Warranty |
The Epoch 12V 172Ah is designed primarily for marine applications. Below is a guide to confirmed compatible uses and important limitations to be aware of before purchasing.
OUTBOARD ENGINE COMPATIBILITY
| Confirmed Compatible |
All outboard motors up to 250hp |
| Engine Brands |
Mercury, Yamaha, Suzuki, Honda, Evinrude, Tohatsu |
| Charging from Outboard Alternator |
Compatible. Use a DC-to-DC charger between the outboard and battery for regulated charging and alternator protection on stator-based charging systems. |
VESSEL TYPE
| Center Console Boats |
Fits standard Group 31 battery boxes and trays |
| Bay Boats |
Compatible |
| Offshore Fishing Boats |
Compatible |
| Pontoon Boats |
Compatible where Group 31 tray is available |
| Inboard / Sterndrive Boats |
Compatible for starting and house use |
CHARGING SYSTEM COMPATIBILITY
| Shore Power Chargers |
Compatible use a LiFePO4-compatible charger set to 14.2V–14.6V |
| Solar Charge Controllers |
Compatible set to LiFePO4 profile, 14.2V–14.6V absorption |
| DC-to-DC Chargers |
Compatible recommended for alternator charging |
| Victron Energy Equipment |
Compatible with Victron chargers, MPPT controllers, and Cerbo GX via Bluetooth |
| Standard AGM Chargers |
Not recommended use only chargers with a LiFePO4 or programmable profile |
IMPORTANT LIMITATIONS
| Series Connection |
Not supported this battery operates at 12V only and cannot be connected in series for 24V or 48V systems |
| Self-Heating |
Not included. Charging is not possible below 0°C (32°F). The BMS will automatically prevent charging in cold conditions. Suitable for warm-climate use year-round. |
| Voltage Compatibility |
12V systems only |
To get the longest service life from your Epoch 12V 172Ah, program your charging components to the following settings. Charging components include shore power chargers, solar charge controllers, DC-to-DC chargers, and inverter/chargers.
| Bulk / Absorption Voltage |
14.2V – 14.6V |
| Absorption End Condition |
Stop when charge current drops to C/20 or after 15 minutes maximum |
| Float Voltage |
13.4V – 13.8V (disabled preferred for longest cell life) |
| Re-Bulk Voltage |
13.2V |
| Equalization |
Disabled (do not equalize LiFePO4 batteries) |
| Temperature Compensation |
Disabled 0mV/°C |
| Recommended Charge Rate |
50% of bank capacity (86A for a single battery) |
| Absorption Time (2 batteries in parallel) |
30 minutes minimum |
| Charge Temperature Range |
0°C to 55°C (32°F to 131°F) BMS will prevent charging outside this range |
Note on charger selection: Not all marine chargers support multistage LiFePO4 charging. If your charger does not have a LiFePO4 profile, verify that it can at minimum be programmed to the bulk/absorption voltage of 14.2V–14.6V and that equalization and temperature compensation can be disabled. Consult your charger manufacturer if unsure.
Note on alternator charging: When charging from an outboard alternator, a DC-to-DC charger between the engine and battery is recommended. LiFePO4 batteries accept charge at near-full alternator output until full, which can stress small outboard charging systems. A DC-to-DC charger regulates this current and protects both the battery and the alternator.
Can this battery start my outboard motor? +
Yes. The Epoch 12V 172Ah is rated for all outboard motors up to 250hp. It delivers 1,000A for 5 seconds sufficient cranking power for reliable cold starts on gasoline outboard engines including Mercury, Yamaha, Suzuki, Honda, and others. It replaces both your starting battery and house battery in a single unit.
Can I charge this battery directly from my outboard alternator? +
You can charge from an outboard alternator, but using a DC-to-DC charger between the engine and battery is recommended. LiFePO4 batteries accept charge at near-maximum alternator output until full. On smaller stator-based outboard charging systems, this can stress the alternator similar to switching off the battery while the engine is running. A DC-to-DC charger (such as the Victron Orion series) regulates the current and protects both the alternator and the battery. On inboard engines with regulated alternators, this is less of a concern.
Does this battery have a self-heating function for cold weather charging? +
No. The Epoch 12V 172Ah does not include an internal self-heating element. The BMS will automatically prevent charging if the battery temperature drops below 0°C (32°F) to protect the cells. The battery can discharge down to -20°C (-4°F) without issue only charging in freezing temperatures is restricted. This battery is designed for use in warm and temperate marine climates where below-freezing charging is not a regular requirement.
What charger settings should I use? +
Program your charger to the following settings: Bulk/Absorption 14.2V–14.6V, Float 13.4V–13.8V (or disabled), Equalization disabled, Temperature Compensation disabled (0mV/°C), Charge rate 50% of bank capacity. If your charger only allows a single voltage setting, set it to 14.4V and disable all other stages. See the Charging Guide tab for full details.
Can I use my existing AGM battery charger? +
Not recommended. AGM chargers typically use charge profiles that include equalization cycles and temperature compensation that are not appropriate for LiFePO4 chemistry. Use a charger with a dedicated LiFePO4 profile, or a programmable charger that allows you to set the absorption voltage to 14.2V–14.6V and disable equalization and temperature compensation.
How does this battery compare to a Group 31 AGM in weight? +
The Epoch 12V 172Ah weighs 40 lbs. A comparable Group 31 AGM battery typically weighs between 55 and 75 lbs. The Epoch 12V 172Ah weighs 40 lbs significantly lighter than a lead-acid equivalent, which meaningfully reduces hull weight, improves fuel efficiency, and makes installation easier.
What is the actual usable capacity compared to a 172Ah AGM? +
A LiFePO4 battery can be safely discharged to 80% depth of discharge without damage, giving approximately 137Ah of usable capacity from this 172Ah unit. A 172Ah AGM is typically limited to 50% depth of discharge before capacity and lifespan degrade significantly, giving approximately 86Ah of usable capacity. This battery provides roughly 60% more usable energy than a same-rated AGM.
How do I monitor the battery on my boat? +
The Epoch 12V 172Ah includes built-in Bluetooth. Download the Epoch Batteries app on iOS or Android and connect directly to the battery to monitor state of charge, voltage, current draw, cell voltages, and temperature in real time from your phone. No external battery monitor or shunt is required for basic monitoring, though a dedicated shunt monitor can be added for more precise tracking in multi-battery systems.
Can I connect multiple batteries together? +
Yes, up to 4 batteries can be connected in parallel for a combined capacity of 688Ah / 8.8kWh at 12V. Parallel connection is plug-and-play. Series connection is not supported this battery is designed for 12V systems only and cannot be wired for 24V or 48V configurations.
How should I store the battery between fishing seasons? +
Store the battery fully charged in a dry location between 0°C and 35°C (32°F to 95°F). Do not store it in a fully discharged state leaving a fully depleted LiFePO4 battery in storage for an extended period can permanently damage the cells and voids the warranty. If storing on the boat over winter, disconnect the battery and check charge level periodically.
What does the 11-year warranty cover? +
The 11-year limited warranty covers defects in materials and workmanship. Full replacement coverage applies for the first 36 months from the date of purchase. From months 37 through 132, warranty coverage is prorated. The warranty is non-transferable and applies only to the original purchaser. Battery must be registered on the Epoch Batteries website within 90 days of purchase for the warranty period to begin from the purchase date rather than the manufacturing date. Read warranty Tab
Is this battery safe for saltwater marine environments? +
Yes. The IP65 enclosure rating means the battery is fully protected against water jets from any direction and against dust ingress. The ABS and PC blend case with UL94-V0 flame rating is appropriate for marine environments. Standard marine installation practices apply avoid submerging the battery and ensure terminals are protected from prolonged direct exposure to saltwater.
Will it fit in my existing battery box or tray? +
The Epoch 12V 172Ah (SKU: 12172A-DP) measures 12.91" x 6.22" x 8.46" (L x W x H) and fits Group 31 battery trays. Verify your existing tray dimensions before purchasing. Note that while this battery replaces a Group 31 lead-acid or AGM physically, it weighs significantly less confirm your mounting hardware secures the battery firmly to prevent movement underway.
Does it require any maintenance? +
No maintenance is required. LiFePO4 batteries do not require water checks, terminal cleaning, equalization charges, or periodic full discharge cycles. The internal BMS handles cell balancing automatically. Keep terminal connections clean and tight as standard practice.
