Heated, Bluetooth LiFePO4 deep-cycle power in a Group 31 marine footprint.
Quick answer. The Epoch 36V 50Ah Essential Series (SKU 3650A-H) is a heated, Bluetooth LiFePO4 deep-cycle battery in a Group 31 case. It stores 1.92 kWh, delivers 100A continuous discharge, and is built for 36V trolling motor and marine deep-cycle use. One battery replaces a three-battery 12V lead-acid 36V bank. It is deep-cycle only and is not for engine starting. It supports up to 4 batteries in parallel and 1 in series, weighs about 35 lbs, is IP65 rated, and carries an 11-year manufacturer warranty.
The Epoch 36V 50Ah Essential Series is a lithium iron phosphate (LiFePO4) deep-cycle battery designed for 36V trolling motor systems and compatible 36V marine and off-grid power. It packs 1.92 kWh of usable energy into a standard Group 31 case, so anglers can retire a heavy three-battery 12V lead-acid bank and run a single lithium battery instead.
It is built for fishermen who want less weight at the bow, more consistent thrust, and simple monitoring. Internal self-heating supports charging in cold conditions, built-in Bluetooth reports state of charge and voltage to the Epoch app, and an advanced BMS protects the cells. What sets this model apart from a basic 12V lithium battery is that it is a single 36V unit purpose-built for 36V trolling motors, delivering a flat discharge curve that holds thrust deep into the pack.
Why anglers choose this battery
- 36V 50Ah (1.92 kWh) LiFePO4 in a Group 31 case for 36V trolling motors
- Replaces three 12V lead-acid batteries with one unit at about 35 lbs
- Internal self-heating with low-temperature charge protection
- Bluetooth state-of-charge monitoring via the Epoch iOS and Android apps
- IP65 enclosure, 4,000+ cycle life, and an 11-year manufacturer warranty
What each feature means for you
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Flat LiFePO4 discharge curve, holds voltage and thrust through most of the pack, so speed does not fade the way it does with lead-acid.
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Single 36V design, one battery, one set of connections; no three-battery bank to wire, balance, or maintain.
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Internal self-heating, supports charging in cold weather and protects the cells from low-temperature charge damage.
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Bluetooth monitoring, check remaining charge on your phone instead of guessing how much fishing time is left.
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IP65 enclosure, dust-tight and water-jet resistant for wet decks and spray.
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4,000+ cycles, maintenance-free, long service life with no watering or acid upkeep.
Applications
Marine trolling motors, fishing boats, and compatible 36V power systems.
The 36V 50Ah Essential Series is built for 36V trolling motor and marine deep-cycle use, and for other 36V power systems where voltage, current, and charger requirements match.
Best applications
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36V trolling motors: the primary use; a single 36V battery powers the motor with a flat, stable discharge.
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Bass boats, fishing boats, pontoons, skiffs, aluminum boats: the light Group 31 package frees bow weight and storage.
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Systems commonly used with Minn Kota, Garmin, and Lowrance motors, when the motor's voltage and current requirements are compatible.
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Compatible 36V solar, off-grid, and backup systems, when charging and inverter equipment are built for 36V and lithium.
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Cold-weather fishing, internal heating and low-temperature charge protection help in freezing conditions.
Who should buy this
- Anglers running a 36V trolling motor who want to drop three 12V lead-acid batteries down to one lithium battery.
- Boaters who need to cut bow weight and free storage without losing runtime.
- Fishermen who want Bluetooth state-of-charge visibility on the water.
- Owners in cold climates who need cold-weather charging support.
Who should not buy this
- Anyone needing an engine-cranking or outboard-starting battery this is deep-cycle only. Consider a dual-purpose cranking model instead.
- Anyone needing a 12V, 24V, or 48V battery, this is a 36V unit and cannot be wired in series to raise voltage.
- Anyone who needs more than 50Ah in a single case, add batteries in parallel, or choose a higher-capacity platform.
Estimated Runtime
How long 50Ah lasts depends on your trolling motor's average current draw.
Estimate runtime by dividing usable amp-hours by the average current your 36V trolling motor draws. LiFePO4 delivers close to its full rated capacity, so roughly 50Ah is usable. Because a 36V motor draws fewer amps than a 12V motor for the same thrust, a 36V 50Ah battery goes further on the water than the number alone suggests.
| Average 36V current draw |
Approx. continuous runtime |
| 5A (spot-lock idle, low speed) |
~10 hours |
| 10A (light cruising) |
~5 hours |
| 15A (steady cruising) |
~3.3 hours |
| 20A (moderate) |
~2.5 hours |
| 25A (moderate-high) |
~2 hours |
| 30A (high) |
~1.7 hours |
| 40A (near max thrust) |
~1.25 hours |
| 50A (max thrust) |
~1 hour |
Estimates use 50Ah ÷ average continuous draw. Actual draw varies with thrust setting, wind, current, boat weight, hull type, and how often the motor runs. These are estimates, not guaranteed runtime.
Real-world fishing days
Most fishing is intermittent spot-lock, drifting, repositioning, and breaks so continuous draw rarely applies across a full day. In typical use with spot-lock and sonar or LiveScope-style running, owners frequently report a full day on the water with substantial charge remaining. As two reported owner examples: one angler finished about 5 hours running an Ultrex with LiveScope and had roughly 78% remaining, and another logged about 6.5 hours of trolling-motor use with roughly 60% remaining. These are individual reported experiences, not manufacturer runtime ratings.
Need more runtime? For longer days or higher-draw conditions strong wind, current, heavier boats, or aggressive continuous running, add capacity by wiring matched batteries in parallel, up to four for as much as 200Ah.
Compatibility
What it works with, what to verify first, and what it is not for.
Works with
- 36V trolling motor systems with compatible voltage and current requirements
- Group 31 battery trays that fit a 13.0 in × 6.8 in × 9.44 in case
- Single-output 36V LiFePO4-compatible chargers set to the recommended lithium profile
- 36V-capable solar charge controllers and inverter/chargers programmed for lithium
- Up to four matched 3650A-H batteries wired in parallel (up to 200Ah)
Verify before buying
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Tray fit: confirm your tray accepts 13.0 in × 6.8 in × 9.44 in and the hold-down straps reach.
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Terminals: this battery uses M8 female terminals, confirm your cable lugs and bolt length match.
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Charger: confirm you have a single-output 36V lithium charger, not a three-bank 12V onboard charger.
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Motor requirements: confirm your trolling motor's continuous and peak current stay within 100A continuous / 130A peak.
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Cable and fusing: confirm cable gauge, fusing, and disconnects are sized for your load.
Not designed for
- Engine cranking or outboard starting, this is a deep-cycle battery.
- Series wiring, a maximum of one battery in series; it cannot be combined to make 72V.
- Mixing in the same bank with lead-acid or other-chemistry batteries.
- Submersion, pressure washing, or standing water around the terminals (IP65, not submersible).
Charging & Installation
Use a single-output 36V LiFePO4 charger set to Epoch's recommended profile.
| Recommended charging setting |
Value |
| Bulk / absorption voltage |
42.6V – 43.2V |
| Absorption end condition |
Stop at ≤ C/20, or 15 minutes max |
| Float voltage |
Disabled preferred, or 40.0V – 40.8V |
| Re-bulk voltage |
39.6V |
| Temperature compensation |
0 mV/°C (none) |
| Equalization |
Disabled |
| BMS high-voltage cutoff |
43.8V |
| Recommended charge rate |
50% of capacity (about 25A) |
Charger sizing and charge time
A 36V 15A lithium charger recharges a fully depleted battery in roughly 3.5 hours plus a short absorption stage. A larger charger (up to about 25A, or 50% of capacity) shortens that time. Charge time is approximate and depends on the charger, starting state of charge, and temperature.
Onboard, solar, and cold-weather charging
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Onboard chargers: use a single-output 36V lithium charger. A three-bank onboard charger designed for three separate 12V batteries is not compatible with one 36V lithium battery.
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Alternator: this battery is not designed for direct charging from a 12V boat alternator; use a 36V lithium charger or an appropriate DC-DC solution.
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Solar: charge through a 36V-capable MPPT solar charge controller programmed to the lithium settings above.
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Cold weather: internal self-heating supports charging in cold conditions, and the BMS provides low-temperature charge protection. Stay within the approved temperature range.
Installation checklist
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Footprint: Group 31, 13.0 in L × 6.8 in W × 9.44 in H, about 35 lbs.
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Terminals: M8 female, match cable lugs and bolt length.
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Wiring: size cable, fusing, and disconnects for your motor's current.
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Configuration: up to 4 in parallel (matched batteries), maximum 1 in series.
What's included
The 36V 50Ah battery unit. A compatible 36V charger and a battery tray are sold separately. Confirm any small terminal hardware supplied with your order.
What you may also need
- A single-output 36V LiFePO4 battery charger (for example, the Epoch 36V 15A charger)
- A Group 31 battery tray or hold-down for the 3650A-H
- Marine-grade cable, ring terminals, fusing, and a battery disconnect sized for your system
Specifications
Manufacturer-verified against the physical battery label and Epoch data sheet.
| Electrical & System |
| Model / SKU (MPN) |
3650A-H |
| Series |
Essential Series |
| Chemistry |
LiFePO4 (prismatic, 12S) |
| System voltage |
36V (38.4V nominal) |
| Capacity |
50Ah |
| Energy stored |
1.92 kWh (1920 Wh) |
| Operating voltage range |
30.0V – 43.8V |
| Max charge voltage |
43.8V |
| Group size |
Group 31 |
| Current Ratings |
| Max continuous discharge |
100A |
| Peak discharge |
130A (10 seconds) |
| Max continuous charge |
100A |
| Max charge current |
120A (10 seconds) |
| Series / parallel |
Max 1 in series / max 4 in parallel (up to 200Ah) |
| Temperature |
| Charge temp (with heating) |
-20°C to 55°C / -4°F to 131°F |
| Cell / battery charge temp |
0°C to 55°C / 32°F to 131°F |
| Discharge temp range |
-20°C to 60°C / -4°F to 140°F |
| Storage temp (max 12 months) |
0°C to 35°C / 32°F to 95°F |
| Reconnect temp |
50°C / 122°F |
| Mechanical |
| Dimensions (L × W × H) |
13.0 in × 6.8 in × 9.44 in |
| Weight |
35 lbs (approx. 15.9 kg) |
| Terminal type |
M8 female |
| Case material |
ABS & PC blend, UL94-V0 flame rating |
| Enclosure protection |
IP65 (dust-tight, water-jet resistant) |
| Monitoring, BMS & Compliance |
| Bluetooth |
Yes, Epoch iOS and Android apps |
| BMS protection |
Overcharge, over-discharge, over-current, short circuit, high/low temp disconnect |
| Low-temp charge protection |
Yes (with internal heating) |
| Certifications |
UL 1642 (cells), UL 9540A (cells), IEC 62619:2022, CE, RoHS |
| Shipping classification |
UN 38.3, Class 9 |
| Cycle life |
4,000+ cycles |
| Warranty |
11-year limited manufacturer |
Lithium vs lead-acid at a glance
| Attribute |
Epoch 36V 50Ah LiFePO4 |
Three 12V lead-acid (typical) |
| Usable capacity |
Close to full rated 50Ah |
Often about half of rated, to preserve life |
| Weight |
About 35 lbs (one battery) |
Roughly 180–210 lbs (three batteries) |
| Voltage under load |
Flat and stable |
Declines as it discharges |
| Cycle life |
4,000+ cycles |
Commonly a few hundred cycles |
| Maintenance |
Maintenance-free |
Flooded types need watering |
Lead-acid figures are typical category ranges for comparison and vary by product.
Bluetooth app and safety
The Epoch app (iOS and Android) connects over Bluetooth to show state of charge, voltage, current, and battery status. Bluetooth is a direct phone-to-battery connection and does not need an internet connection while you are near the battery. The advanced BMS protects against overcharge, over-discharge, over-current, short circuit, and temperature extremes. Protection features guard the battery, but they do not make it immune to installation errors, incorrect chargers, or physical damage.
FAQ
What is the Epoch 36V 50Ah Essential Series battery?
The Epoch 36V 50Ah Essential Series (SKU 3650A-H) is a 36V lithium iron phosphate (LiFePO4) deep-cycle battery in a Group 31 case. It stores 1.92 kWh of energy, delivers 100A continuous discharge, and includes internal self-heating, Bluetooth monitoring, and an advanced BMS. It is designed for 36V trolling motors and compatible 36V marine and off-grid power systems.
Will the Epoch 36V 50Ah fit my Group 31 battery tray?
It is built around a Group 31 marine footprint and measures 13.0 in L by 6.8 in W by 9.44 in H, so it fits many existing Group 31 trays and straps. Before installing, verify your tray size, cable clearance, terminal orientation, and hold-down fitment, since tray designs vary between boats.
How long will the Epoch 36V 50Ah run my 36V trolling motor?
Estimate runtime by dividing about 50 usable amp-hours by your motor's average current draw: roughly 5 hours at 10A, 2.5 hours at 20A, and about 1 hour near max thrust. Because fishing is usually intermittent with spot-lock and sonar, many anglers report a full day on the water. Draw depends on thrust, wind, current, and boat weight.
Does the Epoch 36V 50Ah replace three 12V trolling motor batteries?
Yes. In a compatible 36V system, this single 36V lithium battery replaces a traditional three-battery 12V lead-acid trolling motor bank, saving significant weight and space. Confirm your trolling motor voltage, charger compatibility, tray dimensions, and cable sizing before swapping out an existing bank.
Can the Epoch 36V 50Ah start an outboard engine?
No. The Epoch 36V 50Ah Essential Series is a deep-cycle battery for trolling motors and compatible 36V power applications. It is not designed for engine cranking or outboard starting. For starting duty, choose a dedicated cranking or dual-purpose battery of the correct voltage.
What charger do I need for the Epoch 36V 50Ah?
Use a single-output 36V LiFePO4-compatible charger or a programmable lithium charger. Recommended settings are 42.6V to 43.2V bulk/absorption, float disabled (preferred) or 40.0V to 40.8V, equalization disabled, and temperature compensation disabled. A charger around 15A to 25A suits this 50Ah battery.
Can I use my existing onboard or multi-bank charger?
Only if it is a single-output 36V charger with a lithium profile. A multi-bank onboard charger built to charge three separate 12V batteries is not compatible with one 36V lithium battery, because it expects three individual 12V banks. Confirm your charger outputs 36V on a lithium setting before use.
How long does the Epoch 36V 50Ah take to charge?
A 36V 15A lithium charger recharges a fully depleted battery in roughly 3.5 hours plus a short absorption stage. A larger charger, up to about 25A, shortens that time. Actual charge time depends on the charger, the starting state of charge, and temperature.
Can I wire multiple Epoch 36V 50Ah batteries together?
Yes, in parallel only. You can wire up to four matched 3650A-H batteries in parallel to increase capacity: two make a 36V 100Ah bank and four make 200Ah. This model supports a maximum of one battery in series, so it cannot be combined to raise system voltage above 36V.
Is the Epoch 36V 50Ah waterproof?
It is IP65 rated, meaning it is dust-tight and protected against low-pressure water jets, which suits wet decks, rain, and spray. It is not intended for submersion, pressure washing, or installation where standing water can collect around the battery, terminals, or wiring.
Will the Epoch 36V 50Ah work with Minn Kota, Garmin, or Lowrance motors?
It is designed for compatible 36V trolling motor systems, including those commonly used with Minn Kota, Garmin, and Lowrance motors, when voltage and current requirements match. Its 100A continuous rating covers many 36V motors. Always confirm your motor manufacturer's battery requirements before installation.
Does the Epoch Bluetooth app require internet?
No. The Epoch app connects directly to the battery over Bluetooth, so you can view state of charge, voltage, current, and status while your phone is near the battery without a cellular or Wi-Fi connection. Internet is only needed to download the app initially.
Can I monitor more than one battery in the app?
The Epoch app connects to compatible Epoch batteries over Bluetooth and can display battery data for connected units. If you run several batteries in parallel, check each battery's status individually in the app. Bluetooth range is limited, so stay within a short distance of the batteries.
Does internal self-heating mean I can charge in freezing conditions?
The built-in heating system supports charging in cold conditions when paired with a compatible charger, and the BMS includes low-temperature charge protection to prevent charging damage. Always follow Epoch charging guidance and avoid charging outside the approved temperature range.
Can I charge the Epoch 36V 50Ah from solar?
Yes, through a 36V-capable MPPT solar charge controller programmed to the recommended lithium settings, including a 42.6V to 43.2V bulk/absorption target and float disabled or set low. Confirm your controller supports a 36V lithium battery and can be programmed to these values.
Can I charge it from my boat's alternator?
This battery is not designed for direct charging from a standard 12V boat alternator. Charge it with a single-output 36V lithium charger, or use an appropriately configured DC-DC charging solution designed to safely charge a 36V lithium battery. Verify voltage and current limits before connecting.
Can I mix the Epoch 36V 50Ah with lead-acid batteries?
No. Do not wire this lithium battery together with lead-acid batteries in the same bank. Lithium and lead-acid have different voltage and charging characteristics, and mixing them can cause improper charging and reduced performance. Run this battery as its own 36V lithium bank.
What happens if the BMS shuts the battery off?
The advanced BMS can disconnect the battery to protect it from conditions such as over-discharge, over-current, short circuit, or temperature extremes. When the protective condition clears, or after correct charging within the approved temperature range, the battery resumes normal operation. Repeated shutdowns usually indicate a wiring, load, charger, or temperature issue to correct.
How much does the Epoch 36V 50Ah weigh and what are its dimensions?
The Epoch 36V 50Ah weighs about 35 lbs and measures 13.0 in long by 6.8 in wide by 9.44 in high, matching a standard Group 31 marine footprint. That is a large reduction from a three-battery 12V lead-acid bank, which can weigh roughly 180 lbs or more.
What is the warranty on the Epoch 36V 50Ah?
The Epoch 36V 50Ah carries an 11-year limited manufacturer warranty. Coverage is strongest in the early years and steps down over the term, and registration shortly after purchase is required for full coverage. Confirm the current warranty terms and registration window directly with Epoch when you register your battery.
Is 50Ah enough for a full day of fishing?
For many weekend and tournament anglers, 50Ah of usable LiFePO4 energy supports a full day in moderate conditions, especially with spot-lock and intermittent motor use. Heavy wind, strong current, larger boats, and continuous high-thrust running shorten runtime. For demanding days, add batteries in parallel to increase capacity.
Is the Epoch 36V 50Ah worth the cost over lead-acid?
Compared with a three-battery 12V lead-acid bank, the Epoch 36V 50Ah offers close to full usable capacity, a much lower weight of about 35 lbs, a flat discharge that holds thrust, a 4,000+ cycle life, and maintenance-free operation. Whether the higher upfront cost is worth it depends on how often you fish and how much you value weight savings and cycle life.
