Epoch 3650A-H 36V 50Ah Lithium Trolling Motor Battery – Group 31 LiFePO4, Heated + Bluetooth
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Most 36V trolling motor setups run on three heavy lead-acid batteries, and hauling that bank in and out of a boat gets old fast. The Epoch 3650A-H is a 36V lithium trolling motor battery that does the same job from one Group 31 case weighing about 35 pounds. Drop it into a tray where one of the old batteries sat, land your leads on the M8 terminals, and take well over a hundred pounds out of the boat.
The chemistry matters as much as the weight. A lead-acid bank loses voltage as it drains — you feel it at the pedal by mid-afternoon. LiFePO4 holds nearly full voltage through most of its 50Ah capacity, so the motor pulls at dusk the way it did at first light. It recharges faster and takes 4,000-plus cycles with no watering or acid service, ever.
Lake Erie fishing doesn't quit when the weather turns, and neither does this battery: built-in heating warms the cells so they can charge safely below freezing, where ordinary lithium batteries shut charging down. The free Epoch app connects over Bluetooth from your phone and shows state of charge, voltage, and current, so you know at the dock whether you have a full day in the tank. Walleye and bass boats running out of Mentor Harbor, Fairport, and Grand River put exactly this kind of demand on a trolling bank.
Two things it will not do. This is a deep-cycle battery, not a starting battery — it will not crank your outboard, so keep a dedicated starting battery on the big motor. And never wire it in series: one battery runs a 36V system, and you can add up to three more in parallel (200Ah total) for longer days. You'll also need a 36V lithium-compatible charger; the onboard charger that maintained a lead-acid bank almost certainly has the wrong profile. Call us and we'll match one to it.
Fits These 36V Applications
- 36V trolling motor systems, including Minn Kota, Garmin, and Lowrance motors when voltage and current requirements match
- Direct replacement for a three-battery 12V lead-acid trolling bank in compatible 36V systems
- Group 31 marine trays — case measures 13.0 × 6.8 × 9.44 inches
- 36V solar, off-grid, and backup power banks with compatible charging equipment
- 36V auxiliary and electronics loads with properly sized cable and fusing
If your application isn't listed, call us with the machine and we'll check it. We'd rather check twice than sell you the wrong battery.
36V 50Ah Group 31 Lithium Battery Specifications
| Part Number | 3650A-H |
|---|---|
| Voltage | 36V (38.4V nominal) |
| Capacity | 50Ah / 1.92kWh |
| Chemistry | LiFePO4 (lithium iron phosphate), deep cycle |
| BCI Group Size | 31 |
| Max Continuous Discharge | 100A |
| Peak Discharge | 130A for 10 seconds |
| Charge Voltage | 42.6–43.2V bulk/absorption; float disabled or 40.0–40.8V |
| Series / Parallel | Max 1 in series / up to 4 in parallel |
| Cold Weather | Internal self-heating for sub-freezing charging |
| Monitoring | Bluetooth — free Epoch iOS and Android app |
| Enclosure | IP65 — dust-tight, water-jet resistant (not submersible) |
| Terminals | M8 female |
| Dimensions | 13.0 L × 6.8 W × 9.44 H inches |
| Weight | 35 lb |
| Cycle Life | 4,000+ cycles |
| Certifications | UL 1642 / UL 9540A cells, IEC 62619, CE, RoHS; UN 38.3 for transport |
Warranty: 8 years. If it fails in normal service inside five years, bring it back to the counter and we make it right.
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Local Pickup in Northeast Ohio
This battery is available for pickup at our Willoughby shop, serving anglers from Eastlake and Mentor-on-the-Lake up the shoreline to Fairport Harbor and Madison. Call with your boat, motor, and charger model before you drive over — we'll have the fit checked and the battery charged and waiting at the counter.
If you have any questions about this product, please let us know by filling out the form below, and we will contact you as soon as possible.