Trolling Motor Batteries 101: Sizing and Setup

Trolling Motor Batteries 101: Sizing and Setup

The two most common questions I get every single week are:

  1. “What size battery do I need for my trolling motor?”

  2. “Should I use a single battery or multiple batteries in series?”

This post will tackle both questions and give you the information you need to make the right choice for your boat, your trolling motor, and the way you fish.

How to Size Your Trolling Motor Battery

When it comes to sizing your trolling motor battery bank (measured in Amp Hour capacity, or “AH”), there are a few key factors that matter most:

  1. Boat Size, Weight, and Type

    • A lightweight skiff with a 12V 55lb thrust motor doesn’t demand the same capacity as a 25’ bay boat with a 36V 112lb thrust motor. The heavier and larger your boat, the more energy your trolling motor needs to move it effectively.

  2. Trolling Motor Voltage (12V, 24V, or 36V)

    • The higher the voltage system, the more efficient your setup usually is. A 36V system will operate more efficiently compared to a 12V or 24V trolling motor.

  3. Conditions You Run In

    • Calm lake? You’ll use far less energy compared to running in tidal current or wind. Anglers who fish saltwater flats on calm mornings often need less capacity than offshore guys holding position in heavy chop.

  4. Desired Run Time

    • How long do you really need to be out on the water before recharging? Some boaters are fine with 4–6 hours. Others want 10+ hours or multiple trips between charges.

Rule of Thumb:

  • Lighter boat + short trips → Smaller AH battery is fine. Usually, a 50AH setup.

  • Lighter boat + long trips or multiple trips before needing charge → Invest in 100AH setup.

  • Heavier boat + short trips → Smaller AH battery can work. 50AH setup.

  • Heavier boat + long trips in current/wind → Invest in 100AH setup.

  • If your current lead-acid setup is meeting your demands every trip, a 50AH LiFePO4 is usually enough.

Single Battery vs. Multiple Batteries in Series

This is where a lot of confusion comes in. Should you run one large battery system or several batteries in series? Let’s break it down:

  • Single High-Capacity Battery (e.g., 24V 100AH or 36V 100AH LiFePO4):

    • Pros: Lighter, more compact, easier wiring, less to maintain. Operates more efficiently.

    • Cons: Bigger upfront cost.

  • Multiple Batteries in Series (e.g., three 12V 100AH in series for 36V 100AH system):

    • Pros: Budget-friendly. Some boats already have trays, cabling, and chargers set up for series batteries, making the swap simple.

    • Cons: More wiring, heavier, takes up space, and balancing issues can occur.

Note: Most LiFePO4 manufacturers recommend a single battery system over multiple in series. One battery has one Battery Management System (BMS) to keep everything balanced. With multiple batteries, each BMS is its own “team,” and your overall system will only be as strong as the weakest battery.

Real LiFePO4 User Feedback

Hearing from real boaters gives the best perspective on what these setups look like in action:

12V Systems

  • Bass boat on freshwater lakes (12V 50AH):
    Fisherman consistently gets 6+ hours per trip in calm conditions, with plenty of reserve left over.

24V Systems

  • Alumacraft fishing boat (24V 100AH Lithium upgrade from lead acid):
    Previously got ~6 hours with lead acid in heavy wind. With the new Epoch lithium, fished 12 hours straight in moderate-to-strong winds and still had power left. Battery fit perfectly in the stock compartment with no modifications.

  • 22’ Pathfinder bay boat (24V 100AH setup):
    Angler fishes inshore 2–3 days at a time and regularly gets through an entire weekend without recharging.

36V Systems

  • Grady White 247 with twin 150s (36V Kraken Trolling Motor + Epoch 36V 100AH):
    Holding spot lock all day in Rhode Island current and still finishing trips with 40% capacity remaining.

  • 26’ Pilothouse (~7,000 lbs) with Minn Kota Terrova (Epoch 36V 100AH):
    After a full season in both fresh and saltwater, power output has been consistent. Still had 75% charge left after a full day fighting tides.

  • Key West bay boat (~3,000 lbs) with 36V 109lb thrust Xi5 Motor Guide (Epoch 36V 100AH):
    After 3 short trips (about 8 hours total runtime) without recharging, battery was still at 86%.

  • Bass boat switching from 3x 100AH lead acid to a single Epoch 36V 50AH:
    Owner was skeptical about downsizing but reports fishing 5 hours on an Ultrex (level 6–8, scanning with LiveScope) and still had 78% charge left according to the app.

  • Ranger Bass boat with 36V Ghost Trolling Motor (3x Epoch 12V 105AH = 36V system):
    After four full-day trips in windy conditions, batteries finished balanced and still between 83–91% charged.

Final Thoughts

Choosing the right trolling motor battery setup comes down to your boat, trolling motor, environment, fishing style, and desired run time between charges. There’s no one-size-fits-all answer, but if you know your needs, you’ll find the perfect match.

If you’re curious about the Epoch lineup of trolling motor batteries, or you need help with choosing the right battery setup, please don't hesitate to reach out! I work with boaters every day to match them with the right setup — Message Us