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Powering Your Trolling Motor: A Comprehensive Guide to 12V, 24V, and 36V Battery Hookups

For any serious angler, a trolling motor is an indispensable tool, offering quiet propulsion and precise boat control. But the heart of any trolling motor system lies in its battery bank. Understanding how to properly hook up your batteries for 12-volt, 24-volt, and 36-volt systems is crucial for optimal performance, longevity, and safety. This detailed guide from Reel Schematic will walk you through each configuration, ensuring you’re powered up and ready to hit the water.

The Fundamentals: Volts, Amps, and Series vs. Parallel

Before we dive into specific hookups, let’s clarify some basic electrical concepts:

  • Voltage (V): Think of voltage as the “pressure” that pushes electrical current. Your trolling motor is designed to operate at a specific voltage (12V, 24V, or 36V). Mismatched voltage can damage your motor.
  • Amperage (A): Amperage is the “volume” of electrical current flowing. Trolling motors draw a certain amount of amperage, and your batteries need to be able to supply it. Battery capacity is measured in Amp-hours (Ah).
  • Series Connection: Connecting batteries in series increases the total voltage while keeping the amperage capacity the same. This is achieved by connecting the positive terminal of one battery to the negative terminal of the next.
  • Parallel Connection: Connecting batteries in parallel increases the total amperage capacity while keeping the voltage the same. This is achieved by connecting positive terminals to positive terminals and negative terminals to negative terminals.

Safety First! Always prioritize safety when working with batteries.

  • Disconnect Power: Before making any connections, ensure all power is off and the trolling motor is disconnected.
  • Eye Protection: Always wear safety glasses to protect your eyes from accidental sparks or battery acid.
  • Gloves: Wear appropriate gloves to protect your hands.
  • Insulated Tools: Use tools with insulated handles to prevent accidental short circuits.
  • Ventilation: Work in a well-ventilated area, especially when dealing with lead-acid batteries, which can produce hydrogen gas.
  • Fuses and Circuit Breakers: Always install an appropriately sized fuse or circuit breaker as close to the battery bank as possible to protect your wiring and trolling motor from overcurrents. Refer to your trolling motor’s manual for the recommended fuse size.

Battery Types for Trolling Motors

While various battery chemistries exist, the most common for trolling motors are:

  • Lead-Acid (Flooded): These are the most traditional and often the most budget-friendly. They require maintenance (checking water levels) and should be kept upright.
  • AGM (Absorbed Glass Mat): A type of sealed lead-acid battery that is maintenance-free, spill-proof, and more resistant to vibration. They charge faster and have a longer lifespan than flooded batteries.
  • Lithium (LiFePO4 – Lithium Iron Phosphate): The most advanced option, offering significant weight savings, a much longer lifespan, consistent power output, and faster charging. While more expensive upfront, their benefits often outweigh the cost over time.

For this guide, the connection principles remain the same regardless of battery type, but always follow the manufacturer’s specific charging and maintenance guidelines for your chosen batteries.

1. 12-Volt Trolling Motor Systems

A 12-volt system is the simplest and most common for smaller trolling motors.

Required Components:

  • One 12-volt deep cycle battery (or two 6-volt batteries wired in series to create a 12-volt battery).
  • Battery cables (appropriately gauged for your motor’s amperage draw and cable length).
  • Battery terminal connectors.
  • Inline fuse holder or circuit breaker.

Hookup Procedure (Single 12V Battery):

  1. Position the Battery: Securely place your 12-volt deep cycle battery in a well-ventilated battery box or tray.
  2. Connect Positive (Red): Connect one end of your positive battery cable (typically red) to the positive (+) terminal of the 12-volt battery.
  3. Install Fuse/Breaker: Connect the other end of the positive cable to one side of your inline fuse holder or circuit breaker. If using a circuit breaker, connect the “load” side to your trolling motor.
  4. Connect to Trolling Motor: Connect a second positive cable from the other side of the fuse holder/breaker to the positive (+) terminal of your trolling motor.
  5. Connect Negative (Black): Connect one end of your negative battery cable (typically black) to the negative (-) terminal of the 12-volt battery.
  6. Connect to Trolling Motor: Connect the other end of the negative cable directly to the negative (-) terminal of your trolling motor.
  7. Double-Check Connections: Ensure all connections are tight and secure.

Alternative Hookup (Two 6V Batteries for 12V):

Some users opt for two 6-volt golf cart batteries, which are known for their robust deep cycle capabilities. To achieve 12 volts, you’ll wire them in series.

  1. Position Batteries: Place both 6-volt batteries securely.
  2. Series Connection: Connect a short jumper cable from the positive (+) terminal of the first 6-volt battery to the negative (-) terminal of the second 6-volt battery.
  3. Connect Positive (Red) to Trolling Motor: Connect your main positive battery cable from the unused positive (+) terminal of the second 6-volt battery (the one with the jumper connected to its negative terminal) to your fuse/breaker, and then to the trolling motor’s positive terminal.
  4. Connect Negative (Black) to Trolling Motor: Connect your main negative battery cable from the unused negative (-) terminal of the first 6-volt battery (the one with the jumper connected to its positive terminal) directly to the trolling motor’s negative terminal.
  5. Double-Check Connections: Verify all connections are tight and correct.

2. 24-Volt Trolling Motor Systems

A 24-volt system is common for medium to large trolling motors, offering more power and efficiency than a 12-volt system. This setup requires two 12-volt batteries wired in series.

Required Components:

  • Two 12-volt deep cycle batteries.
  • Battery cables (appropriately gauged).
  • Battery terminal connectors.
  • One short jumper cable (same gauge as main cables).
  • Inline fuse holder or circuit breaker.

Hookup Procedure (Two 12V Batteries in Series):

  1. Position Batteries: Securely place your two 12-volt deep cycle batteries side-by-side.
  2. Series Jumper Connection: Connect one end of your short jumper cable from the positive (+) terminal of the first 12-volt battery to the negative (-) terminal of the second 12-volt battery. This creates the 24-volt series connection.
  3. Connect Main Positive (Red): Connect your main positive battery cable from the remaining open positive (+) terminal of the second 12-volt battery (the one with the jumper connected to its negative terminal) to your fuse holder/circuit breaker.
  4. Connect to Trolling Motor: Connect a second positive cable from the other side of the fuse holder/breaker to the positive (+) terminal of your 24-volt trolling motor.
  5. Connect Main Negative (Black): Connect your main negative battery cable from the remaining open negative (-) terminal of the first 12-volt battery (the one with the jumper connected to its positive terminal) directly to the negative (-) terminal of your 24-volt trolling motor.
  6. Double-Check Connections: Ensure all connections are tight and secure.

Important Note on Charging 24V Systems: When charging a 24-volt series system, you’ll need a 24-volt compatible battery charger, or you can use two separate 12-volt chargers (one for each battery) or a “12/24V” charger that can be switched to the 24V setting. Never attempt to charge a 24V series system with a single 12V charger connected to only one battery, as this can lead to unbalanced charging and damage.

3. 36-Volt Trolling Motor Systems

A 36-volt system provides maximum power and run time, typically found on high-thrust trolling motors for larger boats. This setup requires three 12-volt batteries wired in series.

Required Components:

  • Three 12-volt deep cycle batteries.
  • Battery cables (appropriately gauged).
  • Battery terminal connectors.
  • Two short jumper cables (same gauge as main cables).
  • Inline fuse holder or circuit breaker.

Hookup Procedure (Three 12V Batteries in Series):

  1. Position Batteries: Securely place your three 12-volt deep cycle batteries.
  2. First Series Jumper: Connect one short jumper cable from the positive (+) terminal of the first 12-volt battery to the negative (-) terminal of the second 12-volt battery.
  3. Second Series Jumper: Connect a second short jumper cable from the positive (+) terminal of the second 12-volt battery to the negative (-) terminal of the third 12-volt battery. These two jumpers complete the 36-volt series connection.
  4. Connect Main Positive (Red): Connect your main positive battery cable from the remaining open positive (+) terminal of the third 12-volt battery (the one with a jumper connected to its negative terminal) to your fuse holder/circuit breaker.
  5. Connect to Trolling Motor: Connect a second positive cable from the other side of the fuse holder/breaker to the positive (+) terminal of your 36-volt trolling motor.
  6. Connect Main Negative (Black): Connect your main negative battery cable from the remaining open negative (-) terminal of the first 12-volt battery (the one with a jumper connected to its positive terminal) directly to the negative (-) terminal of your 36-volt trolling motor.
  7. Double-Check Connections: Ensure all connections are tight and secure.

Important Note on Charging 36V Systems: Similar to 24V systems, charging a 36-volt series system requires a 36-volt compatible battery charger. Alternatively, you can use three separate 12-volt chargers (one for each battery) or a “12/24/36V” charger that can be switched to the 36V setting. Proper charging is critical for battery health and longevity.

Cable Gauging: Don’t Skimp on Wire!

Using the correct wire gauge is paramount for efficient power transfer and to prevent overheating. Undersized wires can lead to voltage drop, reducing your trolling motor’s performance and potentially damaging it or even causing a fire.

  • Consult Your Trolling Motor Manual: Your motor’s manual will provide the recommended wire gauge based on its amperage draw and the length of the cable run.
  • General Guidelines (Always verify with manual):
    • 12-24V Systems (up to 50 amps): Often require 8 AWG for shorter runs, 6 AWG for longer runs.
    • 24-36V Systems (50-100+ amps): Typically require 6 AWG for shorter runs, 4 AWG or even 2 AWG for longer runs.
  • Longer Runs = Thicker Wire: The longer the cable run, the more resistance it has, and thus a thicker gauge wire is needed to minimize voltage drop.

Maintenance Tips for Your Trolling Motor Batteries

  • Regular Charging: Recharge your batteries as soon as possible after each use, even if they’re not fully depleted. Avoid letting them sit discharged for extended periods.
  • Use a Smart Charger: Invest in a multi-stage smart charger that matches your battery type (lead-acid, AGM, or lithium) and voltage system. These chargers optimize the charging process and prevent overcharging.
  • Check Connections: Periodically inspect all battery connections for corrosion, tightness, and wear. Clean terminals as needed with a wire brush and a baking soda/water solution (for lead-acid).
  • Keep Batteries Clean: Wipe down batteries to remove dirt and grime.
  • Store Properly: If storing your boat for an extended period, fully charge your batteries and disconnect them. Consider a trickle charger or maintenance charger for long-term storage.
  • Monitor Water Levels (Flooded Batteries): For flooded lead-acid batteries, regularly check the electrolyte levels and top off with distilled water as needed (never tap water).

Conclusion

Properly hooking up your trolling motor batteries is a fundamental aspect of maximizing your time on the water. By understanding the principles of series wiring for increased voltage and following these detailed instructions, you can ensure a reliable, efficient, and safe power supply for your 12-volt, 24-volt, or 36-volt trolling motor system. Always prioritize safety, use appropriate components, and adhere to your trolling motor and battery manufacturers’ recommendations. Happy fishing!