Marine Battery Hub

Best Marine Batteries for Trolling Motors

Your trolling motor is only as good as the battery powering it. Run the wrong battery and you will find yourself with a motor that slows down halfway through the day, a battery that fails after two seasons, or worse — stranded on the water when you need to get back to the ramp.

This guide covers everything you need to know about choosing the right battery for your trolling motor — from understanding what trolling motors demand from a battery, to sizing your bank for a full day on the water, to the best chemistry options available at West Marine.

In This Guide

  1. What Trolling Motors Demand from a Battery
  2. Why You Should Never Use a Starting Battery for a Trolling Motor
  3. Deep Cycle vs. Dual-Purpose for Trolling Motor Use
  4. AGM vs. Lithium for Trolling Motors
  5. How to Size Your Trolling Motor Battery Bank
  6. 12V vs. 24V vs. 36V Trolling Motor Systems
  7. Group Size and Physical Fit
  8. Key Specs to Look for on the Label
  9. Charging Your Trolling Motor Battery
  10. Making Your Trolling Motor Battery Last
  11. Quick Selection Guide by Fishing Style
  12. Where to Shop

1. What Trolling Motors Demand from a Battery

A trolling motor is one of the most demanding electrical loads on any fishing boat. Unlike engine starting — which requires a massive burst of current for just a second or two — a trolling motor draws steady current for hours at a time. On a full day of fishing, a trolling motor might run continuously for 6 to 8 hours at varying speeds.

This type of use is called deep cycling — drawing a battery down slowly and steadily over a long period, then recharging it fully before the next use. It is fundamentally different from starting use, and it requires a fundamentally different battery design to handle it reliably over years of use.

The key demands trolling motors place on a battery:

  • High amp hour capacity: enough stored energy to power the motor for the full day
  • Deep discharge tolerance: the ability to be discharged significantly and then fully recharged hundreds of times without plate damage
  • Consistent voltage output: maintaining motor speed and performance throughout the discharge cycle
  • Vibration resistance: fishing boats — especially bass boats — run hard and pound through chop constantly

2. Why You Should Never Use a Starting Battery for a Trolling Motor

Starting batteries use thin, numerous lead plates designed to maximize surface area for high-current bursts. These thin plates are not built to withstand the slow steady discharge and repeated deep cycling that trolling motor use demands. Using a starting battery for a trolling motor causes:

  • Rapid plate degradation — the thin plates buckle and shed material when repeatedly deep cycled
  • Dramatically shortened battery life — a starting battery used for trolling motor duty may fail within a single season
  • Reduced runtime — starting batteries lose capacity quickly under sustained loads
  • Poor performance late in the day — voltage drops off faster than a proper deep cycle battery

Even a dual-purpose battery, while better than a starting battery, will not deliver the same runtime or longevity as a dedicated deep cycle battery for serious trolling motor use. If you fish hard, use a dedicated deep cycle battery for your trolling motor.

3. Deep Cycle vs. Dual-Purpose for Trolling Motor Use

For most fishing applications, a dedicated deep cycle battery is the right choice for your trolling motor. However, there are situations where a dual-purpose battery makes sense:

Battery Type Best For Not Ideal For
Deep Cycle Serious fishing — all-day trolling motor use, tournament anglers, heavy electronic loads Starting the engine (use a separate starting battery)
Dual-Purpose Casual fishing — shorter trips, light trolling motor use, single battery setups on small boats All-day heavy trolling motor use — will not match deep cycle runtime or longevity

If you run your trolling motor for more than 2 to 3 hours on a typical outing, invest in a dedicated deep cycle battery. The performance and longevity difference is significant.

Shop all marine batteries: westmarine.com/marine-batteries/

4. AGM vs. Lithium for Trolling Motors

Both AGM and lithium are excellent choices for trolling motor batteries. The right one depends on your priorities.

AGM Deep Cycle Batteries for Trolling Motors

AGM is the most popular choice for trolling motor batteries and delivers excellent performance for most fishing applications. Key advantages for trolling motor use:

  • Sealed and spill-proof — safe in the vibration and splash environment of a fishing boat
  • Maintenance-free — no water top-ups, no electrolyte checks
  • Vibration-resistant construction handles the pounding of bass boat use
  • Compatible with all standard multi-bank marine chargers
  • Lower upfront cost than lithium

The main limitation of AGM for trolling motor use is usable capacity. To protect cycle life, AGM batteries should not be regularly discharged below 50% of their rated capacity. This means a 100Ah AGM battery has approximately 50Ah of practical usable capacity per outing.

Lithium Batteries for Trolling Motors

Lithium is increasingly the choice of serious tournament anglers and heavy trolling motor users. Key advantages for trolling motor use:

  • More usable capacity: lithium can be safely discharged to 80 to 100% of rated capacity — a 100Ah lithium battery delivers nearly twice the usable energy of a 100Ah AGM in daily use
  • Flat voltage curve: trolling motor runs at consistent speed from full charge to near-empty — no slowing down late in the day
  • Significantly lighter: 50 to 70% lighter than AGM — critical for tournament anglers where every pound of weight affects boat performance
  • Longer cycle life: 2,000+ cycles vs. 300 to 500 for AGM
  • Faster recharge: fully recharged faster between fishing days

The trade-off is upfront cost and the requirement for a lithium-compatible charger. For anglers who fish frequently and run their trolling motor hard, lithium typically pays for itself over time through its longevity and superior usable capacity.

Shop sealed AGM deep cycle batteries: westmarine.com/sealed-marine-batteries/

5. How to Size Your Trolling Motor Battery Bank

Battery sizing is the most important calculation for trolling motor use. Too little capacity and you run out of power before the day is done. Too much and you are carrying unnecessary weight.

Step 1: Find Your Trolling Motor's Amp Draw

Your trolling motor's maximum amp draw is listed in the owner's manual or on the motor itself. Common amp draws at full throttle:

Motor Thrust Approximate Max Amp Draw Average Amp Draw (varied speeds)
30 lb thrust 30 amps 15 to 18 amps
45 lb thrust 42 amps 20 to 25 amps
55 lb thrust 50 amps 25 to 30 amps
80 lb thrust 56 amps 28 to 35 amps
112 lb thrust 52 amps (24V) 25 to 32 amps

Step 2: Calculate Required Capacity

Multiply your average amp draw by the number of hours you want to fish:

Required Ah = Average Amp Draw x Hours of Use

For an AGM battery (50% usable capacity), double the result to get the required rated Ah. For a lithium battery (80% usable capacity), multiply by 1.25.

Example — 55 lb thrust motor, 8 hours fishing:

  • Average draw: 27 amps
  • Required energy: 27 x 8 = 216Ah
  • AGM required rated capacity: 216 / 0.50 = 432Ah (two 200Ah+ batteries)
  • Lithium required rated capacity: 216 / 0.80 = 270Ah (one 300Ah lithium battery)

This shows clearly why lithium is appealing for serious anglers — significantly less battery weight and bulk for the same real-world runtime.

6. 12V vs. 24V vs. 36V Trolling Motor Systems

Many higher-thrust trolling motors run on 24V or 36V systems rather than 12V. These systems require multiple batteries wired in series:

"Batteries Required
System Voltage How They Are Wired Typical Use
12V 1 battery Single battery Small to mid-size boats, motors up to 55 lb thrust
24V 2 batteries Two 12V batteries in series (positive of one to negative of other) Mid to large boats, motors 80 to 112 lb thrust
36V 3 batteries Three 12V batteries in series Large boats, heavy-duty tournament use, maximum thrust motors

When wiring batteries in series for a 24V or 36V system, always use batteries of the same chemistry, brand, age, and capacity. Mismatched batteries in a series bank charge and discharge unevenly, which shortens the life of all batteries in the bank.

Each battery in a series bank still needs to be charged individually — a multi-bank charger with one output per battery is the correct charging solution for multi-voltage trolling motor systems.

Shop multi-bank marine battery chargers: westmarine.com/marine-battery-chargers/

7. Group Size and Physical Fit

For most trolling motor applications, Group 27 and Group 31 batteries are the most common sizes. Group 31 batteries offer the highest capacity in a standard case size and are the preferred choice for serious trolling motor banks.

  • Group 24: lower capacity, lighter weight — suitable for small motors on small boats with limited battery space
  • Group 27: mid-range capacity — a practical balance of size, weight, and amp hours for most fishing boats
  • Group 31: highest capacity in the standard range — the preferred choice for all-day serious trolling motor use and multi-battery banks

Always measure your battery compartment and verify the group size fits your battery tray before purchasing. Trolling motor battery trays on bass boats and fishing boats are typically sized for Group 27 or Group 31.

Shop battery boxes and hold-downs: westmarine.com/battery-boxes-hold-downs/

8. Key Specs to Look for on the Label

When comparing trolling motor batteries, focus on these specifications:

Spec What to Look For Why It Matters
Amp Hours (Ah) As high as your budget and weight allowance permit — minimum 100Ah for serious use Directly determines how long you can run the motor
Reserve Minutes (RC) Higher is better — 180 minutes or more for serious fishing Real-world measure of sustained power delivery
Chemistry AGM for best value; Lithium for best performance Determines usable capacity, cycle life, and charger requirements
Type Deep Cycle — not Starting or Dual-Purpose for serious use Only deep cycle batteries are designed for repeated sustained discharge
Weight Lightest option that meets your capacity needs Affects boat trim, performance, and fuel efficiency

9. Charging Your Trolling Motor Battery

Proper charging is critical to getting the most life and performance from your trolling motor battery. Best practices:

  • Charge after every outing — do not let a discharged battery sit overnight or for days between uses. Sulfation begins immediately in a discharged battery and compounds over time.
  • Use a multi-bank onboard charger matched to your battery chemistry. A two or three bank charger charges each trolling motor battery independently and simultaneously while the boat is in the slip or garage.
  • Match charger chemistry mode to your batteries — AGM mode for AGM batteries, lithium mode for lithium. Using the wrong mode damages batteries over time.
  • Size the charger appropriately — at no more than 20% of the battery's Ah rating per bank. A 10-amp output per bank is appropriate for a 100Ah battery; a 20-amp output for a 200Ah battery.
  • Use a maintainer during extended storage — if the boat sits for weeks between outings, keep batteries on a smart maintainer to prevent self-discharge.

Shop marine battery chargers: westmarine.com/marine-battery-chargers/
Shop portable chargers: westmarine.com/portable-chargers/

10. Making Your Trolling Motor Battery Last

  • Never discharge below 50% for AGM — if performance starts dropping significantly, it is time to head in and recharge, not keep fishing
  • Keep terminals clean and corrosion-free — trolling motor connections carry high current and corroded terminals cause voltage drop and reduced motor performance
  • Secure batteries properly in a battery box with hold-downs — trolling motor batteries on bass boats take constant vibration and impact
  • Store fully charged over winter with a smart maintainer connected — batteries stored in a discharged state develop sulfation that permanently reduces capacity
  • Test at the start of each season — West Marine offers free in-store battery testing; a battery that cannot pass a load test should be replaced before the season starts

Shop test meters: westmarine.com/test-meters/

11. Quick Selection Guide by Fishing Style

Fishing Style Recommended Battery Minimum Capacity
Casual fishing — short trips, small motor, single battery boat Group 24 or 27 AGM Dual-Purpose 65 to 80Ah
Weekend fishing — half-day outings, mid-size motor Group 27 AGM Deep Cycle 80 to 100Ah
Serious fishing — full-day outings, large motor Group 31 AGM Deep Cycle 100 to 105Ah per battery
Tournament angler — maximum runtime, weight-conscious Lithium Deep Cycle 100Ah lithium (equivalent to 200Ah AGM in usable capacity)
24V trolling motor system Two matched Group 31 AGM or Lithium batteries in series 100Ah per battery minimum
36V trolling motor system Three matched Group 31 AGM or Lithium batteries in series 100Ah per battery minimum

12. Where to Shop

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