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A Practical Guide to Choosing Your Trolling Motor Battery

2025-08-27 | Eric

The last thing you want on the water is your trolling motor running out of juice. Your battery is the heart of your setup — pick the wrong one and you’ll cut a day of fishing short; pick the right one and you’ll spend more time where it matters: reeling fish and enjoying the wind. This guide walks you through the main battery types, what matters when you buy, realistic runtime expectations.

Types of trolling motor batteries
Why many anglers prefer LiFePO4 today
How to choose the right battery
Real-world runtime: quick math and examples
FAQs
Final recommendation

Types of trolling motor batteries

There are three deep-cycle battery families commonly used with trolling motors:

Flooded lead-acid (FLA)

Pros: Lowest upfront cost; widely available.
Cons: Heavy, bulkier, require regular maintenance (water top-ups), and aren’t great in cold or vibration-heavy environments.

AGM (Absorbent Glass Mat)

Pros: Sealed and spill-proof, better resistance to vibration, less maintenance than flooded cells, and generally longer life than basic flooded batteries.
Cons: Heavier than lithium and still limited by lead-acid depth-of-discharge and cycle life.

LiFePO4 (Lithium Iron Phosphate)

Pros: Far lighter, much longer cycle life, faster charging, consistent voltage during discharge, and higher usable capacity. Popular for serious anglers.
Cons: Higher upfront cost (though total cost of ownership often favors lithium for frequent users).

Why LiFePO4 is often the best choice

Weight: A 100Ah LiFePO4 commonly weighs under ~35 lb vs 60–80 lb for an equivalent lead-acid deep-cycle.
Cycles & lifespan: Quality LiFePO4 cells often rate in the thousands of cycles (3,000–5,000 typical), compared with lead-acid batteries that last a few hundred to a low-thousand cycles.
Usable capacity & charging: LiFePO4 lets you use a greater percentage of the pack without damage and charges faster, so downtime between trips drops.

How to choose the right battery — practical checklist

1. Match voltage to your motor

Trolling motors run on 12V, 24V, 36V (or more). Follow the motor manufacturer’s recommendation: small motors (≤55 lb thrust) usually run on a single 12V battery, mid-range motors often use 24V (two 12V batteries in series), and high-thrust setups use 36V (three 12V batteries in series). Check your motor’s manual for exact wiring.

2. Capacity (Ah) and realistic runtime

Amp-hours (Ah) tell you how much energy the battery stores. Runtime ≈ battery Ah ÷ motor amps at the chosen speed. For example, a 100Ah battery powering a motor that draws ~50A at full throttle gives roughly 2 hours at full speed. Runtime improves dramatically at trolling speeds or partial throttle.

3. Size & weight (fit your boat)

Measure your battery compartment and plan wiring space. On small boats or kayaks, lithium’s weight savings and smaller group sizes often let you carry more gear and improve handling.

4. Durability & BMS (battery management system)

A good LiFePO4 pack includes a robust BMS that protects against overcharge, over-discharge, over-current and temperature excursions. For marine use, look for packs with marine-grade protection (IP rating, corrosion resistance) and a proven BMS.

5. Reserve & redundancy

If you fish in wind, current, or remote waters, more Ah or dual batteries (for redundancy) is smart. recommends sizing a deep-cycle marine battery at 110Ah or larger for many trolling setups as a starting point.

Real-world runtime: practical examples

Full speed (heavy load, e.g., 55 lb motor at full): ≈ 2 hours
Medium/trolling speed (~50% draw): 4–6 hours
Low/spot-lock or drift: Many hours — lithium’s steady voltage means better low-speed efficiency and longer usable time.

Remember: real amps drawn change with boat load, wind, current, and prop efficiency — always test your combination before committing to a long run.

FAQs

Q — Is LiFePO4 worth the extra cost?

A — For frequent anglers or those valuing weight savings and longer life, yes: LiFePO4 often wins on total cost of ownership because of far more cycles and better usable capacity.

Q — How many batteries for a 36V motor?

A — Typically three 12V batteries wired in series. Follow your motor’s wiring diagram and manufacturer guidance.

Q — Can I mix battery types (AGM + lithium)?

A — No — mixing battery chemistries or different ages is a bad idea. Use matched batteries of the same chemistry, capacity, and age in series/parallel setups.

Q — What maintenance do lithium packs need?

A — Minimal. Ensure terminals are clean/tight, keep the BMS healthy (avoid extreme temps), and use a compatible charger.

Final recommendation

If you're buying one battery to upgrade your trolling setup and you fish often, go LiFePO4 (12V 100Ah or larger) — it’s lighter, lasts far longer, and charges faster. If budget is tight but you want a sealed, low-maintenance option, choose a high-quality AGM. For infrequent users who don’t mind upkeep, a flooded deep-cycle can still do the job.

Ready to upgrade?

Want help choosing the exact model for your boat and motor (make/model of motor, boat length, and typical trip duration)? Send those specs and I’ll recommend a battery size and wiring setup that fits your rig — including estimated runtime and a short shopping checklist.