For your trolling motor, the best battery choice is typically a deep-cycle marine battery. These are designed to deliver consistent power over long periods and can be discharged deeply without damage, unlike car starting batteries. Lead-acid (AGM or gel) deep-cycle batteries are common and reliable, while lithium-ion offers lighter weight and longer lifespan but at a higher cost.
Heading out on the water with your fishing boat is an exciting prospect, but a dead trolling motor battery can quickly turn a great day into a frustrating one. Choosing the right battery might seem a bit confusing with all the options out there. What makes one battery better for your trolling motor than another? That’s where I come in! I’m Roy Walker, and I’m here to help you make sense of it all. We’ll break down what you need to know in simple terms, so you can pick the best battery with confidence. No confusing jargon, just clear, practical advice to get you powered up and ready to fish!
Understanding Your Trolling Motor Battery Needs
Your trolling motor is the workhorse that keeps you quiet and in position on the water. Unlike the quick burst of power a car needs to start its engine, a trolling motor requires steady, sustained energy over many hours. This means you can’t just grab any old battery off the shelf. You need a battery built for this specific job.
Think of it like this: a car battery is like a sprinter, giving a lot of power very quickly, then resting. A trolling motor battery is like a marathon runner, needing to keep a steady pace for a long, long time. Using the wrong type can lead to poor performance, a shortened battery life, and even damage to the battery itself.
The Difference Between Starting and Deep-Cycle Batteries
This is the most crucial difference to understand when picking a battery for your trolling motor. Let’s break it down:
Starting Batteries (Car Batteries)
These are designed to provide a huge surge of power for a short time to crank an engine. They have many thin plates to maximize surface area for this quick burst. Repeated deep discharges will drastically shorten their lifespan.
Deep-Cycle Batteries
These are built to deliver a steady amount of power over extended periods. They have thicker plates that are more resistant to the wear and tear of being discharged deeply and then recharged. This is essential for a trolling motor that runs for hours.
Always opt for a deep-cycle battery for your trolling motor. It’s the single most important factor for reliable performance and battery longevity on the water.
Types of Deep-Cycle Batteries for Trolling Motors
Once you know you need a deep-cycle battery, you’ll find a few different technologies available. Each has its own set of pros and cons to consider based on your budget, weight concerns, and how you plan to use it.
1. Flooded Lead-Acid (Wet Cell) Batteries
These are the traditional, most common, and often the most budget-friendly deep-cycle batteries. They contain lead plates submerged in a liquid electrolyte (sulfuric acid and water).
Pros:
- Most affordable upfront cost.
- Widely available.
- Can be recharged from a deeply discharged state if not abused.
Cons:
- Require regular maintenance (checking and topping up electrolyte levels with distilled water).
- Must be kept upright to prevent leaks.
- Can emit explosive hydrogen gas, requiring good ventilation and caution around sparks.
- Heavier than other types.
- Generally have a shorter lifespan compared to AGM or Lithium.
If you’re on a tighter budget and don’t mind a little maintenance, flooded lead-acid batteries can be a solid choice. Just remember to keep them topped up and ensure your battery storage area is well-ventilated.
2. Absorbed Glass Mat (AGM) Batteries
AGM batteries are a type of sealed lead-acid battery. Instead of liquid electrolyte, the electrolyte is suspended in fiberglass mats between the plates. This makes them maintenance-free and more robust.
Pros:
- Maintenance-free (no need to add water).
- Sealed design means they are spill-proof and can be mounted in various positions (though upright is still best for optimal cooling).
- Much more resistant to vibration than flooded lead-acid.
- Hold a charge longer and have a lower self-discharge rate.
- Can handle higher charging rates.
- Safer, as they don’t vent explosive gases like flooded types.
Cons:
- Higher upfront cost than flooded lead-acid batteries.
- Can be more sensitive to overcharging.
- Weight is similar to flooded lead-acid.
AGM batteries are a very popular and reliable choice for trolling motors. They offer a great balance of performance, convenience, and safety, making them a go-to for many anglers.
3. Gel Batteries
Gel batteries are another type of sealed lead-acid battery. Here, the electrolyte is a thick, gel-like substance. Like AGMs, they are spill-proof and maintenance-free.
Pros:
- Maintenance-free and spill-proof.
- Good deep discharge capability.
- Lower self-discharge rate than flooded batteries.
- Less sensitive to overcharging than AGMs.
Cons:
- Higher upfront cost than flooded lead-acid.
- Can be sensitive to high charge rates and can be damaged by them if not careful.
- Generally have a shorter lifespan than AGMs, especially when deeply discharged frequently.
- Can be slower to recharge than AGMs.
- Performance can degrade in very cold temperatures.
Gel batteries are a good option, but for trolling motor applications where deep discharges are common, AGMs often hold up better and offer a more robust performance profile. Always check the manufacturer’s recommendations for charge rates.
4. Lithium-ion (LiFePO4) Batteries
Lithium-iron-phosphate (LiFePO4) batteries are a newer, premium technology for trolling motors. They use lithium chemistry that is considered safer and more stable than other lithium-ion types.
Pros:
- Significantly lighter weight (often 50-70% lighter than lead-acid).
- Much longer lifespan (can last 3-5 times longer than lead-acid).
- Can be discharged much deeper (often 80-100%) without damage.
- Faster charging times.
- Consistent voltage output throughout the charge cycle.
- Maintenance-free and sealed.
- Higher energy density means more power in a smaller, lighter package.
Cons:
- Highest upfront cost.
- Require a compatible charger (you can’t use your old lead-acid charger).
- May require a Battery Management System (BMS) built-in to protect the cells and ensure safety, which adds to the cost.
- Performance can be affected by extreme cold without heating elements.
While the initial investment is high, the longevity, weight savings, and performance benefits of LiFePO4 batteries often make them the best long-term value for serious anglers. For example, Dakota Lithium, a reputable manufacturer, offers specialized LiFePO4 batteries designed for marine use. You can learn more about their battery technology on their website.
Key Specifications to Consider
When you’re looking at different batteries, you’ll see a few important numbers and terms. Knowing what they mean will help you make the best choice for your trolling motor.
1. Voltage (V)
Trolling motors come in different voltage configurations: 12V, 24V, and 36V. Your motor’s voltage requirement must match the battery or battery bank you choose. You cannot use a 12V battery to power a 24V motor, for example.
- 12V Motors: Use one 12V battery.
- 24V Motors: Use two 12V batteries wired in series, or one 24V battery (less common).
- 36V Motors: Use three 12V batteries wired in series, or one 36V battery (very uncommon).
Always check your trolling motor’s manual to confirm its voltage requirements.
2. Amp-Hour (Ah) Rating
This is the most important spec for determining how long your battery will last. It tells you the capacity of the battery – how much energy it can store.
A battery with a 100Ah rating can theoretically supply 100 amps for one hour, or 10 amps for 10 hours, or 5 amps for 20 hours, and so on. The higher the Ah rating, the longer your trolling motor will run on a single charge.
How to Estimate Your Needs:
- Check your trolling motor’s manual for its average amp draw at a typical speed (e.g., 50% power).
- Estimate how many hours you typically spend fishing with the trolling motor running.
- Multiply your average amp draw by your estimated run time to get a rough idea of your required Ah capacity.
- For lead-acid batteries, you shouldn’t discharge them below 50% to maximize their lifespan. So, double the result from step 3 to ensure you have enough usable capacity. For LiFePO4, you can use closer to 80-100% of their capacity.
Example: If your motor draws 25 amps at 50% power and you want to fish for 4 hours:
- Calculated need: 25 amps 4 hours = 100 Ah
- For lead-acid (discharge to 50%): 100 Ah 2 = 200 Ah. You’d need at least a 200Ah lead-acid battery.
- For LiFePO4 (discharge to 80%): 100 Ah / 0.8 = 125 Ah. A 125Ah LiFePO4 would suffice.
3. Cold Cranking Amps (CCA) and Marine Cranking Amps (MCA)
These ratings are found on car batteries and indicate their ability to start an engine in cold weather. They are not relevant for trolling motor batteries, which need sustained power, not a quick burst.
4. Reserve Capacity (RC)
This rating indicates how many minutes a fully charged battery can deliver 25 amps at 80°F (27°C) before dropping below a usable voltage. A higher RC generally means a longer run time, especially at lower speeds.
5. Physical Size and Weight
Trolling motor batteries, especially deep-cycle ones, can be quite heavy. Consider where you’ll store the batteries on your boat and if you have the physical strength to lift them. Lithium batteries offer a significant advantage here.
Battery Configurations: Single, Dual, or Triple Battery Setups
The number of batteries you need depends on your trolling motor’s voltage and how long you need it to run.
1. Single Battery (12V System)
If you have a 12V trolling motor and don’t need extremely long run times, one 12V deep-cycle battery might be sufficient. Ensure it has a high enough Ah rating for your needs.
2. Dual Battery (24V System)
For a 24V trolling motor, you’ll need two 12V deep-cycle batteries connected in series. To connect batteries in series, you link the positive (+) terminal of the first battery to the negative (-) terminal of the second battery. The motor then connects to the free negative (-) terminal of the first battery and the free positive (+) terminal of the second battery. This adds their voltages together (12V + 12V = 24V) while keeping the Ah capacity the same as a single battery.
Important Note on Wiring Batteries in Series: Always use two identical batteries (same make, model, and age) when wiring in series. Mixing batteries can lead to uneven charging and discharging, reducing the life of both.
3. Triple Battery (36V System)
A 36V trolling motor requires three 12V deep-cycle batteries wired in series. The process is similar to the dual battery setup, just with an additional battery. Connect them in a chain: (+) Bat 1 to (-) Bat 2, (+) Bat 2 to (-) Bat 3. Your 36V motor then connects to the free (-) of Bat 1 and the free (+) of Bat 3.
Again, using three identical batteries is paramount for performance and longevity.
Maintenance and Charging Best Practices
To get the most out of your trolling motor battery, proper maintenance and charging are key. This applies to all types, but especially lead-acid.
Charging Your Battery
- Use a Marine-Specific Charger: Always use a charger designed for deep-cycle marine batteries. Car chargers can overheat and damage deep-cycle batteries.
- Match Charger to Battery Type: Ensure your charger is compatible with your battery chemistry (flooded lead-acid, AGM, gel, or lithium). Lithium batteries require specific charging profiles.
- Don’t Overcharge: Most modern marine chargers are “smart” chargers that will automatically stop or switch to a maintenance mode when the battery is full.
- Charge After Each Use: It’s best to recharge your batteries fully after each outing, rather than topping them up over multiple days. This helps keep them in optimal condition.
- Avoid Partial Charges (for Lead-Acid): Allowing lead-acid batteries to sit partially discharged for extended periods can lead to sulfation, which reduces their capacity and lifespan.
Maintenance for Flooded Lead-Acid Batteries
- Check Water Levels Regularly: Inspect the electrolyte levels in each cell at least once a month (or more often in hot weather). If the plates are exposed, add distilled water until the plates are just covered.
- Keep Terminals Clean: Corrosion on battery terminals can impede the flow of electricity. Clean them with a wire brush and a mixture of baking soda and water, then rinse and dry. Apply a terminal protector or petroleum jelly.
- Ensure Proper Ventilation: Always use flooded batteries in well-ventilated areas to prevent the buildup of explosive hydrogen gas.
Maintenance for AGM and Gel Batteries
These are sealed and maintenance-free in terms of water levels. The main concerns are:
- Keep Terminals Clean: Just like flooded batteries.
- Avoid Overcharging: Use a charger compatible with AGM/Gel and follow its instructions.
- Protect from Extreme Temperatures: While more robust than flooded types, extreme heat or cold can still affect performance and lifespan.
Maintenance for Lithium-ion (LiFePO4) Batteries
LiFePO4 batteries are the most maintenance-free. The primary needs are:
- Use a Compatible Charger: This is critical! A lead-acid charger will not work correctly and can damage a LiFePO4 battery.
- Monitor State of Charge: While they can be discharged deeply, it’s still good practice to charge them when you have the opportunity to keep them healthy.
- Temperature Protection: Some LiFePO4 batteries have built-in low-temperature cutoff protection. Ensure they are not charged if the battery temperature is below freezing (0°C or 32°F), as this can cause permanent damage.
For more detailed care instructions, always refer to the specific manufacturer’s guidelines. You can often find excellent resources on battery care and maintenance from battery manufacturers or reputable marine supply stores.
Choosing Between Brands and Price Points
The world of batteries can seem overwhelming with so many brands and price tags. Here’s a general breakdown:
Budget-Friendly Options (Flooded Lead-Acid)
Brands like DieHard, EverStart (Walmart), and various store-brand marine batteries fall into this category. They offer the lowest initial cost but require the most maintenance and will likely need replacing sooner.
Mid-Range Options (AGM and Gel)
Brands like Optima, Odyssey, ACDelco, and many dedicated marine battery brands offer reliable AGM and Gel batteries. These are a step up in performance, convenience, and price, making them a popular choice for many boaters.
Premium Options (Lithium-ion LiFePO4)
Specialty companies like Dakota Lithium, Battle Born Batteries, and Relion (among others) focus on high-performance lithium batteries. While the upfront cost is significant, the longevity and weight savings can make them the most cost-effective over the battery’s life.
When comparing batteries, don’t just look at the price. Consider the warranty, the manufacturer’s reputation, and reviews from other users. A slightly more expensive battery that lasts longer and performs better can save you money and hassle in
