What Size Fish Finder Battery Do I Need? 2025 Updated

Fish finders require a stable power source to operate efficiently, and selecting a battery with the right capacity ensures that the device runs for the necessary duration without power issues.

This article will explain how fish finders are powered, how to determine power requirements, and how to choose the correct battery size.

How Are Fish Finders Powered?

Fish finders typically operate on low-voltage DC power, usually within the 10V to 20V range, with 12V being the most common. However, more and more anglers are now using 16V batteries for fish finder due to the clearer imaging, stronger signal strength, and stable power.

Types of Power Sources

Fish finder batteries are designed for boats, kayaks, and other watercraft that need power to operate electronic equipments. The most common power sources include:

• Lead-Acid Batteries – Traditional sealed lead-acid (SLA) batteries are widely used for fish finders. They are relatively inexpensive and come in different capacities, but they are heavier compared to modern alternatives.
• AGM (Absorbent Glass Mat) Batteries – One type of lead-acid batteries. Compared to SLA options, AGM batteries offer better performance, have lower internal resistance, and are more resistant to vibrations.
• Lithium Batteries – LiFePO4 lithium batteries have become the preferred choice for fish finders due to their lightweight design, longer lifespan, and high efficiency. They also provide consistent voltage output, ensuring stable performance.

Factors Influencing Fish Finder Battery Runtime

Several factors affect how long a fish finder battery lasts. Understanding these factors can help you choose the right battery and maximize its efficiency.

Battery Type

The type of battery significantly impacts runtime and performance.

LiFePO4 Lithium batteries maintain a steady voltage throughout their discharge cycle, meaning your fish finder receives stable power until the battery is nearly depleted. This results in a longer and more efficient runtime compared to lead-acid batteries of the same capacity.

Lead-acid batteries, on the other hand, experience voltage drop as they discharge. As the voltage decreases, the fish finder may receive insufficient power, reducing effective runtime even if some capacity remains in the battery.

Usage Patterns

How you operate your fish finder directly impacts battery life.

• Brightness Settings – Higher brightness consumes more power, especially in bright outdoor conditions.
• Sonar and GPS Features – Basic fish finders use standard 2D sonar, which has relatively low power consumption. Advanced sonar modes and GPS mapping increase energy use, draining the battery faster.
• Intermittent vs. Continuous Use – Using the fish finder only when needed extends battery life compared to continuous operation.

Environmental Conditions

• Temperature: Extreme cold or hot temperatures can affect battery efficiency. Cold weather, in particular, can reduce battery capacity and runtime.
• Water Temperature: The temperature of the water can also impact battery performance, especially in colder water, which might cause more energy drain for deeper sonar readings.
• Water Depth and Sonar Sensitivity: Deep-water fishing requires stronger sonar signals, which may increasing power consumption. If you rely on high-powered sonar settings, your fish finder will use more power compared to shallow-water fishing.

Additional Functions

Many modern fish finders have Wi-Fi connectivity, Bluetooth, or GPS navigation. If these features remain open, they increase power consumption even when the fish finder is idle.

What Size Battery Do I Need to Run a Fish Finder?

The size of a fish finder battery depends on the desired runtime and amp, which can vary with the fish finder's brand, screen size, and features.

Determining Battery Capacity

To determine the ideal battery size, consider the fish finder’s amp draw and the battery capacity. 

Here are some common types of fish finders and their approximate amp draw, which is based on a 12.8V LiFePO4 battery. Using a 16V LiFePO4 battery can reduce the fish finder’s current consumption:

• Portable Fish Finders: Approximately 0.5A to 1A.
• Fixed Fish Finders: Typically between 1A to 3A.
• High-End Fish Finders: Can reach 3-5A or higher, especially when using multiple sensors and display features.

For instance, if a fish finder draws 1.5A and needs to run for 8 hours, the required capacity would be:

1.5A × 8h = 12Ah

For longer trips, adding a margin ensures reliable performance. A 15Ah or 20Ah battery would provide extra runtime.

Matching Battery Size to Fish Finder Requirements

For kayaks and small Boats, compact lithium batteries in the 10Ah to 20Ah range work well due to their lightweight design. For example, the Redodo 12V 20Ah battery for fish finder weighs just 4.92 lbs, with the compact dimensions of L7.13 x W3.03 x H6.69 inches.

For medium-sized boats, fish finders drawing around 1A to 3A require 20Ah to 50Ah batteries.

For large boats with multiple electronics, a higher-capacity 50Ah to 100Ah batteries may be necessary, especially if running multiple devices.

Do I Need a Separate Battery for My Fish Finder?

For avid anglers or those using advanced fish finders with GPS, sonar, and live imaging, a dedicated lithium battery is the best way to ensure reliability, longer runtime, and cleaner power for optimal performance.

If you have a small boat, kayak, or fish for long hours, a separate 12V or 16V fish finder battery (10Ah-30Ah) is a smart choice for uninterrupted power.

However, if you fish occasionally and have a large-capacity main marine battery, you may not need a dedicated battery for your fish finder, but monitoring power usage is crucial.

It's important to avoid using a lithium trolling motor battery to power both the fish finder and the trolling motor at the same time, as it can cause interference and power issues.

Pros of Using a Separate Battery

• Prevents Interference – A dedicated fish finder battery reduces the likelihood of electrical interference from your boat’s motor or other electronics, ensuring clearer sonar readings and reliable GPS data.
• Ensures Reliable Power – By using a separate battery, you avoid draining your main boat battery, which is critical for powering other essential systems. This ensures that you have enough power for both the fish finder and your boat’s primary functions.
• Lightweight and Portable – Smaller lithium kayak batteries are lightweight and easy to carry, making them an ideal choice for fishing on kayaks or smaller boats, where space and weight are important considerations.

Recommended Lithium Batteries for Fish Finder

Choosing the right battery to run your fish finder ensures longer runtime, stable power, and reliable performance on the water. Here are three best fish finder battery options from Redodo:

Redodo 12V 20Ah LiFePO4 Battery – Lightweight & Reliable

The 12V 20Ah lightweight marine battery is a great budget-friendly option. It features super lightweight design and offers continuous power for small boat fish finder.

✅ Ideal for kayaks, small boats, and portable fish finders

✅ Provides 10-20 hours of runtime for fish finders drawing 1-2A

✅ Weighs only 4.92 lbs, making it easy to carry and install

✅ 4,000+ cycles, lasting up to 10 years

Redodo 12V 20Ah Lithium Battery $79.99 Shop Now

Redodo 16V 30Ah Fish Finder Battery – Enhanced Performance

For those seeking improved efficiency and longer runtime, we recommend considering a 16 volt lithium battery for fish finder.

Compared to a 12V battery, the 16V 30Ah fish finder battery provides higher voltage, which reduces the amp draw, resulting in less strain on the battery and longer operating times.

This makes it especially beneficial for running advanced sonar and GPS features. Make the switch to a 16V system and enjoy enhanced performance.

✅ Designed for high-powered fish finders, GPS, and live sonar systems

✅ 16V output for more stable voltage level and improved clarity on fish finder displays

✅ Delivers 15-30 hours of operation for fish finders drawing 1-2A

✅ Weighs only 7.63 lbs, ideal for small boats and kayaks

✅ Smart Bluetooth monitoring and low-temp protection for reliablity

Redodo 16V 30Ah Lithium Fish Finder Battery $129.99 Shop Now

Redodo 12V 50Ah Bluetooth Lithium Battery – Maximum Runtime

For those who want full control over their power usage, this Bluetooth-enabled 12V 50Ah LiFePO4 battery offers the longest runtime and smart monitoring features, making it the best choice for extended fishing trips.

✅ Perfect for running multiple electronics (fish finder, GPS, lights, sonar, etc.) and trolling motors up to 70 lbs thrust

✅ 50Ah capacity supports 25-50 hours of operation for fish finders drawing 1-2A

✅ Built-in Bluetooth monitoring to track voltage, capacity, and usage in real time

✅ Advanced BMS protection ensures safety and efficiency

Redodo 12V 50Ah Bluetooth Battery $122.99 Shop Now

Conclusion

Selecting the right fish finder battery size depends on power consumption, amps draw, expected runtime, and battery type. A lightweight 12V lithium battery in the 10Ah to 30Ah range is ideal for most fish finders, while larger setups may need 50Ah or more.

Redodo lithium batteries for fish finder offer lightweight designs, long cycle life, and stable power output, ensuring your fish finder runs efficiently throughout your trip. Upgrade your fish finder power today!

FAQ about Fish Finder Batteries

What kind of battery does a fish finder use?

Fish finders typically use either lithium (LiFePO4) or lead-acid batteries.

Lithium Batteries (LiFePO4) – These are the best option for fish finders because they are lighter, more efficient, and last longer. They provide consistent power throughout their discharge and can last 4,000+ charge cycles, making them ideal for long-term use.

Lead-Acid Batteries – These are cheaper but heavier and bulkier. They don’t maintain a consistent voltage and last only 200-500 charge cycles, making them less reliable over time.

What's the difference between 12V and 16V lithium batteries for fish finders?

Both the 12V and 16V lithium battery can power 12V fish finders. A 16V lithium battery maintains a steady voltage above 15V before entire discharge. This ensures the fish finder runs smoothly, delivering accurate sonar readings, and clearer imaging. It can provide longer running time for fish finder and livescope.

On the other hand, a 12V battery for fish finder may lead to slight voltage drops when the battery is running low, which may affect your fishing experience.

Read More:

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