Choosing the Best Battery For Your Fish Finder

Posted October 31, 2022

Fishing often means spending countless hours on the water tracking down fish, but to accomplish this task you will need a battery that can power your fish finder reliably no matter where your trip takes you. In order to know which battery is the right choice for your fishing needs, it is important to know what options you have and what the pros and cons of each choice are. Making the right decision is imperative, as a fish finder battery is an invaluable asset that can power many devices on your boat, and a strong one can give you peace of mind while you are out on the water. Below we cover what exactly a fish finder is, the myriad ways you can power your fish finder, as well as what you should look for when it comes to selecting the right battery to power your device.

What is a Fish Finder?

A fish finder allows you to locate schools of fish underwater by reflecting sound energy. It can be placed on any type of boat - from large ones to smaller ones like kayaks and canoes. These devices make your fishing experience more fruitful and easier, but only if you select the right battery for the job. If you are unsure about what kind of battery is the safest and most efficient choice, read on to learn more.

What is a fish finder? Lawrence Ghost

What Powers Fish Finders?

On larger boats, a fish finder is powered through the onboard electrical system of the vessel, which draws power from the boat’s marine battery. Large boats generally always have built-in marine batteries, but for smaller boats like a kayak, you will need an external battery to power a fish finder.

Historically, most boats have relied on a 12V lead-acid battery, but these have increasingly been replaced by top performing 12V lithium batteries like the RB100, which provide a lighter, more energy-dense alternative that also lasts for many more hours at a time than a traditional lead-acid battery. On smaller vessels, where extra weight is a significant burden and can often slow down the boat, light batteries that offer long-lasting energy are of utmost importance.

100ah Lithium Bass Boat Battery Installation

What is the Best Marine Battery Choice?

Sealed Lead-Acid

Sealed lead-acid batteries are made with sulfuric acid, lead sulfate, a water solution, and lead. These deep-cycle batteries are often selected because they offer a cheaper upfront price point to boaters. However, this initially lower cost is quickly outweighed by the fact that sealed lead acid batteries also tend to last a much shorter period of time and cannot be discharged more than 50 percent without causing damage to the battery. A lead-acid battery delivers far less energy per kilogram of weight compared to lithium batteries which can offer nearly 6x that amount of energy. Additionally, a lead-acid battery can only handle about 400 renewal cycles before needing to be replaced, which can become costly for those who are on their boats a great deal. Since they require many more replacements over the course of a single lithium battery’s lifespan, lead-acid batteries are therefore usually less cost-effective over the long run as a result.


Lithium batteries are becoming a top choice for boaters because they offer a longer-lasting and more powerful battery alternative. Lithium iron phosphate batteries (LFP or LiFePo4), like the ones used by RELiON, also offer a very safe option for fish finder batteries. This is due to the fact that these batteries are the most environmentally benign option on the market and because they are not prone to thermal runaway or fire, unlike lithium cobalt-based batteries. LFP batteries also do not use toxic chemicals like lead-acid batteries.

Although lithium batteries have a higher upfront price point, they can last up to 10x longer than lead-acid, making them a more economical choice long-term due to avoided replacement costs. In addition to being lightweight and able to last for many more years, lithium batteries have the advantage of charging at a much faster rate, allowing you to get back out on the water sooner. They are also able to be discharged between 80 and 100 percent of their capacity without causing damage to the battery.

What To Look For In Your Fish Finder Battery

In addition to your specific energy needs, there are several key features and benefits you should be looking for in your fish finder battery. While each person’s needs will differ, depending on factors such as how long you usually spend on the water and what type of water you are usually traversing through. Here are the reasons why lithium marine batteries are the better choice over lead-acid:

  • water resistant
  • long-lasting
  • lightweight
  • reliable
  • low-maintenance
Lightweight Lithium Marine Battery 100Ah


You should be careful to always select a battery that is made for marine applications. If your battery is not in fact suitable for the water, you may risk damaging the battery and also leaking parts of the battery into the water. RELiON lithium batteries are IP67 certified, meaning they can withstand being fully submerged in water up to 1 meter for 30 mins.


If you spend considerable time on the water, such as through fishing tournaments, the last thing you want to worry about is your battery getting drained too quickly and potentially leaving you stranded on the water. A long-lasting battery is important, and the larger your fish finder is, the higher your energy needs will be. Lithium-ion batteries are known to last up to 10x longer, on average, than lead-acid batteries and are an ideal choice if long-lasting energy is a concern for you.

You can calculate how much energy you will need with the formula below:

Amp-hours of your battery / Amp draw of your fish finder = hours of run time


A small and lightweight battery is crucial for many reasons. Those on a smaller boat will need to be able to move the battery around, and they also cannot have excess weight on their boats, which could significantly slow the boat down or prevent it from navigating more shallow waters. Lithium-ion batteries offer an optimal solution because they are the smallest and lightest batteries available for a fish finder. This is because lithium batteries have a much higher energy density, which allows them to weigh about 1/3 less than a lead-acid battery, while still providing more power as well as longer-lasting energy. The need for a portable and lightweight battery that is smaller is particularly important for those on fishing kayaks or any other small vessels. The greater usable capacity in lithium-ion batteries means that you receive more energy per pound, allowing you to free up crucial space on your boat without sacrificing functionality.


You need to ensure you are looking for a battery that is known to be reliable to avoid any unforeseen occurrences such as being stranded on the water or having to cut your fishing trip short. Lithium batteries are again an ideal choice because they are able to last a long period of time and do not require long charging times, all while being able to be used reliably even after being drained past 50 percent.


While you are on a boat fishing, the last thing that you want is to spend a large portion of your time babysitting the battery. Being able to charge it and then forget about it is ideal, and you need to look for a battery that offers you this peace of mind so that you can concentrate exclusively on fishing and enjoying your time outdoors. Unlike many lead-acid batteries, lithium batteries do not need to be monitored closely or watered. Lithium batteries like RELiON’s marine batteries also come with a battery management system (BMS) to automatically ensure that the battery is protected from overcharging or over-discharging, allowing you to focus far less on your battery needs and more on fishing.

Learn about lithium batteries for your fish finder

Learn More About Lithium Batteries For Your Fish Finder System

The benefits of lithium batteries for anglers are undeniable and as a result, they are increasingly turning to lithium batteries to level up their game. For those in the know, like Bassmaster Elite Pro Angler Matt Arey and Major League Fishing Pro Angler Matt Becker, RELiON has become the go-to choice for their fish finder batteries because they offer reliability, safety, and value that is unmatched. If you are looking for more information about the best fish finder battery or to learn if lithium batteries are right for you, contact us to speak to a RELiON expert today.