How To Choose The Right Fish Finder Battery? Expert’s Opinion

How To Choose The Right Fish Finder Battery

When it comes to investing in a good fish finder we all know how expensive that is and this is why you must know about the necessary aspects related to every apparatus of a fish finder. Here is an expert’s opinion on How To Choose The Right Fish Finder Battery? A fish finder’s battery is an undeniable asset because it’s not only for fish finders but it is capable of powering several other equipments. It can also run for quite a long time if maintained properly. The things to look for when it comes to a fish finder’s battery are:

  1. Construction of the battery
  2. Battery power
  3. Size of the battery
  4. Weight of the battery

The former are the main things to look for in a fish finder’s battery when it comes to a marine environment.

How To Choose The Right Fish Finder Battery

Construction of the battery

When it comes to a fish finder’s battery there are two main types that work marvelously in marine environments. Though other types of batteries exist, they are not usually recommended due to environmental concerns. Most of them are not sealed and do not have the ability to tackle the harsh saline water of the ocean. Due to their different orientations and constant motion, they are not the most suggested options, and not the best choice.

Sealed Lead Acid Battery (SLA):

These batteries are dedicated to working in the deep water because no matter what way they are oriented they work well in the deep marine environment. These special batteries are sealed and hence they are leakproof. The major disadvantage of such batteries is that they are very heavy. However, as they are easily available, cheap, and can be operated at multiple temperatures, the angler does not mind their weight. It is also crucial for such batteries not to be discharged more than eighty percent or the battery’s life will be damaged. These batteries are also known as Absorbed Glass Matt batteries or AGM batteries. These batteries are quite different from the standard lead acid-flooded batteries and cannot be used on a bot or a kayak.

Lithium Batteries (LifePo4):

In my opinion, these batteries are the best in the business and are the most efficient when it comes to powering up your fish finders. As compared to other batteries, these are smaller in size, lightweight, and pretty compact which makes them easy to use and install. Also, these batteries are capable of discharging a hundred percent without suffering from any battery health and life issues. Hence it provides a relatively stable current for the electronic equipment attached to it. The only con when it comes to this battery is its price because it’s pretty expensive. But if money is not a problem for you then this is one of the best batteries you can get your hands on for your kayak or fish finder.

Power of the Battery

I usually go for the batteries when it comes to testing them for 12V and 10 AH (ampere-hours). The reason for choosing this power range is that this voltage is excellent to test and compare them for a full day of empowering the fish finder and other electronic equipment. As this power voltage works great, I would always recommend investing in a battery with this amp hour rating. If you want to get an estimate of how long your battery will last then you have to do some basic math regarding the amp hours and current draw.

For that you have to focus on the following factors:

  1. What is the current draw from your fish finder? You will find this figure mentioned in the specifications given by the manufacturer and it’s usually around 1A or even less.
  2. You also need to determine how many amp hours your 12V battery can operate, this is also mentioned on the side of the specifications.

Once you have the above numbers, you can do this simple calculation to estimate your battery’s life:

Amp hours of the battery / Amp Draw of the fish finder = Total hours of the run time OR Battery Life

Battery size and its weight

The size and weight of the battery is an important considerations particularly when you have to operate it on a kayak or a small boat. Because on such boats every added ounce of weight can cause the boat to spill. Lithium batteries are the most lightweight and compact batteries and hence are excellent for such small ventures, but they do come with a heavy price tag. However, you can’t have a battery weighing more than 6lbs on your kayak so you have to narrow down your options. Also, keep in mind fishing is not a cheap sport, so if you aim to come into this industry, always make sure to keep a nice amount of savings.

Similarly, size is also a necessary factor while fishing on kayaks. As these boats have limited space available and have small hatches, you can’t handle a huge battery along with your fishing gear in such a confined space. When it comes to finding a battery for your kayak always go for “small”, and “light.”

Does the fish finder drain the battery?

Generally, Fish finders are not very heavy equipment and thereby they do not put much effort into the battery and hence do not drain them. However, if you are someone who loves to fish all day long then you may suffer from battery drainage. To cope that the anglers can get a solar panel to share the load with the battery. I usually prefer to keep some jumper cables in my bag pack in case I need them. Read more about How To Wire Fish Finder To Fuse Box.

Most fish finders run on 2 amp hours, and hence you can run it for fifty hours. Most of the trolling motors use One ampere per pound when operating at their maximum power. So if you operate a fifty-pound motor (thrust) at its maximum speed and power for up to two hours your battery would be dead in no time.

What size battery is needed for a fish finder?

For traditional and typical fish finders, most of the anglers prefer a battery of 12V and 10 ampere per hour. As it is evident that the storm would have a voltage of twelve which means you can operate it for ten hours pretty nicely at that voltage. The ampere-hours determine the longevity of your battery and in other words battery life. The more ampere-hours, the more highly the battery will sustain for a more extended period.

My suggestions for your fish finder’s battery setup depend on batteries as per their usage:

  • For a bow motor or an electric outboard, there must be a separate battery.
  • A spare battery for other electronic equipment.
  • For initiating your outboard engine, you also require another battery.

For each of the above categories, the battery specification matters a lot. These include current, Speed of discharge, etc. For operating your outboard engine, it will require a short burst of current but at peak, like 300 Ampere. On the other hand, your sounder will require a steady continuous current flow of less than 5 Ampere if you want to last it for a whole fishing day. The trolling engine at your boat will need a steady-moderate current discharge of 50 Ampere.

How long will a battery run a fish finder?

The timing of a fish finder’s battery is primarily determined by its size which you are using currently for empowering your fish finder. However, the most commonly used batteries by anglers are Lithium-ion (LiPo4) ones. Let’s say if you have one of the Lithium-ion batteries of 12 Ampere per hour, that battery is capable of running a fish finder for twenty to twenty-four hours continuously.

However, as fish finder’s batteries are expensive, and if you are a little low on budget and are using a lithium-ion battery of 7 Ampere per hour, they can still operate pretty well for five-seven hours. These batteries also work efficiently and can run your fish finders smoothly without the fear of discharging and poor battery health. However, you should never forget to keep the battery charger, just to be on the safe side.

Can you wire a fish finder directly to the battery?

Yes! You can definitely wire a fish finder directly to the battery. First, you have to place your battery into a full protective waterproof box, and then you can connect your device to the battery. For safety purposes, the fish finder’s battery is usually placed at the rear end of the boat, and therefore to connect it with the device you will need extended power cables to connect both.

Connect both of the power cables together using a soldering iron and then tape them. Now after cutting and joining they are long enough to be connected with the battery and the fish finder, no matter how far they are from each other. Now you can easily use your fish finder and locate fish from any direction from your boat.

Do all fish finders need a battery?

Yes! All of the fish finders require batteries in order to operate even the portable ones which are not mounted on the boat usually. Most anglers prefer batteries with twelve and twenty-four volts, which is more than sufficient to operate fish finders operating on kayaks and small boats. While purchasing a fish finder’s battery you should look for its voltage and ampere-hours, so that you can choose wisely depending on your conditions. For your certain fish finder, you can also calculate the amp capacity by calculating how many amperes current your fish finder uses in an hour.

Can you run a fish finder and trolling motor on the same battery?

It is not impossible but not recommended. Though you can run fish finders and trolling motors on the same battery but then you must be prepared for a common issue that comes with this and that is “Interference.” As most of the time fish finders and trolling motors operate at the same frequency electromagnetic disruptions can occur risking your fish finder’s readings.

In addition to interference with the frequency, you will also suffer from screen interference, and that is why you should never wire your trolling motor and the fish finder to the same battery. Additionally, you should not run your trolling motor and other equipment with your battery. If you do this your battery will have to recharge.

What kind of charger does a lithium-ion battery use?

For all batteries and especially lithium-ion ones, chargers are essential components. As their life and performance depend greatly on the charging, if not done right your battery health can suffer a lot. In addition, unlike other batteries, lithium-ion batteries do not charge with average charging devices such as those available for Nickel-Cadmium batteries (NiCd), and Sealed lead-acid batteries (SLA). The lithium-ion batteries use LifePo4 compatible chargers only and should be of 10-ampere minimum.

How many watts a fish finder will use?

It depends majorly on your fish finder, as they consume different amounts of electrical current. Normally, traditional fish finders consume 400-500 watts RMS, and peak-to-peak ranges from 2400-3200 watts. If you are an angler who loves to fish in blue waters then you must look for fish finders with more than 1000 watts of power.


When it comes to fish finder batteries one has to look into a lot of factors like their size, power, voltage, and several other things. It is highly recommended to understand your fish finder and then take a wise decision about your battery. If you own a small boat or a kayak then you necessarily go for lightweight Lithium-ion batteries so that you can easily place your device and battery and still have enough space to operate the display screen of your fish finder.

For larger boats, one can go for mounted-hull batteries that are high in power but are also expensive and huge in size. Also, when it comes to connecting the battery, always do a little research about all the power cables and how to connect them in order to avoid any misadventures.

Ricki Cooper

I have been fishing for 11 years. I believe in the famous saying "If fishing is interfering with your business, give up your business".

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