What fish finder battery do you need

Have a fish finder to locate underwater schools of fish with reflected sound energy to make fishing even better! You just need a way to reliably power it. If you want the best fish finder battery, you’ve come to the right place. If you’re confused about the type of fish finder battery, we’ve got you covered too!

This article will introduce the different power supplies for fish finders and give you our main recommendations. Our fish finder battery picks are safe, easy to transport, and keep you on the water longer.

How is the fish finder powered

The boat’s power supply powers the fish finder, which connects to the boat’s 12V electrical system and draws power from the boat’s batteries. If you are in a kayak or have a portable fish finder, it will still be battery powered. 

Typically,  fish finder uses 12V lead-acid or lithium batteries. Lead-acid batteries have been the standard for many years, but more and more fish finders use lithium batteries.

Maxworld fish finder

There are two kinds of fish finder batteries that you can buy. That’s lithium batteries and SL A batteries. An SLA battery stands for sealed lead acid batteries. SLA batteries are the older kind of battery.

One battery will typically last about two days on full brightness.

When connecting your fish finder to power, it is important to use separate batteries for the engine generator and the fish finder if possible. The reason for this is that there can be a lot of engine noise interfering with the signal to the fish finder.

Do you need a separate fish finder battery

If you have a boat with an electrical system, it will run both your boat and the fish finder. The built-in marine battery is an important part of the system. However, if you want to go out in a kayak or other boat without an electrical system, you’ll need a separate battery.

In both cases, we think lithium is the best option! Let’s learn about the different types of fish finder battery.

maxworld fish finder battery on boat

What kind of fish finder battery can you use for your fish finder

You can use any 12V marine battery to power your fish finder, but as mentioned above, we prefer Li-Ion batteries. However, let’s take a look at the two battery types so you can decide for yourself.

Sealed lead acid

Sealed lead-acid marine batteries are available in lead, lead dioxide, sulfuric acid, lead sulfate and aqueous solutions. These deep cycle batteries are standard on most boats and vehicles. They have a lower upfront cost, but don’t last as long as other battery options (3-5 years with little maintenance).

Sealed lead-acid batteries are heavy, can only be discharged to 50% without damaging the battery, and last about 10 times as long as lithium batteries.

Lithium Battery

Lithium marine batteries are rechargeable batteries that use lithium phosphate ions as a power source and do not involve liquids or acids. So these batteries are lighter and you can install them anywhere. They have become popular in the aerospace and military sectors as well as in the consumer industry. For example, lithium-ion batteries are in your laptops and cell phones.

One of the advantages of lithium-ion marine batteries is that they have a lifespan of between 10 and 15 years.

Why are lithium batteries the best choice for fish finders

Lithium batteries are the clear winner when it comes to powering any deep cycle application, including fish finders. Here are some of the main benefits of using lithium fish finder batteries.


Lithium-ion marine batteries are extremely lightweight; in fact, most weigh only 50% the mass of their lead-acid counterparts. These batteries are easy to get to and from your boat, and you can even use them in a kayak to power your trolling motor outside of your fish finder.


Lithium batteries are safe and reliable. To illustrate this fact, let’s compare them to lead-acid batteries, which should not discharge more than 50% of the battery’s capacity. Doing so will damage the battery, and after a few times like this, your battery will be completely dead.

However, when you use a lithium battery for your fish finder, it can be discharged to 20% of its capacity without damage. Most Li-Ion batteries have a failsafe switch that registers the battery as dead once it reaches 20% capacity, so you don’t have to risk damaging it. So in a sense, you can drain it to 100% without worrying about it.

Fast charging

Lithium-ion batteries can be charged four times faster than lead-acid batteries at the same charging current. This is because lithium batteries accept charging better. They have low internal resistance and charge at higher currents. Because they have low internal resistance and charge at higher currents, they are able to accept all the energy during a charge cycle, effectively charging much faster than lead-acid batteries.

How long will the fish finder battery last

If you’re using a lead acid battery in your fishfinder, you may need to replace the battery within one to five years, depending on usage.

Lead-acid batteries typically last 500 to 1,200 charge/discharge cycles. If these batteries are discharged to more than 50% of their capacity or exposed to extreme temperatures, their lifespan will be shortened.

However, as mentioned earlier, lithium-ion batteries last 10 times longer than lead-acid batteries. They can go from 3,000 to 5,000 charge/discharge cycles. Also, compared to lead-acid batteries, lithium batteries are less susceptible to damage, shortening their lifespan. For example, you don’t have to worry about over-discharging lithium batteries.

Maxworld fish finder battery

Conclusion: Choose Lithium Battery for your fish finder battery

When weighing the choice between traditional lead-acid batteries and lithium fish finder battery, marine lithium batteries seem like a no-brainer.

They are lighter, last 10 times longer, use more frequently and are more efficient. You’ll get your money’s worth over time, and you’ll love the product’s solid functionality and reliability.

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