BFE Tech Talk: Do Lithium Batteries Actually Make Your Sonar Clearer?

If you spend enough time around boat ramps or tackle shops, you’ve heard the rumor: "Switch to Lithium batteries and your graph picture will get clearer."

Is this just sales hype, or is there actually science behind it?

We put a Millertech Lithium side-by-side with a standard AGM in the shop to break down exactly what’s happening. The short answer is yes, but it’s not because Lithium has some magical "clarity" dust inside. It’s all about voltage consistency.

Here is the breakdown of why your image quality changes depending on your battery type.

1. The Morning Launch: A Tie Game

When you first launch the boat at 6:00 AM, both batteries are fresh off the charger.

• Lithium: Resting around 13.2+ Volts.

• AGM: Resting around 12.8 Volts.

At this point, your electronics (whether you run Garmin, Humminbird, or Lowrance) are getting plenty of juice. Your image will look crisp, bright, and detailed on both batteries. If you only fish for two hours, you’d never notice a difference.

2. The "After Lunch" Slump

This is where the AGM starts to lose the fight.

Lead-acid and AGM batteries suffer from significant voltage drop as they discharge. By Hour 4 or 6 of your fishing day, that AGM is likely dipping below 12 Volts under load.

Why does this matter? Modern fish finders are essentially high-performance computers. When the input voltage drops below that 12V threshold, the unit struggles. You’ll notice:

• The screen brightness dims.

• The sonar return gets "weaker" or grainier.

• You lose that sharp target separation.

Basically, as your AGM gets tired, your picture deteriorates.

3. The Lithium Advantage: The Flat Line

This is why the pros and the hard-core grinders run Lithium.

A Lithium (LiFePO4) battery has a flat discharge curve. That means it maintains a steady 13.0V - 13.2V for almost its entire capacity.

You can be at Hour 10, 12, or even 16 of a long tournament day, and that battery is still feeding your units over 13 Volts. Your LiveScope or 360 imaging will look exactly the same at sunset as it did at sunrise.

The Verdict

If you are a casual angler who goes out for a few hours on Saturday morning, a good AGM is fine.

But if you are a grinder—someone who spends 8+ hours on the water, fishing tournaments, or scanning deep structures all day—Lithium isn't just about weight savings. It’s about keeping your eyes underwater sharp when it matters most (usually late in the day when the big ones bite).

Ready to stop the voltage sag? Check out our selection of Marine Lithium batteries in the shop. If you have questions on rigging or sizing your AH (Amp Hours) for your specific setup, give us a shout

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