Multiple sonar/gps systems now create huge current draw from 12-volt systems, requiring special energy sources to avoid short term drainage.

Frank Sargeant
Frankmako1@gmail.com

If you run a big screen sonar/gps on a bass, walleye, crappie or saltwater flats boat, chances are you’ve seen the dreaded “Low Battery” warning on screen way more often than you’d expect. Add multiple baitwell pumps, spreader lights, electric reels and other accessories and the need for a whole lot of juice is obvious.

But the monster screens—now up to five on a single boat, typically 12” models in bass and walleye fishing, 16” or larger on saltwater boats—suck power at an incredible rate, leading engineers to seek all sorts of solutions.

Norsk now offers a combination battery designed to separate power for a 36-volt trolling motor and a high-draw sonar, all in a single compact case.

More Power from Outboards

If you run a recent model V8/V10/V12 350-hp and up outboard, it will have an alternator that puts out enough charge to light up the New Year’s Ball in New York City, and this largely solves the problem so long as you occasionally start the engine.

The big outboards put out what would have been unthinkable in terms of charging current a few years back.

Mercury’s new 350 and 400 hp V-10’s and the awesome 600-hp V12 will deliver 150 amps of charging power at 1,500 rpm, more than twice that of the older 2.6-­liter inline-­sixes from the company.

Yamaha’s largest motor the XTO Offshore 450, produces up to 96 net amps per engine (at 12 volts)

Suzuki’s largest, the DF 350 produces 80 percent of its 54-amp (at 12 volts) maximum output at 1,000 rpm.

Mercury even offers an extra cost option of a 48 volt alternator on their V-10 and V-12 outboards, designed to work with Navico’s Fathom ­e-power system to blast out so much current that big saltwater boats can do away with a separate generator while still running air conditioning and other high-draw equipment.

Note that all of these motors do the job at low rpm—trolling speed or just over idle speed, so you don’t have to rev up to recharge the battery banks. Smart charging systems direct the current first to the starting batteries—so you won’t get stranded out there—and then to the “house” or auxiliary batteries.

Trolling motors are growing ever more powerful, and also require high-output batteries to endure a full day of fishing.

What About Older Outboards?

But most of us do not have new outboards—we have outboards that were around when Obama was still a Senator from Illinois.

That’s why you may be only half way through your fishing day when all your fish-finding power goes blank.

On smaller boats where the 12-volt starting battery is also the sonar/gps battery, you may not be able to start the outboard when it’s time to go home.

A few lithium battery providers are answering the call this year. Norsk Lithium recently introduced a new line of 36+28V 60Ah batteries, which features two sets of independent terminals, offering dual voltage functionality within a single battery.

From one set you get 36-volt power for a big trolling motor. From the other, you get 28V of clean, interference-free power to the sonar module. And, the company says, this setup does the job without complicated wiring, regulators, or shut-off switches.

This is a “smart battery” with a battery management system that tracks the last time power was drawn from the 28V terminals, and if there’s no draw in 60 minutes, the terminals shut off. They automatically “wake up” if a sonar module turns on. The result is all-day power.

As you’d expect, this is not a cheap battery, but it’s no-where near the most expensive in the pricey lithium world. The heated version, for northern climes, is $1399, the non-heated model $1299. As with all lithium batteries they are considerably lighter than comparable lead-acid models, promising better boat performance particularly where several batteries are used.

There’s no truly inexpensive way to run all the electronics many of us have on our boats today, but as they say, good whiskey costs money—you have to pay to play in the end.

See details on the Norsk setup here: https://norsklithium.com.

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Battery Type: Lithium Iron Phosphate (LiFePo4)
Nominal Voltage: 38.4V
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Size: 13 X 6.81 X 9.25 inches
Lifespan: 4,000+ Cycles, Est. 15-20 years
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MAP $1,299.00