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This week's Feature Blog

Powering HD Sonar, GPS & Video Units

Just about everyone who has used a high definition sonar/GPS unit or the newer underwater video machines has come to the conclusion these fishing tools are invaluable for finding fish, structure and fish holding cover. The problem with these units is they pull a lot of amp power and if you’re not prepared dead batteries are going to be the norm of the day!


In my boats I rig two cranking batteries wired in parallel (positive to positive and negative to negative) to double the amp hours and keep the voltage at 12 volts. Typically I use two 27 group batteries with the one being connected to the outboard a cranking battery and the one powering accessories a deep cycle model.

Not only do large screen sonar units require a lot of power to operate, even when switched off they have a static amp draw that can ruin a battery if not managed properly.

If there isn’t room in your boat for two batteries, I opt for one 31 group CCA model. The extra amp hours virtually guarantees that I will have power not only to start my boat, but to power all my high end electronics.

Most anglers don’t realize that electronics are creating a static draw on the batteries even when the units are shut off. Over time, this modest draw will cause the batteries to fail.

It’s also important to note that the engine alternator is not able to keep both of these batteries fully charged. To compensate I wire into my boat a 10 amp two bank charging unit. After each day of fishing, I plug in this charger to maintain the batteries at full strength. Deep cycle batteries used to power the electric motor are given a similar treatment.


For ice fishing it simply isn’t practical to lug around a heavy 12 volt battery. The lead acid batteries sold with ice fishing machines and ice fishing kits are barely adequate for the job. Most of these are 7 or 8 amp hour batteries which will not power a high definition sonar unit for more than a few hours.

The lead acid batteries that are sold with portable sonar and video units are barely adequate for the job. Investing in 10 amp hour lithium batteries is the best way to enjoy hours of fishing fun on the ice.

I recommend using a lithium battery that has 9 or 10 amp hours of life for ice fishing applications. My experience with these batteries is they will last a full day so long as they are fully charged. Lithium batteries require special chargers. They are also expensive compared to lead acid batteries. The ones I am using are produced by Dakota Battery and are available in a 7 amp or 10 amp version. The 10 amp version costs about $100.00 and they are worth every penny.


For fly-in fishing trips I’m using the same high end sonar I typically use in my boats, but smaller units mounted portable in a Lowrance “ice bag”. Again I recommend using lithium batteries for this work. Normal lead acid batteries simply won’t cut it for more than about six hours of fishing.

I pack two lithium batteries with me on fly-in trips. While I am using one of the lithium batteries the other is being charged. The larger 10 amp hour versions are the best option for delivering maximum power for long days on the water.


The latest generation of HD sonar units that GPS, sonar and video options require a huge amount of power to operate. Ordinary batteries aren’t going to cut it when it comes to keeping these units running properly. In a word the answer is “lithium”, but these batteries aren’t cheap. In time the price of lithium batteries will come down and their amp hour ratings will go up. In the meantime, bite the bullet and fish on.

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