Thursday 13 May 2021
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Installing a Transferable fish finder for winter pt 3

Powering The Unit

Main Photo

The toughest, and most time consuming,  part of this install was deciding on what to use for a power supply.  I initially wanted to run a Lithium Iron Phosphate battery (LiFePO4) because of how light they are (35ah ~ 4lbs), but at $340 a lighter battery also meant a lighter wallet.  I decided to deal with the weight and purchase a sealed lead acid battery.

The first order of business was to factor the power consumption rate of the HDS unit and Structure Scan, then find a battery capable of handling the load.  The unit’s max power consumption rate is 0.9A at 13VDC and Structure Scan is 0.75 at 13VDC, so as a whole the unit draws 1.65 amps per hour.  To figure out what size battery I needed I worked the equation backwards, looking toward the length of my fishing trips for the answer.  My day trips last 10 – 12 hours on average and I also go on two day trips every now and then.  There are times where I don’t have access to an electrical outlet or don’t have time to fully charge the battery.  I took all of these things into consideration and began looking for the right battery.


The cycle life of a Sealed Lead Acid battery is directly related to the depth of discharge.  Discharging to 50% of a battery’s amperage rating is an ideal range. If your power consumption stays around 50% your battery will last longer than if you drain the battery 80% or greater.


Once you figure out how much time you typically spend on the water and you know how much power your unit requires, you can begin to figure what size battery you need.  I searched the internet for the most common battery sizes and began playing with numbers.  The battery sizes I used were 26 amp, 30 amp, 33 amp, 35 amp, and 40 amp.  I eliminated the 26, 30, and 33 amp batteries by taking 50% of each amp rating and dividing my max power consumption into the number (ie. 26/2 = 13, 13/1.65 = 7.88).  The 26 amp battery would reach 50% after 7.88 hours; much too small for the time I plan to be on the water.  The price more than doubled when I began comparing the 35 amp to the 40 amp battery, so It was either the 33 amp or the 35 amp battery.  Comparing the two, there was only a small increase in price and weight with the larger battery and I could gain a half hour of run time, so I went with the 35ah battery.  Draining 50% of the battery gives me 17.5 amps, which equates to 10.6 hours of use; draining 80% of the battery gives me 28 amps or 16.97 hours of use with every power hungry feature running.  With the majority of my trips being day trips I should be able to easily get 2 years from this battery.



Battery location protects the battery from the environment, wires are ran without cutting large holes into the deck of the kayak, battery disconnects for easy loading/unloading and charging.

Parts Used














The Cuda center hatch can be purchased through your local JK dealer or through the store on this website.


Important Battery Features

  • The majority of SLA batteries on the internet have terminals that extend off the battery.  These batteries aren’t a good idea if you don’t plan on enclosing them in a case of some sort.  The long terminals would be a good place for something metal to touch and cause sparking.
  • Including a waterproof 2 pin quick disconnect keeps with the theme of being able to transfer everything from this system to other kayaks that I may have in the future and also help with removing the battery for charging.
  • The 35ah battery that I chose weighs 24 lbs, so I wanted an easy way to carry it after disconnecting the wiring.  A battery with carrying handles were a must.


The Battery Location


battery11Who really wants to fumble with pliers, worry about attaching the wrong wire to the positive side, or deal with the possibility of loosing the screws that secure the wires? I didn’t, so I opted for a waterproof 2 pin quick disconnect and attached a waterproof inline fuse holder to the positive lead. This allows me to pull the plug and disconnect the wires leading to the unit.  After separating the wires the handles on the battery lift and I can pull the battery out of the Cuda’s center hatch insert. The battery itself was a perfect fit for the hatch. I used the foam that came with the hatch insert to create a divider by roughing up the area where I wanted the divider to sit and adding a good amount of adhesive to the foam.
DSC_0351The  connectors from the transducers that plug into the unit are really large and I didn’t wan to cut huge holes into the walls of the kayak just to pass the connectors through, so I cut a 1/4″ slit into the edge of the center hatch and removed the plastic.
DSC_0352 DSC_0320Once the wires pass through the edge of the center hatch most of the wiring is in the hull of the kayak, just the connectors and the length of wiring needed to reach the unit is fed into the hatch insert.


If I want to remove the transducers I can pull the wires out of the hatch insert, remove the insert, and lift the wiring out of the hull of the kayak.The wiring runs from the center hatch area, under the front of the seat, and finally exiting from the left side of the seat. Running it this way keeps it out of the way when standing.

Charging The Battery

The charging is handled by a charger (NOCO Genius G3500 6V/12V 3.5 Amp Smart Battery Charger and Maintainer) that protects against overcharging and is made to handle an SLA battery.  At 3.5 amps the charger fully charges the battery in 5 hours after a full day trip.  I decided to go with the charger under “parts used” because it provided what I needed as far as charging amps, the safety features, and all the great ratings.