SLA or LFP Accessory Battery for your Kayak

In a short period of time Fishing kayaks in most cases a single user vessel have begun using many of the electronics that power boats use. Portable power has become a necessity. Running Fish Finders on a battery pack of AA batteries is a thing of the past. In the present we have Fish Finder/Chart Plotter combos, kayak lighting, and  the ability to charge battery powered devices while away from home is important.

Previously we built a waterproof battery box for a fish-finder/chart plotter. Since then there have been many advancements in batteries. This article explains the difference between the traditional Sealed Lead Acid Battery (SLA) and the latest Lithium-iron-phosphate battery (LFP). Here I list the pros and cons of both. You make the decision!

A SLA battery

SLA Battery Pros:

• Inexpensive (Economically Friendly)
• Fully Sealed Package
• Rechargeable
• Recyclable

SLA Battery Cons:

• Poor weight-to-energy (8 lbs 12aH)
• Cannot be stored in a discharged condition
• Inconstant discharge voltage
• Limited number of full discharge cycles
• Lifespan (300 charge cycles)
• Sulfation
• Memory
• Not Environmentally Friendly
• Contains Lead

There are many cons to the SLA battery for use on a kayak the first being weight. The 12aH SLA will weigh in at 8 lbs. That’s a lot of weight to travel with on any kayak. Battery life is another issue you may get a season or two total out of the lifespan.

New and improved Lithium-iron-phosphate batteries (LiFePO4 or LFP) are slowly replacing Traditional SLA batteries. Although still pricey LFP batteries have many advantages over the previous generation technology of SLA’s.

LFP Battery Pros:

• Excellent Weight-to-energy (3.5 lbs 12aH)
• Very constant discharge voltage
• Low Discharge Rate compared to SLA
• Rechargeable
• No Memory (Can Be fully Discharged without cell damage)
• Lifespan (2000+ charge cycles 5-10+ years)
• Recyclable
• Thermal and chemical stable aka Safer (as opposed to Lithium Ion cells)
• No Environmental Thermal concerns (provides maximum output at hot or cold temps)

LiFePO4 Battery Cons:

• Cost (Expensive)
• Contains Phosphates

Looking forward to this conversion. Will report on the experience in the near future.

Installing electronics on a kayak can bring on many challenges. One of the major challenges are how to wire through the kayaks bulkhead and what products are manufactured to cap large drilled holes post wiring the fish finder. This article covers common Types of Hull Pass-Throughs.

After a lot of research here are a few types of hull pass-through caps for wiring electronics on your kayak.

Rubber Stopper 1/4″ – 1.5″ Drill

Commonly used for drain plugs and scupper holes the Rubber stopper can also be used for Thru Hull Wiring. Simply with a sharp box cutter cut a slit from the outer diameter to the center hole. This will allow you to pass the wire into the center of the stopper. Runt he connecting plug through the hole and simply press the stopper in small diameter of the flange first to make a seal. This method works but is not recommended for a permanent install. The stopper over time can come loose so check it every now and then. It wouldn’t hurt to silicone them in.

Cable Gland 1/4″ – 1″ Drill

The cable gland is a wiring connector that is able to match wire diameters with a grommet that seals tightening down a lock nut.

On the bottom of the gland is a threaded portion that is able to pass through a drilled hole in the hull and tightened down with an included ring nut. Cable glands do work great but the only problem i see with them is the protrusion they create. They are easily snagged by fishing line. In areas that fishing line will not snag they are great.

Cable Clam pass through 1″ – 2″ Drill

Cable clams are a good solution but protrude the most. They require 4 large screws holes perfectly aligned. Personally I think they are the most unsightly for applying on a kayak. They are purposed more for boats. They are also the most expensive and hardest to install.

TH Marine CeaCap 3/4″ Drill

The CeaCap is the most flush option but will only work with cable plugs that will pass through a 3/4″ hole. It is threaded and will turn the wire 90 degrees so it is flush with the hull. IT will allow for two 12 gauge wires to pass through.

West Marine Wire Cap 1″  Drill

The best out of them all I have found for large connectors is the West Marine Wire Cap. Fish finder connectors with 1″ diameter will work with this cap to cover the required hole to pass through the wire for both the transducer and the power. You may run two wires at 14 gauge through this cap max and 1 wire at 8 gauge id say max.

Creating a semi-permanent install for multiple kayaks is a challenge. Since most of us fish on a budget two separate fish finder units is not feasible. For about 1/4 the price of a new Lowrance Elite 5 HDI unit you may purchase a new Transducer, Power cable, and the neat Lowrance kayak scupper mount kit. This application is only for sit on top kayaks like the Big Rig with round scupper holes. The mount and this particular transducer as of 2014 other Jackson Kayak Models will not work due to the oval scupper shape and being that the bottom of the supper is simply not wide enough to accept the transducer mounted flush.

In the photo to the left shown is the un-boxed scupper mount and the transducer and cable. This transducer has been a challenge to mount to other kayaks until the Big Rig with its enlarged hull scupper clearance as it is Raymarine ready.

To install simply using the bolt washers mount to the bottom of the scupper mount as you would the transom mount. Once this is completed pull the plug end of the transducer wire from the bottom of the scupper through towards the deck. Once all of the cable is pulled then insert the threaded plastic into the scupper. The transducer should face bolted end/cable to the bow. Then slide the gray fitting down the threaded shaft and tighten the thumb nut all the way down until snug. Once fit you may cut the shaft and place the Lowrance cap on top. Done!!

This is the best way to install any transducer out there. You get accurate temperature readings and a completely better signal for clarity rather than the shoot thru hull option.

I prefer to hide all of my wires and cables within the hull of the kayak. Just less mess less things to snag your hooks on and the best way to protect expensive electronics cables. Due to the 1″ diameter colors on the Lowrance HDI plugs we need to drill a 1″ hole to get these cables inside the hull. Now that’s a huge hole. It took a while to find a part to seal this with for a really clean install. I’m not the type that likes to run cables through hatches. West Marine makes a hull pass through that worked perfectly for this application. I have never seen these used on a kayak before but they are excellent. Low profile watertight and clean!

To start use a 1″ boring drill bit. The hull pass through fitting includes a rubber grommet. I used this as a template placing it exactly where the fitting would be placed. Marked the center with a punch and drilled. See drilled hole to the right. Run sonar plug through and using the thru hull cap press firmly with a screwdriver and screws will self tap. The rubber will push out and this when it is tight. Do not over tighten as the screws will strip out the plastic therefore becoming loose.

Do the same steps for the opposite side but this time with the power wire and the transducer plug through 1 hole. This one bring the sonar plug through the hole first. Then snake through from the outside the power wire. The power wire will be then run to your battery location. Mine will be in the stern. The white wire in the photo runs back to the stern for the battery box hook up. I will splice that into the power wire for the unit.

Along with the standard molded in center Gear Track on the Big Rig and paired with a Ram Mounts Electronic Mount for Lowrance this is an excellent system! There are now multiple places to position the unit. The option to slide forward or back or mount to the side Gear tracks however is most comfortable.

If you have any questions about this install or anything else please leave me a comment.

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