Relocating battery?

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Joined: 24 Apr 2017, 10:52

Relocating battery?

Post by zuren »

Hi All,

I'm looking to redistribute weight in my 1974 Smokercraft fishing boat with a 9.9hp 2-stroke Merc. With me (175 lbs.), a gas can, a transom mount trolling motor, a Group 24 battery, and any gear either all in the stern or very close to it, it struggles to get out of the hole and up on plane. I have the height and tilt of the engine adjusted correctly to the hull.

Of the various options to improve performance, I think the easiest approach is to redistribute weight and move the battery forward (please correct me if I'm wrong). Other options I've flirted with are getting the gas can forward, and install a hydrofoil on the motor. I looked into the triangular gas tanks for the bow and off-the-shelf options are too big for my bow well; I'm sure I could have something custom made, but that would be pricey and the battery is much heavier than a couple gallons of gas. So I'm looking closer at the battery.

I do not have a great way to route wires from the bow to the stern. My boat has a floor riveted in, so I can't easily lift the floor. Along the gunwales and sides of the hull are not great options as there is nowhere to tuck 6 ga. wire out of sight or harms way.

Between the hull and floor, there is a drain tube that runs from the bow well and to the "bilge" area in the stern (see the pic with the white stuff in the hole; mice were helping me with my floatation). This is a 1"+ diameter tube. There is a similar hole in the stern. I'm assuming the design is for when a wet anchor is lifted into the bow, any water drains to the stern. It is mostly dry, completely protected from boat occupants, and can easily access the openings at each end. The only thing I do not love is running electrical wires where water is intended to be, but the ends will be above any bilge water. If water gets to those ends, I have bigger issues. The wires would be fished through that tube and connected to remote battery terminals at the stern of the boat.

What are everyone's opinions on this plan?

The next part will be securing the battery better. In the pics, the 2 front corners of the battery are resting against the hull and back, top edge leaning against that front bench seat. I need to fiddle with it to see if I can get it under that bench and on platform.

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1974 14' Smokercraft w/ 1986 Mercury 9.9HP 2-stroke
Project: Old Mirro for the pond
Location: SE Michigan

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Relocating battery?

Post by DaleH »

Can you? Sure. Would I do it that way? Nope ... but admittedly that's just my personal bias.

I personally would punch (holesaw) a ~2" hole through each seat bulkhead and insert a length of PVC through each seat, where an end of 1 tube sharpened to an edge (on the OD, by filing off the ID) would cut through any foam by rotating the tube, even cutting 'saw type' teeth in the plastic), then routing the cables through that.

Regardless, make sure to check the ampacity for the total length of the run (going BOTH ways) and buy your cables sized correctly. Most trolling motor companies have charts to tell you what size cable to use depending on the amps and run length.

IMHO they work awesome on a small boat and if setup correctly, i.e., the motor height, don't rob you of any speed, if much at all. I now prefer the 'gull-wing shaped' fins of the foil by Attwood, $25, as the ends are out of the water whilst up on plane. RichG here runs 'smart tabs' and likes them too.

Attwood Foil.jpg
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Joined: 22 Feb 2010, 21:35
Location: Snohomish, WA

Relocating battery?

Post by clarkbre »

The battery up in the bow will distribute weight very evenly. To secure it, use a piece of 1 1/2" or 2" angled aluminum mounted low on the front seat. This will support the battery towards the rear and the front corners can sit on the hull. Also, use a battery box strap to secure it from moving around. I've had this set up in my boat for over 10 years with no ill effects.

For transferring power from the battery to the rear of the boat, the PVC conduit idea is cheap, effective and protective. As said above, use a good size diameter. I think mine is 1" inside diameter and it allows for heavy gauge wire to carry the amperage for the trolling motor. There is also 2 more smaller circuits running to a switch panel for the depth sounder, bilge pump and 12v outlet.

For the fuel, I used a 3 gallon fuel cell that is narrower than the middle seat is wide. Using a piano hinge and the original seat material, I whittled out just enough foam to fit the fuel cell and used the seat material to make a hatch. Having the battery and fuel cell tucked away and the weight distributed evenly throughout the boat was a game changer.

Here are pics of what I'm talking about:
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2000 Lund WC16, 1997 Suzuki DT15C
Boat modification thread: ... 61#p141161

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Joined: 07 Aug 2019, 20:53

Relocating battery?

Post by coosa »

You have already gotten good advice on moving the battery and putting it in a secured box. I did something similar years ago on a 14' flat bottom with a 9.9 Evinrude on it and moving the battery to the front definitely improved performance. Of course, it still didn't go very fast, but it got on a plane quicker and didn't porpoise as bad.

Personally, I would buy a high quality cable and feed it through that drain that you already have in the boat. It's not like it is normally full of water; it's just gonna occasionally drain whatever gets into the front. I would let at least a foot of the cable turn up before pulling the wires out of it and then seal around the ends so that water could not get inside the cable. Good luck with which ever route you choose.