Building a portable power; water resistant; Charging Station; for 2-3 12aH wire parallel batteries:

The intent of this parallel portable power pack is for primitive camping areas. Having the ability to charge devices, power LED lighting and even run a small 12V fan in your tent can keep you very comfortable!

Materials needed:

  • Water Resistant Ammo Case
  • Volt Meter, 12V Receptacle, USB
  • (6) Female Spade Crimp On Connectors
  • (2) 18″ length – 14 AWG Copper stranded wire w/ insulation Red & Black
  • (2) Butt Connectors
  • Fuse Block or Inline Fuse
  • Parallel battery harnesses (previously made here)


  • Wire strippers/crimps
  • Power Drill
  • Heat Gun
  • Hole Saw
  • Screwdrivers

Using an Ammo Crate I purchased from the portable power battery pack can be expanded to run from a total of one to three batteries this size. Using the box creates a water resistant seal for all the electronics. Also adding a latching switch along with a 12V receptacle, USB charging port, and a volt meter.

The combination of the 3 can be purchased on

The ammo crate is not water proof but water resistant. It does however have a gasket in the lid. The primary use of this battery box is for charging things such as phones and other electronics while camping. It will also be set up for Running a 12V oscillating fan on hot tent nights.

For a kayak battery box with parallel batteries I would recommend a smaller box first of all and the PVC style LFP battery packs.

Installing the port plate:

Remove the USB, Volt Meter, and the Cigarette lighter receptacle from the plate. Locate where you would like to mount it. Remember the receptacles will protrude inside the box 3″ also require room for spade connectors to wire them. So install where there  be about 4″ if rear clearance. Score a center line for each hole to be drilled. Using a hole saw drill out the 3 holes. Reinsert the accessories into the plate. Recess them into the box. Silicone the plate (optional) then drill 4 holes for the corner screws.

Wire each accessory to the positive and negative sides. Wire int he switch and your battery box is complete.

Waterproof Kayak Battery Box Mods & Upgrades

batt_box_finishedThis article illustrates how to modify and wire a 12V plug port and a USB receptacle for charging electronic devices such as cell phones and running GoPro’s with out an internal battery for an all day charge. Using the existing waterproof battery box from a previous article we will first replace the 12V 12 aH Sealed Lead Acid (SLA) Battery. See SLA or LFP Accessory Battery for your Kayak write up for the differences in batteries and pros/cons of both. I have opted to now use a LFP battery for its long list of great qualities.

Products & materials you will need.

Battery Box Wiring Diagram

Wiring Diagram 8X11




  • hole ocationsFirst thing you will do is remove the existing battery and all of the wiring in the box. We are going to replace everything inside. Keep the cable gland as it will be reused.
  • Using a hole saw drill match up the diameter to the outside of the hole saw with the two receptacles. Try to keep the holes even and equal distance apart for aesthetic reasons. After drilling the holes trim the excess from the edge of the holes. Set the receptacles and tighten the collar down.
  • Drill a hole using a hole saw that matches the diameter of the switch in your desired location. Make sure the internal protrusion will not interfere with the battery or the 12V receptacles. Install the switch.
  • battery box portsNow we will splice 2 wires together to connect the negative side and the positive sides of the receptacles together. Make one for each RED and BLACK.
  • Connect the spade connectors to the correct terminals on the receptacles + with + and – with -.


  • Using a butt connector connect the RED + wire from the Fish Finder Plug to one inline fuse.
  • Using the 3 Way Female to 2 Male connector connect the Two Inline Fuses to the Male ends and the White 12V Positive from the switch with a male spade to the female end on the 3 way its good to tape this connection with electrical tape or purchase a insulated connector.
  • Connect the Red + wire from the switch using a female spade connector to the battery.
  • battery box wiredConnect the BLACK – wires by crimping on a female spade connector from the 12V receptacles, the 12V Fish Finder connection and the black wire from the switch together. Simply twist the (3) wires together feed into the hole on the connector and crimp using the crimping tool.
  • Then Connect the Female Spade with the (3) black wires to the – Negative side of the battery.


Upon Completion:

Test by pressing the switch to the ON position. The LED Indicator should light up. Test all receptacles and that the fish finder powers up. You now have a portable waterproof kayak battery box with the option to run additional lighting on your kayak, Charge electronics, and run cameras VIA USB power.


This concludes the Kayak Battery Box modifications & Upgrades article. Please leave comments on your thoughts!




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