This Instructable will tell you how to convert abandoned common Fish Aggregating Devices (FADs) to create rugged solar-charged 12V power supplies and lamps that can provide light for an entire night.

FADs play a key role in indiscriminate, unsustainable fishing practices in the seafood industry. Every year, thousands of these marine snares are deployed in the world’s oceans, attracting any and all types of fish.

Many have sophisticated beacons with satellite, temperature or sonar sensors that tell fishing companies and ships where they are and exactly how many fish have gathered underneath. But it’s not just tuna: all sorts of ocean life swarm around FADs, only to be scooped up by these fishing vessels, who pick out the tuna and dump everything else – the bycatch – back in the sea, dead. It means many times more unsaleable species are killed.

Thousands of these FADs are deployed each year in the world's oceans and many are lost, ending up on shorelines, where they pollute coastal environments or snag on coral reefs. For the enterprising hobbyist, the components of the beacons on these devices can be upcycled to provide shade, light and electricity. This Instructable explains how to do this with one of the most common models found (M3i or M4i).


· Marine Instruments M3i or M4i beacon

· Flat screwdriver

· Phillips screwdriver

· Side cutters

· 2 x 7mm socket / wrench / shifting spanner

· Hacksaw

· Soldering iron

· Solder

· Paperclip or piece of wire

· Permanent marker

Step 1: Open Up the Housing


The circuit is live when you open the unit up, so avoid touching any of the electronics. Even after the battery is disconnected there are still some large capacitors that store lots of energy. Be extremely careful with the batteries: do not put them on a metal surface or allow them to short circuit. There is a fire hazard.

Step 1 - Remove translucent dome and the black gasket.

There are 20 x 7mm bolts around the edge of the beacon. Each one has two washers, one stainless steel nut, and one copper nut. (Pic 1)

When removing the dome, take care to keep the rubber gasket in place so it's easier to replace later. There should be some grease on the gasket to help maintain a waterproof seal. (Pic 2)

Step 2 - Unplug the solar panel and remove the screws.

Carefully disconnect the solar panel's wire from its socket. Push the small white tab to release it. (Pic 3)

There are five screws along the perimeter of the while plastic plate - you can easily distinguish them, because they don't have lock washers. Remove the screws and carefully tilt up the white plastic plate. (Pic 4)

Underneath you’ll see the electronics – be careful not to strain any of the connected wires. (Pic 5)

Step 3 - Unplug all the cables.

(Pic 6, 7, 8)

Step 4 - Remove the screws from the wooden cover.

Remove the screws from the wooden cover that holds the battery assembly in place, and pull out the battery assembly from the bottom of the buoy. (Pic 9, 10)

Step 2: Extracting the Batteries

Step 5 - Break open the battery assembly and remove the rechargeable NiCd batteries.

The battery assembly contains rechargeable (white) NiCd batteries at the top, and D-cell alkaline batteries along the bottom. For this Instructable we will be using the NiCd batteries. (The D-cell batteries should be in good condition, so you can use them in anything else you might need them for.

Wedge the flat screwdriver into the wood to lever off the part covering the rechargeable NiCd batteries. (Pic 1)

The NiCd batteries are attached to the wood using silicon adhesive. They have very fragile electrical contacts, so be careful when you peel them off. (Pic 2)

Step 6 - Cut the wires from the D-cell batteries.

Use the side cutters to cut the two wires coming from the D-cell battery pack. Cut the wires as close as possible to the batteries - we will be using these wires later. (Pic 3)

Step 7 - Cut the wires off from the bottom of the housing.

There are two wires at the bottom of the unit - one from the transducer, and one from the temperature probe: cut both off. We will be using the red and yellow one. (Pic 4)

You should now connect the battery pack and three wires. (Pic 5)

Step 3: Modifying the Circuit Board

Step 8 - Remove the electronics from the white plate.

We have to remove the electronics from the bottom of the white plastic plate by removing all the screws with lock washers.

Sometimes when you turn the screws, the brass cylindrical standoffs between the electronics and the plastic will turn too. You may have to use a shifting spanner or a second screwdriver to allow you to loosen the screw. (Pic 1)

You should now have the items pictured. (Pic 2)

Step 9 – Cut the circuit board.

We will be cutting two parts out of the electronics:

1. The charging circuit (around the white plug)

2. The LED lights.

Mark the area you will cut out with permanent marker. (Pic 3)

Use the hacksaw to cut out the marked area on the circuit board. Be careful to not damage the LEDs of any capacitors while cutting the circuit board. Try to avoid touching any exposed contacts on the circuit board. (Pic 4, 5, 6, 7)

Step 10 - Remove two diodes on the charging circuit.

The diodes are the little black squares on the edge of the circuit next to the white plugs. Use a screwdriver to pop off the ones on the edges. Leave the two diodes in the middle intact.

The diodes are like one-way streets that allow the solar panel to charge the battery, but won't let the battery discharge through the solar panel. (Pic 8, 9)

Step 4: Rewiring

Step 11 - Cut and strip the wires.

Slide the black plastic covers off of the wires. Identify the yellow and red wire bundle (Pic 1) and cut 2 x 3cm-long segments from the red wire. Strip the ends off the wires. (Pic 1, 2, 3)

Step 12 - Tin the ends of the wires using the soldering iron.

You may find this Instructable useful for this step. (Pic 4)

Step 13 - Solder two pins together on the charging circuit.

You need to connect the positive pin of the battery connector to the positive pins on the sockets on each side. This will create two 12v sockets that we can use to power the light and any accessories.

The entire circuit board is covered in silicon spray so you may need to heat the contacts up a bit before the solder will make good contact. Pic 5, 6)

Step 14 - Prepare the wires for the switch.

Cut the yellow wire off close the connector. Cut the cable in half. Strip a short length off one end of each cable and a large amount off the other end. (Pic 7, 8, 9)

Step 15 - Solder the yellow wires into the power cable for the LEDs.

Take the black and red power cable and strip the ends; cut the red wire in half and strip the ends you just cut. Twist the short end of each yellow wire onto each red wire. Solder them together. Insulate them with some tape. (Pic 10, 11, 12, 13, 14)

Step 16 - Locate the power connectors for the LEDs.

This is perhaps the trickiest step in the process. If you look carefully at the back of the circuit board that the LEDs are mounted on, you'll see three small 'pads' with a little bit of solder on them.

There are two round ones (negative - that's where the black cable will go). There is one square one (positive - that's where the red cable will go). (Pic 15, 16 - connectors highlighted)

Step 17 - Solder the power cables onto the LED circuit board.

The red wire will need to be soldered onto the small square pad. The black wire can go onto either of the round pads, but the furthest is probably easier.

One you are finished, put the LED circuit with its freshly soldered wires aside. (Pic 17, 18)

Step 18 - Prepare the 12v auxiliary power cable.

Take the other black and red power cable, and strip 3-4cm off the ends of each wire. Put some temporary insulation tape over one of the ends to prevent a short circuit. (Pic 19, 20)

[Picture MYEZ_WR-5683]

[Pictures MYEZ_WR-5686]

Step 5: Assembly

Step 19 - Prepare and install the battery pack and fuse.

Be careful to not touch any of the electrical terminals. The battery pack is very fragile, so be very gentle while handling it.

Place the NiCd batteries on the piece of wood as pictured. Use some tape to secure it to the wood. Install it into the housing of the lamp. (Pic 1, 2, 3)

Now you need to add a simple handmade fuse. A fuse is a safety device to switch the power off in case of an accidental short circuit, to prevent possible fire due to batteries overheating.

Screw two screws into the wood, next to the battery pack, approximately 2cm apart. Take the red wire from the battery, cut it in half and screw the ends around the screws. Take a single thin strand of copper wire from one of the leftover wires and use it to connect the two screws. (Pic 4)

If there's an accidental short circuit, the large current flowing through the circuit will quickly burn down this strand of copper, which can be replaced after determining the cause of the problem.

Step 20 - Mount the LEDs.

Install one of the brass standoffs as shown. Screw the LED circuit into it. Feed the wires through the square hole. Plug the wire into the charging circuit. Feed the yellow wires through one of the holes on the edge. (Pic 5, 6, 7, 8, 9)

Step 21 - Plug the 12v wire into the other socket.

Plug the other black and red wire into the other socket on the charging circuit. Run the wires to the other side of the white plate. (Pic 10)

Step 22 - Connect the battery.

Plug the battery socket into the charging circuit. It goes between the LED and auxiliary power wire. (Pic 11)

Step 23 - Install the whole assembly back into the housing.

In it goes. (Pic 12, 13)

Step 6: Finishing Up

Step 24 - Wire up the 12v aux power terminals.

These optional 12v power terminals can be used to power other things, such as car accessories to charge mobile phones or run laptops. You will probably have to make some modifications, for example cutting off the wires going to the cigarette lighter plug and connecting these (check the polarity!) to the terminals.

We will use an upside-down bolt as the battery terminal. Insert one of the bolts from bottom to top. Put one washer on. Twist the black wire around the bolt and put another washer on top.

Remove the insulation from the red wire, and repeat the process with another bolt next to it. (Pic, 1, 2, 3)

Almost done! We're going to do the same thing as above with the two yellow wires. (Pic 4)

Step 25 – Replace the transparent dome.

Carefully replace the transparent dome and rubber seal, taking care to line up the holes with the battery terminals.

Step 26 - Complete the 12v aux power terminals.

The terminals consist of a nut followed by two washers, followed by a nut. (Pic 5)

Step 27 - Make the light switch.

In order to make the light switch, bolt the paperclip onto one of the terminals.

The other terminal will have a washer between two nuts so that the paperclip can easily hook onto it. All you need to do now is hook the paperclip to the other terminal to switch the light on! (Pic 6, 7, 8)

Step 28 (optional) - Replace all the other bolts.

You can replace all the bolts along the edge of the housing to improve the unit’s waterproofing.

Step 29 (optional) - Modify for ambient light.

You can sand down the dome to give softer, more ambient light. When you want more direct light, you can flip it over.

<p>this is brilliant, nice bit of repurposing something destructive into a useful item. very cool</p>
<p>I never heard of these before, but now I want to go find some to mod them like you did :)</p>
<p>Thanks Lorddrake - and good luck!</p>
<p>Where do you find these things? I live in Southern California and never have seen anything like this wash up on the beach.</p>
<p>Hi buirv, FADs are deployed all over the world's oceans, but they're especially abundant in the Indian and Pacific Oceans. I'm glad they're not littering the coastline where you are (although just because you haven't seen them doesn't mean they're not helping fill your local supermarket's tuna cans out at sea).</p>
<p>That is a really cool solar lamp. I love the fact that you found a way to reuse old marine lights.</p>

About This Instructable




Bio: Working as radio operator on Greenpeace ships, also a budding radio amateur back home in Panama, HP1-MIR
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