12V Fan Switch

Recently a fan was installed to cool the solar components, like controller, battery charger, etc. As it is not necessary to run the fan continuously, a switch can regulate its use.

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Radio Shack sells this 12V switch with a ground (+), a power (-) and a accessory spade.

Right now there is a wire running to the batteries, a 12V socket, the fan and the switch that have to be interconnected.
First the red (-) fan wire gets a connector.

102103After crimping the tiny wire, a little bit of solder is applied for an improved connection.

100For increased longevity of these joints, this assortment of heat shrink was acquired from Harbor Freight.

104The fan wire plug is finished by adding the heat shrink.

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After adding all the required plugs to the different wires, we move from the workshop to the van to make the final connections.

105The solder iron is clamped to the bed rail in order to have both hands free.

The 12V socket comes with two short wires. The power (-) wire that slides on to the center of the socket has a ring connector on the other end, which is replaced with a square one that will connect to the switch (-). Then the wire is folded in half and some insulation is stripped from the new end, without cutting through the wire.

106The battery wire is then guided through the loop and folded to create a stronger joint. The wire is heated by the solder iron until the solder flows into the joint.
107The heat shrink is slid onto the connection and heated.
108What we have is the power from the batteries that is split into two wires, one to the socket and one to the fan switch.

109110The other power socket ground wire (+) is doubled up similarly, joined with the black fan ground wire (+) and connected to the ground (+) of the battery wire. There is no electrical hazard, as the batteries haven’t been installed yet.

111112Now the wiring is largely completed, a hole is drilled with a Forstner bit to accommodate the fan switch.

113First we’ll check that the switch fits, then we pull the wires through.

114The ground (+) is connected to the left blade, power (-) to the center and power (-) to the fan to the right. Slide the switch into the hole and fasten it.

115Now there is a small bundle of wire that has to be sorted out.

116117Two small staples will collect most of the wires.

118The remaining battery wire is guided along the top of the compartment towards the batteries.

119The wiring cleans up nicely.

120Finally the exposed connectors of the switch are treated with a tiny bit of anti-oxidant, which is available at your local hardware store.

To complete the installation the thermal sensor of the fan needs to be attached, the circuitry must be tested and a fuse box installed. All that is done at a later stage of this project.

Close up look of the socket, switch and fan. Only the fan is really visible; the 12V power socket and the switch are largely hidden from view by the overhang of the bed.
 

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