Electrical cutoff switch,...
Electrical cutoff switch, with key in place, ready to install in the vehicle.
Big posts on either side of...
Big posts on either side of the spade connectors are for battery cables. For the device, mounted toward the middle of the cockpit, off-the-shelf, pre-made battery cables can be used. We recommend 1 gauge cable for less resistance. The switch also comes with a rubber cap for when the key is removed.
Four power control connectors...
Four power control connectors are provided to wire the switch into the ignition and coil circuits.
An ERK 3.3R resistor comes...
An ERK 3.3R resistor comes with the switch and has to be wired to a connector and ground. The resistor drains off any residual power after the switch is turned off.
Once the resistor is in place,...
Once the resistor is in place, the rest of the wires are routed from the spade connectors to the ignition and coil.
Wiring a new kit car, or rewiring an old one, can be frustrating, especially when you discover little problems at the end of the installation. When building a kit car, we learned early on the benefits of installing a cutoff switch in the system. Along with added security, the switch acts as a safety device to disable the electrical system, once the car is finished and on the road. It is easier to turn a key than to disconnect the battery cables each time work needs to be done on the electrical system.
We use a Cal Term Pro Battery Cutoff Kill Switch, designed for race cars. Its ruggedness also makes it ideal for street car applications. In a race car, it's mounted on the outside of the car, or up high on the dash in open cars. This switch also will prevent the alternator circuit from being damaged by high-voltage surges.
For our Speedster replica applications, we mount the switch under the passenger seat to keep it out of view, and rely on it primarily as a security device. The switch allows you to turn off the power when you are away from the car, and keep the key with you to foil would-be thieves.
About the only concerns you may have with this installation are devices--radio, clock, thermostat-controlled fans, or alarm--that require a continual power supply. Such gear can be wired directly to the battery through a separate circuit.
An added benefit we've found is that by wiring the switch to the ignition and coil, it prevents run-on by disconnecting the alternator circuit from the ignition circuit.
Regardless of the specific reason for an electrical cutoff switch in your project car, $15 for the device is an inexpensive price to pay for security and peace of mind.