Wiring
Kill Switch
Each car must have a kill switch or removable link that stops all current flow from the battery or all batteries to the motor(s). The operation of the kill switch should be obvious and it must be accessible so it can be used by marshals in an emergency.
Removable Links
An appropriately rated battery connector can be fitted with a wire link, which stops current flowing out of the battery when disconnected
Isolators
Battery isolator switches for cars, caravans and boats are usually rated to switch reasonable DC currents. They may often not be rated to the full battery voltage used by Hacky Racers, but are still quite a good choice. Simple models featuring a quarter turn removable key work okay, but it is possible to accidently turn off the key by knocking the switch. US teams also note that these are particularly prone to contacts welding. Tecniks BS01 100 Amps Battery Isolator Cutoff Switch Other models are available which are high current battery isolators, but are actuated by twist-on, push-off. Heavy Duty Battery Isolator Switch Twist On / Push Off - Emergency Stop 250A Depending on your controller, large inrush currents may cause pitting and welding of the contacts. If your controller does not feature a soft start, this can be implemented using another switch and a resistor. Standard e-stop style buttons are often not rated to break large amounts of DC current, and are not ideal.
Battery Connector
- XT90
- Anderson forklift connector (50/175A)
- XT60 (low current rating - not ideal)
- 4mm HXT - only designed for 12AWG wire, which is a little small.
Cable
Silicone insulated copper wire with a high strand count is commonly available for RC/drone use and is a good choice for hacky racer builds due to its flexibility and high current rating.
12AWG (4mm2) is typically suitable for short runs and is the maximum size which can practically be used with some connectors. Races are usually short in duration, and cables are well ventilated. For significantly longer runs, 10AWG (6mm2) may be a better choice.
Normal household copper wire can also be used, although usually has fewer, thicker strands and will be less flexible. Tri-rated equipment wire is a happy medium. Aluminium and copper clad aluminium are sometimes found in cheap audio cables with a higher resistance, so should be avoided.
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