Donnie Posted September 7 Share Posted September 7 In your view, on what circuits are relays mandatory? Thanks in advance Link to comment Share on other sites More sharing options...
CarlB Posted September 7 Share Posted September 7 All depends on what the amp rating the switches you are using. The wire is important as well, but generally the switch is the component with the low rating. Link to comment Share on other sites More sharing options...
Marek Posted September 7 Share Posted September 7 Switches, connections, and long wire runs are your most likely sources of either current drop or over-heating (the prime motivators for using relays). As a general rule, that means beams (front lights), fans, and pumps. You can also generalize to say any circuit which is 14AWG or larger; assuming your harness was appropriately sized. If you are replacing the wires, this list is a decent rule of thumb on wire gauges for motorsports: Automotive use (longer wire runs ) 10/14/20AWG: Battery Positive Direct 10AWG Battery Negative Direct 10AWG Other Battery Positive 14AWG Fuel Pump Positive 14AWG Radiator Fan 14AWG Switched Ignition 20AWG 12V 5A Fused 20AWG Tach Output 20AWG Sensors 20 AWG Injectors 20AWG For motorcycle use (short wire runs) 14/18/16/20/22AWG: Injectors 20AWG (better seal plugs) Lambda Sensor (5) 20AWG to Autosport Lambda Harness: 12V+ 20AWG, Heater(-) 20AWG, Vs 22AWG, Ip 22AWG, Lambda Analog GND 22AWG 5V Sensors 22AWG; Fuel Pump +/- 16AWG VBat+ 14AWG Chassis Ground VBat- 14AWG References: https://dsl.torque.net/tech/relays/relays.html https://www.rbracing-rsr.com/wiring_ecu.html 1 Link to comment Share on other sites More sharing options...
jbcollier Posted September 8 Share Posted September 8 Can’t give advice without an application. A pre-crossflow with a 20 amp generator and a pair Webers is a completely beast to a fuel injected, Duratec with all the mod-cons. Link to comment Share on other sites More sharing options...
Donnie Posted September 8 Author Share Posted September 8 Funny. You had plenty of erroneous advice to give when my Series 1 was on BAT. 1 Link to comment Share on other sites More sharing options...
jbcollier Posted September 8 Share Posted September 8 More to hand, no worries. Link to comment Share on other sites More sharing options...
Donnie Posted September 8 Author Share Posted September 8 I can't wait. Link to comment Share on other sites More sharing options...
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