In regards to the opto gas engine kill switch V 2.0 I am talking about the opto with only two wires and one LED older ignition modules only required 6 volts the new ones can take higher voltage up to 8 volts there is no longer a need for a second battery the two wire kill switch simply plugs into the receiver and into the ignition module that all you have to do. I received this information directly from Valley View RC