ok so after looking at some options, I think I have 2 choices to make:
V1: CUT EVERYTHING
I cut off everything at the positive side of the battery, but then I don't control where the potential alternator spike will go. Hopefully it will not blow something in the electrical system before going into the resistor.
V2: CUT WTH HELP OF IGNITION SWITCH
I follow more closely the switch manual and tap into the alternator wire more specifically, which will guarantee the potential spike will go only to the resistor when switch is off. And use the other switch pole to cutoff the ignition wire.
Result is that same but the electrical cutoff is similar to removing the ignition key. There is still power in many wires around the car, even though the car will be stopped.
Anybody has opinion on the which way to go
?
see my schemas attached, an also the 3 pages of the electric manual relevant to the install.