@gee, I'm going to swap to a Delco Remy 27SI alternator (100A) into my Datsun tomorrow, and I wanted to make the kill switch safe. Right now, the alternator is setup so that the charge wire runs to the small terminal on the kill switch on a 10 gauge wire, which probably isn't safe even with the 50A unit that's on it right now.
View attachment 499
The above is the "longacre" wiring diagram for their switch (the Moroso instructions for my kill switch just shows my unsafe-as-fuck setup), but isn't the field wire supposed to run to ignition switched power?
The SI alternator has battery, field, and sense terminals (3-wire).
Right. Alternator field goes to +12V switched, otherwise you'll have a parasitic drain which will kill your battery. I'm thinking that diagram is intended for a race car without an ignition switch, where you'd use the kill switch as the master switch for the car and use a pushbutton or whatever to start the thing.@gee, I'm going to swap to a Delco Remy 27SI alternator (100A) into my Datsun tomorrow, and I wanted to make the kill switch safe. Right now, the alternator is setup so that the charge wire runs to the small terminal on the kill switch on a 10 gauge wire, which probably isn't safe even with the 50A unit that's on it right now.
View attachment 499
The above is the "longacre" wiring diagram for their switch (the Moroso instructions for my kill switch just shows my unsafe-as-fuck setup), but isn't the field wire supposed to run to ignition switched power?
The SI alternator has battery, field, and sense terminals (3-wire).
So, my only option is to re-run the charge wire, ugh.Right. Alternator field goes to +12V switched, otherwise you'll have a parasitic drain which will kill your battery. I'm thinking that diagram is intended for a race car without an ignition switch, where you'd use the kill switch as the master switch for the car and use a pushbutton or whatever to start the thing.
For a 100A alternator, you'll want a minimum 4ga, preferably 2ga path between alternator and battery, 4ga will probably get toasty if the battery is close to dead and you're winding the car up. Also make sure the kill switch is good for 100A, I figure it is if it's rated to have a starter run through it.
Couple of options for how to wire it up:
- Cheap and easy: if it's convenient to do on the motor, daisy chain the battery and starter on the existing starter harness.
- Make work project: Do a distribution block. Battery -> kill switch -> dist block -> separate paths to alternator/starter/audio/rest of car. Buy some gold plated Stinger thing from a car audio shop or whatever and make sure water can't get in it with how it's mounted.
Fuck. I re-read the installation instructions, and the fucking alternator kill on the switch is only rated for 20A.
I'm going to just share the battery-side post of the kill switch with the alternator (each with its own 2 ga cable), and use the 12V 10 ga cable as the "sense" side of the voltage regulator. That only takes mA of current.
It keeps the alternator cable hot during a wreck even if the kill switch is hit, but it should cut power to the rest of the car, and I guess I'll have to put a fuse on it.
Finally, something electrical that @Valve1138 could really get on me for.
Yeah, with the battery in the hatch, there has to be a kill switch mounted to the rear-most panel on the car if I want to run it at the drags.Just put a fusible link in the alt/battery connection. Likewise with the battery/starter connection. Works for the rest of the automotive world.
Any reason you've got a kill switch on there anyway? required for running the car on a track?
I figured it out.Right - battery's in the back.
Battery -> kill switch (upgrade it to something that can do 100A, or get a smaller alt) -> heavy gauge to engine compartment -> distribution block -> alt/starter/car harness. Bring the alt field wire to switched ignition. Tap off the battery with a fuse holder for your rear audio stuff.
Also make sure you've got a heavy gauge ground path from engine block to chassis and batt to chassis.
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I figured it out.
Battery -> kill switch (175A continuous, 2000A surge post) -> distribution block -> alt battery post
Battery -> kill switch (20A continuous post) -> relay signal line (triggered by ignition voltage) -> alt field wire
alt sense wire -> new fuse block constant +
new fuse block constant + -> distribution block