Ignition Cut Out and Alternator Question
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OK, I think I've got this sorted! We will be useing "super mini" Denso alternators and I am reliably informed that they are not self exciting as I assumed they would be, this means that simply interrupting it's ignition live feed will stop it charging so the Moroso switch should have no problem doing the job. Self exciting alternators such as the lucas ACR's and Mopar ones need to have the main feed interrupted to kill the engine, and for that you'd need a switch with a rating in excess of your alternator output, unless you like the smell of burning..... Thanks for your input guys!
“It’s good enough for Nancy”
I've been looking at this exact thing recently and I think it should be relatively straightforward now I've got me head around it.
Easiest and safest way is the so-called "MAD" way . that's MADelectrical.com who I think have stopped publishing the full diagram on their site.
Basic principle is to run the big fat rear-to-front battery cable via a starter type relay at the battery (I'm gonna use a popular US Motorcraft one). This way the main cable is only ever live during cranking. good news when you jack up you car by it or slice through it. Stops your car burning to the ground . the starter cable is the only one you can't fuse protect easily cos it will take all the current the battery can give.
The alternator battery feed comes direct from the alternator to the battery side (yes) of your kill switch - which by the way never sees cranking current now so no need for a huge one. from the other side of your kill switch comes the main feed for everything else. It takes a lot less current than a starter, and can be protected via a fusible link.
So, if the car is running, you shut off the kill switch and it stops the main electrical feed - so your ignition, fuel pumps etc all stop. The battery cable is already disconnected cos you ain't cranking - and even if you were it would stop because power to the trunk relay is gone.
Loads of people are doing it this way, I know of a guy running it who passed NHRA tech spec.
BTW - Kev and Blue, I might have a couple of kill switches that would do the job fine. I've been using one for years no prob. It will take full battery current if you use it that way (I did)
Easiest and safest way is the so-called "MAD" way
. that's MADelectrical.com who I think have stopped publishing the full diagram on their site.Basic principle is to run the big fat rear-to-front battery cable via a starter type relay at the battery (I'm gonna use a popular US Motorcraft one). This way the main cable is only ever live during cranking. good news when you jack up you car by it or slice through it. Stops your car burning to the ground
. the starter cable is the only one you can't fuse protect easily cos it will take all the current the battery can give.The alternator battery feed comes direct from the alternator to the battery side (yes) of your kill switch - which by the way never sees cranking current now so no need for a huge one. from the other side of your kill switch comes the main feed for everything else. It takes a lot less current than a starter, and can be protected via a fusible link.
So, if the car is running, you shut off the kill switch and it stops the main electrical feed - so your ignition, fuel pumps etc all stop. The battery cable is already disconnected cos you ain't cranking - and even if you were it would stop because power to the trunk relay is gone.
Loads of people are doing it this way, I know of a guy running it who passed NHRA tech spec.
BTW - Kev and Blue, I might have a couple of kill switches that would do the job fine. I've been using one for years no prob. It will take full battery current if you use it that way (I did)
Gavin Chisholm - 414ci W2 Stroker SmallBlock Panther Pink '71 Challenger convertible - in bits
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