Been needing to replace the battery for a few years but after looking at prices (Motobatt has almost doubled in price since 2010 and seems to pull a premium compared to the PC680's etc) and function, I have wanted to go with a more radical setup. This meant I really had to implement the momentary switch circuit for my heavy phantom draw solenoid.
Didn't want to sleep tonight before finishing (I work till 6 AM on weekdays anyways) so I could get this problem off my back and feel confident ordering my new battery.
Now, I can turn the key on, nothing happens, hit the momentary switch next to the key, systems/fuel pumps fire up and everything is GO. Turn off the key and everything shuts down.
All I really did is add a switched power activated relay in the middle of my kill switch ground. Then, my momentary switch is a temporary ground for the 100amp solenoid. Hit the button and I gain switched power and then the relay takes charge of continuing the ground path to the rear switch. Interestingly, this means you can shut off my car with the kill switch in back but I can power up my systems if I hold down that momentary switch constantly (not to easy to drive a 5 speed like that). I didn't want to ground my momentary switch to the kill switch for a "just in case" type situation....and less wiring.