So that would go over to a push button.. how long would you hold it cuz if you heat them to long it will burn the GP up right?
The GPs have a certain number of cycles in them.They are essentially just little electric heaters. And all electric heaters eventually burn up the elements. These are no different.
This is one of the reasons FOR going to a manual setup. The original setup turns on the GPs EVERY time the key is turned from off to on.
Once I get it started in the morning, every single time, the rest of the day that I start the truck, a GP cycle is wasted. Also, when I am just working on the truck, testing things, etc... Yep wasted cycles.
But as for burning them out from leaving them on too long... I recall seeing here a post by someone showing one of our beru plugs being hooked directly to a battery. All by itself. And left for a LONG time. I can't remember if it was all day, or a couple days, or what. But it was a LOT longer than you'd expect. Thing is, once he unplugged it. Plugged it in the next day, and it was still good to go.
Everyone's truck is a little different. Some need more GP, some need less. Best thing you can do is to set up the manual system. Then experiment to see how much GP YOUR engine needs to get started. It will change with the seasons. But what you are going for, is not to figure out the absolute minimum you can squeak by with, to get the engine started. Now you are putting unnecessary wear and tear on
everything. Do figure that out. But say for instance, you run them for 5 seconds, and the truck starts, but has a hard time starting. Add a couple seconds to that. Keep adding, until the truck starts easy. It's cheaper to replace the GPs, than the starter, and/or the batteries, etc.
I think way too much 'mystery' is attributed to the GPs, And way too many graphs and numbers bandied about and used to bludgeon one another with.
Bottom line... real world... they are little heaters. Try to get the best ones. I think the Beru fits the bill, well enough. Hook them up good and solid. Make sure they get steady solid juice. And quit worrying about getting the exact length of the exact gauge of wire, and all the rest. Use a solenoid that will do the job. Put in a fuse, or fusible link, or just wire it direct. Whatever works for you. And trigger your solenoid with a cheap momentary on pushbutton.