On another note about my circuit. I do not know if this is because I have partial analog components, like the relay and LED, but this is what i am seeing.
On the bench, the circuit works perfectly. My hysteresis, when set to my desired levels, drops to where I want it. When I set the Vset to 4.6 V it triggers fine. Then immediately, the V drops across the comparitor to about 4.1v. Nice healthy drop and exactly what I wanted. So I go to install it, and it works fine with the exception that at the trigger point, it modulates. In other words, the trigger identifier (LED) goes first "on"--then "off"..then "on" during this transition. (maybe 2 blinks per sec.) Now I do not know why, I am confident that my Vsrc is not dropping all the way down to 4.1v, so I am not sure why it is doing this. I was thinking of the clock speed of the components, the LED, the Relay, and maybe I should install some form of an RC in there to keep the voltage up slightly and have it "drain" slower. Now, I could be totally wrong, and my Vsrc is in fact dropping below the hysteresis of 4.1, then back up, then back down, etc. But I am pretty sure it is not. I also noticed that the LED brightness is dimmer when it is in this modulated process. Other testing at higher levels, the LED is blinding bright. Not sure if this means anything. Would removing or increasing the size of the disc cap between tins 2 and 3 do anything? Or maybe remove as you stated, and drop one in there to ground.
Lastly, is there any reason to change to a V regulator and remove the power to the LM393 from the car's 13.8v source? (poor quality). But continue to use it for the relay and LED, etc.
Always, appreciate any ideas.
Stu