Hi! This looks like an excellent forum. I have a situation on a 1986 Buick Riviera that randomly kills its battery overnight. After many years, I have finally discovered the culprit. The car is equipped with a dash mounted touch screen CRT. Within the CRT case is a relay that randomly develops contacts that stick leaving 12 volts on the CRT filament which draws 2 amps.
I have identified the battery voltage supply lead to the CRT unit. Now, I am looking for a circuit that will monitor the battery voltage and remove the 12 volt supply when the battery voltage drops below a set voltage. The circuit must not draw too much current since it must be active all the time and, therefore, must not discharge the battery itself.
This need just occurred and I am going to attempt to design such a circuit. It just seems silly to do that if such a circuit already exists. So, if anyone knows of such a circuit, I would like to see it. If I do not find one and have to design one, I will post my solution here for others to find.
For anyone interested, I cannot easily repair or replace the CRT unit. The unit was manufactured by Zenith and data (schematics) nor parts are available for it. It is no longer available. I think GM discontinued its use in 1989.
Thanks and I really enjoy reading the forum.