i'm running my project by using car battery,future will change to deep cycle battery, i'm using below battery indicator circuit to indicate the voltage level of battery, when the voltage drop until red LED, red LED light will turn on and my system will switch off.i'm using below power relay (SRU-12Vdc-SL-C,10A) to test by connecting with transistor (do not know what is the suitable value, just test on 2n3904) and resistor(1K).unfortunately when i switch on all the system, LED will automatically on without any control, probably power relay is not suitable use for this application.
the output of LED is around 11.6V, 12V will be using to power my system
Or i just using 12 V transistor as a switch?
any opinion?