I am sorry, I think I have not clearly explained the scenario.
I have only one source of power that is the vehicle battery which is around 12.0 volts to 12.5 volts. Now i have connected one of my hardwares which reads this battery voltage and briefly tells me the voltage of the battery or indirectly the state of charge of the battery, so reading the battery voltage is important for me. My problem is, this board works only upto 10.5 volts and not below it. So, i want to design one more hardware board which would start operating when the battery voltage goes below 10.5 when the engine is cranked. The new hardware board should only provide the voltage when the actual battery voltage falls below 10.5 volts and when the battery voltage is above 10.5 after engine cranking then the battery voltage should be going to the first board as reading the battery voltage is important for me. So, finally there is only single source of supply that is battery and when this voltage falls below 10.5 i should still generate a voltage of minimum 10.5 for some time and then come back to my battery voltage. Hope i have explained clearly. i have attached my idea of implmenting could someone suggest me if it is correct and what components i can use to acheive the same.
thanks in advance,
regards,
Satish