Hi, I want my arduino and gsm shield to be powered even on power failure. I have one 12V 3A acdc adaptor and 6V 4.5 AH lead acid battery. I'm thinking of using a relay or a diode. which one is better? I already have a 1N5822 schotkky diode for lower voltage drop.
Here is the schematic. The LED represents the arduino and gsm shield.