I have two power supplies that share the same load, an LED string. The one power supply (Circuit A) comes from the AC Mains which is rectified and with the help of a switching mode driver IC, it supplies a constant current to an LED string.
Should there be a power failure in the AC mains, I would like the second power supply (Circuit B) to AUTOMATICALLY kick in to power that same string of LEDs. The second circuit is powered from a 12V lead acid battery which with the help of another switch mode IC it provides a constant current to the LED string. Should the power in AC return, then it must switch back to the AC mains circuit.
My question is: Will I be able to perform this automatic switching using a relay or relays? If so, could you please guide me as to how I can go about this? If this is not a good idea, may I please ask for a better suggestion. In the third diagram I drew my thought pattern on how I was thinking to switch between the two circuits.
I apologise in advance for anything that might be unclear or vague, I will gladly explain more if need be.
Your help would be greatly appreciated! Thank you!
PS. The circuits I drew are not the full circuits, I just drew them roughly so that you can get the idea behind them.