I'm trying to design a power backup system for my saltwater aquarium. In short, the system will be powered by a 12VDC power supply while the mains power is on. On power failure, the system will automatically switch to a battery source until the mains comes back on. At this point, it will switch back to the 12VDC power supply. I believe I have all that worked out, no issues.
The only thing I'm stuck on is the 12VDC power supply that runs the system under normal conditions. If this power supply fails, the system will detect this as a power failure and switch to the battery bank. The batteries will eventually run out because they're meant for short term life support, not for indefinite running. At this point, it seems like the greatest weakness in the system is the 12VDC power supply that runs the system during normal operation.
So, my question: would it be safe to wire two identical 12VDC power supplies in parallel for redundancy purposes only? Note, I am NOT trying to gain additional capacity from this configuration, only redundancy. One power supply could very easily handle the entire load. The power supplies in question will be 12V 40A, and the consumption of the system tops out around 300W.
Thanks in advance for any help regarding this.