I have an SRAM containing critical data (game saves), backed up by a CR2032. The problem is that it gobbles power and drains the battery within six months. There is also the problem with exchanging the battery as the circuit probably will discharge before I get the new battery in.
I thought of using a 3V battery eliminator which in turn is backed up by a CR2032; the power is supplied with the eliminator while it's plugged in, and whenever it is disconnected, the CR2032 takes over until the eliminator is connected again. What kind of circuitry would I need to make this work?