Hi all,
I have a requirement to retain memory in an Arduino while AC power is not availeble (for about few minutes). I am expecting to use a 3.6V memory battery. How can I use it with Arduino Uno ? or ATmega328P.
Can I use a Super Capacitor instead ? If so How can I interface. I can power off most of the functions in Uno.
What would be the ideal solution if I need to power up a Bluetooth module (HC06) too.
Your kind help is much appreciated.
Thank you

If you must keep the processor running then you either need to use a real battery (there are some nice LiPo charging solutions available for Arduino) or you throw away the UNO and use a much more energy efficient board to run the Atmel processor on the capacitor or memory battery.
But maybe you don't need to keep the processor alive? You just need to remember the last setting that it was set to? Then use the EEPROM. That's what it is for.
Remember the Arduino has almost no boot-up time so it can appear to be always ready whenever there is power.
Thanks Friend,
Since the read/write cycles are limited. I'd rather go with the first option. (Proper Battery)
Could you please tell me what are the efficient boards compared to UNO.

The most efficient is the one you build yourself. You can get the power consumption down to the point where a coin-cell battery lasts months or years. See https://www.gammon.com.au/power
With regular batteries, like 4xAA batteries, you can do good work with a Micro or Mini Arduino.