Battery backup as concept for next Arduino design

I understand Arduino is looking for ideas for the next Arduino. I would love to see circuitry such that if energy disapears from the plug, that the Arduino automatically switches to a battery backup and continues running. I am thinking that the barrel jack normally receives energy from an AC adapter. If this one should fail, it would be nice for the Arduino to have a pair of screw terminals that would accept a battery input of a given range and continue running. It would not use the battery until necessary and would maybe even alert when the battery voltage is below a given level. Or even maybe recharge the battery from the AC source.
What do you think?
Migs

Well the concept of an automatic battery backup is pretty straight forward, the details and added features (like auto recharging or auto power down on low battery) one might want can take some extra thought.

The easiest way to implement automatic battery back-up while normal power is being supplied to the Arduino external power jack is to wire a battery with greater then around 8vdc to the Vin pin and ground pin, with a series isolation diode (1N4001 is fine) between the battery positive lead and the Vin pin, with the cathode wired to the Vin pin. With a two resistor voltage divider you can also monitor the battery terminal voltage via a analog input pin.

PS: This is probably not the best sub-forum to post this topic.

Lefty

Thank you Lefty. Sorry about the wrong place to post, its just I thought it a good idea for a future Arduino. I'm going to try and figure out you verbal schematic and implement it, but the overall concept might be for you to keep in mind and consider.

Thanks for your words!
-Migs

The "powerpath controller" devices made my Linear Technology do what you
are looking for in a single chip. IIRC Maxim and TI have similar offerings.

Even if you are not interested in these particular devices you should be able to
find schematics and application hints in the various datasheets.

(* jcl *)


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I think a better solution is a step-up. We use the ADP1613 and works fine, it evean resists a short-circuit with a screw driver bestween it's output and GND. So you can use about 3 AA/AAA batteries and get enough power for the Arduino.