Dear,
Is there a battery setup for the Arduino Nano where you not have to replace the batteries soon, longer then a year, using with an RFID reader.
(Sorry for bad English).
I hope my question is clear.
How much power does the RFID reader use when it's being used and how often will it be used?
Those things draw a lot of power since they power the tags they read.
I doubt you'll find a battery that will last a year for regular use.
Try this one
battery
41,000 mAh
that rations you 112mAh a day, assuming magically ideal everything
that rations you 112mAh a day, assuming magically ideal everything
Don't we always assume "ideal everything" here on the forum ? 
If this unit is out in the daylight, use a rechargeable and a few solar cells.
Using an ID-12 RFID reader, needs to be a small sized battery.
marvinarets:
Using an ID-12 RFID reader, needs to be a small sized battery.
Then you can not run it for a year from one battery.
You can run it for at least a year on almost any battery of the right voltage.
If you only scan it once a year.
Your problem isn't about finding a battery, your problem is figuring out how many times you expect to use it and letting us know that information.
May be more then 1, but needs to be small...
Scans could be different each day. Say 20 a day.
Not a chance.
marvinarets:
Scans could be different each day. Say 20 a day.
The point is that you do not know when the scans are going happen so the reader needs to be powered up all the time.
But you could fit a PIR sensor and only turn on the reader when there is some one about. However, that is going to take some current to drive.
A single rechargeable lithium cell (14500, 18650, etc) will be your best bet. Might last you a week per cell, wired up in parallel depending on how many you want to carry.
Not sure what situation wouldn't allow any charging. Sounds like it's portable. And if it's portable, it can be moved to a power source.