How to setup a Real Time Clock on a Raspberry Pi B v1.1
If you didn’t know, the Raspberry Pi doesn’t hold the time very well, this is because there is no on board Real Time Clock.
To keep the devices time accurate we need to add a module that holds the time whenever the RPi has no power running to it and then updates the RPi with the time saved on the battery powered module when the full power is restored and the system starts running again.