A solution that includes adding a resistive divider as somebody else suggested, but connect the mid-point to an input that has a comparator and can generate an interrupt when voltage drops. That way you don't need to keep reading the ADC. Save your data in the ~200ms you get. Cat [Non-text portions of this message have been removed]
Message
RE: [AVR-Chat] Re: ATmega88PA EEPROM Memory Life
2012-12-13 by Cat C