>>> I am using a PIC at 32K and a 3V Rechargeable Cell (VL2020). > Its rechargeable, Russell. I know - it's still very dear. But it has lovely self discharge characteristics. If I needed backup over vast periods of time I'd possibly use one too. Over more normal periods I'd desperately search for a cheaper solution :-) RM -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist