Anyway, here's the plan: 2 NiMH rechargeable cells (I know I OUGHT to use straight NiCads but in this case what I have is NiMH) as the backup battery in the '6790. That voltage (~3.4VDC) sound OK to y'all? Ed Tanton ***Ed,I assume a typo here,two nicads in series are 2.4Volts,not 3.4V. Brian G.