> > I can imagine a system which would monitor it's own battery, > > and alert the user if the battery was low With magnetic impulse charging the battery should stay topped up under normal circumstances. It's what I plan to do for the 6V sealed lead I use for my LED lights -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body