I believe you can get them without, but if not, relays. The added benefit is real power disconnect for an off state as well, no ESD issues, and consumption is a small fraction of load consumption anyway for micro types. You also get the delay with just a cap. David VanHorn wrote: > On Feb 19, 2008 12:29 PM, Dr Skip wrote: > > That's not as easy as you think, there's a body diode that will allow > both batteries to feed to each other. > google batfet. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist