Saving Cell Phone & PDA Power: Hey, Is This Theory On the Money?

I'm sure, when buying a new computer, you've felt the way I have: Why can't a big computer company like Dell or HP write an instruction manual that really tells you how to use your new desktop or laptop to its fullest? 

Or, at least, why can't computer manufacturers offer really helpful tips?  Here's something that road warriors may find useful, but I can't vouch for its accuracy: To conserve battery power in a laptop, TURN OFF YOUR wireless connection if you're not using it.  Doing that apparently could add as much as an hour to your battery's life. 

It seems that when your computer is searching for a wi-fi signal, it's gobbling up extra battery power.  And the same goes for your Blackberry or cell phone.  If you're running low on juice and you're in an area with poor cell coverage, turn your device off until you absolutely need it unless you can easily recharge.

This came up last week when I spent some time on Italy's mostly rural Amalfi Coast.  Cell coverage was dicey at the villa my family and I rented, but I couldn't figure out why my Blackberry so quickly lost its power each day--after all, I was hardly using it.  Someone smarter than I am (that would be my son-in-law, Alex Eaton) told me it's because they Blackberry was constantly searching for a cell signal, and that eats up power. (And, no, that's not me with the clunky cell phone on the left, though I will confess I once owned a phone like that.  I think it cost me $700 in the '90s.)

Now, I'm no engineer or computer/cellphone/PDA expert.  Maybe you are.  If so, I'd love to hear your reaction to this.  Does keeping a cell phone, PDA or computer with wi-fi on in an area with poor signals drain a battery more than normal?  Clue me and other folks who live on the road with these electronic devices some of us don't understand in, won't you?