John,

I suspect this is by design since phones will typically go into Analog mode without a digital signal which burns through the battery power very quickly. Then without the presence of a cell tower it uses max power to effectively "ping" the surrounding area until it finds a tower it can connect to.

Couple this to their use of cell towers to help triangulate and increase gps accuracy, I suspect you will easily burn through your battery unless the phone disables pinging for a local cell tower automatically or you manually disable this 'feature'.

To combat this without turning off my phone I instead ensure my phone is plugged to 12v power when wheeling outside of the net. The moment you take it off power, you'll see how quickly battery reserves are depleted (hours instead of days).

If you're using it's gps features, better keep it plugged in. <img src="/forums/images/graemlins/kewl.gif" alt="" />