Hello David,

 MV>> Look at it this way: The battery in my cell phone (Siemens M35i)
 MV>> is 3.6 Volts, 500 mAh. Or 1.8 Wh. That's enough for 3 to 4 days
 MV>> of average operation. A 500mW generator could charge the battery
 MV>> in less than 4 hours. So 500 mW is plenty for a cell phone.

 DW> It depends on the conditions. Cell-phones automatically
 DW> increase their transmission power when the local cell site
 DW> is difficult to communicate with, for example if it is distant,
 DW> or if there is a lot of stuff in the way that reduces the signal
 DW> strength. So phones use up batteries faster under these difficult
 DW> conditions than when communication is easy.
 DW> A phone that is capable of operating under very
 DW> difficult conditions (which most of the little new phones are
 DW> *not* capable of doing) may transmit several watts of power.

My cell phone operates according the the GSM standard, Maximum ¨output
power in 2 Watt PEP on 900 MHz and 1 Watt PEP on 1800 MHz. ¨As there are 8
time slots in a channlem and it takes up just one ¨time slot that
corrresponds to 250 mW respo, 125 mW average ¨maximum. And then you have to
keep talkong all ethe time because ¨it only transmits when one actually
speaks.

A half Watt generator should provide /plenty/ to keep it running
¨indefinitely exept perhaps under the most extreme conditions.

Cheers, Michiel

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