Arduino mini power problem ( 7-9v)

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1

Hi guys, in my project i want to use an arduino mini and it will be battery powered to last months..

The problem is that the power supply it takes ranges from 7 to 9v and most lead acid batteries i want to use are 6v or 12v.... this is my main problem... i wouldnt want to use and external regular only if it is the only options...

I also need to use a gsm/gprs shield for communication i already have some in mind, but does anyone recommends anyone in special, not so expensive, i just want to send information via internet, php or something.

edit:
Sorry guys just quick question, is it possivel for a gsm shield to be sleeping and wakeup when recieving a call or sms and that way wake up arduino as well?
I want to use this one (http://iteadstudio.com/store/images/produce/Shield/IComSat/icomsat%20V1.1_DS.pdf) but it has a power supply of 9v minimum... but it says it is arduino compatible? what if i power arduino with usb cable? will it work also ?

Thanks guys!

2

You could tie directly into the +5v pins instead of using the on-board regulator (the 9v input). Since your battery voltage is probably too high, you can step it down with an efficient DC-to-DC converter and probably use less power compared to the on-board linear converter. Another option might be to use a couple diodes between the battery and +5v input, taking advantage of the 0.7v drop per diode. Buut... I would just use a regulator.