Update Readme

README.md

@@ -11,7 +11,7 @@ If you like Safepi you can [donate via paypal](https://www.paypal.com/cgi-bin/we
 
  * It notify the Raspberry when primary power is absent on a configurable GpIO (pin 36 or 38) and then give enough time to shutdown from the batteries. 
  * When the RPi is on and the primary power is connected, it recharge the batteries.
- * It provide safe voltage regulator giving the ability to power the RPi from 8V to 25V. 
+ * It provide safe voltage regulator giving the ability to power the RPi from 7V to 25V. 
  * Battery drain when switched off if minimal (less than 10mA/h)
 
 ![SafePI 1.0](/safepi1.jpg)