Do you think that a 9.6V rechargable will work?
Will a 7% over voltage harm it
http://www.mahaenergy.co.uk/acatalog/rechargable.html
Powerex MH-AA96V200 - 9V battery
200mah does seem quite small
The duracells are 550mah and give say 20 hours.
So it will give you 7-8 hours.