There are hundreds of posts & thousands of page views about iPhone 4S Batter Life at Apple Support Forums. A few days, I’ve faced same problems a few days like I had no sim and sim failure errors, network losses and a few hours with full charge ! It seems problem is related directly with Apple but still there are solutions, at least two things worked for me;
1 – Changing SIM card with new one ( currently 64Kb micro sim ) solved network loss and sim failure errors.
2 – Turning off a few location based services;
The result is surprising, my iphone batter is 70 % with 1 day standby and 1 hour usage.
You can still have 2 days standby with a few hours usage.