There is nothing wrong with your screen on time. 3h30m is normal. And losing 1% every 2h? Come on that's really good. That's like 8,3 days standby time.....
Samsung Galaxy S 4 I9505 | WanamLite v2.6
Samsung Galaxy S II I9100 : AOKP 4.2.1
HTC Touch Pro2 | ROM: Valkyrie 6.5.23115TR2.5
HTC HD2 | DarkStone1337 [FroyoStone Sense - V3.2]
HTC Desire : Oxygen v2.1.3