well since the original battery had a bigger capacity, expect mo talaga na yung bago na smaller capacity hindi talaga tatagal ng tulad ng dati. kung dati lampas 2 hours, malamang nga hindi na aabot ng 2 hours. that is to be expected
as to your specific question, hindi masasagot yan since we don't know the exact model, the charger, the usage etc. hindi pareho usage time niyan kahit the same ang capacity ng battery. example, gagamit ako ng 49Wh din na battery sa laptop ko, it could mean it will only last less than 1 hour and sa ibang laptop, it could last 3 hours. a more powerful laptop (i.e. has a video card, more ram, more hard drives, etc) will of course consume more power and will drain the battery faster