Hello all, i just wanted to ask simple question regarding laptop battery. no worries, i wont ask about how to keep em long, just analysis about the battery capacity. i noticed that many ppl uses different standard to define battery capacity. there are mWH, mAh, as well as cell count. i suppose the mWh is equivalent to the voltage of battery times mAh. so, i wanted to ask, how to determine that a battery of laptop will last longer? since many laptop comes with different voltages. some 10V with 4000mah, some 15v with 4000mah is it going to provide same hours since those batteries have same 4000mah but have different voltage rating? i hope someone have reference or from the net since i've spent time googling and find no result. i found one said 71W battery 8-cell, others 48.8W 6 cell. while others said 6-cell is usually 4400mah and i do not understand the conversion unit.