Battery status in menu bar doesn't work correctly

Hello there!

I've recently replaced my factory battery for a brand new Anker.

To be honest, at first i was quite disappointed. The battery duration was the same (2 hours). At least, it seemed so.

Every time the battery dropped to 10% i went running for the charger.

However, a few days ago i let it drop to 7% and discovered that the battery lasted for almost 2 hours more until it hit 0%.

So, my guess is that the overall battery duration is like 4 hours (using wifi navigation, Outlook, Word and a bit of Photoshop, at 40% brightness in Snow Leopard).

Which is good news.

But, and here is my question, how do i make the battery status indicator in the menu bar to work properly?

Because going from 100% to 10% in 2 hours and then from 10% to 0% in 2 hours it's not quite right.

Thanks in advance,

Leandro