Battery drains Immediately

[Gulanowski]

I've come across something strang that I've never found in any other device. I have the Mugen 3600mah extended battery (I KNOW, I should have gotten the Seido, lol). Immediately upon unplugging it, it drops from 100% to 96%. It has gotten worse too, it used to drop to 98%. This is after charging it for 8+ hours too, so I know that it has had long enough.

I have two possible theories for why this happens...

1) The Mugen battery sucks
2) The phone is not "trained" to read the extended battery. I should let it drain to 0% and then fully recharge it?

Any help would be much appreciated.