Exactly. The Mamba esc needs big amps to get the motor going under load....amps that cheap batteries can't provide. The motor will rev up very nicely when no load is there, but under load cheap batteries can't keep up with the amp draw of the Mamba and what happens is it bogs, or is known as "cogging".

It's the same way with using the Mamba systems in micro cars/trucks/buggies. GP1100's or lipos are the way to go.