For what it's worth, as saratoga stated, it really doesn't matter.
Most users will literally never see the estimated runtime (this is NOT related to the battery percentile displayed), and I sincerely doubt this is actually a 2Ah battery.
Also worth noting is that if this really is a 2Ah battery, you almost certainly needed to change the iPod internals to accommodate it (ie. by way of a solid state storage medium conversion), in which case the estimated runtime will be hilariously wrong anyway since it needs to make some assumptions about the hardware and its known power requirements in order to make the estimation.
[Saint]