[X4U] Battery Capacity Question

[Lee Licata]

Dear List,

I have a 17" G4 Powerbook that I purchased in November 2004.

It has an applecare contract.

The 5400 mAh battery's current capacity is 5097 with a cycle count of  
112.

On June 18 of last year, it was 5609 with a cycle count of 54.

On March 10 of this year, it was 5353 with a cycle count of 98

In a "use-to" job, it was a guide that batteries are to be replaced  
when capacity reaches 80%. But, those were lead-acid batteries, and  
MUCH bigger.

So, is there consensus as to how long I should expect this battery to  
last, at what point should it be replaced?

As a non-scientific point of reference, when sitting on the couch  
wirelessly retrieving my mail, surfing the web, etc, etc, I seem to  
get just over 2.25 hours from the battery....

Thanks in advance!

Lee