Original capacity of 15 inch Late 2008 MBP

Question

I'm just a little confused as to what the starting capacity of the late 2008 MBP battery is. The battery itself reads that it is at 50 Wh. But, according to Coconut Battery and iStat Pro, the original capacity is 4600 mAh.
I'm debating whether to buy a new battery since my battery has 463 cycles on it, and it's current capacity is at about 4023 mAh. If the battery started with 50 Wh, then I'm right at about 80%, and my battery should be replaced soon, but if it started at 4600, then I'm at about 87%, and it's a-okay.
The battery definitely doesn't last as long as when it was new, but I'm just trying to figure out if buying a new battery will be worth it to me at this point, or if I should give it another 100 cycles, then buy a new one.
Thanks guys!
P.S. My battery never charges all-the-way to the full holding capacity. The computer always reports that it's charged at 3900 mAh, give or take, which is about 98% of the reported capacity of 4023.

Answer 1

Your model's battery had a maximum capacity of roughly 4.5 hours under the minimum load. Watt-hours is not a capacity measure but a power delivery measure. The capacity measure is 4600 mAh. That is what it was when new. The battery has an expected life of 500 cycles so yours is near the time for replacement. At the point where it is now the battery should power the computer for a maximum of about 4 hours.