Chosen Solution
I’m thinking abut buying a used early 2009 Macbook Pro 15 at a college sale, so these will have been used by different students (one student per laptop though). I have a 2006 Macbook Pro 17 that has 454 cycles, and using terminal it shows the “MaxCapacity” = 4746, “DesignCapacity” = 6300. It lasts a couple hours still, but when it dies, it is unable to sleep, and just shuts down. I’m hoping to avoid this with the newer laptop. So I’m wondering what the threshold is for replacement (so I can add that to the price if needed). To see what your battery cycles/capacity are, in terminal use: ioreg -l | grep Capacity
Variations in use and manufacturing likely make purchase decisions based on cycles probably a bad idea. what if you only discharge halfway? What if you drain the battery until the laptop dies everytime? What if you operate in greatly varying temperatures? Is the laptop in your backpack getting banged around often? All these things have the potential to reduce battery life. Really you just want to find the laptop with the least use (if possible). And hey, worst come to worst, we have plenty of guides for MacBook Pro 15" to help you swap the battery quick and painlessly!
For our stocking purposes, after about 200 cycles you’ll see decreased performance and over 500 may need to be replaced. But this is mostly bad info. What you really want to look at, are the mAh (milliAmp hours) numbers you included which is basically a count of the number of electrons that the battery can contain. So your battery can hold ~75% of the electrons it used to be able to. It should be replaced, if possible.
I’ve got a 5 year old Macbook 15" with 1653 cycles that lasts a number of hours (never bothered to check) before running out of battery. iStat claims the battery to be at 92% health… Any thoughts on the matter?
