Chosen Solution
Hi, I have installed the battery in my 2012 13 retina Macbook Pro. I found that the battery take so long to charge to 100% (~5-6 hours to complete a charge) and when I was using it the battery percentage suddenly drop from ~50% to 6% and after it can stay like that when I use for 1 hour and the battery completely died. I have calibrated for 2 times and still didn’t work please follow up. Thank you! Update (12/14/2018) I got my battery from ifixit
I would return the battery for a replacement, if possible. If you cant get a replacement, Id buy one from iFixit or another reputable source.
