Chosen Solution
I got this Mac off of eBay and have noticed that coconut battery shows no manufacturing date or info I don’t know the history of this machine at all but the battery looks to be OEM but I am not sure how to tell. Common with these batteries or some issue? No signs of swelling or bulging in the casing.
EDIT: I forgot to add that the battery healer can be rather sporadic jumping from 77% health up to 88% health. The battery full charge capacity also reflects this.
This looks like a rebuilt battery! Basically, a collection of cells from a bunch of bad batts are put together into a working set. The person wiped the BMC of its info and didn’t program the info. A new battery would have been batched programmed with all of the details. As it’s very easy to program the BMC you really can’t trust it he info. Also don’t forget there are no real OEM batteries on the open market as Apple doesn’t sell them. These batts are all third party so you do need to be careful! I would return it and get your money back and go to one of the major brick & mortar stores which offer a good warranty.
