2015 Macbook Pro battery replacement super fast degradation

I believe you are being sarcastic but the absolute worst possible option for a replacement Mac battery is eBay. Apple does not sell OEM batteries for that particular model Mac to anyone, and their suppliers are prohibited from selling to the general public. That means the seller is being disingenuous at best. Don't conduct business with liars.

Im convinced this is not my fault beyond all reasonable doubt, but i am looking for second opinions to see if this seller has a leg to stand on with this dispute.

He has none. You hold all the cards for the reason I stated and then some. Return it in accordance with eBay's policies, get your money back, and purchase a replacement from a reputable source. The only reputable source I have used and can recommend is OWC, and even then only when your Mac is too old for Apple to replace the battery.

Your best option is a battery from OWC or iFixIt. However, even from these two respected vendors, you may still get a bad battery. I recently got a battery from iFixIt and it lost capacity during the initial calibration phase, but I continued testing it to see if it would stabilize, but the degradation continued. In fact, the laptop would not go into hibernation when it neared 0% charge. They sent me a replacement battery under warranty (no hassles, but I was also able to provide great details with the failure too). I've purchase batteries from OWC in the past....some have been fine, others did not hold up well.

Unfortunately the quality of all third party Lithium batteries is extremely poor, but it helps to purchase from a respected vendor known to provide good support.

As @ku4hx mentions, there are a lot of sub-quality items out there....some are even out right fakes.

FYI, after installing a third party battery and calibrating it, I highly recommend running the Apple Diagnostics to see whether the diagnostic will pass the battery. It isn't to verify the battery is good, but to see if the diagnostic will pass it so later on when you encounter a problem, you will know whether the diagnostic failure is legitimate or if the battery is not compatible with the diagnostic. The iFixIt battery I received failed the diagnostic the first time I ran it, but the second time I ran the diagnostic immediately after the failure....the diagnostic passed. Not sure what to make of that except maybe it saw an actual issue the first time.

Even Apple and other OEMs have trouble getting good quality Lithium batteries. If they have issues acquiring good Lithium batteries, then you know that the quality of third party batteries will be even worse. Keep in mind some of the third party batteries may be ones that did not pass Apple's stringent quality tests.

For it to be Apple brand, you have to get it from Apple. eBay is fraught with misinformation.

3rd party batteries may be Apple "compatible", but are not compliant with Apple acceptance criteria.

You can do what you want, but if you want top quality, Apple should service the battery. Opting to save a few dollars at the expense of poor performance and reliability is false economy.

All this was your decision. Your fault is not for this forum to address, but you made the decision.

John Galt wrote:

The only reputable source I have used and can recommend is OWC, and even then only when your Mac is too old for Apple to replace the battery.

Completely agree, an Apple battery repair is always the best option if the part is still available even though it is much more expensive due to the battery being part of the Top Case Assembly. Unfortunately the OP now has no option since the original battery has been removed so Apple will no longer (or highly unlikely to) provide a battery repair.

Unfortunately the OP now has no option since the original battery has been removed so Apple will no longer (or highly unlikely to) provide a battery repair.

I was going to point that out but decided not to rub salt in the wound.

You're most welcome young Jedi!

DoubleCheese wrote:

Oh well, but i will take one more battery from him and one more fake and potentially dangerous battery out of someone else’s life. Im a bit uncomfortable taking it further with them selling fake products because I’m not sure if this retailer has access to my address.

It may not be a fake battery per say, just a standard third party battery. Even if it is identical to the OEM, it would be one Apple likely rejected. Like I said, even buying a Lithium battery from a respected vendor is no guarantee of getting a good battery. If that eBay vendor has mostly positive reviews, then a replacement battery from them may be Ok, just like it was for me and iFixIt (so far anyway). Another part of the problem with Lithium batteries is whether they are properly stored (sufficient charge & proper storage temperature, plus you don't want one that has been sitting for years on the shelf).

I didn’t want to pay £245 for a service at Apple when i know I can fit the battery myself if i can get hold of one. Lesson learned.

I can certainly understand as I feel the same way especially for an older laptop like this.

Yes, it would definitely rub salt in the wound hahah.

Sorry, that wasn't my intent...only to inform. It may depend on what tech you get and whether they notice it has a third party battery installed. And whether they still have the part in stock since the laptop is now considered "Vintage".

Good luck, I hope the warranty replacement battery you get from eBay is good.