[ELI5] How do “OEM replacement” batteries exist for a device that is several years discontinued? And do they genuinely work better than the battery they are replacing?

Question

I bought a used $20 Samsung Galaxy J7 (2015) since the screen looked to be in perfect condition. I do not know if the seller replaced the battery, but even so, how would a “brand new” battery from 2015 be any better than the current battery inside?

In: Technology

Answer 1

It’s most likely aftermarket, honestly. Brands really only started offering genuine parts to the general public within these last two years.

The problem with buying a replacement battery is that you’re most likely getting old stock. Nobody is going to be manufacturing a battery for a 2015 phone in 2024.

(Lithium) Batteries don’t do very well sitting with no charge for a couple of years, so any replacement battery is not going to last as long as when the phone was new. Expect a significant but unsignificant boost in battery life, something like 30%, 2 hours screen on time jump to 3 or something like that for battery replacement on a 9 y/o phone.