On 12:55 28 Apr 2021, Theo said:

In uk.d-i-y Chris in Makati wrote:
Phone manufacturers source their batteries from various
third-party suppliers. Each of those suppliers probably sell
their batteries via different channels to any number of other
customers.

So is a battery still "genuine" if it came from the same factory,
but didn't have a particular label on it?

I think the 'made in the same factory as Kelloggs' argument is
overdone. Most top-tier brands (Apple, Samsung, etc) have
agreements with major contract manufacturers (Foxconn, etc).
Foxconn have enough of a reputation to protect that they won't
build knockoff iPhones on the late shift and let them into the
market.

However a manufacturer can run two lines with one producing
batteries of lower spec (and lower cost) than the other.

For lower level components it's possible the same part is branded
multiple ways (like different cars can share the same part), but I
imagine the volume of Apple, Samsung, etc is such they buy all the
production of factory X with no scope for running a late shift.
Plus if Apple found out the contract would be terminated very
fast. Most of the parts you might replace (screen, case, battery,
etc) are bespoke so there's no sharing between different brands
than there might be for oil filters or wheel bearings, where you
might buy a Skoda part cheaper than an Audi part.

So when we're looking at aftermarket parts I think it's fair to
assume we're looking at those from secondary suppliers. The QC is
only as good as the effort they put in and the supply chain that
got it to you.

This is separate from the increased risks of fakes in 'genuine'
parts, as against aftermarket brands which aren't worth faking.

Theo