So does using these cheap chargers that you find in stores actually damage your phone? Do they just charge slower because they aren't as high quality and poorly made?
a bad wall-to-USB can fuck with your phone. If the capacitors on the inside are of low quality, the screen's sensitivity gets impacted. So basically, if you use a shitty charger, it'll charge, but your phone will spaz out at you once in a while.
The cable's mostly a passive component. Cheap chargers often have absolutely shitty filtering and regulation that let the voltage vary way outside specifications. This can mess with the phone if its USB port is not built defensively enough.
it's a dirty dc wave (or the existence of one rather) that most of concern. Dirty ac to dc conversion on cheap ass transformers is common, actual voltage would tend to be fine. Solder job and improper (ie no proper separation high voltage ac and low voltage dc side) are the other big concerns.
Good phone should protect pretty well but obviously they can't shield it against everything. To be fair though it's just not worth the risk using one as a main charger, get a decent one that won't fuck up your shit and will charge it faster.
>parents use cheap shitty dollar store usb wall adapters
>wonder why their phones charge slowly
>chargers reek of electric smoke
Everytime I visit I bring one or two good ones for them since I get so many but they just never use them for long before they switch back accidentally, forget and just accept having to let their phones take 12 hours to charge.