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My iPhone sometimes reboot by itself while playing games it all happened after I replaced my iPhone battery twice the first battery is ok but I was not happy because the battery health is 99% so I replaced it again and it got 100% battery health a few weeks has passed while playing games and connected to original apple charger it just went off and turn back on showin an apple logo and sometimes you see the battery percentage 1% and go back to its real percentage like 56% the only thing to fix this is remove the aftermarket battery flex that is connected on iPhone and place back in and it went back to normal but it just happened twice now after 2 months. What seems to be the problem? And also if I didn’t remove the flex, when I charged it, it was just stock to its battery percentage let’s say 20% and it just keep on like that and the iphone will restart again. (Sorry for my grammar English is not my language)

your text is completely readable firstly I would like to admit the replacement battery you got wasn’t an OEM battery this usually affect the screen or the performance which is yours in this case firstly try clipping the battery again with a tape this time run the test by using it if still persist try getting a mid range OEM battery if you can’t afford apple’s battery replacement charges because apple won’t sell the battery to you they will insist on fixing it hence the price good luck bro NOTE !!!!! the tape shouldn’t be interfering with any other component in the phones cut as little as possible just to hold the battery connection and the battery it self in place

For the first replacement battery - did it have this problem too? The battery health does not display decimals, for all you know, it could have been 99.999999999%. If this battery solves this problem, it would be a good idea to use it. Swapping the battery over less than a percent seems a bit pedantic.