Why does my iPhone reboot after operating normally for a few minutes?

Hi. I actually purchased the ifixit replacement battery after installing another company’s replacement battery. The problem then was the 5S rebooting after several minutes of operation (black screen, then Apple logo., then startup resembling a hard reset.) I installed the ifixit battery and the problem remains unchanged.

I have no problems with the ifixit product. It seems to be a splendid product. I’m not asking for a refund, since there doesn’t seem to be anything wrong with the kit.

Either I somehow dinged the 5S while doing the original install or IOS is detecting a non-Apple battery and is blocking proper operation somehow. I’m thinking the latter, since the problem is suspiciously *very* regular and repetitious.

I’ve tried running the battery to zero and fully recharging it. No joy.

Thanks to all,

Jerry