I have an old iphone 4s that i still use. The issue though is i had the battery replaced twice a while back. This was at those phone repair shops though where i paid i believe $25 or $30, i don't recall exactly how much. I had issues where the battery drained very fast. Then the battery goes out at 18 percent. I replaced the battery the first time, i had similar issue. I then later went to another repair shop and when they replaced my battery, the battery only charges up to 90 percent. Then it drains pretty quickly but not as bad as before. I bought this iphone 4s on ebay back in 2014 used on ebay. At the time, that iphone was used but excellent condition. That seller had the iphone for a few years and said it worked great. So the battery was great, everything was great. I would like to know, does that mean my iphone 4s battery cannot be replaced and there is something wrong with my iphone? Also the last time i got battery replaced, the guy also replaced the charging dock/port because it had issues recognizing the iphone to a computer etc. I do have an iphone SE as well. The only reason i got the SE was because the 4s had battery issues. If it worked the same as it did few years back, i would continue using it. But now i want to know, does that mean my iphone 4s is useless? I do know that the battery i got from those places who put in the new battery, those definitely are not the ones from apple etc. And if you buy a new battery for the iphone4s, doesn't that cost like $100 or so? I mean is my iphone 4s worth anything at all then? Most importantly i want to mention, i did a factory reset of my iphone 4s. Still same issue... battery charges up to 90 percent only and battery definitely drains. And of course it shuts down when at 18 or 10 percent etc.