Phone battery replacement woes - Page 1
Forum section: electronics / repair

author: highvoltageboogie
author_rank: Contributor
timestamp: March 05, 2024, 06:52:58 pm
content: Hi all,I decided to replace the aging battery of my phone, Oneplus 3T. And ran into some problems. I'd like to hear people's opinions on this matter, and perhaps posting this will help someone else.I opened the phone, and removed the old battery as it was done in the first teardown video that I saw on Youtube. I simply pulled the plastic tab on the battery to remove it. I had to pull very hard, it took a lot of force to break the adhesive, and the battery was badly bent when it finally came off. But luckily the casing was not broken and it didn't start to heat or smoke.Only then I watched another teardown video in which a small amount of alcohol was used to soften the adhesive first.Then I realized that the old battery was wrapped in some kind of black, plastic-like foil, but the new battery came without that foil. In a third youtube video, the battery was carefully removed from the foil instead of tearing the foil away with the battery. This looked like a very elegant way to do it.I was confused when there was no foil in the new battery, and after some thinking I removed the foil from the old battery and wrapped the new one in it. This was quite easy to do, unlike tearing the battery/foil from the phone. Then I put the new battery into the phone and secured it with a small amount of two-sided tape.Not the cleanest replacement job, perhaps, but it worked. However, there's one issue left: When the old battery was removed, very strong smell of something came from the bottom of the battery compartment. Probably from the old adhesive, but it was not like an ordinary "solvent" smell; it was sweet, even fruity, like some sweet pastry, slightly alcohol-like.When I charged the phone for the first time, I could soon notice this smell in the room. It's apparently diffusing through the seams of the phone. It's not strong but very noticeable anyway, and it seems to stick in the leather case of the phone too. Thankfully not in my fingers, though. The smell seems to start when the phone warms up during charging or use.Now I'm still confused about two things:1)What is this black foil, what is its purpose?Would it be a good idea to open up the phone one more time, throw away this foil and try to clean away the old adhesive with solvents? Then secure the battery with two-sided tape.2)What substance is used to glue this foil-battery package into the phone, and why does it smell so much? Is it a health hazard?Many people in reddit and elsewhere keep telling that a leaking battery smells like that. But I think this is not the case for two reasons. Neither the old nor the new battery were smelling anything, and the old one was also not punctured even though it was bent. And it's a lithium-polymer battery so the electrolyte should not leak anyway.I also found some complaints from people who noticed such smell after getting their phone back from a professional service shop. Apparently, they were having a similar issue as I do.For reference, some teardown videos:Video #1:Video #2:Video #3:

author: Jwillis
author_rank: Super Contributor
timestamp: March 06, 2024, 07:04:49 am
content: That it of plastic around the battery is just extra protection from shock and possible leakage. Mostly to keep the battery snug in the carrier. You can reuse it if you like or not. Just make sure the battery isn't going to dislodge and move about during operation. Two sided foam tape will work fine.

author: highvoltageboogie
author_rank: Contributor
timestamp: March 06, 2024, 04:23:02 pm
content: Quote from: Jwillis on March 06, 2024, 07:04:49 amHm, thanks for answer. I think the plastic wrap keeps it quite nicely there, not sure if it can still move a bit if the phone drops for example. I fixed the wrap to the phone with some two-sided tape, but didn't put anything between the wrap and the battery. There was some old adhesive left but I'm not sure how well it sticks to the battery. And some old pieces of tape holding it to the battery.If it works, don't fix it?The stench coming from the phone has decreased, I think. I hope it goes away over time. I noticed that it smells almost exactly like a type of glass cleaner that I use in my car. It contains plenty of fragrance. It's weird how strong the smell was when the battery was removed, and how it even comes through the seams of the phone.

author: Jwillis
author_rank: Super Contributor
timestamp: March 06, 2024, 08:35:04 pm
content: Quote from: highvoltageboogie on March 06, 2024, 04:23:02 pmAll synthetic substances give off different gases at varying rates depending on the molecular structure and age. Adhesives are no different. Disturbing adhesives can release these gases trapped within. These gases can accumulate inside the cases during and after manufacturing. As they dissipate in the air after release, the scent goes away because they human sense of smell is limited. Exposure is small, so I wouldn't worry to much about it being a health hazard.

author: John B
author_rank: Frequent Contributor
timestamp: March 06, 2024, 09:51:54 pm
content: You said the old battery was bent. Are you sure it didn't leak, hence the strong solvent smell, aka the electrolyte?

author: highvoltageboogie
author_rank: Contributor
timestamp: March 07, 2024, 07:11:37 pm
content: Quote from: Jwillis on March 06, 2024, 08:35:04 pmHm, sounds reasonable, thanks for your answer.I hope the battery doesn't move around too much. More tape may have been useful but I thought that the old adhesives may hold it a little bit.Quote from: John B on March 06, 2024, 09:51:54 pmI placed the old battery elsewhere and came back a bit later, and it didn't smell anything. So I think it couldn't be electrolyte.It also said "lithium polymer battery" so shouldn't it be unable to leak any liquid?

author: MarkT
author_rank: Frequent Contributor
timestamp: March 07, 2024, 07:56:20 pm
content: The sweet smell might be due to esters in the glue - the classic ester is ethyl-ethanoate, aka pear-drops. Of course there are many sweet-smelling compounds, some are definitely nasty, but I doubt anything highly toxic goes into a phone unless its essential to function. See this list of esters:https://en.wikipedia.org/wiki/Ester#List_of_ester_odorants

author: highvoltageboogie
author_rank: Contributor
timestamp: March 11, 2024, 03:23:58 pm
content: Ok, thanks for answers, I think this case is mostly solved... There's not much smell left.I think I'm not going to open the phone again to install the battery better... unless some problems arise.Battery lifetime is noticeably longer with the new battery, but my original problem didn't actually go away completely... The phone used to suddenly shut down during use. Often happened when the battery was somewhat low (15 or 20% for example) but could happen even at charge level over 60% when the phone was cold.Now it seems to do this less often but it has happened at least twice. The battery should be an original part and it was bought from a reputable shop, but if it was made when this phone was still being sold, it may not be in mint condition anymore. I'm not sure if an aftermarket battery would be better after all.