Hi I recently was given a second hand mobile fone a Samsung Galaxy s1910 it's a great little fone the only 2 issues I have are that 1 when charging it from either a amazon mains charger or from an onn 5000mAh portable power bank it charges to about 92% then on the mains charger it will briefly stop charging then restart multiple times till it gets to around 97% then it stops and refuses to charge any further with the onn power bank it gets to around the same sort of level then stops and I have to manually start it charging again. However when using a signalex power bank it goes to full charge does anyone know why this is happening? When I got the fone I bought it a new battery so it's not that it's not a thermal thing because as an experiment I put the fone on a cool table top just in case it was a thermal issue. The second issue is it won't let me access this forum or the vintage radio forum it says a secure connection couldn't be established whatever that means however I can get into this site via eMail notifications this a minor irritation but the charge thing irritates and concerns me hope someone knows the answer!
The advice about 20%-80% is good, but I would also add a caveat that overcharging li-ion batteries is bad for them (even if you ignore the thermal runaway problem). I messed up my phone battery through forgetting to take it off charge on numerous occasions and had to buy a replacement (battery, not phone). By being more wary, the replacement battery has already lasted much longer than the original and shows no discernible degradation.
If you want to check up on different battery types there is a very good website I refer to called 'The battery university'. I don't have it bookmarked, but it comes up high in any list when you search for battery information.
The quick check on the condition of a phone battery is to take it out, put it flat on a table or counter and try spinning it.
If the battery has started to fail and swell up it will spin quite easily, if it hasn’t you won’t get it to spin.
Andy Betteridge
That assumes you can actually get the battery out of the phone without destroying the phone and the battery in the process. Many phones these days are designed to be disposed of, not repaired. The cases are glued together, and the batteries glued into the phones.
I am still using my (pocket-sized) iPhone 4s. I plug it in and leave it until I need to take it with me. As far as I can tell, the battery is still within spec.
