Yet Another Slow Charging Issue - Why?

[AC Question]

Samsung Galaxy Tab S2 9.7" running Android 6.x. Device is 14 months old.

My apologies in advance, but I have been trying to solve my problem for about a month now and have had no luck so far with the solutions found specific to my slow-charging issues. When I first got my Tab it would take about 2 hours to charge. I know the Samsung website says 4-5 hours but that was not the case with my device. I used to charge fully and wait until it was below 20% remaining. So it was charging more than 80% in about 2 hours. For a couple of months now it's been taking 4-5 hours to charge, or about 20% per hour. As of the last few days, it is now charging at 10% per hour. I have been using the 40-80 rule for about a week now, but I am still concerned with the increasingly slower charging times. The actual battery life seems to be the same, I think. Maybe its a bit shorter, I'm really not sure about that. My next step is to take it to a local Samasung repair shop ans have them diagnose it, but I thought I would try this forum first.

Something else of note. I had CM Security installed for a few months and about 3 months ago I tried enabling their battery charge monitor (or whatever it was). It was supposed to prevent overcharge and use trickle charging I think. The first thing I noticed was that this method increased charging time from the 2 hours to 4-5 hours. So I disabled this option and was back to 2-hour charging. About a month later, this option enabled itself. I only noticed because it was again taking 4-5 hours to charge. So I again disabled this option (while it was still plugged in) but it didn't solve the problem this time. It has been taking 4-5 hours to charge ever since, and now it's down to 10% per hour. Needless to say, CM is now uninstalled. I have tried Malewarebytes and Avast and they didn't find anything. They are both now uninstalled as well.

I have tried a soft reset, different wall outlets, different charger with different charge cord (2 amp from my Samsung phone) and I've tried recharging with the power off. Still no solution.

Any suggestions would be very appreciated. Thanks

 

[Rukbat]

When I first got my Tab it would take about 2 hours to charge. I know the Samsung website says 4-5 hours but that was not the case with my device.

That depends on what charge level you're charging from.

I used to charge fully and wait until it was below 20% remaining.

After 14 months of mistreating the battery like that (you shouldn't let it drop to below 40% charge), the battery is probably pretty well shot.

Something else of note. I had CM Security installed for a few months and about 3 months ago I tried enabling their battery charge monitor (or whatever it was). It was supposed to prevent overcharge

The phone itself does that. No phone charges a fully-charged battery. And you should NEVER install a Cheetah app in your phone - none of them actually work, and some of them do exactly the opposite of what they claim to do.

I have tried Malewarebytes and Avast and they didn't find anything. They are both now uninstalled as well.

You should reinstall both of them. They work.

Have the battery replaced, and start charging it at no lower than 40%. (Charging it when it's almost fully charged doesn't hurt it. Letting it run down to 20% does.)

 

[ForeverRogue]

Hello Rukbat - thank you very much for your time and for your concise reply.

After 14 months of mistreating the battery like that (you shouldn't let it drop to below 40% charge), the battery is probably pretty well shot.

Can you now please clarify the term "pretty well shot?" Do you mean that the battery will now drain quicker? Can you also please recommend a good app to test the battery health? Maybe one that might show bad cells? The few I've tried seem to indicate a "good" battery health.

Thanks again! Cheers!