Galaxy Tab S 8.4 battery drains when off

radioham1

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Dec 23, 2016
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Hi,
I've been using this Tab S since July 2014 and been very pleased of it.
I only use it every night for Web browsing or watching movies.
Not any games or any social network or anything draining the battery.
Average autonomy was around 7 to 8 hours.
9 months ago it has started to drain a little bit more and especially when off (totaly off, not in sleep mode)
Before that event I was turning it off at night and 24 hours later the battery level was exactly the same. (zero percent of drift)
Then it started to suck a little bit every day: 1%, 2%, 3% each 24 hours when completly OFF.
First thing I've done was to make a wipe cache/data and restore to factory settings from recovery mode.
It didn't help.
Then Samsung released Lolipop Upgrade so I did it.
It didn't help any more.
So I ordered a new battery to an official dealer and replaced it.
You know the answer.... didn't help.
Then Marshmallow has come and I did it.
.... idem.
So as electronics and automation technician I am, I decided myself to do some measurements.
I opened the Tab S and checked battery voltage when off every hour with a high accuracy Fluke D.M.M.
And I found that it was loosing ~34mV every 24 hours, which makes the 3% loss.
(Boring calculations just for knownledge : LiPo Vmax 4350mV - LiPoVmin 3200mV = 1150mV corresponding to 100% capacity.)
First thing I did after that was to make the same check but with battery disconnected to the Tab S.
And you know what? not even a mV drained in 24 hours when not connected to Tab S PC Board!
Then I measured the resistance between + and - socket on the PC board : value between 800KOhms and 1,2MOhms.
Same values when I crossed the wires.
Theses values are too low, I should have found many many MOhms.
I've also checked the battery connector that some other guys said it was loosy or bad soldered: that's not the case but I've soldered it.
same problem.
MY CONCLUSION: it's a hardware problem.
Maybe it's a drifting component, probably a capacitor which as lost insulation, or a defective diode.
Unfortunately I don't have the diagrams of this Tab S and can't diagnose it.
Has anybody had the same problem?
 

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