Samsung Galaxy Tab 2 10.1 Tests

I have had the opportunity to test a Samsung Galaxy Tab 2 10.1  GT-P5110 model  running under Android 4.0.3

1°) Battery charge:

The  wall charger coming with the Tab is given for a 2A nominal charging current.

Up to now most  Samsung smartphones did not give access to the battery current, fortunately it is possible to get the actual battery current on this Tab, so  I have installed Battery monitor widget to record it

Samsung Galaxy Tab 2 10.1  Tests sgt2-charging-cycle

The duration for a complete charge cycle is about 5h20mn. The charging current is 1.8A, and even at such a high current the Tab do not get hot. The max recorded temperature was less that 30°C.

The charging current is stopped when it gets down to 260mA and  simultaneously the battery is declared 100% charged.  Discontinuing the current through the battery once fully charged is good way to increase battery life. This is a good choice because battery is not removable……

The screen is switched on at the end of charge and gets on until the charger is disconnected.

It is possible to charge the battery with other charger model , even if the current they are able to deliver is lower than 2 Amps. I have tested different models:

sgt2-charger-tests

The V(I) curve is the same in the end of charge region so it is possible to calculate the expected full charging time as a function of charger current capacity

sgt2-charge-time-eval

The charging time do not increase so much when the charging current is only 1.2Amps, but is becomes prohibitive with USB PC 430mA sources….. 15 hours!!!!!

Some charger are not able to work with the Tab, for example the HTC wall charger coming with Diamond or Desire. This is a well known problem related to overcharged switching power supply

2°) Battery discharge:

 A full discharge test has been made with the screen manually set at max brightness and GPS Test continuously running

sgt2-discharge-cycle

When the state of charge get down 5% , most activities of the Tab are shut down and the screen is set at min brightness. Almost nothing can be done at this stage except charging it !!!! In fact this 5% residual charge is of no use!!!!

The calculated battery capacity from different charge and discharge full  cycles is comprised between 6600mAh and 6800mAh ,very close to the  nominal 7000mAh indicated by Samsung

The discharge current is continuously increasing during this test…. why??? nothing was change , no 3G , WiFi and Bluetooth off…. A further analysis shows that the Tab is working at constant power and not at constant current:

sgt2-constant-power-discharge

 

An analysis of the screen  battery consumption confirm this finding:

sgt2-screen-test

A full white photograph screened at max brightness draw a bit more than 4 Watt. A full dark photograph needs a little bit less than 4 Watt in the same condition.On the other hand a full white photograph at min brightness needs only 1.5 watt. This means that the screen is the highest  power draining part of the Tab. As a comparison the GPS alone  needs 98mA ( 0.38 Watt)

The screen brightness can be automatically adjusted depending on the ambient luminosity. It is highly recommended to select this option.

3°) State of charge indicator:

The comparison of the calculated  state of charge  from the full  discharge current data and the indicated state of charge by the tablet are in perfect agreement

soc-comparison

This means that the battery gas gauge system of this tablet is based on  »coulomb counting » method. 

Such a method has had some drawback with for example the HTC Desire as reported here.  May be this method has been improved since then?

4°) Other observations: 

 The GPS get a fix very quickly. It works with both GPS ( US) system and Glonass  (USSR) system simultaneously. It is also very sensitive, but some care should be taken to avoid to mask the antenna from viewing the satellites.

WiFi connection is also very quick, and sensitivity is better than Galaxy Nexus.

The screen  drains more current than standard USB PC is able to deliver. This might be a problem for developers working all day long with this Tab……

It is impossible to read bar codes or QR codes because  the camera is not  autofocus. It is a very  big problem

 

 

 



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