What is the maximum power SGS2 can use when charging, given a capable charger?

I use power-consuming apps while driving a car (navigation + video registrator), and looking for ways to minimize battery drain. Ready for custom ROM if it will allow higher current.

3 Answers 3


According to this youtube video, where the user measured actual current drawn while adjusting the settings, the maximum is 650ma (.65a).

Contrary to the first answer, the charging device cannot in any way "push" current into any device; it is like the AC outlet, which can supply a lot of current, but will never supply too much unless there is a defect or short.

The charger can only supply current, hopefully enough to satisfy the amount the device is trying to draw. You cannot damage your device by using an adaptor that supplies higher current, you can only slow down the charging by supplying too little. The device itself contains the charging circuitry that controls how much current is drawn at various stages of charging.

If the wall adaptor could damage a device by supplying too much current, then it would not be safe to plug it into the computer USB port, which is often capable of supplying higher current when properly negotiated by the device.


As @logos has said rightly having any modifications on ROM does not have any effect on the charge/Discharge.

  • First of all let's understand the simple concept of battery consumption.

    The device requires charge to run the software and perform various tasks done by the processor(graphics, antenna, GPS, Bluetooth etc.). It only depends on which kind of processor is used by your device and not by the ROM,having an updated or Increased ROM will only give you speed but not charge. IF this processor design is not good then due to some usage itself the device gets heated up thereby raising health concerns.

  • As the number of charge consuming hardware increases(NFC, Wi-Fi, Bluetooth, Graphic card, high output speakers, camera etc.) the battery capacity also increases (2500mAh or 3500mAh).If the battery capacity is less then you will suffer from low battery very soon and if the battery capacity is high(i.e. around 3000mAh) then the time required to do a full charge(100 % charge) will take some time
  • Due to this many smartphones in the market having higher capacity battery(Devices with high capacity battery are fixed permanently in your device for example Motorola e has higher capacity battery which can easily last for a day, has its battery soldered permanently in the phone and cannot be removed)

So next time you purchase a device go for a high capacity battery as well as the latest Android 4.4.4 operating System(the latest operating system of android is by far the best for consuming less and efficient battery management) .

Visit this site for further details about smartphone batteries.

Now coming to your phone usage in order to improve the battery life

  • Try reducing the screen brightness to optimum level and not automatic brightness.
  • Turn off the mobile data/Wi-Fi/G.P.S when not in use.
  • Use headphones instead of a speaker on your device wherever possible.
  • Last but not the least as you would be traveling a lot in your car invest in a Car charger accessory which is readily available and also gives you charge on the move.

Chraging is generally limited by hardware, not the ROM - ie, the charging cable and the device charging input and battery. Different charging adaptors can provide different amperages (eg, the Note II charger provides a 2amp feed). Using the wrong amperage may damage your device by overloading the charging port or battery, depending on your hardware; it's unlikely tho as the hardware should limit this.

If you're finding that your car charger is not providing enough juice, you might want to try buying a charging cord with higher amperage than the charging cord you're currently using. The maximum charge rating for a Galaxy S II is for 5V/1Amp.

  • "The maximum charge rating for a Galaxy S II is for 5V/1Amp." -- I wonder if there is any link confirming 1A here?
    – yurkennis
    Nov 3, 2013 at 20:09
  • "Chraging is generally limited by hardware, not the ROM - ie, the charging cable and the device charging input and battery" I believe it will be more correct to say that it can be limited by each of them. Although cable is much less likely to be a bottleneck -- more likely a charger and a device itself. And this comment suggests ROM can also limit the current -- the question is (a) whether any kernel allows more than 950mAh, (b) if not, to find an official confirmation Siyah really allows 950.
    – yurkennis
    Nov 3, 2013 at 20:49
  • @yurkennis: Google is your friend.
    – Logos
    Nov 4, 2013 at 0:23
  • This is where I started in the first place, prior to posting here.
    – yurkennis
    Nov 4, 2013 at 15:52
  • Well, you can either take my experience and general knowledge of the phone or leave it as you like - I'm afraid I can't provide supporting material for everything I know. I recall picking up the 1amp fact (all chargers are 5V, for whatever reason) on xda-dev when reading about 2amp Note II chargers, but wouldn't swear to that being the source. As for the ROM being able to modulate charging rate, I've not heard of such a thing myself but I'd be extremely leery of fiddling such if it was present - sound like a sure recipe for disaster.
    – Logos
    Nov 4, 2013 at 18:35

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