Slow charging when connected to computer's USBSupport

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  1. joop1987

    joop1987 Member

    If anyone is wondering why their Optimus V is charging slow I found out why. The OEM charger outputs 5.1V while the USB connected from the computer is only 5.0V. When the phone sees 5.1V is goes into "AC Power" charging mode. You will notice it charges a lot faster and the battery will get warm.

    Download the app OSMonitor and select the Misc tab. You will see what mode your phone is charging; AC Power or USB Power.

  2. TVCCS

    TVCCS Well-Known Member

    Actually...I believe it's 500ma (0.5 amp) from the USB port. The OEM AC charger is 5.1 volts, but its output is 700ma (0.7 amp) - that's the actual output being delivered by the charger/port. There is some pretty detailed electrical analysis by a user at Howard suggesting the port on the phone is regulated to accept no more than 400ma (0.4 amp).

    All that being said, the phone does seem to charge faster from the AC adapter than a USB port.
  3. lynx2cross

    lynx2cross Well-Known Member

    Every phone I have every owned does the same thing, and when yo think about it, makes perfect sense that the battery would charge much quicker plugged directly into an electrical outlet compared to going through your computer usb port.
  4. jetfactor

    jetfactor Well-Known Member

    i left my USB charger at work on accident and had 10% battery left. i've always had LG phones so i dig through my desk and found a charger that would work and plugged that sucker into the wall. damn, way faster!
  5. radiotecha1234

    radiotecha1234 Well-Known Member

    I used to have an HTC Evo. While I had it I found out that if you take a car charger or a usb cable and solder the two inside pins together (the data lines) it tells Android you are on a wall charger and charges at the higher rate. I tested this setup with my new Optimus V at lunch and it works for that one too. If you download spare parts from the market and go to battery information it will show what type of charging it is doing. Here is just one of many links that cover the subject over at XDA dev [FAQ] Charger mod, howto USB fast charge. [Archive] - xda-developers
  6. TVCCS

    TVCCS Well-Known Member

    I assume the cable is useless for data at that point...or not?
  7. radiotecha1234

    radiotecha1234 Well-Known Member

    Actually, the way I did it was I got a Scosche usb dc charger from Walmart. Similiar to this adapter here: ZIP-LINQ USB to Car Power Adapter, iPhone Compatible: Computers

    Then you just open it up and solder the two inside pins on that board. That way you won't mess up a good data cable. But, you can do it either way. The guy on the link in the post above used a "jumper" or short extension cord to make the connection. Either way works.

    When I went back to work I tried it on this : Wireless Gear/Triple 12 Volts and USB quad outlet power source splitter (TW2911) | 12 Volts Socket Adapter |

    And it worked great. It is only supposed to be able to output 500 mA. But, my meter showed my phone was pulling 650 mA through it just fine with no heating of the internal components which is fine considering the whole adapter is fused for 3000 mA or 3 amps.
    The phone will pull as much current as it is designed for that's why sometimes the battery can get quite hot. The charger is designed to help prevent thermal runaway of the battery. The HTC I used to have was rated 5.0 Volts @ 1 amp and that sucker could get hot as heck. Especially, if you are wireless tethering.
  8. Leslie Ann

    Leslie Ann Well-Known Member Developer

    It's probably protection in case someone plugs it into a usb 1.0 port.

    Some old USB ports can barely pull 400 or 500ma, while newer ports can provide as much as 900ma or more. Add an unpowered hub and you are cutting that down even more.

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