Are 450mA enough?(tablet charging)

Discussion in 'Power Electronics' started by UnnamedUser159, May 19, 2016.

  1. UnnamedUser159

    Thread Starter Member

    May 3, 2016
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    Hi there.
    Have one piece here. The microusb port is gone as option. I saw the jack power supply ability. Took one Nokia charger(new from store)5v but i see it`s 450mA. I ve heard that when the battery is totally discharged it has to be bringed back to life with 500mA charge. Are these 450mA enought and how many hours to wait for effect? If i put it now for charge in 12:30 is it problem if tonight is not ready to wait for tommorow morning - 10 for example?
    The battery has controller yh/maybe "M"/-jz-5045-c

    Greetings.
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,036
    The answer depends on your particular device, how it handles an unrecognized power source. For instance if I supply my iPhone a low current, it will not indicate charging but will slowly charge. Some devices may refuse to allow any charging if they do not see an adequate supply, or may limit themselves to charging at 100mA, the USB standard for an un-negotiated power connection.
     
  3. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    I measured now the voltage and it`s 3.4**.

    I hope everything will be fine.
     
  4. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    I`ve got a problem :(

    I think nothing happened with this 450ma adapter;

    had one new adapter from store - 5v/1a and put him a new small jack.

    put the adapter in wall socket and then into the tablet board. Take one multimeter in my hands and voltage was increasing. i thought "that`s that, success"

    Some seconds and the good noise of something burnt was heard.

    the adapter(ljh-186) is gone, no visible damage to the tablet board and 2 of the fuses where i work were in down position.

    what now?
     
  5. MrAl

    Well-Known Member

    Jun 17, 2014
    2,425
    490
    Hi,

    Dont you have a battery monitor in the Tablet itself you could check?
    You could use that to find out if the 450ma charger is working, letting it sit for some time like 1 hour.
    If the tablet is still working it may work.

    The adapter for my tablet is 5v and 2 amps. The charge is regulated inside the tablet.
     
  6. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    I think i left the 450ma charger for a long time and nothing happened.

    When i have time i will plug it again with 450ma and tell you what`s going on.
     
  7. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,036
    It may have shut itself down due to overheat. It might reset once it cools. It likely is undersized for your tablet.
     
  8. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
    1,190
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    Most tablets pull like 2amp and wont charge with anything less..
     
  9. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    16:00 local time 3.428/9 v.

    Let`s try again :)

    The 2A charger is gone. I am sure. I hear some noises when i shake it. Maybe the fuse is on pieces.
     
  10. UnnamedUser159

    Thread Starter Member

    May 3, 2016
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    0
    17:50 : same voltage :(
     
  11. dl324

    Distinguished Member

    Mar 30, 2015
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    What is the output voltage of the charger with no load and loaded?
     
  12. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    the charger is ac-11e

    on it i see 450ma
     
  13. dl324

    Distinguished Member

    Mar 30, 2015
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    Is this the adapter part number? Can you post a picture of the adapter specs?
     
  14. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
  15. MrAl

    Well-Known Member

    Jun 17, 2014
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    Hi,

    Sorry i cant help more, but it's hard to tell what is going on without measurements and such. A typical measurement would be to measure the current from the adapter to the tablet.
    Mine only requires about 1 amp average when running for example.

    Another method of charging is to remove the battery and charge externally, but this is harder to do when the battery is built in because you have to take the tablet apart and disconnect the battery wires, so you have to be proficient at doing soldering and stuff like that.
     
  16. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    So. i desoldered the wires of battery and push the power button to take the voltage out of the board. When i saw 0.000 soldered the wires, put the Nokia charger but for couple of hours only 0.002 V were added to battery.
    If charger N1(450ma nokia) is not compatible what else can i try? Of course i want to skip the adapters which are gonna go to salt inside.
    If the adapter 5v/1a was burned is it right to say that 1A is big for round type charging for this tablet ?
    The tablet is Firebrand F700. If someone can help me find the maker of this tablet i can write the people an e-mail and ask about Ac charge to circle port.

    Thanks
     
  17. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,036
    Try a charger rated at 2A or more. For instance see the charger here.

    If you cannot find one with the right tip to fit your tablet, see if one of those "universal" adapter kits can solve that for you. At worst, you can attach a new plug on the end. Be very careful about matching the proper polarity.
     
  18. hp1729

    Well-Known Member

    Nov 23, 2015
    1,950
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    450 mA is what my old cell phone draws when charging. To tell the current draw I hook it up to 1USB port with a USB meter. I got the meter from Electronic Goldmine for about $10.00. Part number G21309 I think it was.
     
  19. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    About the last post - the truth is i dont have weeks to purchase new device and i really dont understand what this can help me;
    If i understand right you offer me a device with i can measure how many A provides really the charger X,Y or Z.

    What is the logic to buy 2A charger when 1A worked seconds and then explodes? Wouldn`t be effect the same ?
     
  20. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,036
    No! Overloading a charger can cause it to overheat and fail. (A GOOD one has built in thermal protection, but a cheap one just dies.) A charger rated for the load you place on it is crucial. Note that it can be rated for a much larger load (5A, 10A, etc.) and it will be fine. You've been trying to squeeze blood from a stone.
     
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