My first notebook battery cells replacing. Have some questions

Discussion in 'The Projects Forum' started by UnnamedUser159, May 9, 2016.

  1. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    Hi there.
    The first item i will try with is samsung aa-pb9nc6b

    So i begin..
    Does this battery requiere a voltage while i am doing the replacing of the cells? If yes how many should be that voltage because i don`t have the original charger by myside?
    Would you recommend me some cells trademark ?
    After doing the replacement i should do full charge and discharge of the battery for reseting these flags. Full Charge - ok - i will connect to charger and measure the voltage with digital multimeter and will find when it`s fully charged. How to discharge the battery - what load can i use?
    Finaly test the battery with new cells plugged in the Mainboard socket and try to charge more that 30 secs?

    Thanks in advance

    edit - i read http://batteryuniversity.com/learn/article/how_to_repair_a_laptop_battery
     
  2. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
    1,190
    156
    With any kind of repair like this it's hit or miss .. The problem comes as these pack have a battery gauge that pretty kills the pack and tells the laptop it needs to be replaced. Sometimes you get lucky and have a dead cell or 2 but won't know till you open it up..
     
  3. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    The battery is open and in front of me.
    Cells:
    1.672
    2.646
    -0.484 ?!
    1.673
    2.646
    -0.482

    i measure the voltages directly when just only opening the case.
    1st cell 2 3
    4 5 6

    Which cells should be replaced ? :)

    Nice day

    ...and what is the one "good" voltage and what is bad? I have here some notebook bateries and maybe one day will renew them ;
     
  4. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,999
    745
    The two cells reading -0.48V, these are damaged.
     
    Dr.killjoy likes this.
  5. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    So...

    The battery rating i see is 11.1v How to put backup voltage while replacing the cells? Call my friend to tell me what voltage is his charger for notebook and find one piece with such voltage and connect it via R 100 Ohms?

    The original cells are Samsung ICR18650-22F 2200mAh (Green)
    I have 6 cells here model se us18650gr.
    But i see they are 2550mAh. Would be that a problem?

    Nice day :)

    Edit #1 I see that i have to replace the cells if they are below 2.4-2.9V. Why i dont have to replace the other 2 too(1.672 and 1.673) ?
     
  6. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,999
    745
    The bigger capacity will hold the voltage longer,2250mah will do.
     
  7. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    Hi again.
    I have one small notebook from a lot of time here.
    I want to use it to test some items not from my office, because it`s size. I have nothing to lose - this battery is dead;

    "To assure continued operation when changing the cells, supply a secondary voltage of same voltage level through a 100-Ohm resistor to the circuit before disconnection. Remove the outside supply only after the circuit receives voltage again from the new cells. Furthermore, some fuel gauge chips run wires to each cell. These must be reassembled in the correct sequence beginning with cell one, then two, three and so forth."

    So. If the battery voltage is 11 volts for example i should supply to the electronic board the same voltage thought 100 Ohm resistor added to + ?
    How in real life to do that ?

    Greetings ;)
     
  8. wayneh

    Expert

    Sep 9, 2010
    12,153
    3,058
    That's the way I read it. Instead of placing the leads of an 11V supply directly to the device, I'd add a 100Ω resistor in series. This would cause the voltage seen by the device to drop by 1V for every 10mA of current draw. That doesn't make sense to me but whoever wrote those instructions must of had a reason to choose 100Ω. I speculate – wild guess – that the normal current draw while on standby, to avoid resetting the clock, hold the information in RAM, or whatever, is in the mV range. But if your device is already dead, there's no reason to worry about it going while you change the battery. It may be too late for that.
     
  9. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    "But if your device is already dead, there's no reason to worry about it going while you change the battery"

    You mean cells, right?
     
  10. wayneh

    Expert

    Sep 9, 2010
    12,153
    3,058
    I mean that you don't need to worry about supplying a little power to preserve the memory if it has already been stone dead for a long time. The memory would already be long gone in that case. Just put in the new battery and start over.
     
  11. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    I find inside 6 cells type sf us18650gr
    They are now 3x2.
    The two cells are connected by a plate which i can`t really understand how to deinstall.
    0.051 and going to 0
    the other cell is -04.09

    How to proceed? :)
     
    Last edited: Aug 18, 2016
  12. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    I have modified my last Post and want to put this thread up :)
     
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