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Checking the battery capacity with a meter?

airbites 60625 15
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  • #1
    airbites
    Level 22  
    Hello, I have a question. How can I check the battery capacity, i.e. fingers, batteries in a cell and others with a meter? or do you need to calculate ?? because I know there is a charger with a capacity measurement function, but I have two chargers with a timer. Regards.
  • #2
    Rzuuf
    Level 43  
    Hello!
    With such an "ordinary" meter you cannot measure the capacitance, but you can make another valuable measurement: short-circuit current (with a multimeter, range 10A, short!).
    Sticks, i.e. AA, can give even a dozen Ampere (as they are charged and good), and the smaller "AAA" give up to 8A.
    Sticks that give less than 5A are suitable for even less ambitious applications, and those that give 1 - 2A can be scrapped.
    If you connect rechargeable batteries into batteries, try to choose them so that in one "package" all of them have a similar short-circuit current.
    After reaching the state of discharge, when the device (e.g. a camera) refuses to work, measure the batteries again - first the voltage, then the short-circuit current. Save your results! It will be useful for later selection.
    To measure the capacity, the batteries must be discharged with the "C / 10" current, which can last even more than 10 hours.
  • #3
    User removed account
    Level 1  
  • #4
    gregor50+
    Level 19  
    Hello.
    I propose a method for calculating the internal resistance.
    On this basis, you will assess the condition of the battery or accumulator.
    All you need is a "small" current, a good voltmeter, and an exact load value.
    This is how the service life of the battery is professionally assessed.
    Of course, if you do not have output data (a new source), you have to compare it with other sources.
  • #5
    airbites
    Level 22  
    I have a short-circuit current up to 10A in the meter and I will give the result:
    AA fingers: TRONIC 2100 mAh 1.2V
    test with meter:
    one battery: 1.249V 2.73A
    long battery: 1.257V 3.15A
    3rd battery: 1.259V 2.21A
    fourth whip: 1.263 V 2.68 A.

    On the third and fourth, the digital camera does not fully respond to the power button.
    And on both batteries, the digital camera responds and a low battery appears on the shutdown and turns off.

    And one more thing I tried to check how much the digital camera is tearing the current out with a mulimeter, but it gave a result like 1.1 A but the camera did not turn on, the screen does not show and the object does not extend.
  • #6
    Rzuuf
    Level 43  
    Unfortunately, the value of these cells is below the requirements of your camera.
    If the short-circuit current is 2.5A, then with a load of about 1.1A, the voltage on the cell is only about 0.7V, instead of about 1.2V (well, let's say 1.1).
    Thus, you can qualify cells with a short-circuit current of about 8-10A, preferably higher, as "fit".
    My best "fingers" gave even 15A, the photo camera works on them, it is a joy to look at ...
    One more way: you put the cells into the camera, turn on the flash mode and count how many seconds (or the light flashes) before the camera is ready. This way, you can select your batteries according to their efficiency. See the manual, as the camera manufacturer states, what is the time for ready to shoot with a flash, on this basis you can exclude cells with too low efficiency from use.
    One more thing: all measurements must be made on fully charged batteries.
  • #7
    airbites
    Level 22  
    I have recharged these batteries and I give the result:
    1.459V 3.70A
    2.451V 4.65A
    3. 1.423 V 3.31 A
    4.452V 4.26A

    I was charging for 10 hours and with a charging current of 270 mA.
    Do I count well, for example 3.70 And is 3700 mAh ??
  • #8
    Rzuuf
    Level 43  
    Well, now try how No. 2 and No. 4 will work, now they are the best.
    And one more thing: self-discharge of NiMH batteries is at the level of 1 - 1.5% A DAY! It means that a fully charged battery after a month of "standstill" has only 1/2 - 2/3 of the charge ...
  • #9
    airbites
    Level 22  
    I checked the batteries 1 and 3 and took a few photos and it turned off, i.e. the message that it is exhausted: /. now I will check batteries 2 and 4.
  • #10
    Rzuuf
    Level 43  
    I read your post again: charging 2100mAh batteries with 270mA current is too intense, if you charge "on time, and you have no voltage limitation," overcharging "may cause excessive pressure inside the cells and" dry "the electrolyte - and thus destroy the batteries. It is safe to charge up to a final voltage of 1.42V per cell, if you want, I will give you a diagram of such a safe charger.
  • #11
    airbites
    Level 22  
    Then give this diagram :) And I have a time charger: / Tronic KH 967 and GP companies, but also on time, but it charges at 450 mAh and so I counted on time. And I was charging for about 10 hours. and after that they were so sick that I almost burned my hands: / And can you give me some good chargers that control the temperature, etc. ?? I am thinking about this BC 700 charger (?) But I do not know if it is good because it shows the capacity of mAh there and I do not know if it shows the capacity of, for example, alkaline and ordinary batteries ??
  • #12
    Rzuuf
    Level 43  
    Here you have a diagram:
    Checking the battery capacity with a meter?
    You choose R1 so that half of the nominal current on this resistor gives about 0.5V. For 2100mAh, the nominal current is 210mA, so R1 = 5 to 10?.
    You choose R2 so that the output is n times 1.42V, where n = the number of charged cells connected in series.

    The charger works in such a way that after switching on the LED diode lights up continuously, and when charging is finished, the diode flashes - initially fast, then slower and then goes out.
    The system should be powered from a source with a voltage higher by approx. 4 - 5V over 1.42V times the number of cells, so for 4 cells it should be approx. 10V.

    The charger works unattended, and its final charging voltage does not allow the cells to be overcharged.
  • #13
    airbites
    Level 22  
    Thanks and you can show me the picture because it will make it even easier for me. I know a little about this diagram. if I do something, it's a short circuit only.

    PS on two batteries as a conference, I took about 250 photos with the flash and I still do. Although it shows that the battery is exhausted.

    Added after 13 [minutes]:

    Ok, he took about 310 photos on batteries 2 and 4 and on 1 and 3 he did max 10 photos.
  • #14
    Rzuuf
    Level 43  
    Well, you have a practical confirmation of the method of estimating the value (or efficiency) of the rechargeable batteries.

    I will not show you the photo, the system is assembled WITHOUT a PLATE inside the charger housing for the wireless mouse.
  • #15
    airbites
    Level 22  
    AA I also have such a charger for a wireless mouse and this lamp becomes weak and very weak, it means that it is charged.
  • #16
    oj
    Level 42  
    airbites wrote:
    I am thinking about this BC 700 charger (?) But I do not know if it is good because it shows the capacity of mAh there and I do not know if it shows the capacity of, for example, alkaline and ordinary batteries ??


    It does not show because you cannot put (disposable) batteries there. Buy normal batteries, not some grandfathers.


    Besides, such testing (for short circuit) only destroys the batteries and does not indicate any efficiency.