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ANALOG AMMETER READING HELP

Discussion in 'Gen 2 Prius Technical Discussion' started by Dxta, Oct 3, 2017.

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  1. Dxta

    Dxta Senior Member

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    Goodmorning, everyone.
    Please can anyone help with how to read this analog ammeter? Have being trying to see if I could use it as an ammeter during my battery rebuild processes, and I'm kinda getting frustrated not able to read it. It sure works, but how can it be read?

    If you look down beyond the 50 graduation, you'd see an approximate something like a 2.5 with a T inverted. What does that mean?

    Is it possible to use it as an instrument to measure the capacity of my modules, for instance? How should it be connected to a circuit during the discharge/charge cycles?

    Can I use a battery % monitor along side the ammeter to determine SOC?

    The battery % monitor is for 12-24V batteries, that are used for home solar inverters.
    Appreciate your responses

    PS: Please correct me if I'm wrong.

    This is how I get it connected when I'm reconditioning:

    One of the leads on the ammeter goes to the positive battery charger alligator clips, and the other ammeter lead goes to the negative of the battery charger alligator clip, before I connect to the battery poles of the batteries I'm charging.

    Do I need some sites of 1Kohm resistors in series to make the ammeter read the capacities of batteries while charging?

    This is what I find amazing: each time the leads are connected to commence charging a module, I usually noticed that the ammeter reading would be 12.0A(I don't know whether that's the reading), if the module voltage has a OCV of 6.50V. But as the module cells pick up some juice, you see the ammeter reading begins to rise to about 15.0A. It stabilizes to 16.0A, as the module voltage stabilizes at 8.50V.

    The question now is, does it mean the 16.0A is the actual capacity of the module, or its just that I'm not getting the readings correct(I don't know what the 2.5 with an inverted T meant)?

    Does it mean the 16.0A*2.5
    =40.0A would be the actual capacity of the modules?

    Dxta
     

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    #1 Dxta, Oct 3, 2017
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  2. Dxta

    Dxta Senior Member

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    #2 Dxta, Oct 3, 2017
  3. edthefox5

    edthefox5 Senior Member

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    You have to be in series with a battery load to measure current. There's no current flowing between neg and pos terminal on a battery.
    Thats how you measure voltage. Be aware most dvm's will not handle alot of dc current in ammeter mode. Its the best way to blow up a meter. Make sure there is a fuse installed to protect the meter port on the dvm.

    You should read up on some basic electronics.
     
    #3 edthefox5, Oct 3, 2017
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  4. Dxta

    Dxta Senior Member

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    OK, would do that.
     
    #4 Dxta, Oct 3, 2017
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  5. Dxta

    Dxta Senior Member

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    I'm not using a DVM ammeter.
    If you carefully look at the picture I sent, its an analog ammeter.
    Are you saying a fuse must be used on that ammeter in the picture to get the setup working?
     
    #5 Dxta, Oct 3, 2017
  6. ChapmanF

    ChapmanF Senior Member

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    As edthefox pointed out already, no, that's no way to use an ammeter. Putting it directly across a current source like that, it will try to measure the maximum current the source can produce. If you start, as you suggest, by just connecting it across the charger leads, it will show you your charger's maximum current, which probably won't destroy the ammeter, but also won't be a number you needed to know (you can probably read it from the label on the charger, anyway). But if you then attach the same clamps to your battery (where the answer to "what's its maximum current?" is "A LOT"), you will again get an answer that isn't interesting or useful, but that answer will also leave you without an ammeter, possibly without a battery, and possibly thinking nostalgically about your hands and eyes.

    Generally, you use an ammeter by adding it in series within an existing circuit that draws a controlled, limited current, so you can see what that current is.

    -Chap
     
    #6 ChapmanF, Oct 4, 2017
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  7. Dxta

    Dxta Senior Member

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    " without an eye, and...?" Heheheheh! Got you right and clear. That was what I really needed to know.

    Thanks Chap!


    Dxta
     
    #7 Dxta, Oct 4, 2017
  8. laser411

    laser411 Junior Member

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    If you are trying to test the maximun amperage of the batterry cell, you should either use a digital battery tester that tests internal resistance and then does the calculations for amperage. Either that or a load tester. Neither of those will do the pack at once and neither should you try either as it is very dangerous.
     
    #8 laser411, Oct 4, 2017
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  9. Dxta

    Dxta Senior Member

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    I think I'd consider the capacity tester thing.

    Dxta
     
    #9 Dxta, Oct 4, 2017
  10. VFerdman

    VFerdman Senior Member

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    Remember this: an ammeter presents very low impedance (ideally zero) and voltmeter presents a very high impedance (ideally infinity). So by connecting your ammeter in parallel to the battery you are basically shorting the battery out, same as connecting a wire instead of the ammeter. If your ammeter is not protected, you'll fry it and/or the battery. I have no idea what that ammeter in your picture is like, but if it's still alive, connect it in series with your battery, not parallel. Voltmeters go in parallel.

    In general, it will behoove you to invest into a decent DMM like Fluke or similar. These things are well protected and novice mistakes can be paid for with a cost of the fuse rather than the whole meter and/or battery module.
     
    #10 VFerdman, Oct 4, 2017
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  11. Dxta

    Dxta Senior Member

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    I have never said I wanted to connect it in parallel.
    Glad I did some few googling today, and got some of the information I had wanted.

    My initial question was is it possible to use an analog ammeter to measure battery capacity, and if possible, how do you read such a value on the graduated scale of an analog ammeter?

    Here's what have learnt so far today, finding out (1), hiw to read an analog ammeter connected serially in a circuit; (2), ammeters are pretty sensitive, and they kinda act as non load when connected in series in a circuit having a load.


    PS: I have a PEAKTECH DVM already.
    I just wanted to know how to make use of an analog ammeter, that's all.


    Dxta
     
    #11 Dxta, Oct 4, 2017
  12. MTL_hihy

    MTL_hihy Active Member

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    Couple things here.......

    1) Battery capacity is not measured in amps, it's amp-hours (number of amps divided by number of hours)
    2) You need to hook up both a DVM and the ammeter to the circuit correctly (ammeter - brown, voltmeter - black, load - resistance)

    [​IMG]

    In order to do a very crude capacity test you need to measure the number of amps the battery puts out over time (basically creating a plot of amps/hours). Obviously most would just purchase a basic digital RC battery tester to do this for you but I know your resources are a bit more limited than others.
     
    #12 MTL_hihy, Oct 6, 2017
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  13. edthefox5

    edthefox5 Senior Member

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    Very nice MTL.
     
    #13 edthefox5, Oct 6, 2017
  14. fuzzy1

    fuzzy1 Senior Member

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    As written, this is a parallel connection:
    My only advice would be: back off from this project, and get some electrical training. You are not yet betraying enough electrical knowledge to be safe or to do much of anything useful. Any additional advice I might try to give would only expose me to liability when you experience fire or smoke or 'unintended rapid disassembly'.
     
    #14 fuzzy1, Oct 6, 2017
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  15. edthefox5

    edthefox5 Senior Member

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    Yes URD is always exciting lol.....
     
    #15 edthefox5, Oct 7, 2017
  16. Dxta

    Dxta Senior Member

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    You
    You're probably right, but I clearly understand the dangers you're talking about.
    This was carried out on some of my test modules, and won't expose me to what you might be insinuating.
    In essence, what I wanted to jnderst was to see if one can use that analog ammeter for capacity test, and whether if the connections I did would do that. Someone here already said wasn't supposed to be parallel to even measure current, and that can't be used.

    So, right, have done some research about ammeters some few days ago.


    PS: I also asked whether the way I read the analog ammeter was correct.
    Appreciate your concerns.

    Dxta.
     
    #16 Dxta, Oct 7, 2017
  17. Dxta

    Dxta Senior Member

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    @MTL_hihy . GREAT!!! This has being what I was looking for.
    Youve cleared ALL the assumptions I was having about the analog ammeter thing, and whether it could be used for capacity testing.
    Thanks a thousand!

    Dxta
     
    #17 Dxta, Oct 7, 2017
  18. Dxta

    Dxta Senior Member

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    Heheheheh!
     
    #18 Dxta, Oct 7, 2017
  19. Dxta

    Dxta Senior Member

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    That was the kind of response I was expecting initially, but you know how it is....
     
    #19 Dxta, Oct 7, 2017
  20. MTL_hihy

    MTL_hihy Active Member

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    Remember to take your amp readings at regular intervals (every 5 mins or so should be enough) too because when you go to calculate the capacity you will be using the average amps over that time period and if your intervals are not exact then the calculation will be off.
     
    #20 MTL_hihy, Oct 7, 2017
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