Current Clamp Meter Accuracy

Discussion in 'General Electronics Chat' started by chevylu, Sep 8, 2008.

  1. chevylu

    Thread Starter New Member

    Aug 15, 2008
    5
    0
    Is anyone familiar with the Current Clamp Meter kit available at http://www1.jaycar.com.au/productView.asp?ID=KC5368&CATID=25&keywords=&SPECIAL=&form=CAT&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=265

    .
    The kit appears to follow this article: http://www.siliconchip.com.au/cms/A_30669/article.html.

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    My multimeter has 5 DC Voltage ranges as follows:
    Range.....Resolution
    400mV.....100 microvolts
    4V........1mv
    40V.......10mV
    400V......100mV
    1000V.....1V
    .

    Do you think the kit would be able to provide accurate readings down to about 25 milliamps? I would like to use it to measure the parasitic battery drain on my car without having to insert the ammeter in line with a battery cable.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Not with the meter you have. 100uV = 0.1mV, and 0.1mV = 100mA current. You would need four times the resolution on your meter to be able to measure in increments of 25mA.

    A 90mA constant drain on your vehicle's battery will likely result in discharging the battery sufficiently over a few weeks' time to discharge it enough so that you won't be able to start it without a jump, or recharging the battery.

    It's hazardous to your meter attempting to measure current on a motor vehicle, an un-planned for sudden load (such as opening a door, a remote being activated, etc.) will at least blow the fuse.

    Consider purchasing a 1 Ohm power resistor, and install it temporarily (for troubleshooting purposes) between the battery + terminal and the + lead. Since I=E/R, measuring the voltage drop across the 1 Ohm resistor will allow you to directly read the current being used by your vehicle. 1mV=1mA. Not as convenient as a clamp-on ammeter, but certainly less expensive.

    As far as the clamp-on meter goes, I suppose it's output could be amplified - but I'm not going to pay for a subscription to Siliconchip.com.au for the privelidge of reading the article.
     
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