Measure low current with mV range?

[ElectricPower]

The answer is possibly very simple, but i want to buy an Currentranger for measuring deep sleep current of arduino etc.

All videos i have seen show that everybody uses the multimeter in mV range for measure current. For a beginner like me thats strange. I have always used uA and mA mode.

Why can't i use my multimeter in current mode for measuring current with Currentranger?
And how can i be shure the Arduino pulls uA or mA when i measure with mV mode?

Thats strange to me... 

[IanB]

All videos i have seen show that everybody uses the multimeter in mV range for measure current.

Do you have a reference for such a video? Can you post a link?

To measure current you wish the meter to have the lowest resistance possible. A voltmeter theoretically has a very high resistance. So if you try use a voltmeter to measure current by passing the current through the meter, it would upset the measurement. You could use a voltmeter to measure the voltage drop across a resistor perhaps. You need to provide a reference before we can understand your question.

[ElectricPower]

All videos i have seen show that everybody uses the multimeter in mV range for measure current.

Do you have a reference for such a video? Can you post a link?

To measure current you wish the meter to have the lowest resistance possible. A voltmeter theoretically has a very high resistance. So if you try use a voltmeter to measure current by passing the current through the meter, it would upset the measurement. You could use a voltmeter to measure the voltage drop across a resistor perhaps. You need to provide a reference before we can understand your question.

Look from 07:10 in this video. The multimeter is in mV range:

[bdunham7]

Why can't i use my multimeter in current mode for measuring current with Currentranger?
And how can i be shure the Arduino pulls uA or mA when i measure with mV mode?

Because the output of the Current Ranger is in mV.  That's what it does--allows current through it and then outputs a voltage proportional to the current.  It says right on the front--"mV per nA/µA/mA".  Your multimeter actually does the same thing internally when you use it to measure current.  There's a shunt, the current flowing through the shunt results in a voltage drop, the meter measures that voltage and then calculates and displays the current.  The only meters that truly measure in current are analog movement meters from eons ago.

[ElectricPower]

Why can't i use my multimeter in current mode for measuring current with Currentranger?
And how can i be shure the Arduino pulls uA or mA when i measure with mV mode?

Because the output of the Current Ranger is in mV.  That's what it does--allows current through it and then outputs a voltage proportional to the current.  It says right on the front--"mV per nA/µA/mA".  Your multimeter actually does the same thing internally when you use it to measure current.  There's a shunt, the current flowing through the shunt results in a voltage drop, the meter measures that voltage and then calculates and displays the current.  The only meters that truly measure in current are analog movement meters from eons ago.

Ahh... then i understand. Thank you very mutch

[WattsThat]

The current ranger is an auto-ranging adaptation of Dave’s uCurrent (which is about half the price - when available).

For a good explanation why the devices exist, check out YouTube for “ammeter burden voltage” or Dave’s “building a better ammeter” video series.

[ElectricPower]

The current ranger is an auto-ranging adaptation of Dave’s uCurrent (which is about half the price - when available).

For a good explanation why the devices exist, check out YouTube for “ammeter burden voltage” or Dave’s “building a better ammeter” video series.

Thanks. I will do that