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I have read some threads here and elsewhere about how to read what current range the multimeter might be displaying when a rotary switch has 10, 200m, 20m, 2m selections.

In the picture below i have a reading 01.7 when rotary switch has selected 200m setting.

I am taking my car’s idle current draw to determine parasitic draw.

I am not sure if the value is 170mA that is for sure too much or 17mA that is suspiciously low.

What is the correct interpretation?

enter image description here

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3 Answers 3

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There is an operational error here. The 200mA scale is selected but the positive probe is connected to the 10A (unfused) terminal. At this range and with this terminal, you'd have a 100mA resolution.

Be aware that to measure lower currents the other terminal should be used but it may cause the fuse protection to be opened. So, only use it if you are sure that the current measured is below the maximum range.

There seems to be an user manual available here, where this is to be found:

enter image description here

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    \$\begingroup\$ Okay, I will try the other one later on when i have access to the multimeter. Does the reading tell anything real or is it just bogus? \$\endgroup\$
    – Ilkkae
    Commented Nov 17 at 17:00
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    \$\begingroup\$ It is not possible to tell without knowing the internals of the multimeter. \$\endgroup\$
    – devnull
    Commented Nov 17 at 17:01
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    \$\begingroup\$ One thing to watch with looking for parasitic loads on cars is that you measure on 10A, it settles immediately to a few mA, you switch to a mA range, and blow the fuse. Changing modes breaks the circuit, but there's often a pulse of current drawn, too fast to register when you connect a car battery. 2 fuses later I realised that what I needed to do was connect the mA terminals, with an additional wire joining them, then put the meter in the circuit, then remove the wire. \$\endgroup\$
    – Chris H
    Commented Nov 18 at 15:09
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The reading of 01.7 on the 200m DC current range means 1.7 mA. However, the black the black lead is the COM terminal and he red lead is in the 10A terminal. This is an invalid combination of the dial setting and lead connections.

Either:

  1. If you expect a maximum current of < 200 mA set the dial to 200m and plug the red lead in the mA terminal.
  2. If you expect a maximum current > 200 mA and < 10 A set the dial to 10 and plug the red lead into the 10A terminal.
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  • \$\begingroup\$ I expect the car to ”wake up” and draw over 1Amp when battery is connected after removing negative wire.And when doors are locked after this i expect the car to go to ”sleep” and draw idle current. So i think then i might not be able to catch the correct range with one or the other red leads. \$\endgroup\$
    – Ilkkae
    Commented Nov 17 at 17:07
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  1. Make sure the car key is in your pocket. And everything inside is off, truly off. Car can draw surprising amount of current if you accidentally turn something on. Putting the key in an turning it, even to "just lights" position is not recommended (Guess how I blew up my first multimeter)

  2. It seems you have wrong scale selected. Turn the dial clockwise and see if the reading takes all 4 digits. If it doesn't, go clockwise again. Always try to use the full resolution of the instrument.

  3. The 'wrong terminal plugged in' shouldn't affect much, but it depends how the multimeter is wired internally. Most likely it just bypasses fuse, with warning that you should measure for N seconds then back off for K seconds to let the device cool down. It is recommended you use fused terminal here, as there may be surprise currents happening.

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    \$\begingroup\$ Thomas - Hi, Thanks for trying to help. However site members are flagging that this does not properly answer the specific question about how to interpret that reading on the meter. To reduce the likelihood of downvotes, can you edit the answer to improve it? Are you really sure you want to say "The 'wrong terminal plugged in' shouldn't affect much" without knowing whether that's definitely true for that specific meter? TY \$\endgroup\$
    – SamGibson ♦
    Commented Nov 18 at 9:21
  • \$\begingroup\$ @SamGibson Oh, its normal for the site to downvote answers into oblivion for any reason whatsoever. I just hope op or future readers see the advice to not put they key in, as that is an easy way to blow up their meters. The rest is just a restatement of other obvious errors. I did say "shouldn't" not "does not" regarding to wrong cable terminal, and noted it depends on internal wiring - cheap models have the terminals wired together, high end ones may have separate circuit for 10A, who knows. I do not need to write a paper on multimeter construction here I presume. \$\endgroup\$
    – Thomas
    Commented Nov 19 at 11:22

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