Digital multimeter - test parasitic draw 12v

[ajm]

Have I got this set up properly to test car battery for parasitic draw?IMG20250526194628.jpg

[droog]

Check the make / model and see what the user manual says but the way I read it it is set up to measure current up to 10A on the next position clockwise.
Parasitic draw ??? , what current draw are to attempting to measure?
Remember if you are attempting to measure a current and go over the rating the protective fuse in the meter will blow so do not get it set up and then turn on some normal loads by accident.

[mic-d]

I have had great success asking chat GPT with things like this. It helped me diagnose a fault in a small dust extractor. I uploaded your photo and asked for you and here is the reply. Note Droogs warning too. Just for example. I suggest you do your own chat though it seems like it offers some sensible info about the multimeter setup.

Thanks for the image. Based on what I see, the multimeter is set up incorrectly for measuring parasitic current draw in a car. Here's why:
What's wrong with the current setup:

1. Red probe is in the 10A port: This port is typically used for measuring high current (up to 10A), but parasitic draw in a car is usually milliamps (mA) — far below 10A.
   
2. Dial is set to a high current (A) range: This will not give accurate resolution for the small current draw typical of parasitic drain, which is usually in the range of 20–100 mA.
   
3. The circuit might not be correctly broken: From the image alone we can't confirm, but remember that to measure current, the multimeter must be connected in series with the circuit (i.e., between the battery and the disconnected terminal).

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Correct way to measure parasitic current draw:

1. Turn off everything in the car and let it sit for ~30 minutes to allow all ECUs/modules to sleep.

2. Set up the multimeter:

• Red probe in the mA port (marked µA/mA — the rightmost port in your image).
  
• Black probe stays in COM.
  
• Set dial to mA or µA (or auto-ranging current mode, if available).
  
• Ensure the meter is fused properly for mA measurements.

3. Break the circuit:

• Disconnect the negative battery terminal.
  
• Connect the multimeter in series between the battery negative post and the disconnected cable.

4. Read the value:

• A healthy parasitic draw is usually below 50 mA.
  
• Anything above 100 mA may indicate a problem.

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Safety Note:

• Never attempt to crank the car or turn on high-load devices while the multimeter is in-line — it can blow the fuse or damage the meter if in mA mode.

[ErrolFlynn]

The trouble with this is that modern vehicles all (in so far as I'm aware) have a battery draw. So, unless you know what the current should be, the measurement you get may not be much of an indication. From little circuits that flash a red light on the dash that pretend to be some kind of antitheft device (that does nothing) to the clock that goes 'ticking' away (that you probably want on anyway), it would be difficult to know what's good or bad.

I can park my 30-year-old Toyota and go back to it, having not touched it in six months, and turn the ignition key, and it will start. If I try that with my Commodore, I'd be lucky if the interior light would come on. I fancy that different cars demand different amounts from their battery, to say nothing of batteries that just slowly go flat by themselves because some happen to have been made better than others.