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How to read amps on a Multimeter?

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Old 10-03-2012, 10:50 AM   #1
jeep&vette
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Default How to read amps on a Multimeter?

Okay - I've followed Bill Curlee's advice/threads on Battery Drain Tests.

He mentions 20 milliamps is good - once the car has gone to sleep.

I'm showing the following:

When meter is set to A - .104
When meter is set to mA - 1.04

Does this equate to 104 milliamps? or am I at 10 milliamps?

I checked every fuse under the hood and the footwell - not one fuse changed the reading.

Thanks
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Old 10-03-2012, 11:03 AM   #2
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.104 A = 104 mA

On mA scale, are you sure it read 1.04?

for the purpose of what you are doing, setting to the A scale is just fine. You've got 3 digits of resolution, and probably a 5% accuracy. Close enough for this. If you want to get fussy later, then switch to mA and get a more accurate reading. For now, you just know the draw is too much.

Leave it sit for a minute that way, and see if the reading doesn't go down some. Mine starts at 300ma, then to 150, to 80, and some time after drops to 25.

Last edited by K-Spaz; 10-03-2012 at 11:06 AM.
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Old 10-03-2012, 11:12 AM   #3
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Quote:
Originally Posted by K-Spaz View Post
.104 A = 104 mA

On mA scale, are you sure it read 1.04?
Pretty sure it showed 1.04. I'll do it again tonight and let it sit longer.

Thanks for your reply.
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Old 10-03-2012, 12:31 PM   #4
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Are the fuses in the meter good. Some meters have no fuse for the A scale and a small fuse for the mA scale. I would be suspect of the meter unless you can get both ranges to read similar values.
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Old 10-03-2012, 03:14 PM   #5
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Are you POSITIVE that you have the meter set up properly and,, are you in { SERIES } with the circuit???????????????

If it were 1.04 AMPS,, you could NOT see .104 ma

Look at it this way .999 milliamps is ONE micro amp less than 1 amp.

SO,,, your .104 ma can NOT be 1.04 amps. That reading does NOT make any sense..

I suspect the meter OR the method in which you using the meter OR an improper meter set up.

The NEGATIVE cable on the battery MUST be disconnected from the battery and the meter leads MUST be placed between the battery terminals and the battery neg cable.

The meter mode selector MUST be in the AMP or Milliamp position. Most meters have a specific separate jack to read current.

Recheck your set up. 20 milliamps should read out as .020 on the AMP SCALE OR 20.0 on the milliamp scale.

Last edited by Bill Curlee; 10-03-2012 at 03:17 PM.
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Old 10-03-2012, 03:57 PM   #6
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99% sure it was on "200 ma" setting with the 1.04 reading. This is why I always buy digital autoranging multimeters! I'm an electrical engineer, and I still trick myself out on what the reading actually says sometimes.

Like the other's said, just leave it on "Amps", and let the car sit for a bit and get another reading.

Also make sure you leave the hood open and unplug the underhood light
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Old 10-03-2012, 05:53 PM   #7
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Quote:
Originally Posted by Bill Curlee View Post
Are you POSITIVE that you have the meter set up properly and,, are you in { SERIES } with the circuit???????????????

If it were 1.04 AMPS,, you could NOT see .104 ma

Look at it this way .999 milliamps is ONE micro amp less than 1 amp.

SO,,, your .104 ma can NOT be 1.04 amps. That reading does NOT make any sense..

I suspect the meter OR the method in which you using the meter OR an improper meter set up.

The NEGATIVE cable on the battery MUST be disconnected from the battery and the meter leads MUST be placed between the battery terminals and the battery neg cable.

The meter mode selector MUST be in the AMP or Milliamp position. Most meters have a specific separate jack to read current.

Recheck your set up. 20 milliamps should read out as .020 on the AMP SCALE OR 20.0 on the milliamp scale.
Bill, unless I'm misreading his first post, he got .104 on AMPS, so 104ma. If so, he should have seen 104 on the ma scale, not 1.04. Either way though, one of the two readings doesn't jive.

Last edited by 65GGvert; 10-03-2012 at 05:55 PM.
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Old 10-03-2012, 06:14 PM   #8
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EXACTLY! The 1.04 reading is out to lunch..
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Old 10-04-2012, 08:53 AM   #9
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Thanks guys - I'm pretty sure I have the connections correct.

I'm going to redo the test tonight and if I can't figure it out I'll post pics of the meter/readings.
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