Multimeters, How to check for current draw?

Submitted: Sunday, May 31, 2009 at 11:06
ThreadID: 69357 Views:3490 Replies:6 FollowUps:8
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I have a multimeter that I have had for a while and don't know how to use it to check for current draw.
Can some-one give me an idea on how to?
Shane
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Reply By: Member - Redbakk (WA) - Sunday, May 31, 2009 at 11:17

Sunday, May 31, 2009 at 11:17
Shane...you are limited to what they will measure (check scale) and they often have a seperate port for large readings (10 to 20 amps on some meters) otherwise you use a clamp or a shunt to measure large current values.

My meter will handle only up to 20 amps, but I also have a tong or clamp meter ac/dc that will measure up to 2000 amps.

If you can indicate how much current you desire to measure and or give us a description of your meter or make and model number and if we can we will google it and be able to help you more.
AnswerID: 367734

Follow Up By: Member - Shane D (QLD) - Sunday, May 31, 2009 at 11:52

Sunday, May 31, 2009 at 11:52
Image Could Not Be Found
The only ID on this uniy is : model MY68
I think it can only handle 10 amp
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FollowupID: 635368

Follow Up By: Member - Mike DID - Sunday, May 31, 2009 at 19:24

Sunday, May 31, 2009 at 19:24
Move the RED plug to the "A" terminal, and then connect the Red and Black leads in series with the wires taking the current - i.e you'll have to break into the wire.
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FollowupID: 635416

Reply By: Member - John and Val W (ACT) - Sunday, May 31, 2009 at 11:28

Sunday, May 31, 2009 at 11:28
Shane - see thread 67545 (Solar Panels....) where measuring current was discussed in some detail. As said already, there may be limitations with your meter.

A good way of measuring battery currents is to include a known calibrated resistor in series with the battery. Suitable high current ones of 1/1000 (that's one thousandth) of an ohm are available from Jaycar and elsewhere for $20+. By measuring the voltage drop across such a resistor you can get an accurate measure of the current flowing. With a 1/1000 th ohm resistor each amp results in 1 millivolt.

HTH

John
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AnswerID: 367736

Reply By: Time - Sunday, May 31, 2009 at 11:31

Sunday, May 31, 2009 at 11:31
Can I suggest you have a look at this website. Most informative.
AnswerID: 367738

Follow Up By: Member - Redbakk (WA) - Sunday, May 31, 2009 at 11:47

Sunday, May 31, 2009 at 11:47
Very nice mate.

.
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FollowupID: 635366

Reply By: Member - Norm C (QLD) - Sunday, May 31, 2009 at 12:35

Sunday, May 31, 2009 at 12:35
To measure current draw, you really need a 'clamp' meter, not a multi meter.

Until recently DC clamp meters were very expensive, but not so any more.

I bought this clamp meter on E Bay and it has been very good. It is a combined multi meter and clamp meter.

There are lots of others available, but this was about the cheapest and so far, it has done the job. I find it very handy when working on the 12 Volt systems in the vehicle and van.

Norm C

AnswerID: 367748

Follow Up By: Member No 1- Monday, Jun 01, 2009 at 08:14

Monday, Jun 01, 2009 at 08:14
thats an AC Tong tester
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FollowupID: 635451

Follow Up By: Member No 1- Monday, Jun 01, 2009 at 08:16

Monday, Jun 01, 2009 at 08:16
well at least the pics says it is

maybe they have used the wrong image?
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FollowupID: 635452

Follow Up By: Member - Norm C (QLD) - Monday, Jun 01, 2009 at 16:17

Monday, Jun 01, 2009 at 16:17
Not sure what pic you are looking at No 1. It is an AC /DC Clamp meter / Multi Meter. Have a look at the specs and the image is correct - identical to the one I have.
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FollowupID: 635509

Follow Up By: Member No 1- Monday, Jun 01, 2009 at 17:18

Monday, Jun 01, 2009 at 17:18
isnt DC represenetd by = while AC has the tildy '~' ?
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FollowupID: 635520

Reply By: Member - Mike DID - Sunday, May 31, 2009 at 19:21

Sunday, May 31, 2009 at 19:21
To measure current using a multimeter, you need to "break" into the wiring in which the current is flowing.

You need to use the current-measuring terminals on the multimeter.

BE SURE to move you test leads back to the voltage-measuring terminals when you've finished !! The current-measuring terminals are like a short circuit and will result in BIG sparks if you connect them across a battery to measure its voltage.


Jaycar make a special current-measuring adapter that plugs into a fuse-holder.
AnswerID: 367810

Follow Up By: Member - Shane D (QLD) - Monday, Jun 01, 2009 at 17:05

Monday, Jun 01, 2009 at 17:05
Thats it, Thanks for that, I didn't want to swap plugs around and fook something totally, thanks again.
Shane
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FollowupID: 635515

Reply By: Dunedigger - Monday, Jun 01, 2009 at 07:35

Monday, Jun 01, 2009 at 07:35
Here is the same one with free postage from Hong Kong for 38.67
http://www.dealextreme.com/details.dx/sku.15220

I havent bought from these people yet but will try then soon

Dunedigger
AnswerID: 367863

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