Amp Draw-Equipment needed and directions how!

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I would like to measure current[Amp]draw for several of my lights/batteries.

What equipment do I need and how is it done?

All I have is a Voltage meter. I would think more is needed?

,,,,,,,,Thanks
 

hiuintahs

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As you are aware, in order to make a current measurement, you have to break the circuit and put the meter in series. If you have a decent DMM, you can put the meter in current mode, move the leads to the current out jack and insert the leads between flashlight tail cap and battery. A more sophisticated route is to use a precision resistor in series with your device and then measure the voltage across the resistor and use ohms law to come up with the current. The drawback here is that you need a small resistor in most cases so as to not interfere with the operation of the device for which you are trying to measure.
 

Enderman

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Use a clamp meter like the UT210E.
It's cheap and works great, almost all modders/testers over on the other flashlight forum have this exact model.
Unlike a multimeter, it doesn't go in series in the circuit, so it gives more accurate readings without changing any resistance.
All you need to do is put the clamp around one main power wire and set it to measure DC current.
 
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Thanks everyone.

archimedes link helped me measure several lights by placing probe on battery and the other on the body. As the article stated if they are anodized the method presented will not work.

I have to read more and find out the simplest method to measure current draw for my lights that are anodized and ones w/ 3 or 4 batteries.
 

archimedes

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Thanks everyone.

archimedes link helped me measure several lights by placing probe on battery and the other on the body. As the article stated if they are anodized the method presented will not work.

I have to read more and find out the simplest method to measure current draw for my lights that are anodized and ones w/ 3 or 4 batteries.

You are welcome.

That is not my article, by the way, it was written by another CPF member here.
 
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The numbers race back and forth for awhile until they stabilize. The longer I hold the probes on the higher the Amps get.

I guess if I choose the highest number that would be the MAX Amp draw?
 
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^^^^

I am sure that UT210E is more accurate.The numbers did not fluctuate back and forth. I saw them range in price from ~ $20 to $60.

On the other hand the guy in the video struggled a lot more w/ his readings than I did. His battery seemed a lot looser, the DMM was all over the place and he was having difficulty keeping the light on.
 

hiuintahs

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Use a clamp meter like the UT210E.
It's cheap and works great, almost all modders/testers over on the other flashlight forum have this exact model.
Unlike a multimeter, it doesn't go in series in the circuit, so it gives more accurate readings without changing any resistance.
All you need to do is put the clamp around one main power wire and set it to measure DC current.
It won't necessarily give a more accurate reading.........just depends on the system that is being tested. I have the UT210E. I bought it to measure the parasitic drain on my truck which is around 50mA..........because I didn't want to unhook the battery terminal just to occasionally check the current. The lowest setting is 2A so you would have 3 decimal place current. So that is 1mA, but it jumps all over the place. And you constantly have to zero it out. It's tough for these clamp meters to read small currents and can't read a small current like the uA of parasitic drain of electronic controlled switched lights because the resolution isn't there. It has its place but I guess it just depends on the device of which you are trying to measure the current.
 

Enderman

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It won't necessarily give a more accurate reading.........just depends on the system that is being tested. I have the UT210E. I bought it to measure the parasitic drain on my truck which is around 50mA..........because I didn't want to unhook the battery terminal just to occasionally check the current. The lowest setting is 2A so you would have 3 decimal place current. So that is 1mA, but it jumps all over the place. And you constantly have to zero it out. It's tough for these clamp meters to read small currents and can't read a small current like the uA of parasitic drain of electronic controlled switched lights because the resolution isn't there. It has its place but I guess it just depends on the device of which you are trying to measure the current.
From reading OP's post it seems like he wants to measure the amp draw of his lights when they are on, not parasitic drain in microamps.
The UT210E is great for regular flashlight amp draws, because it doesn't add anything to the circuits and therefore gives an accurate reading.
It may not be as precise as a multimeter with 4 decimal places, but what matters here is accuracy not precision.
 

KITROBASKIN

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From what it looks like, using the method shown will not test the resistance of the flashlight switch, and therefore amperage draw while in normal use is unknown.

Could an accurate light meter and a timer be used to get relative comparisons between batteries, or emitters? Is there another way?
 
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Use a clamp meter like the UT210E.
It's cheap and works great, almost all modders/testers over on the other flashlight forum have this exact model.
Unlike a multimeter, it doesn't go in series in the circuit, so it gives more accurate readings without changing any resistance.
All you need to do is put the clamp around one main power wire and set it to measure DC current.

Thanks for the suggestion.

1.Can this[UT210E] device measure lights that are anodized and ones that have multiple batteries? If so, what is the method for accomplishing that?

2. For now, is there any way w/ a DMM to measure Amp draw for lights w/ multiple batteries. Battery carriers w/ 3 or 4 batteries that are anodized?

Thanks
 

Enderman

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You just need to put a wire somewhere that completes the circuit outside of the battery carrier and measure the current through that wire.
 
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You just need to put a wire somewhere that completes the circuit outside of the battery carrier and measure the current through that wire.

Ok,,,Thanks.

Do you know the answer to question #2?


I was able to position the flashlight better and my readings were much more stabilized. I actually got them to stop for 5 seconds or more.
 
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I do not know a lot about electricity but this still baffles me.

I was only able to test amp draw w/ my DMM. It would not check voltage anymore. So I took it apart hoping the fuse blew. It did and I replaced it and both are working now.

How can a DMM measure Amp draw w/ a blown fuse and Not voltage?! I would think the entire DMM would be inoperable.
 

hiuintahs

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..........How can a DMM measure Amp draw w/ a blown fuse and Not voltage?! I would think the entire DMM would be inoperable.
Something doesn't add up there so not sure why.

I've accidentally blown the fuse before. It happens when you get in a hurry and forget to move the leads off of the current jack on the DMM before you move the dial over and make a voltage measurement. I'm not sure what brand of DMM you have but the Fluke I have will beep at you if you move the dial while the leads are still in the current measurement jack. When measuring voltage, the meter is a high impedance to that voltage source and will not draw much current at all from the measuring source. When measuring current the meter is a low impedance (ie: through a small sense resistor in the meter). Thus its necessary to have a fuse inline to protect the workings of the meter. However my experience is that with a blown fuse, voltage measurements still works but the current won't.

But if its working now with fuse replaced, I wouldn't worry about it.

What light are you having trouble measuring the current on? A picture of your setup?
 
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The only lights I had trouble with are the anodized ones. In the link archimedes provided it stated it would NOT work w/ anodized threads.

LOL,,,I think I just got my answer as to why it worked w/ Amp draw and NOT Voltage. At bottom of DMM on Left[10A] it states "Unfused" and on Right it states "Fused". The Two holes on Right are for my Voltage readings.

Etek_DMM.jpg
 
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