Amp Draw-Equipment needed and directions how!

[IlluminationDomination]

I saw a video of a guy checking Amp draw w/ a DMM. He had his own custom[thicker] wires w/ the tips soldered. He got an increase of ~ 1amp compared to using the leads that come w/ the DMM. He said the increase was because the leads have little indents/notches at the end which restrict the current flow.Similar concept as a bottle neck restricting water flow.

If that is true why don't they make the leads completely solid instead of having the indents/notches at the end?

Thanks

 

[hiuintahs]

Even with anodized threads, the flashlight tube should still be bare aluminum on the tube end, right? That is where I make my connection point with one of the DMM leads.

 

[IlluminationDomination]

Even with anodized threads, the flashlight tube should still be bare aluminum on the tube end, right? That is where I make my connection point with one of the DMM leads.

That is not the case w/ my U21 and M2X.

 

[hiuintahs]

Olight M2X-UT? I don't have one but was looking at Going Gear's review and I could see bare aluminum on the end of the battery tube where the tail cap would make electrical contact once screwed all the way on.

 

[IlluminationDomination]

^^^

You are correct. The first time I was down too far on the threads. The second time I went inside the tub[anodized]. The Third time was the charm.

 

[Curious_character]

A problem with measuring flashlight current is that any ammeter drops the voltage, so you're not measuring the current at the actual voltage the flashlight sees when operating normally. Sometimes it doesn't make much difference, but in direct drive lights and a lot of single 18650 cell lights, it can. If you can get sufficient resolution, use the 10A DMM scale rather than a lower current scale. That will reduce the voltage drop. But I made up a meter with even less voltage drop:

The wire is about 7 inches of #22 copper wire connected, as you can see, directly between the probe tips. The probes go to an inexpensive DMM set to the lowest mV scale. Connect the probes to the device under test like you would for any current measurement. The scale factor is 10mV/amp, or 100mA/mV. This is a smaller drop than a typical DMM but of course the resolution isn't adequate for low current measurements. If you do something similar, make sure the wires solidly connect right at the probe tips. You can use a measured voltage and known resistance to adjust the exact wire length (for example, 5.0 volts and a 5 ohm resistor which should measure 10mV for the 1A that's flowing).

c_c

 

[hiuintahs]

Good info CC. I once had a class in college titled "Electronic Measurement". There actually is more to making measurements than meets the eye. Some times it matters and other times the error associated with hooking up test equipment is so small that it doesn't matter. One just has to understand how their test equipment may be affecting the circuit under test and whether that error matters or not.

 

[IlluminationDomination]

I saw a video of a guy checking Amp draw w/ a DMM. He had his own custom[thicker] wires w/ the tips soldered. He got an increase of ~ 1amp compared to using the leads that come w/ the DMM. He said the increase was because the leads have little indents/notches at the end which restrict the current flow.Similar concept as a bottle neck restricting water flow.

If that is true why don't they make the leads completely solid instead of having the indents/notches at the end?

Thanks

Does anyone know WHY DMM leads are not solid?

It seems that CC'S post verifies what the guy in the video proposed even though he used wire w/ soldered tips.

 

[HKJ]

Does anyone know WHY DMM leads are not solid?

Usual DMM's must have a very good isolation (The can be used at 600-1000V) and the probe wires are made for that.
A probe marked CAT IV 1000V must handle up to 12000V peak!

 

[IlluminationDomination]

Usual DMM's must have a very good isolation (The can be used at 600-1000V) and the probe wires are made for that.
A probe marked CAT IV 1000V must handle up to 12000V peak!

Ok Thanks. I do not totally understand that! Does that mean if they are solid the isolation will be bad?

What is the meaning and definition of "Isolation" in this application?

Thank you

 

[Curious_character]

I saw a video of a guy checking Amp draw w/ a DMM. He had his own custom[thicker] wires w/ the tips soldered. He got an increase of ~ 1amp compared to using the leads that come w/ the DMM. He said the increase was because the leads have little indents/notches at the end which restrict the current flow.Similar concept as a bottle neck restricting water flow.

If that is true why don't they make the leads completely solid instead of having the indents/notches at the end?

Thanks

Meter leads don't have "indents/notches" at the end that restrict current flow. They're usually fairly small diameter stranded wire, though, to make them flexible. This isn't a problem when measuring voltage, and not not normally when measuring current unless the voltage drop is critical as I pointed out in an earlier post. Making short leads of heavier wire will reduce the voltage drop when measuring current, although I'd expect the drop of the the meter circuitry to dominate in most cases.

c_c

 

[HKJ]

Ok Thanks. I do not totally understand that! Does that mean if they are solid the isolation will be bad?

What is the meaning and definition of "Isolation" in this application?

Good isolation means very thick plastic around the actual copper wire.
I can see from when I buy test cables that I can either get thick copper (i.e. good at high current) or thick isolation (i.e. good at high voltage). It would be possible to combine it, but the cable would be thicker.

Probe cables supplied with meters are always the type for the high voltage.

For cheap meters there is also the price of copper, a thin copper wire is cheaper.

 

[HKJ]

They're usually fairly small diameter stranded wire, though, to make them flexible.

You can also get thicker cable that is very flexible, it has a lot of very fine copper strands, a lot of my test cables are that type.

 

[IlluminationDomination]

@ CC

I think there is some confusion, maybe because I do not know all the terminology.

The PROBES have indents towards the tips. That is what I am referring to, so was the guy in the video. He used copper wire and soldered the tips. Results were getting an additional Amp when measuring the amps at the tail of the light.

 

[IlluminationDomination]

I believe the Probe is the METAL tip and the "Lead" is the electrical connection[wire]?

 

[HKJ]

@ CC

I think there is some confusion, maybe because I do not know all the terminology.

The PROBES have indents towards the tips. That is what I am referring to, so was the guy in the video. He used copper wire and soldered the tips. Results were getting an additional Amp when measuring the amps at the tail of the light.

That do not really matter that indent adds maybe 0.1mOhm

 

[Curious_character]

Those indents won't make any significant difference. Whoever got the additional amp was doing something else different before and after the modification -- it most certainly wasn't because of the indents. Making good and repeatable measurements can be more difficult than most people realize.

I don't know the purpose of the indents -- maybe to accommodate some kind of clip-on accessory.

c_c

 

[IlluminationDomination]

Ok,Thank You ​CC and HKJ

 

[IlluminationDomination]

HKJ helped me with this but I am still not clear about it.

Battery "A" is 4200mAh[Vappower IMR]

Battery "B" is 5750mAh [Orbtronic IMR]

After running on max in the Same light for 25 minutes[incremental] the Voltage for battery "A" is 3.71v and battery "B" is 3.73V.

Since Battery "B" has 1550 more mAh shouldn't it have more than an additional 0.02v since it has 27% more capacity?

Thanks,

Ed

 

[archimedes]

There are a bunch of variables in play ...

• how accurate is your DMM

• were they both fully charged and at identical voltage to start

• do both cells have identical chemistry and discharge curves

• what is the slope of the voltage / SoC curve at that point

• how well regulated is your flashlight

• are all test conditions (such as temperature) identical

• etc etc etc