Clamp Meter & Measuring amps...

[ptolemy]

I started a thread few weeks ago about digital MM not being precise enough to measure amps drawn due to the interference.

Someone had suggected to get a clamp meter, which measures magnetic field, so wouldn't have any kind of interference.

So, I got it, but I am clueless as to how actually measure current drawn with it.

Anyone has any idea? I am using fluke 322 clamp meter

Thank, as always

 

[jhellwig]

That meter only measures AC current, not DC current. A tenth of a amp is probably the lowest that meter will display and even then it won't be that good at that low of amperage. They need to be in over an amp to be close.

A good fluke multi meter will be quite accurate for measuring current draw in the milliamp range. They require breaking the circuit though.

 

[HKJ]

So, I got it, but I am clueless as to how actually measure current drawn with it.

You need to remove the tailcap and use a short piece of heavy gauge wire from the battery to the tube. The wire must pass through the clamp meter.

The clamp meter must be able to measure DC current and preferable be a high sensitive model, i.e. have a resolution of 1 mA DC.

 

[ptolemy]

You need to remove the tailcap and use a short piece of heavy gauge wire from the battery to the tube. The wire must pass through the clamp meter.

The clamp meter must be able to measure DC current and preferable be a high sensitive model, i.e. have a resolution of 1 mA DC.

fluke 322 is not sensitive enough?

and what about using probes and have them pass in the clamp?

if not, could u illustrate in more detail how? im kinda lost here

 

[HKJ]

fluke 322 is not sensitive enough?

Fluke has 10mA resolution, this is acceptable, but because it only measures AC, it can not be used for flash lights.
You need a meter that can measure DC current with the clamp.

and what about using probes and have them pass in the clamp?

if not, could u illustrate in more detail how? im kinda lost here

No, probes are not good enough for this, the wires are usual to thin. I will try to get time to take a picture, probably in about 12 hours.

 

[Curious_character]

As others have said, you need a DC clamp on ammeter. They aren't nearly as common as AC meters, because they require a Hall effect device and a fair amount of circuitry rather than the simple transformer used to measure AC. Google "hall effect ammeter" (without the quotes) to get a sampling of what's available.

c_c

 

[ptolemy]

ok cool.

would something like this then work? mastech ms2108 model would work?

 

[HKJ]

ok cool.

would something like this then work? mastech ms2108 model would work?

I can not find the full specifications for the meter, it looks like it can be used, but it only has a resolution of 10mA. I.e. it will only be useful at the higher brightness settings.

No, probes are not good enough for this, the wires are usual to thin. I will try to get time to take a picture, probably in about 12 hours.

Here is a picture:

To get the best connection, put you fingers on the connection points and press (I did not do it in the photo, because my fingers would have hidden the wires).

 

[ptolemy]

I can not find the full specifications for the meter, it looks like it can be used, but it only has a resolution of 10mA. I.e. it will only be useful at the higher brightness settings.




Here is a picture:

To get the best connection, put you fingers on the connection points and press (I did not do it in the photo, because my fingers would have hidden the wires).

got it

is that the speaker wire, right? i assume the best possible quality the better?

here are specs for that http://www.p-mastech.com/products/05_acdcdcm/ms2108.html

but, it seems like with wires, i will have a more accurance measurement anyway?

 

[HKJ]

got it

is that the speaker wire, right? i assume the best possible quality the better?

The wire is 13 AWG.

here are specs for that http://www.p-mastech.com/products/05_acdcdcm/ms2108.html

but, it seems like with wires, i will have a more accurance measurement anyway?

I found that page, but the "manual" link does not work. I want to see specification where they clearly states 10mA resolution and that DC current is measured with the clamp (It looks like that is the case).

The only "problem" with this measuring technique, is the connection points, 1-2 more or less in AWG will not really matter.
If the current reading is unstable, try cleaning the connections points (Battery - pole and flash light battery tube end) and keep a decent pressure, with you fingers, on the connection point.

 

[ptolemy]

The wire is 13 AWG.



I found that page, but the "manual" link does not work. I want to see specification where they clearly states 10mA resolution and that DC current is measured with the clamp (It looks like that is the case).

The only "problem" with this measuring technique, is the connection points, 1-2 more or less in AWG will not really matter.
If the current reading is unstable, try cleaning the connections points (Battery - pole and flash light battery tube end) and keep a decent pressure, with you fingers, on the connection point.

ok cool, will order speaker cable and report results

thanks!

 

[HKJ]

ok cool, will order speaker cable and report results

thanks!

This kind of cable is probably also used in cars, maybe you has a mechanic close by, where you can get a piece of cable cheap.

 

[QtrHorse]

ok cool, will order speaker cable and report results

thanks!

Why would it have to be speaker wire? Any wire 12ga or larger will be sufficient.

 

[Curious_character]

Yes, go to the auto parts store and get any kind of wire, and you don't need anything as heavy as #12. Get something smaller and easier to work with. Six inches of #18 will produce only 3mV of drop per amp, and #22, 8mV. You're likely to have more than that from the contact points.

c_c

 

[turboBB]

On C_c's advice, I did a search for "hall effect ammeter" and came across this and would like your collective advice on it:
http://wattsview.com/wattsview_dc10000-with-accessories.htm

I plan on only using this for my hobby stuff so the fact that it only measures DC is perfectly fine. The great thing about it is for the price it comes w/the free data logging software (I'm not a developer so wouldn't have been able to come up with one on my own like some of you).

Any thoughts on this are appreciated.

@ptolemy, did you end up getting the Mastech? If so, how has it worked out for you?

Cheers,
Tim

 

[SilverFox]

Hello Tim,

I think that looks pretty good. Let us know how it works out. There may be a few more of us interested in picking one up.

Tom

 

[georges80]

On C_c's advice, I did a search for "hall effect ammeter" and came across this and would like your collective advice on it:
http://wattsview.com/wattsview_dc10000-with-accessories.htm

I plan on only using this for my hobby stuff so the fact that it only measures DC is perfectly fine. The great thing about it is for the price it comes w/the free data logging software (I'm not a developer so wouldn't have been able to come up with one on my own like some of you).

Any thoughts on this are appreciated.

Cheers,
Tim

Well, given they state:

====

NOTE: This sensor is not calibrated and is for indication only. The current measurement only accurate if you take time

to zero it out and check the calibration with a known good current source. The same goes for the voltage measurement.

====

I would think that for nearly $200 they could at least calibrate the thing themselves for you.... Also, it is relatively HUGE for measuring currents that we would typically be interested in.

I'd suggest you look into a decent AC/DC clamp meter like
http://www.extech.com/instruments/product.asp?catid=26&prodid=77

You get great resolution from a well established instrument company for about $130 + shipping etc. It also can take leads (supplied) to use it as a multimeter. Has a small jaw that makes it a LOT easier to get into tight areas and without the need for a long lead to clamp around.

cheers,
george.

 

[turboBB]

@Silverfox, thx will do.

@George, good catch! I confess I didn't pore through the details but I do have an Extech 623 that I can borrow (was actually mine but I sold it) to measure it against.

Thx for the recommendation on the Extech but the thing about the 623 was that it was designed to default to measure AC and doesn't have an auto-sensing/switching AC/DC feature like my Micronta does hence I sold it given I'll mostly be measuring DC.

EDIT: The one you've recommended looks like it can be dialed directly to AC / DC so this may remain an option if I don't go with the setup from Wattsview of which I'm keen of the data logging feature.

Cheers,
Tim

 

[georges80]

Not sure why you would want autoswitching of ac/dc??? You don't get that for voltage, why do you need it for current???

I've used an Extech MA220 for several years now and have never seen a need for autoswitching of ac/dc - in fact I've never seen a meter do that ???

Anyhow the Extech 380950 has resolution down to 1mA - and that's not something you find often in an AC/DC clamp meter that's only around $130. And it does have a dedicated set of DC current measuring switch positions in addition to the AC positions.

Good luck on your search for your 'ultimate' clamp meter

cheers,
george.

 

[turboBB]

Sorry not sure if I explained myself clearly but I did edit my initial reply to mention that the model you recommended is perfect as you could dial in to measure AC or DC directly.

With the 623, I would have to dial-in to the function I wanted to measure and then hit the mode button to switch it over to DC (it defaults to AC). So let's say it's V and I wanted to measure my batteries, I'd turn the dial to it and then hit the mode button.

This was annoying as I' never had to do this w/my Micronta which could auto-sense AC/DC (based on range I assume) and give you the read out accordingly. I simply hit the Power switch and just do my measurments without having to remember to swithc between AC/DC.

Tim