Digital Multitester capable of testing more than 10A of current?

[jonnyGURU]

I'm trying to find a multimeter that will test more than 10A DC.

I already popped the fuse on my Radio Shack Range-Doubler and the wires on my non-fused Actron digital multitester get hot as hell, even at just 10A (which is all it's rated for.)

I looked on Flukes website and couldn't find anything.

Is there such an animal?

 

[Colt45]

digital?

you can get jiggawatt panel meters

or just put a 1ohm 1% resistor in series with the load, measure the voltage across it, do the math

 

[jonnyGURU]

Panel meter isn't really too practical for what I'm doing.

I could use the resistor and do the math, but again that's not really practical as I'd like the same device to be able to measure amperage, voltage, etc. Hence the term "multitester."

I just want a nice multimeter and if I want to measure amperage over 10A, I'd like to be able to do so.

 

[WW]

more than 10A is a lot to run straight through...

I think for that range you need a clamp...either a multimeter with one built in or an add on like:

http://www.tequipment.net/AEMCACDCProbes.html

 

[lobadobadingdong]

....didn't notice it said over 10A DC.

 

[sharkeeper]

Clamps only work with AC.

You need a shunt that will output to mV. One designed for your meter will read directly in amperes. These go considerably larger than 10A.

You can measure >10A on most multimeters for {b]short periods only[/b]. My F27 will read up to 30A and the display flashes with a beeping to let you know that it's bad for the meter. The shunt in the meter can only sustain 10A continously so when it's overloaded it will overheat and can damage the pcb.

Cheers!

 

[Evadman]

You just need a meter with a DC shunt, or an inductive meter. Sharkeeper is a little off, as clamps do work with DC as long as they are inductive. Fluke makes a bunch, the 337 (iirc) comes to mind, but Fluke = $$, but you do get what you pay for. If this is a one time thing, then Fluke is not for you. Of course, I have no idea what your current project is jonny

If you already have a fluke, then you can just get an inductive clamp, but IIRC they are still about $200, but will measure about 600A.

 

[jonnyGURU]

Yeah... A clamp isn't going to work for me. I used to have a clamp for measuring DC going to and from a car battery. Test for bad grounds, etc. But I'm not working with 8AWG wire anymore.

20A isn't all that much when you're only talking 5V and 12V DC.

Now I'm going to show my ignorance..... A shunt is a resistor that will reduce the amperage in mean intervals, correct? My Radio Shack Range-Doubler works this way, but is still only capable of 10A. If that sounds like what I need, where can I get a multimeter/shunt combo that is meant to work with one another and give me correct numbers?

And I know what you mean about "short intervals." That's why my Actron is non-fused. I've had it up to 30A for about 10 seconds without harm, but the leads got so hot it was scary. I just don't want to do that on a regular basis.

 

[jonnyGURU]

$200 for a clamp? Oy vay!

 

[jonnyGURU]

Oh... and I guess I'll let the cat out of the bag....

The current project: http://www.jonnyguru.com/tester

As usual, feedback is more than welcome.

 

[sharkeeper]

You just need a meter with a DC shunt, or an inductive meter. Sharkeeper is a little off, as clamps do work with DC as long as they are inductive. Fluke makes a bunch, the 337 (iirc) comes to mind, but Fluke = $$, but you do get what you pay for. If this is a one time thing, then Fluke is not for you. Of course, I have no idea what your current project is jonny

If you already have a fluke, then you can just get an inductive clamp, but IIRC they are still about $200, but will measure about 600A.

No the post above linked to a passive clamp which will read AC only. Inductive clamps are much more expensive.

EDIT: The 1157 is not a halogen bulb. For that project a 25A panel meter would work OK.

 

[jonnyGURU]

Originally posted by: sharkeeper


EDIT: The 1157 is not a halogen bulb.

Damn! You're right! They're not. I was going to grab halogens, but at the last minute bailed due to price. The 1157's are only $1 each and the sockets are only $2.99. Halogens were about $10 a piece.

 

[jonnyGURU]

Sigh. Well.... A panel meter would be pretty permanent. I'd like to have something I could move off the project easily, but I could always leave this puppy assembled if it's a worth while means of load testing PSU's. I know there's equipmen out there specifically for the task, but that's hundred to thousands of dollars. This is my "ghetto-style" version. A panel meter would sort of tip it up out of the ghetto and into the burbs.

I wish they had a pic of this one. It's 20A and only costs $20 ($1 per Amp!)

http://www.herbach.com/Merchant2/mercha...R&Product_Code=S3-208&Category_Code=PM

 

[Evadman]

An inductive meter will still work on 16 gauge wire . One amp or 1000, you still have the same 2% accuracy rating. (well, usually 2%. fluke is probably better). It will not however hook in like you have the system set up now.

If all you are doing is testing the 12v rail, why not get a 500a automotive battery carbon pile loader? Most will do 6v as well, so concievably, you could test the 5v rail as well. Of course, this wouldn't be much good for anything else, but they are cheap for set amperages.

$14 100A. Will give resulting voltage as well, but set at 100a.
$27 50A
$95 Adjustable Probably too much for one project.

If one of those will nto work, I have an automotive meter that would measure up to 30A somewhere in my garage. I can pull the name/model for ya if need be, but 30A is still within most 5v rail outputs of better PWS's.

 

[Evadman]

Originally posted by: jonnyGURU
Sigh. Well.... A panel meter would be pretty permanent.

I saw some panel meters on ebay this morning when I was looking for cheap shrink tubing. I will see if I can find them again. Personally, I dislike ebay, but hey, whaever floats the boat.

100A $18

Oh, something else I just thought of. Befire the move to hi output alternators, cars had ammeters int he dash, most to 60A. Hell, my lawnmower has one. There have to be some inexpensive ones out there.

 

[jonnyGURU]

I thought about using the adjustable load tester. $95 isn't such a bad price. I might go ahead and do that too. Although, I have to admit that assembling this load tester has been a ton of fun.

I actually have the 100A load tester you showed. Used it a few times to make sure a PSU didn't "blow up" because it's overload protection circuit wasn't functioning properly. Consider it, "the final stage of QC."

 

[TitanDiddly]

You need a current shunt.

 

[jonnyGURU]

Hmm.... Looking at that link... I think I'd want to use one first hand before buying it. For example: How LOW of a load can it do? I mean, if one click on the meter is 10A and a 300W power supply kicks the bucket, it doesn't do me much good. I imagine the incraments must be pretty wide in order to dial all of the way up to 500A! And can I retrofit the big ol' battery clamps to work with a PC PSU?

 

[KMurphy]

You need a Hall effect clamp on probe for measuring DC current. You will also need either a meter to plug the probe in, or an all in one unit; probe and meter. I can measure up to 4000A AC or DC on my scope at work.

 

[Evadman]

Originally posted by: jonnyGURU
I have to admit that assembling this load tester has been a ton of fun.

When you get right down to it, that is really all that matters.

 

[Eli]

Even 10A is a lot of current to be pushing through the typical DMM wires........

 

[Analog]

Originally posted by: sharkeeper
Clamps only work with AC.

You need a shunt that will output to mV. One designed for your meter will read directly in amperes. These go considerably larger than 10A.

You can measure >10A on most multimeters for {b]short periods only[/b]. My F27 will read up to 30A and the display flashes with a beeping to let you know that it's bad for the meter. The shunt in the meter can only sustain 10A continously so when it's overloaded it will overheat and can damage the pcb.

Cheers!

Nope, there are clamp-ons that work with DC. They use the Hall Effect. And they are rated into the 1000s of amps if necessary.

 

[jonnyGURU]

Originally posted by: Evadman

Originally posted by: jonnyGURU
I have to admit that assembling this load tester has been a ton of fun.

When you get right down to it, that is really all that matters.

Oh hell yeah. I get to rip wood with a circ saw, drill holes, trim holes with a dremel and then assemble it all together. Definitely fun.

Originally posted by: Eli
Even 10A is a lot of current to be pushing through the typical DMM wires........

I don't really think so. The distribution block I'm using is actually rated to 10A PER TERMINAL and has a 60A maximum load capacity. It's all running off of a pair of 18AWG wires. Which is thinner than the wires on my DMM.

 

[Evadman]

Originally posted by: jonnyGURU
Hmm.... Looking at that link... I think I'd want to use one first hand before buying it. For example: How LOW of a load can it do?

The one I used to have had a granularity of about an amp, from zero. The dial did not have detents, it was set wherever you wanted. I used it to test alternators, which put out < 60 amps (at least my old jimmy did ). I sold it when I found myself unemployed and with zippo money, and have not replaced it, as i have not had the need yet.

You could probably just run down to the automotive store (pep boys, track, murrys, napa, etc) Sears, or Granger (those 2 are everywhere) and I am sure they have one you can play with.

 

[Analog]

Lemme see if I understand correctly: You are attempting to load test a power supply? Why not just use dummy load resistors and use the b-e junction of a transistor to turn on a go, no-go LED? That would allow you to quickly test the supplies without any messy metering. The other option is to use the LM3914 bar/dot display driver to give you a 1:10 resolution scale for current. Probably sufficient for your cause. That's what I'd do if I didn't have an adequate current meter.