Sensitive DC clamp meter

[aesmith]

Hi,

I have a budget AC/DC clamp meter but have found it disappointing on low current testing. The lowest range is 40A with four digit display, meaning the lowest reading is 10mA. However the spec for the meter quotes an accuracy of 5% (or something) +/- eight counts, meaning it's claimed accuracy is really only something like 100mA. In reality I think it's less accurate still because the reading sometimes clocks up and down when reading something that I would expect to be pretty constant.

So I was having a look around to see whether there's such a thing as a DC clamp meter with a low range, I see there's one from Dilog (DL6506) which has a 2A range giving a resolution of 1mA and claimed accuracy of around 10mA.

Any other suggestions, or comments on alternative measuring techniques would be appreciated. To give an example of intended use I'm trying to track down why the car sometimes runs it's battery down when switched off. My conventional ammeter isn't idea because you have to break the circuit to insert it in the first place, which causes all sorts of things to reset themselves, and I can't switch range without breaking the connection again.

Thanks in advance, Tony S

 

[telectrix]

i have the di-log one you mention ( albeit under a different name). with a 1mA resolution on the 2A scale, it should do what you want. just make sure it reads DC as well as AC.

 

[aesmith]

Thanks. I assume you find the meter OK, bearing mind it's relatively low price compared to Fluke etc. And yes I know exactly what you mean about checking for DC, I've seen quite a few advertised as AC/DC but when you look at the details the DC current measurement is conventional rather than via the clamp.

Another comment I saw elsewhere, suggested looping the circuit under test around the jaws a couple of times, and dividing the displayed reading to match. Is that actually how they work on DC? If so then in some circumstances it might be another way to improve low current readings.

Thanks, Tony S

 

[telectrix]

with the dilog DL6506, just set to the 2A DC range and clamp the cable. works fine.

 

[Strima]

You could always use the fuse voltage drop method. Measure the voltage drop across the circuit fuse in mV then use the chart below to work out the actual current draw on the circuit.

Link to the full range of charts: Fuse Charts Download - http://info.powerprobe.com/fusechartsdownload

 

[ackbarthestar]

My relatively cheap clamp meter with a FSD of 2A has a resolution of 1.0mA. I've never tried to measure DC current with it though.
They are dirt cheap (£20+) but have not seen them advertised for such in the last 10 years.

 

[ackbarthestar]

"You could always use the fuse voltage drop method. Measure the voltage drop across the circuit fuse in mV then use the chart below to work out the actual current draw on the circuit."

Not much good as you are looking for the difference (leakage) not the circuit loading

 

[telectrix]

think he's looking for current flow when there should not be any.

 

[Strima]

"You could always use the fuse voltage drop method. Measure the voltage drop across the circuit fuse in mV then use the chart below to work out the actual current draw on the circuit."

Not much good as you are looking for the difference (leakage) not the circuit loading

It's helped me track down some battery discharge gremlins in the past.

 

[ackbarthestar]

That's something to do with DC volt drop across poor battery terminals as opposed to leakage current to earth in an earthed ac system

 

[Strima]

That's something to do with DC volt drop across poor battery terminals as opposed to leakage current to earth in an earthed ac system

The OP is trying to track down why his car battery goes flat. Last time I checked batteries were DC...

 

[aesmith]

Thanks for the comments. That method of measuring across the fuse looks useful, something I read was advising against pulling fuses to try and eliminate circuits, because doing so might reset something. Not all the fuses have the test points though.

 

[amlu]

1mA - 80A AC/DC Mini Clamp Meter - https://www.tlc-direct.co.uk/Products/TMDL6506.html
THAT. is small and tidy, mA resolution on both AC and DC. I`m using in my workshop for adjusting small currents on various projects. Doubles as a leakage tester when on the job.

 

[aesmith]

Thanks everyone, a couple of positive comments about the device I was considering. That'll go on my shopping list. I haven't seen the same device under different brand names, only Dilog. Nor have I seen any dirt cheap ones with that 1mA resolution.

 

[static zap]

.... Nor have I seen any dirt cheap ones with that 1mA resolution....

The results would probably drift and give the game away.
( They have fun with the Earths magnetic field - Just like
magnetic compasses in Phones -now disappearing)
(..often upset by Cars , Metal bulk + Screen heaters )