Kewtech KT 203 clamp meter review

[Goran]

I have been playing a bit with my new Kewtech clamp meter.
I bought it primarily to monitor starter battery voltage and sleep mode current draw.
The meter is advertised as measuring DC current with 0.01A resolution, one of the main reasons why I bought this model.

There is a major annoyance with DC current measurement with this meter. When you first select the DC current function, the reading will never read zero, it will read around 0.1 to 0.2 amps and the reading will dance around.
The manual advises to always use the zero button before taking a DC current measurement.
Even with the meter zeroed, and no wires nearby, it doesnt stay zeroed for long, the reading usually starts dancing around by 0.04 to 0.08A

I have searched for some info about this, and came accross this review of another meter on Amazon.

This is the key sentence:

"difference between resolution and accuracy"

"The MS2108 does everything it says it does, but the design could use a bit of polishing. First, the clamp reads AC and DC currents, but there is no way to do it through the probes. The AC current seems accurate, but reading DC current takes some getting used to. The basic issue is that the zero is not stable. Pushing the yellow "select" button sets the reading to zero, but it takes awhile to stabilize. Expect to spend 5 to 15 seconds fiddling with the button before zero stays put. One reason I purchased this model is that the minimum DC current resolution is 10 milliamps. However, the last digit jumps around a bit, illustrating the difference between resolution and accuracy.

To be fair, most DC clamp meters offer only .1 amp resolution and this might be why. Virtually all of them are based on linear hall effect ICs, and it is apparent that the signal level associated with tens of milliamps is low and noisy. AC current readings are always credible, but I don't trust the DC readings at low current without flipping the direction of the wire and comparing the plus and minus readings. At high currents the DC stability seems as good as for AC."

[notorious]

I didn't find clamp meter that satisfies this basic criteria:

* should have detachable clamp
* measures mA currents accurately
* should be made by premium brand

There is a good choice of models which can measure 100A currents, but I failed to find any that can measure in the range of 0--20A with good precision.


This is nice model from FLUKE: http://www.tester.co.uk/fluke-772-mi...ss-clamp-meter

High accuracy (0.02%), 0.01mA resolutuon and sensitivity, detachable clamp -- great
BUT: Clamp is too small to embrace battery feed wire and maximum current it can measure is 20mA. Well, my current drain current is 130mA

[Goran]

Potentially this may be a good low range ammeter.

http://www.amprobe.com/amprobe/usen/....htm?PID=73267

1mA resolution in 4A range
1.3% accuracy (so around 0.05A in 4A)
unfortunately again we see resolution set lower than accuracy, pointless.
19mm jaw

can be bought here,

http://isswww.co.uk/Clampmeter-Kits/...FUr4wgodjEQA3g

[M-A8]

I agree with notorius, with amount of cabling in our cars and locations having detachable clamps would be a huge benefit
But, a nice meter mate

[Goran]

Just a little update on meters. Finally I understand how they calculate accuracy.
For my Kewtech 203 this means it is not very good for our application of measuring low currents below 1A,

http://www.aspowertechnologies.com/r...20Accuracy.pdf

[Goran]

Just a little update on meters. Finally I understand how they calculate accuracy.
For my Kewtech 203 this means it is not very good for our application of measuring low currents below 1A,
http://www.kewtechcorp.com/sites/def...a_revamp_0.pdf
So it has a resolution of 0.01A, and accuracy of +-3% and 8 digits! Its this second part that' the killer

So if I am measuring a true current of 0.2A, the accuracy is 3% of this value + 8 digits of resolution, ie +-0.08, so accuracy is +-0.086, round up for resolution, +- 0.09
So that is why the display dances around because its resolution of 0.01A is way below its accuracy of +-0.09A
So if it displays 0.2A the true current could be anywhere between 0.11A to 0.29A. not very useful.

Article about accuracy and resolution:
http://www.aspowertechnologies.com/r...20Accuracy.pdf