DC Clamp meter recommendation.

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halcyon said:
Unless you have a professional use, £35 - £45 are as good as you need, I have 4 of various prices in the workshop and all read to the first decimal place on amps okay. If not mentioned already look at www.CPC.co.uk, retail arm of Farnell components they have a number of choices.

Brian
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Again many thanks for all the input. I've mentioned in another thread that the boat had about five voltmeters onboard and they all read different figures. The reason I'm considering the Fluke is that it should be accurate, for determining the state of charge of the domestic battery bank. Of the 4 mentioned above, how does the voltage compare especially 12-13volts?
Allan
 
Allan said:
Again many thanks for all the input. I've mentioned in another thread that the boat had about five voltmeters onboard and they all read different figures. The reason I'm considering the Fluke is that it should be accurate, for determining the state of charge of the domestic battery bank. Of the 4 mentioned above, how does the voltage compare especially 12-13volts?
Allan
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I use a fluke, used the same one for over twenty years, but for normal current checking I have £40 CPC units, when measuring 25 amp, give or take 0.1 of a amp is accurate enough. When using volts to check battery level remember the voltage to battery state is very variable, 100% @ 16c - 12.70v but @ 27c - 12.65v. But it also varies with age of battery (new batteries can be 13+v @100%), how charged, how discharged, who mixed the electrolyte ( ratio ), battery manufacture, air pressure and on it goes, you only ever get a guide as the battery complies with no fixed rules. Remember also these apply to the specific gravity as well, that's where the battery voltage levels come from.

End of the day buy what your wallet allows, but not £2.50 of Ebay.

Brian
 
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Allan said:
Again many thanks for all the input. I've mentioned in another thread that the boat had about five voltmeters onboard and they all read different figures. The reason I'm considering the Fluke is that it should be accurate, for determining the state of charge of the domestic battery bank. Of the 4 mentioned above, how does the voltage compare especially 12-13volts?
Allan
Click to expand...
Here is an extract from the datasheet of the Farnell item:
Range Resolution Accuracy
60.00V 0.01V ± (0.8% + 3)
That means the possible error is 0.8% of the reading, plus 3 units of resolution.
For 13V that's 104mv for the %age and 30mV for the 3 least significant digits. So 0.134V.

The Figures for a Fluke 175 are
±(0.15%+2)
Which is just under +/- 40mV. If it's been calibrated.
But in practice, cheap meters are often well within spec.

But the real reason I have a Fluke is that different meters behave differently when there is noise or other waveforms superimposed on the DC.
Logical technique should allow you to fault-find anything in the power system of a yacht with a couple of £2.50 Yellow Meters from ebay.

If you want to know the difference, measure the difference (+/- 1%) instead of measuring the two signals (with errors) then subtracting.

Bear in mind, if you are measuring the load voltage and the battery voltage, both of these vary somewhat over time as the load affects the battery.
 
I bought a Dilog 6402 some years back, and then none of the "cheap" (£30) meters would do DC through the clamp, that was about £70 then, but is now around £100. The one unexpected scale I used on it was when we thought the alternator was on the fritz, and used the clamp to measure the ripple voltage and frequency of that voltage.... It does need to be zeroed every time you use it and on the 40A scale will accurately measure below and amp.
 
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