Sharing..........

I been looking for a clamp which can do AC and DC, but must have good shielding for DC works under 50 milliamps.
The baby sized Owon was good, but it was not good enough for working on the car directly with metal magnetism effecting the jaw, when and if under 150-200 milliamps of drain.
Not good is the consistency of reading, because our car is ferrous metal and produce or distord magnetic field .

Current clamp is AC mode is easy, DC mode is a different story and sensor.
Both AC or DC current clamp read magnetic field, but alternating current 50 or 60Hz to be accurate to say 1-2 milliamps is quite easy because
the split core current transformer ( sensor ) gets pulsating-polarity-keep changing magnetic field from the AC 50 or 60 Hz, the device processor can filter out easier near-by
magnetic field from ferrous metal which is not pulsating at 50 or 60hz and has single polarity usually.




DC clamp sensor is using hall effect sensor.


Those who like to learn, below is good :




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Even the earth magnetic field will effect DC milliamps reading, if the device isolation is not good enough.


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Now how sensitive these two are from ferrous metal ?, which will mimick their use in a car.

OWON CM2100B


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Autool BT270


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For giggles, these two vs neodymium magnet

OWON CM2100B



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Autool BT270



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Real test on the car, at 26 to 27 milliamps load, car sleeping and 2 of my OBD2 device is still being powered via OBD.

Autool BT270 , leaning to the left side




Leaning a bit to the right



Leaning a lot to the right



Lean back to left again





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Owon CM2100B


Center reading as the start



Leaning to the left, reading goes up to 76 milliamps from 30mA.




Leaning to the right. Reading goes down to 1mA


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Now current at 6.x to 7.x milliamps.
This is my car true sleep mode without any OBD2 devices, but the BM200 battery monitor is there and it consumes about 1.6 to 2 milliamps. It would be 5ish mA if car only.


OWON CM2100B being moved around, in video



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Autool BT270 being moved around, in video




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Basically I am happy now.
For only US$110 shipped, landed + tax yada yada, this is worth the money.
Yes, this is purely a current clamp only, AC/DC. It can't do anything else.