10-2023 Mini review Benetech GM86 micro power monitor 10A 230V

[Kiriakos GR]

Benetech GM86 micro power monitor 10A 230V, this is a plug-in energy meter / watt meter, using a different IC than all other similar products.
It comes with the specification of Class 1.0 accuracy.

Testing time:
LCD display has good contrast, when your head this is at identical height with the meter, and or when you elevate the meter above your height. 
0.2W Minimum, this is a flimsy specification.     
I was aware from my other 2.5% accuracy Watt meter, that when my Desktop PC this is turned off (standby), the power is approximately 0.3W

GM86 testing at 0.3W and measurement results:
0.30W Average ( severe fluctuation 0.20 ~ 0.69W)
PF 0.010  Average  ( severe fluctuation 0.005 ~ 0.017)
132mA (stable value)
233 VAC

At the range of 4W (Desktop PC sleep)
GM86 measurement (10A)  VS 2.5% AC Power Meter (16A)
140mA  -------   0.140 ACA
PF 0.125  -----  PF 0.10
4.12 W  ------- 4.0 W
237.80 ACV


At the range of 100W (Desktop PC idle)
GM86 measurement (10A) VS 2.5% AC Power Meter (16A)
471mA  -------  0.473 ACA
PF 0.770  -----  PF 0.76 ~ 0.78 (fluctuating)
85.50 W  ------- 87.0 ~ 87.3 W (fluctuating)

Quick summary: GM86 strong points
AC Voltage, very precise (15mV fluctuation)
HZ frequency, extremely  precise at four digit resolution
Power and Power factor stability gets better at over 100W of Load

GM86 weak points:
10A shunt this is the deal breaker if you expect to measure lesser than 5W with it.
Since 0.3W up to 80W you should be patient and to make your own averaging calculation by recording total fluctuation of measured values (Min-Max), especially if you are measuring computer PSU consumption.
Lowest resistive load that I am aware of, it can be a 5Watt light bulb (refrigerator door), at this load I would expect GM86 this to be more stable.     

Timer Function: this accumulates tenths, hundreds or thousands of minutes, but there is no automated conversion to Days + HH:MM format.
   
2200W (220 * 10A) minus 5% of range = 110W at that point and over you may expect Class 1.0 accuracy in Watts.

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Another interesting detail, GM86 backlight this is actually white (but when filmed due digital camera this appears having a blue-ish tint).
GM86 which I got from SUNSKY, this came without user manual, and without nylon screen protector, one year warranty.
 

[Kiriakos GR]

Time to explore true sensitivity of GM86 at very low power. 

Two test performed, all end-up as useful disappointment about expectations.

Test No1: Wall plug timer over the GM86, and this unable to measure AC current difference of when internal electric relay this is powered or not.
Test No2: Triple Neon indicator (true Neon bulb inside), true AC current 3mA,  and GM86 this does not measure anything.
 
Verdict:
GM86 at below the 50mA it act strangle regarding sensitivity.
This also explain of why it fails to measure most USB mobile phone chargers consumption without any load over them.

[Andrew-88]

I love myth busting 

So almost at 3/4 of a Watt and still insensitive.

https://www.ittsb.eu/forum/index.php?topic=1765.0

[Kiriakos GR]

In fact and since the moment that there is no any highly sensitive bench-top power meter in my lab.
Its more appropriate at bellow 1 Watt mark, us using the description of VA power.

Naturally I could insist at testing and to discover the actual quantity of mA that GM86 starts to measure, but this is a subject of a Full review.
And this one, it is a Mini review ( sponsored all by my self).   

My major complain about these Benetech GM meter, they fluctuate too much when measuring Watt.
If the product designer had implement an averaging function for Watt measurement alone, then this thing would be much more usable.     

[Kiriakos GR]

Update:

I am making thoughts so to convert Benetech GM86 in to desktop version.

I did break the warranty seal and got inside.
In my surprise,  my GM86 does not have metal shunt, but instead has one current sense resistor R005 (five Milli-ohm).

PCB this has a date of 20/05/2016 ( I will speculate this is latest revision ).

I did find the electrical standard that GM86 this should comply = GB/T 17215-2002
a) Measurement low current limit.
b) Low PF limits and of how accuracy of power this de-rates  the Class of the instrument. 

https://www.ittsb.eu/forum/index.php?topic=1934.0