Few thoughts about energy meters Benetech GM87 GM86 GM88 GM89

[Kiriakos GR]

Benetech energy meters this is technology of 2013.
These Benetech energy meters never won major popularity at any side of our planet.

Any experts looking to find measuring AC bandwidth specifications, they will not find it, even after weeks of internet research.
But, lucky me, I did find a Benetech products User manual in Russian, and here is the major fact. 

Measuring  ranges 180.0….260.0 V
Frequency  40.0…60.0 Hz

While Benetech - China, never took seriously (in the past ten years) to rewrite product's specifications (proper datasheet written with necessary clarity),  the brand appear to have and second major problem, they do not respond at customer emails either.

I would not even bother talking today about Benetech , if they had never produce GM87 Precision power monitor
Max measuring range 220W
Max current 1A
The product design indicates a power meter designed for stand-by power measurements. 

Benetech uses the description: Precision power monitor at all of their products, and so the text alone this does not translate to anything as quality indicator.
Currently (2023) any web-search this will not deliver images of Benetech power meter  PCB, and or electronics in use.

I have come three times close at getting one from eBay, and to waste about 25 Euro with taxes about it, and I always regret at the last minute and delete the product listing from my eBay list.
Mostly because Benetech - China, this not answering emails, and also because I am now convinced that the brand does not care to earn trust as dedicated energy meters manufacturer.
It was a time (at 2013), that a foreign customer from EU, requested such products to buy (EU importer), Benetech - China made them for him, end of the story.
 

[Kiriakos GR]

I got lucky this time with Benetech, and  my email box started to receive some answers.

In the micro power monitor series,only the GM87 and GM88 were discontinued in 2021 , while the GM86 and GM89 continue to be produced.
I did succeed to get a copy of GM87 user manual in Chinese (there is not any in English).
 
Unfortunately neither GM87 (1A shunt) user manual, this deliver any detailed AC current overload specification.

In theory AC starting current this might  be triple, as such the shunt it should be able to survive 3A peak with out damage.
I did ask Benetech such a in-depth question, but I am holding a small basket, about receiving any answer of higher clarity.

 

[overvolt]

I think that its wiser to totally erase the idea about wasting money for these gadgets.
a) unpopular
b) poorly documented
c) old technology, along overpriced if stock found.
d) Questionable precision and slow measuring refresh rate.

My best advice, keep monitoring this market for any arrival of fresher models and or newer opportunities.

[Kiriakos GR]

I think that its wiser to totally erase the idea about wasting money for these gadgets.
a) unpopular
b) poorly documented
c) old technology, along overpriced if stock found.
d) Questionable precision and slow measuring refresh rate.

My best advice, keep monitoring this market for any arrival of fresher models and or newer opportunities.

Yesterday I did find a YouTube video, these meters in a experiment of measuring low power consumption of a motor capacitor.
Measuring speed this was sluggish, no matter if the 10A GM86 this seemed able to measure down to 0.25W
For dynamic loads, this series its a huge disappointment, and I will never look back.     

[Kiriakos GR]

Today I was testing my skills at Google search again, and I did step over one article of another Blogger.
He had purchase energy meter of Benetech clone , this sold under a Chinese branding, this unknown to us westerns.

His meter had a fall over the concrete floor, then plastics holding retention screws were smashed, eventually all internal electronics shown.
The product split in half ..
He did take quality photographs, of PCB and parts.

After taking the long path, at exploring links and schematics, I am now shocked from surprise...   

https://www.cnx-software.com/2015/10/05/att7039au-micro-controller-features-an-energy-meter-unit-for-power-meters/

The hart of this meter this is ATT7039AU from HiTrend Tech (Shanghai)
ATT7039 uses the R8051XC core and has an architecture compatible with 8051.

The R8051XC is a fast, configurable, single-chip 8-bit micro-controller core that can implement a variety of fast processor variations executing the MCS® 51 instruction set.

The current and voltage waveform sampling values are in two's complement format and are the actual sampling data output of the 16-bit ADC
HiTrend Tech (Shanghai) developed ATT7039 3-2012,  debugging stopped  3-2014, today this chip is EOL, and there is no information's at official website.

Link of the datasheet that you may translate due Google file translate engine.

ATT7039AU Integrated single-phase metering processor chip
https://datasheetspdf.com/pdf/919922/hitrendtech/ATT7039AU/1

Google translate
https://translate.google.gr/?hl=en&tab=TT

------------------------------------------------
My latest conclusion, the technology behind Benetech GM power meters its far more advanced than anything else sold as plug-in energy meter.
The high resolution voltage, current along power factor, they are generated by 16bit ADC !!
So for stable loads the measuring accuracy this is very high.
The chip is also capable for active and reactive power measurements, which Benetech GM never use in their design.

For the measurement of stand-by power consumption, I am now convinced that this meter can do the job.
-----------------------------------------------
HiTrend Tech (Shanghai) this has now available much modern Metering ICs along MCU ICs, so it might be significant technology provider of most AC power meter which are produced at mainland China and has not be exported.

[overvolt]

The most stable load in the world this is the light-bulb. 

The fresh added chart of measuring precision per load, it proves that the 10A shunt its not any good for 5W and bellow.
Also there is no proofs that GM87 with 1A shunt this can do any better.

You need a power meter with significant potentials, so to use it as comparison point for the Plug-in ones.   

[Kiriakos GR]

What bothers me the most, its the unseen or hidden product design ERRORS...

Benetech acted stupidly about the female AC socket,  while the male one for EU models, it is good.
The female socket this is actually American standard, and as such there is no compatibility with our EU socket with earth ground, only two pole EU plug will go inside and good electrical contact this is not warranted because of the inner contact points.

Such a huge mistake it did killed the popularity of this product.
The only logical way to bypass this error is to buy American male plug with round pin (earth), and due a sort extension cord to be added a female schuko plug.
This is approximately a waste of ten EURO in additional materials or parts, so EU plug compatibility to be restored in full.

Second idea:  Take it apart and solder a sort extension cord to be added a female schuko plug.

Benetech GM series does not support min-max Watt stats.
The new conclusion, this item it might shown of value, at applications of light bulb testing and or AC/DC power supply testing.
In other words, its about electrical efficiency tests at 1% accuracy for AC/DC PSU, when load testing this is at fixed vales, due a programmable DC load.
Only then an expert can use Benetech GM series strong points.
While most consumers, can only enjoy the offered accuracy only when testing resistive loads. 

[Andrew-88]

Benetech GM series does not support min-max Watt stats.
The new conclusion, this item it might shown of value, at applications of light bulb testing and or AC/DC power supply testing.
In other words, its about electrical efficiency tests at 1% accuracy for AC/DC PSU, when load testing this is at fixed vales, due a programmable DC load.
Only then an expert can use Benetech GM series strong points.
While most consumers, can only enjoy the offered accuracy only when testing resistive loads.

I do not think that the majority of people will care to have repaired their laptop PSU when this gets damaged.
And much fewer will care to measure AC/DC efficiency of a new PSU.

But I do get it,  Kiriakos enjoying getting involved at advanced measurements.     
GM86 10A if found at reasonable price (20 EUR max), then this is the cheapest way for having 1% of Watt power accuracy.   

[Kiriakos GR]

By changing at Google, the key words to: powerbay SSM energy meter ..
I got a pile of results from China mainland. 

Here is another photograph of PCB and power plug details (Chinese input plug).
The actual distributor as Northwest brand, they have abandoned the manufacturing of these products.
But China has plenty of stock of 10A and 15A versions.

I did find clues of many LED nerds using it, along computer enthusiast so to compare power consumption of different hardware configurations.

[Kiriakos GR]

But I do get it,  Kiriakos enjoying getting involved at advanced measurements.     
GM86 10A if found at reasonable price (20 EUR max), then this is the cheapest way for having 1% Watt power accuracy.

For about 14 Euros (price+VAT+shipping) you may get GM86 10A, from authorized Benetech distributor.
Plenty of stock of GM86 EU. 
https://www.sunsky-online.com/p/S-HC-5388/BENETECH-GM86-LCD-Display-MAX-10A-Micro-Power-Monitor-Energy-Meter-EU-Plug.htm

[overvolt]

The only branded product at sunsky-online.com this is Benetech meter, everything else = Mainland China no-name.

I am sensing that soon we will see Real Benetech GM86 take apart photographs. 

[Kiriakos GR]

The only branded product at sunsky-online.com this is Benetech meter, everything else = Mainland China no-name.

I am sensing that soon we will see Real Benetech GM86 take apart photographs. 

Its a fact, but it will not happen with highest priority from my end. 

But today is our lucky day,  Benetech GM86 electronics the real thing. 

a) Better shunt
b) Long life electrolytic capacitors
c)  Lead-free soldering
d) Somewhat better formed contacts within the female plug
e) PCB not identical with the clone