Mini review of Hopi HP-8 power meter

[Shahmatt]

I recently purchased a Hopi HP-8 power meter from Aliexpress for 39USD. So just to share...

My friend in the electronics industry recommended this brand as they make true RMS (root mean square) power meters. True RMS take into consideration the phase difference between voltage and amps for power calculation. This is more accurate compared to the cheaper power meters in the market.

Some images below. First the box:


The instrument with manual and supplied adapter. The instrument plug is a china style 3 pin plug. Some minor scratches on the screen but it did not affect readout. Instrument is light weight but with good plastic build quality. The adapter feels cheap and I did not use it.


English instructions in the manual:


Readings with my 2400W Braun iron in uH mode (energy use mode):


Display shows Current, Voltage, Power, Power Factor, and the last line is APC or UH. Below the power socket is two entry points for live and neutral wires should you wish to test that way.

I noticed that the SG square plug does not fully seat in the socket as the wire connector openings protrude out and get in the way.

When set to APC it provides a kWH/year measurement - you can set the estimated number of hours use per day and it will give you a value based on what is measured right then and there.

So for my 2200G build (see signature right ->), if I set 24hrs, then the idle kWH measurement shows around 350 kWH. Based on 22.15 cents electricity cost the annual cost of running 24/7 is SGD 77.5. Actual usage may be 2 to 3 hrs per day but this is just to get an idea. I also found out that this PC consumes only 95W on max load prime95 blend test.

I have not tested the uH measurement properly yet but it is an energy used measurement and cumulative - i.e. you can reset to zero and it will keep increasing until you reset again. I'm guessing it is more suitable for use with appliances like fridge or aircon which cools intermittently over the day and night. Will update this review after using on my fridge for a few days.

Thanks for reading.

 

[wwenze]

Nice review. That speaker connector is really a deal-breaker.

 

[Shahmatt]

Nice review. That speaker connector is really a deal-breaker.

I think these are live and neutral output lines - for say, connecting a bulb socket.

Actually no big deal as:
1. You can still get a connection when pushed all the way
2. You can use an adapter to get some height

 

[haylui]

PF = 1.0
where was the plug connected to?

 

[Shahmatt]

PF = 1.0
where was the plug connected to?

Multi socket output.


It only showed 1.00 on this occasion. When testing PC power it showed a PF = 0.34. Now I am testing fridge it is showing 0.91.

 

[wwenze]

Multi socket output.


It only showed 1.00 on this occasion. When testing PC power it showed a PF = 0.34. Now I am testing fridge it is showing 0.91.

I'm guessing your PC's power supply came from China.

 

[Shahmatt]

I'm guessing your PC's power supply came from China.

Yes. What is the implication?

 

[haylui]

Yes. What is the implication?

PF .34 is way too low for a modern switch mode psu...

 

[Shahmatt]

PF .34 is way too low for a modern switch mode psu...

I see. When testing the fridge I noticed that sometimes the PF dropped to around 0.3x but at other times reverted back to 0.9x. Most of the time it hovered at 0.9x.

I will however retest the PC. Could it be an instrument fault though?

 

[wwenze]

Yes. What is the implication?

Nothing. Just means it doesn't have PFC. Gotta cut cost and they can cut it if they're not selling it in AMDK countries.

I see. When testing the fridge I noticed that sometimes the PF dropped to around 0.3x but at other times reverted back to 0.9x. Most of the time it hovered at 0.9x.

I will however retest the PC. Could it be an instrument fault though?

PF is affected by load. PF of 0.9 suggests your fridge is one of those more modern inverter types. The drop to 0.3 may be due to the compressor being off completely.

Your computers also usually measure low PF when off or standby or very low loads (as in just VSB5V). Check jonnyguru for values.

 

[Shahmatt]

Nothing. Just means it doesn't have PFC. Gotta cut cost and they can cut it if they're not selling it in AMDK countries.

PF is affected by load. PF of 0.9 suggests your fridge is one of those more modern inverter types. The drop to 0.3 may be due to the compressor being off completely.

Your computers also usually measure low PF when off or standby or very low loads (as in just VSB5V). Check jonnyguru for values.

Thanks.

For low wattage components like AC-DC adapter running at 90W is PFC important? So based on 90W/230V = 0.391 Amps, which at 0.3 PFC = 1.3A in the wire. Is this understanding correct? I guess the increase from 0.391 to 1.3A will have more heat wastage.

Not sure if the fridge is the modern type. It has the Energy Star 'Good' rating only - 3 ticks.

 

[wwenze]

PFC is mandatory for PSU >75W if you want to sell them in AMDK countries.

The current values are indeed so. 0.4A or 1.3A doesn't matter too much.

3 ticks is most likely inverter already. Power saving is the main aim, high power factor is a side effect but probably enforced by AMDK countries anyway.

 

[wolnavi]

Hey could you PM me the product URL? I can't seem to find it in aliexpress lol

Also, if I use a travel adaptor as shown below to plug the electrical appliance square power plug to the meter, will it affect the reading? Thanks

 

[Shahmatt]

Hey could you PM me the product URL? I can't seem to find it in aliexpress lol

Also, if I use a travel adaptor as shown below to plug the electrical appliance square power plug to the meter, will it affect the reading? Thanks

I use a similar one. Maybe the power readout will be slightly increased due to resistance in the adapter. Otherwise there should be no impact.


Link here: https://www.aliexpress.com/item/Han...tage-power-factor-0-001A-10A/32742327892.html

 

[wwenze]

Current in circuit is same throughout the circuit. There will be voltage drop but you can measure how insignificant it is. And besides, power meter measures what power goes to the load and not how much power is coming from your circuit breaker or whatever.

 

[wolnavi]

Current in circuit is same throughout the circuit. There will be voltage drop but you can measure how insignificant it is. And besides, power meter measures what power goes to the load and not how much power is coming from your circuit breaker or whatever.

I see, actually just want to buy this to measure how much my pc will consume/cost if I leave it on for maybe 24 hours