This energy monitor plug is actually really smart inside. 

set the cost to £1.00 per kWh, and then you can read kWh and instant watts at the same time.

Thanks for the video! I bought two of these about 2 years ago. They both failed recently with blank displays. First look inside saw corrosion of the batteries in each so I ordered replacements. No improvement. Had to delve deeper, and eventually found your video, thanks! First device I tested proved CX1 was low value (0.3uF), so I ordered a bag of 10. When they arrived, I fitted them in both units. One unit burst into life again. The other didn't. Now found that D7 in one device has failed. So I am waiting for yet another delivery now...

I've found if you get your power factor low enough the active power is so delayed, it gets pushed into the next billing cycle, I switch power companies every month and haven't paid a cent in years.

Amazingly they've actually changed the board design over the years. I have a much older unit. I have to hold Function and Cost buttons down to get the date code to show up, which is from Dec 18, 2009 although the board says 2014.Still working fine, although the NiMH battery is corroding, so I'll have to remove or replace it eventually. And yes, I had to resolder the ribbon cable as it broke off. :) My model only has one blob-type microcontroller on the LCD board, which might just be an LCD driver. And then the AC board has a small power analyzer chip, which given the lesser number of pins, might mean a lower model. And it also has the main microcontroller chip, 32 pin or so, on the AC board. Seems they've definitely upgraded this cheap meter over the years. Highly recommend getting one! Especially the models with a backlight

Love these meters . Use them as to determine how much someone on a spur has used and with a pwm controller for distilling to adjust in real time. They are cheap and effective and although I havent even got to the disassembly yet I'm very pleased you chose to tear these down. Great!

We used to use ¼ watt resistors as substitutes for pyrotechnic fuses because you need a licence for the latter. They worked well in theatre pyrotechnic applications.

Lusting after the HOPI, I found and bought one of these cheapies on ebay a year or three ago. I am pleased to see that it gains the seal of approval. Some reviewer or critic at the time (I forget who or where) gave me a moment's pause by a snarky comment about accuracy - but the price was irresistible and I have been very happy with it.

You've been reading my mind! I was just searching for a device like this and was comparing with the hopi meter. Eventually I ordered a similar one, not exactly yours, instead of the hopi. The hopi was too expensive and the cable was not convenient for me. So i ordered the other power meter from China and a few hours later i am watching this video! Thanks a lot Clive. Really. I've been enjoying your videos and learning a lot.

Thanks for the breakdown. I have a couple of these I've used for years and always wondered how accurate they are.

By pure chance I had bought one that arrived the other day not used it yet, so I was so pleased to note your positive comments. Thanks Clive.

My favorite applications for these devices is for getting a rough idea of what you can run on a given current budget, or for making a really nice 'dashboard' for my old school generator. At this point I know I can run one fan, one LED light, and one USB charger per bedroom off our relatively small generator.

This video arrived exactly on time! I have one of these and it stopped working today. I was wondering what to expect when I opened it and now I know :-)

I was on the fence about buying this and you convinced me to take the plunge so thank you! Then I realised I was only 4 mins in and you completely lost me with the rest, perhaps I will be ready for such information one day, very impressive. Great review!

re the 120 vs 120k resistors, its good to know that professionals sometimes have those brain switch-off moments too

Power meter useful for measuring devices that use a crappy capacitive dropper supply uses a crappy capacitive dropper supply.

I've got a slightly older model of the same meter with North American plugs (the main board is V0.9 with a date code 6 months earlier than yours). My tests agree with your findings - surprisingly accurate, especially when you consider the price.

Thank you, that was fun. Giving us a peak inside by taking the meter apart was very interesting. You covered more than I could consume but that's ok. I'll check your channel out. Keep pulling stuff apart.

12:18 - Ah, I see you signed the artwork on the bottom right corner. ;)

I think I learn more here than in my uni. Great video clive!

I've had about 10 of these things over the last few years, I keep lending them out to people who end up asking if they can keep them! They normally cost about GBP8.00 each and simply work. The 8051 was a bit of a surprise, and a blast from the past as I spent about 10 years of my life programming them in PLM51 and ASM51. That said, they are cheap enough and adequately powerful for this sort of job.

I've had one of these around for a while, glad to see an analysis here.

I've got the same model and it died a while back, a surface mount resistor in the power chain had cooked, so I replaced it with 1/2W wire-ended device. works fine now, doesn't get warm either.

I have a older version of this. Less surface mount stuff. The screen was dim as hell making it Basically unreadable. I now opened it up cleaned the contacts for the screen. Works great now. Thanks BigClive I can use it now.

Hi Clive! I have the "PR10 power recorder" and I like it

Beautiful review. I just bought two of these. Yes at 14:47, you query if the pin is for a backlight. Indeed, some units have a blue LED backlight, for a couple of quid more.

I bought one of those from Tesco. It was defective. One of the terminals inside had some really dodgy soldering and was hanging on by a thread. I was going to use it on a high current device (a "large water purifier for the purposes of purifying ethanol-containing water"). Good job I opened it up first and resoldered the connection!

I have the V2.0 of the version of the microcontroller board and its only a 8 pin chip with more welcome improvements. Including a cr2032 replaceable battery and a simpler pcb layout with less components to save cost. Brilliant in my opinion.

Looks identical to the one I bought from Aldi in Australia (sold under one of their brand names). I find it works well and has a nice big display.

I have been using the exact same bodied EU version of the same energy monitor. Its plugged in 24/7/365 for about 2-3 years now, with constant load (100w-2kw). I even tried the oven as a load, and it maxes at around 4.4kw

I'd argue that the popularity of the 8051 architecture is more likely to do with the fact that it's royalty free :)

@2:19.... "and then they exploded..." Keep up the good work, great channel!

Had one for a couple of years - nice to know it’s good.

You just helped me decide which one on eBay to buy. Thank you, Big Clive.

I got an American version from Amazon, the key difference being that it is backlit. I’m glad to know that it’s not a fire hazard.

I've got a similar one branded "Energenie" (green buttons). I opened it for comparison, and has a roughly similar board. I'm glad I did that - one of the electrolytics had leaked, so I will be re-capping it!

I actually got this 2 days ago and just found out you dissected this appliance just now

Nice curvy display board. And a great chip. Now we just need a BigClive series where you build your own including schematic, and have a non flicking screen showing all the pertinent information!

I have the same one I brought a few months ago and I found it surprisingly accurate as well. Mine is back lit by blue LEDs though.

Thanx for making this video! I have one of these but a while back it took a hit because it was plugged into a PSW inverter that went NATO and started outputting some type of square waveform. Naturally this passed too much current through the dropper cap and fried the Zenner diode and fusable resistor feeding it. Up until now I wasn't sure what value the Zenner nor resistor was supposed to be, so I had been waiting to find out that info. And now I have it! Albeit my unit has an older version of the circuit board, which has more through hole components and the circuit is arranged a little differently. In the one I have the 100 ohm is after the rectifier diodes and the Zenner just straps between that and zero volts. What threw me off making a guess was that the filter cap had a 25 volt rating so I wasn't sure exactly what the rail should be. If they had installed a 16 volt cap I would have known it was 12 volts from the beginning. lol Although I did fire it up by feeding in an external 12 volt power source and that worked OK.

15:23 "Quite Complex" - Big Clive "WTF?" - Me

an excellent in-depth description of this energy monitor.

I designed something similar a couple of years ago based around an Arduino and some op-amp input circuitry with voltage and current transformers for sampling house mains power. Every second it calculated and stored RMS current, RMS voltage, real power and power factor to a USB flash store for later download and analysis. The complex bit was not the digital calculations which are actually very straightforward once you have accurate waveform samples, but rather the analogue input circuitry for the current sampling. The problem is the vast range that this has to deal with, and how to maintain sampling accuracy for a milliamp scale waveform versus up to a 50 amp waveform. I wanted it to be able to monitor power consumption for the whole house, including accurate real power measurement of standby loads of single figure wattage. I ended up using an auto-ranging approach, changing the analogue input amplification for different current ranges. I wonder if this chip does the same internally. As you say - interesting stuff.

Aldi sold an identical one in Australia. Nice piece of kit on the bench.

It's nice to see you review a design that's actually *good* for a change, instead of "here are all the shortcuts they took that dragged it well into *unsafe* and *we have regulations for a reason*" :-)

I've repaired one of these that died not too long ago, I think it was a resistor that burned up surprisingly enough, replaced it with 4 1/4W resistors (2s2p) which was the best I had on hand... I had previously had to repair a Kill-A-Watt where the X2 capacitor had died (foil burnt up and capacitance had dropped to the point of the LCD barely being visible, and the measurements being off by a factor of about 2).

I have the 120 volt version of the same meter. It works well. However, the rechargeable backup battery in it gives out if the power outage lasts for than a couple of hours. It's memory then forgets all the last readings and goes back to 00.00.

I've had one sitting in a drawer for a couple of years. Din't think mine did displayed the power factor, so got it out and check. Yep, it does all that your one does. Now it's plugged in to charge the battery.

I have a strange looking variable power supply, 11.5v, if youd like to take a look at it, it uses two bul129d's

Brilliant review

The 'Peacefair' branded power monitoring solutions on AliExpress are pretty good... you can get ones that have all the info on the display at once like the Hopi, ranging between four and six difference bits of info you can access. Plus there are versions that are TTL serial and even RS485 ready... making them PC or microcontroller project ready.

Always feels weird when I see a product I actually own being reviewed. I have the US version of this and I'm pleasantly surprised to learn how well made it actually is inside. I got mine off Amazon for cheap (as I was writing that I got a notification from my bank app on my phone through my PC that my Amazon Prime subscription just renewed).

hey i have that but with a us plug It works well and helped me fix electrical issues and I love that I know how it works now.

Had one of these things for years, totally invaluable.

I bought two of these from Amazon. Both stopped working after 30 minutes of use, just zeros on the display. Sent them back got two more. Both did exactly the same. Replaced with Smart Plugs that give wattage etc on phone app. These are working fine.

Thanks for your hard work. Answered my questions!

I bought one of these a few years ago! It works quite well for its price.

Wow! Wish I had learned more about electricity in the circuits part of my physics class! I stumbled upon your video because I was just curious about how to monitor power usage on my appliances. Now I want to know how ALL circuit boards work! Do you tutor??? Careful though, this is from someone who barely know how to turn off a breaker at the panel! 😄 Seriously, what a great explanation and pictures! If you're not a teacher you should be one! Thank you!

I could use a new power meter, it would be nice if they used that huge screen and showed all the stats like the hopi

Mine is branded Energenie, green buttons, no screw in middle of plug pins and battery compartment on back at top with 2 chunky button sells.

I got one of these a few years ago from amazon cheap. Even had a high current alarm (10A).

Maybe that transistor on the input of the power supply is being fed to the processor to get the frequency of the mains. Should get a nice square wave off that using an internal pull-up.

These watt meters have 2 issues, #1, they crash A LOT from any noise inducted in their proximity. #2, the frequency display is 50/60 so its useless for say setting a generators speed

I have one provided by my power company for joining them years ago. Works great, but my one gripe is that the price per unit is something like 29.35 cents, but since I can enter only two decimal places (i.e. .29 in this case), it's perhaps not as accurate over a long period of time. Actually, a second gripe is that the switches for the power sockets are typically above the socket, and that the device hides the switch, so one has to switch the socket on first before plugging the device in. That's in AU/NZ, anyway.

Yay just got into bed and seen the exact same unit I have :) been using mine for a good few years now and it's still as good as new.

Speaking of discharging capacitors, the worst I've ever seen in consumer electronics was when I was taking apart my DSLR. I knew I should take great care about the capacitor for the internal flash, but the first time I've done it, I just shorted the leads. In the middle of the night, no less. Yeah, what a horrible idea :D That was a hell of a bang still. The next time I made it drain more slowly, that's for sure. I see people taking apart their cameras on the internet all the time, and it's upsetting how many seem completely oblivious to that capacitor and/or don't even bother with a disclaimer to warn the viewers/readers. That capacitor can be dangerous.

I had this model in North America plug for maybee 10 years, got it cheap on ebay and it still works great!

I have the exact same one, only with a North American plug. It's really handy and startlingly accurate.

Hi Big Clive, I have a similar functionality energy consumption meter model number KD-302L, it's using the CS5460A IC.... Reasonable accurate as well...

i have a "paget trading 9149" for maybe 20years, and i've noticed that it 'seems' to accurately integrate over very long times. so for a very small load, if you wait, you eventually get an energy value, seems the accuracy is better than the display resolution. (you can also hack this a bit by using a 'silly' monetary conversion that scales the display up a bit.)

I have one for America plugs and have been pretty happy with it the battery built in is nice

I used one to measure power consumption of an old freezer in my garage. Expected poor efficiency but actually got the opposite. Turned out the freezer wasn't suited to outdoor use and so wasn't working at all when the ambient temp dropped below 12c. Replacing that freezer before winter and saved us from potential food poisoning. Glad I have one now

I have a similar Powermeter. Got it for something like 7€ or so from Pollin at the Time. Can be gotten from various brands. And obviously I got it in the superior SCHUKO Version

I got one of the two days ago, really happy with it

i bought one in Brazil. Surprisingly, it can handle the 220V between 2 127V phases that's used in my city and the 127V between phase and neutral in my friends city. And yes, there's a model with backlight.

Looks like a clone of HAMA 47770 energy meter made by Xavax, later branded as HAMA 111908 XAVAX, LOGILINK EM0003, ENERGENIE EG-SSM-01. The first two made by Xavax are using Cirrus Logic CS5460 chip and there is an eeprom & blob chip on the lcd board. Same battery, similar power design with a few extra protection options like a thermal fuse

Thanks for the review. I have always used Voltcraft energy meters as they were the accurate ones. But The energy meter 3000 failed after 3 years, then a new energy monitor 4000 failed just after warranty period and today I found out that another EM4000 I have bought failed exactly the same way. They started to show random data and after some time totally wrong measurements.

Great teardown/design Thanks for sharing 👍😀

I have this one, works well and accurate 👍 Have compared it to power consumption reported on an android phone and they were the same. A mobile phone has extremely accurate power reporting down to 1mA.

Clive, I bought a pair of those a little over a year ago, for US 110v plugs. Good to know I got something decent (if it's not a knockoff). When I do the DOWN/RESET option, it does not show the initial 0419 2019 screen that yours does. It goes right into the countdown, but starts at 5. Maybe mine is a slightly older model.

I bought four of these excellent meters (under the Status brand) from a clearance sale at Dunelm for £2.49 each. I already had a couple of the Nikkai meters, sourced from Maplin (which you also have used on this channel). The Vangotech V9261F is an interesting device. Thanks for the teardown. 👍

I've had 2 of those for measuring the 24h cost of my diy cannabis lamps,they've both broke current passes through them but they don't measure anything anymore

I have a couple of these I bought a few years ago to read wattage coming in from my solar panels. But the new ones have an overload protection and will not allow inrush current from panels and reads overload.

Since the interface is a UART, it might be possible to swap the display board for a bluetooth serial interface and get a much more complete display on a remote monitor, or even a phone.

I have one running for 2341 days now to monitor my PC consumption. Its at 3028kWh used. Had 0 issues with it, only clean the dust few times a year.

it never fails.. the camera is never rollin when things go boom

I see these be used in all the PC videos I watch and eventually bought this same one to prove to my mum that my LED RGB flood lamp takes up about 0.5W and not 20W as she kept assuming I also have used it on several other devices in the house like the massive fan we use in the summer uses 150W on max power which she thought only did 50W at max. Thanks on how to do the button combos because i lost the instructions.

I have the same monitor, amazing bits of kit.

This was really interesting! Have you ever tried making one? I've been thinking about trying to add something like a DROK power monitoring module to a surge protector? Or maybe a power monitoring module to one outlet, and a power regulating module to another?

I've got one of those. I originally got it to monitor the output of my grid-tie inverter, however, it didn't seem to understand -ve power flow plus it interfered with the inverters synchronization. It's now on my air-conditioner. I shall now view it with more respect.

I got four power meters. A newer one is smaller w/ LED white back light. Founded many electrical appliances with high standby current, I used Wifi plugs to solve the issues, even though it is a Wifi UV air conditioner.

I have a suspicion about the voltage & current sensing chip: It might be one of the 24-bit sigma/delta converters. That way you would get a trimendous sensitivity and range. On the other hand, as you show differential (or maybe instrumentation) amplifier input stages, maybe that would not be necessary. In any case, it is obvious that the key to accuracy without any trimpots is some calibration table, which then requires really good reference(s). Interesting, as you keep saying!

I'd previously looked at them and dismissed them as "a bit cheap looking", so never thought of getting one, but now I know they're actually somewhat decent, I may think about getting a couple... :)

hey i have that one but usa version, it's fairly cheap. good to know it's probably accurate, i like using it to measure how much power my computers actually use for gaming and stuff, so i know if my power supply is properly rated or needs upgrading

The best part of these is they are cheap to make smart by adding an esp8266. They can come with 2 different serial chips, both work

Now we replace the uC in there with a esp32 and we can look them up remotely

I was looking for this on Ali and just before I was going to order the cheapest one available I noticed there's also a model with backlight. Only $2 more and for me well worth the extra cost. So if you want/need backlight, be aware there's 2 models.

It would be cool to check out ANKER power banks and wall plugs see what kind of protections they have because I have had mine under quite a bit of load and they perform quite well

got one of these a while ago. didn't realize it was this good :)

I got one of these about two years ago. The only issue is that the numbers are getting fainter and fainter. I had a timer - also with built in batteries - that was the same. I put new batteries in and the display was back to perfect. I will do the same with this monitor when it becomes unreadable.

Bought the Aussie version of this looking forward to testing my appliances