How accurate are kill-a-watts

[senseless]

I have a bitmain L3+ with the kill-a-watt meter it shows it consuming around 900W at 120v. Since switching it over to my 240V tripplite pdu (+/-1% billing grade current accuracy), the PDU is showing around 720watts consumption. That's a pretty big difference and only about 30watts can be explained by the PSU efficiency increase on 240v over 120v. Starting to think those things (killawatt) really aren't all that accurate.


 

[1714192989]

1714192989

[1714192989]

1714192989

[squallw]

Same coin, same pool, same hashhate?
This is weird, maybe some issue at your kill-a-watt, try to measure with another one.

By the way, my kill-a-watt only work at 127v, you should confirm if your can work ate 240v.

[whitrzac]

Same coin, same pool, same hashhate?
This is weird, maybe some issue at your kill-a-watt, try to measure with another one.

By the way, my kill-a-watt only work at 127v, you should confirm if your can work ate 240v.

They all work at 240v. They just don't say it because 240v is a different plug.

[senseless]

Same coin, same pool, same hashhate?
This is weird, maybe some issue at your kill-a-watt, try to measure with another one.

By the way, my kill-a-watt only work at 127v, you should confirm if your can work ate 240v.

Yes to all. I was only using the kill-a-watt on 120v. I setup a new circuit at 240v for my miners. The enterprise grade PDU is now doing the the measuring, not the kill-a-watt. I'm more likely to trust the enterprise grade PDU than I am the $15 kill-a-watt. But, I couldn't believe the difference was that much.

[Za1n]

I have a couple of kill-a-watt meters and have tested them against a decent Fluke multi-meter and I would say the readings are usually within 5% of each other and the multi-meter. This would mean up to 50 watts discrepancy at 1000 watts, or 45 watts using your 900 watt reading.

So I would agree that there is something else going with your 180 watt difference besides the accuracy of the kill-a-watts. As you said, the switch to 240 may explain 30-40 watts, but not the entire 180 watt difference you are measuring. Maybe the PDU is displaying its reading in output wattage where the kill-a-watt would be monitoring the input wattage. So combining the increased 240 v efficiency with not counting the PSU's inefficiency (probably 8-10%) would get you closer to explaining the difference in the measured values.

[adaseb]

They actually VERY accurate. I've measured before with other diagnostic equipment.

As long as you are not using it to measure the Microwave power consumption...

[Darknicks]

Don't use the Kill A Watt with 220~240V!! It's dangerous!
They were made for only 110~120V!

https://cdn.shptrn.com/media/mfg/15637/spec_file/268685764.pdf

[Za1n]

Don't use the Kill A Watt with 220~240V!! It's dangerous!
They were made for only 110~120V!

https://cdn.shptrn.com/media/mfg/15637/spec_file/268685764.pdf

If you took the time to actually read his post he didn't use the Kill-a-watt at 240V, he only used it at 120V.

He took the 240V readings off his 240V Tripplite PDU. This is why he was inquiring about the accuracy of them (kill-a-watt) as he assumes the Tripplite PDU reading is fairly accurate.

[philipma1957]

Same coin, same pool, same hashhate?
This is weird, maybe some issue at your kill-a-watt, try to measure with another one.

By the way, my kill-a-watt only work at 127v, you should confirm if your can work ate 240v.

They all work at 240v. They just don't say it because 240v is a different plug.

No my kill-a-watts  are all f'd up at 240 volts.

read numbers like 172 volts and 60 watts

when I am  sure it is pulling 500 watts at 239 volts.

I have a p3. model


I have 2 of these coming direct from gb on thursday


https://www.amazon.co.uk/energenie-429-856UK-Energenie-Power-Meter/dp/B003ELLGDC/ref=sr_1_1?ie=UTF8&qid=1516857536&sr=8-1&keywords=kill+watt+meter


I will make adapter plugs and show  the difference.


I have 3 kwatt meters  2 read the same and 5% less then the third.  

I have 2 of these they read the same


https://www.amazon.com/P3-P4400-Electricity-Usage-Monitor/dp/B00009MDBU/ref=sr_1_2?


and run lower then this one  

?
https://www.amazon.com/dp/B0716WQW79/ref=sspa_dk_detail_2?


all three of them ball park to my pdu  but my pdu  does 0.0 to 9.9

then whole like 10-24

[tadeus1]

The problem usually is not the voltage difference but the power frequency. 50hz vs 60hz.
If comparing Europe to Usa. Not sure what is the frequemcy on the US 220v.
Plus the lower watt limit on the kill-a-watt. I would not use the device on 220 as well but for example the TPlinks hs110 are OK if you want meter + smart.

But for accuracy I can say killawatt are good. I've compared with tester, with my ups and my tplink hs110s.

[MarkAz]

As Za1n said, I've done the same thing with my Fluke setup and found similar results... One thing to keep in mind, is that in general the higher the support watts it can monitor, the lower the resolution.  You're not going to be able to measure mW with something that measures thousands of watts - or more specifically, you can but it's going to cost you a bunch of cash.  and as tadeus1 points out, you also need to be able to calibrate it for whatever the voltage source you're using it - and make sure the device can measure the voltage source, in case there are dips, etc.

I used to use a Kill-a-watt ages ago, then I switched to a Watts Up Pro UC (supports 240v), and lately I've fallen in love with these:

http://amzn.to/2DwPJDX

They're cheap as hell, can handle input voltages from 110v up to 240v - and give realtime data.  Better still, you can take a known load, like a space heater or something similar, and calibrate them so they work even better.  The only PIA with these is you have to wire on the connector yourself, but it's not that hard and also gives you the option to use C13/C14 connectors, traditional 3 plugs, etc.  I've also modified all the ones I used to use one of the open-source projects, and then modified that to be more specific to my purposes - all in all an awesome option.

I also have one of these installed at home and at all our mines:

http://amzn.to/2DL0vKo

Worth every penny - you can configure it with all you your utilities billing nonsense and it's accurate within a few dollars of what my bill is every month.  But as I said above, the larger the monitored load, the lower the resolution - so where the first one is accurate within a couple watts, this one is accurate within tens of watts or more depending on the size of the install (like on our 1600a mines).

[senseless]

Here's the print out from the PDU:

Bank1 (15A circuit) has a L3+ and 24 port dlink switch plugged into it. Unfortunately this model doesn't give me per outlet view only total current used on that circuit. My input voltage does seem to fluctuate between 240 and as high as 248. I think I'm just going to throw my kill-a-watt away and upgrade my multi to a fluke.

  Device
   ======
   Number of Circuits        : 2                                                
   Number of Phases          : 1                                                

   Input
   =====
   Input Frequency           : 60.0 Hz                                          
   Input Voltage             : 241.5 V                                          
   Minimum Input Voltage     : 0.0 V                                            
   Maximum Input Voltage     : 248.0 V                                          
   Low Transfer Voltage      : 134.0 V                                          
   Device Mode (Primary)     : Present                                          

   Output
   ======
   Output Source             : Normal                                          
   Output Frequency          : 60.0 Hz                                          
   Output Voltage            : 241.5 V                                          
   Output Current            : 3.00 A - Total                                  
   Maximum Output Current    : 3.00 A                                          
   Minimum Output Current    : 0.00 A                                          
   Total Current Bank 1      : 3.00 A                                          
   Total Current Bank 2      : 0.00 A                                          
   Output Current Precision  : Tenths (0.1A)        

[clyjr]

Are you US based? How do you wire up the Sonoff Pow on US 220v?  I couldn't find any 220 wiring instructions...

As Za1n said, I've done the same thing with my Fluke setup and found similar results... One thing to keep in mind, is that in general the higher the support watts it can monitor, the lower the resolution.  You're not going to be able to measure mW with something that measures thousands of watts - or more specifically, you can but it's going to cost you a bunch of cash.  and as tadeus1 points out, you also need to be able to calibrate it for whatever the voltage source you're using it - and make sure the device can measure the voltage source, in case there are dips, etc.

I used to use a Kill-a-watt ages ago, then I switched to a Watts Up Pro UC (supports 240v), and lately I've fallen in love with these:

http://amzn.to/2DwPJDX

They're cheap as hell, can handle input voltages from 110v up to 240v - and give realtime data.  Better still, you can take a known load, like a space heater or something similar, and calibrate them so they work even better.  The only PIA with these is you have to wire on the connector yourself, but it's not that hard and also gives you the option to use C13/C14 connectors, traditional 3 plugs, etc.  I've also modified all the ones I used to use one of the open-source projects, and then modified that to be more specific to my purposes - all in all an awesome option.

I also have one of these installed at home and at all our mines:

http://amzn.to/2DL0vKo

Worth every penny - you can configure it with all you your utilities billing nonsense and it's accurate within a few dollars of what my bill is every month.  But as I said above, the larger the monitored load, the lower the resolution - so where the first one is accurate within a couple watts, this one is accurate within tens of watts or more depending on the size of the install (like on our 1600a mines).

[MarkAz]

Are you US based? How do you wire up the Sonoff Pow on US 220v?  I couldn't find any 220 wiring instructions...

Yeah, I'm US based and I run it on both 240v and 208v systems no problem - in either case, there's still only 3 wires (assuming you're using C13 or C19 plugs, which you probably are).  The Sonoff has the labels L (line), N (neutral) and E (earth) if I remember correctly - so it should be the same for your plug wiring, the only difference is that they call earth -> ground here typically.  Then just pay attention to their wiring diagram:

https://www.itead.cc/wiki/images/c/c7/Sonoff_Pow_Wiring.jpg

But as you see, they're tolerant 90v to 240v, so they work great.

[senseless]

Are you US based? How do you wire up the Sonoff Pow on US 220v?  I couldn't find any 220 wiring instructions...

Yeah, I'm US based and I run it on both 240v and 208v systems no problem - in either case, there's still only 3 wires (assuming you're using C13 or C19 plugs, which you probably are).  The Sonoff has the labels L (line), N (neutral) and E (earth) if I remember correctly - so it should be the same for your plug wiring, the only difference is that they call earth -> ground here typically.  Then just pay attention to their wiring diagram:

https://www.itead.cc/wiki/images/c/c7/Sonoff_Pow_Wiring.jpg

But as you see, they're tolerant 90v to 240v, so they work great.

The difference between 240v and 120v is that 240v is 2 hots and a ground. 120 volt is a hot a neutral and a ground. You need a 2 pole breaker. The voltage between both poles is 240v.

[Fessy]

They actually VERY accurate. I've measured before with other diagnostic equipment.

As long as you are not using it to measure the Microwave power consumption...

Sorry to bring up an old thread, but I was having trouble with a kill-a-watt and measuring a microwave. The microwave supposedly has 1650 input and 1200 output watts. When I measured it with a kill-a-watt it showed input between 1900 and 2000 watts.

Is there a problem with kill-a-watts measuring microwaves? Maybe because of their higher wattage?

When I saw the above comment by adaseb, I thought he or maybe someone else might know something about this.

Thanks for any help that can be provided.

[efudd]

They actually VERY accurate. I've measured before with other diagnostic equipment.

As long as you are not using it to measure the Microwave power consumption...

Sorry to bring up an old thread, but I was having trouble with a kill-a-watt and measuring a microwave. The microwave supposedly has 1650 input and 1200 output watts. When I measured it with a kill-a-watt it showed input between 1900 and 2000 watts.

Is there a problem with kill-a-watts measuring microwaves? Maybe because of their higher wattage?

When I saw the above comment by adaseb, I thought he or maybe someone else might know something about this.

Thanks for any help that can be provided.

likely startup/peak vs. running - the output watts are likely rated as running/sustained for some period of time.

-j

[64dimensions]

Clamp meter adapter: take one of these:

https://www.homedepot.com/p/Woods-2-ft-12-3-SJTW-Multi-Outlet-3-Outdoor-Extra-Heavy-Duty-Adapter-Extension-Cord-990824/301132652

carefully strip off say 8" of the OUTER cable insulation exposing three well insulated wires.

Typically, I'm within 10% of the power meter. IIRC, a good clamp meter will actually digitally sample  AC waveform for a more accurate reading. Sine the clamp meter is also "faster", you can also see the mining software transients.

[Fessy]

[/quote]

likely startup/peak vs. running - the output watts are likely rated as running/sustained for some period of time.

-j
[/quote]


Thanks for the replies. The above seems to make a lot of sense. I let the microwave run for about 10 minutes though and it never really went down much. It leaves me wondering.