Kill-A-Watt power meter accuracy

[Modelworks]

I had a friend over today that wanted to show me his new purchase, a fluke 1735 , so I thought I would do a quick comparison with the killawatt.

The killawatt isn't a bad meter, especially for the price.

Its does have its flaws though.

Comparing it with a fluke 1735 I found a few differences.
The killawatt is terrible at inductive loads, so don't use it for measuring those.
Inductive loads would be things typically with motors, compressors.
So not good for measuring a refirgertator or washing machine.
It measures them , but its results are not .2% accurate.
Refrigerator with compressor running 921 watts, fluke 841.8 watts

Its not accurate at measurements of small wattages.
Things like the power usage of a dvd player in standby mode are not accurate.
Killawatt said dvd player was using about 5 watts, fluke 2.64 watts.

The sampling rate is very low compared to meters like the fluke, so it can miss quick spikes or surges in usage . When I used it to measure the power usage of a 51" hdtv at turn on, it constantly gave different readings. Range from 410 watts to 504 watts. Fluke 448 to 453 watts.

PC, using a 750watt Ultra lsp model.
Core2, running at 3.3ghz, 7900gtx , pc running gelato (nvidia software that uses the gpu as a fpu, while also using the host cpu), maxes both.
Killawatt 316watts, fluke 329watts.

All that said its still a good device to use.
Its not as good as some of the professional tools like the fluke 1735, but then the fluke meter is over $2000 while the killawatt is less than 20.00

Be aware this is a very old thread.
admin allisolm

 

[MrOblivious]

Yes these among other issues (greater than 100% efficiency) show up when using a Kill-A-Watt with a PC power supply. Unfortunately, most people believe it is accurate all the time

 

[Zap]

Originally posted by: MrOblivious
Yes these among other issues (greater than 100% efficiency) show up when using a Kill-A-Watt with a PC power supply.

I recall the issue as being 100% efficiency, not greater than, and it only happens sometimes with APFC units.

 

[MrOblivious]

Originally posted by: Zap

Originally posted by: MrOblivious
Yes these among other issues (greater than 100% efficiency) show up when using a Kill-A-Watt with a PC power supply.

I recall the issue as being 100% efficiency, not greater than, and it only happens sometimes with APFC units.

The very first example I showed about the issue was greater than 100% efficiency.

http://img.photobucket.com/alb...e_c_t_r_e/100_1218.jpg

OK and seriously for the life of me is there a way to put pictures in and have the show through on the board?

As for it being only some PSU's....there are a lot more than people think that did it originally with more and more newer units giving it problems. As for why it is doing it....well that is a longer story it seems.

 

[Mwing]

i just google kill-a-wat accuracy and this thread showed up

im waiting for my kill-a-watt shipped, just a question here

say my psu has a efficiency of 70%, if kill-a-watt shows 400w, does my computer consume 280w? or do i take the reading on the kill-a-watt and divide it by 70%?

thanks.

 

[imported_Scoop]

Originally posted by: Mwing
i just google kill-a-wat accuracy and this thread showed up

im waiting for my kill-a-watt shipped, just a question here

say my psu has a efficiency of 70%, if kill-a-watt shows 400w, does my computer consume 280w? or do i take the reading on the kill-a-watt and divide it by 70%?

thanks.

It measures off the wall. Your system consumes 400W but the components don't draw more than 70% off the PSU.

 

[Zap]

Originally posted by: Mwing
say my psu has a efficiency of 70%, if kill-a-watt shows 400w, does my computer consume 280w? or do i take the reading on the kill-a-watt and divide it by 70%?

Basically.

 

[Aluvus]

Originally posted by: MrOblivious
OK and seriously for the life of me is there a way to put pictures in and have the show through on the board?

No, it's been disabled.

Originally posted by: Mwing
say my psu has a efficiency of 70%, if kill-a-watt shows 400w, does my computer consume 280w? or do i take the reading on the kill-a-watt and divide it by 70%?

Your first number is correct. You would multiply the reading on the Kill-a-Watt by 70%. This is only an estimate, because your PSU's actual efficiency will vary with different loads, but it should be good enough for most purposes.

 

[SparkyJJO]

Originally posted by: Zap

Originally posted by: MrOblivious
Yes these among other issues (greater than 100% efficiency) show up when using a Kill-A-Watt with a PC power supply.

I recall the issue as being 100% efficiency, not greater than, and it only happens sometimes with APFC units.

Well then I guess I won't bother getting one. I thought it would be handy, especially so I know how much my crunching farm is using so that I won't pop any breakers if I decide to expand, but if it goofs up with APFC, no point. Not all my systems have APFC, but my main rig does.

 

[ch33zw1z]

Just want to point out the vast price difference between a Kill-A-Watt, and the referred Fluke 1735. Looks like the Fluke goes for about $2k, Kill-A-Watt starts about $20...Of course there's going to be a difference..

 

[Zap]

Originally posted by: SparkyJJO
Well then I guess I won't bother getting one. I thought it would be handy

It IS handy. Don't let the inaccuracies stop you from buying this. Heck, even the most expensive $2k gear sometimes have issues with certain PSUs. IMO as long as you know not to take the readout as gospel, the Kill-A-Watt (or Seasonic Power Angel - same product in different plastic) is handy to give a rough comparison between systems for power draw.

 

[Modelworks]

Originally posted by: SparkyJJO


Well then I guess I won't bother getting one.

As I said in the first post.

All that said its still a good device to use.
Its not as good as some of the professional tools like the fluke 1735, but then the fluke meter is over $2000 while the killawatt is less than 20.00

 

[erwin1978]

I have the P4460. I have a LED desklamp with clock. If clock is on by itself the meter won't read it. If I turn the light on as well then it will read both. Not accurate at low current draw.

 

[sdifox]

you dug up a nine year old thread for that?