I have proved Kill-A-Watt accuracy .. NOT GOOD.

[taisingera]

I have my computer plugged into a KAW and that plugged into a Surge Protector with ON/off switch. I had been getting 35W idle when I switched the surge protector off each night. For the last 4 nights, I have not switched it off, and this morning, at idle I was sitting at 65W and it peaked at 102W booting up. I just switched the surge off and then back on and I was back at 35W idle.

 

[Zap]

That proved nothing. Modern computers always draw more power when booting up than when sitting idle in Windows. Also, were you positive that your system was idling? There may have been some background process going on, or for whatever reason your CPU wasn't going into low power mode.

That said... yes, the Kill-A-Watt is not 100% accurate. It potentially can be off quite a bit, especially with some circuits and PSUs with Active PFC. And yes, that has been "proven" using calibrated equipment.

However, the Kill-A-Watt is still a very useful tool to have, for various reasons.

 

[taisingera]

Usually KAW is good, but I found it strange that power usage was 30W higher both at idle and boot compared to what I have seen before with the same system.

 

[taisingera]

Nevermind, the difference was from KAW reading Watts vs VA.

 

[philipma1957]

Nevermind, the difference was from KAW reading Watts vs VA.

duh . Don't you just hate when you make a mistake like that! BTW takes a real person to admit a mistake. my hat is tipped to you!

 

[Blain]

duh . Don't you just hate when you make a mistake like that! BTW takes a real person to admit a mistake. my hat is tipped to you!

Editing the original post with the updated information would have been even better.

 

[Maximilian]

duh . Don't you just hate when you make a mistake like that! BTW takes a real person to admit a mistake. my hat is tipped to you!

A real hero!

http://www.youtube.com/watch?v=-DSVDcw6iW8

 

[jvroig]

While we're on the subject of Kill-a-watts, what's the power consumption of the Kill-a-watt itself? If I had two, I'd daisy-chain them to see the difference they are reporting, but I only have one at the moment. I'm guessing <2W?

 

[Red Squirrel]

Anyone know if KAW's are true RMS? I usually use a clamp on amp meter but I don't know how accurate that is as I only paid like 100 bucks for the meter so I doubt it's true RMS.

 

[Zap]

Nevermind, the difference was from KAW reading Watts vs VA.

duh . Don't you just hate when you make a mistake like that! BTW takes a real person to admit a mistake. my hat is tipped to you!

Serious props to the OP! :thumbsup:

While we're on the subject of Kill-a-watts, what's the power consumption of the Kill-a-watt itself? If I had two, I'd daisy-chain them to see the difference they are reporting, but I only have one at the moment. I'm guessing <2W?

I should try that some day. I have both a KaW and a Seasonic Power Angel, which might (internally) be the exact same thing.

Strangely, I haven't seen the two in one place at the same time. Maybe it IS the same thing, and I just haven't noticed? [Queue Twilight Zone music)

 

[bononos]

Nevermind, the difference was from KAW reading Watts vs VA.

How can it account for almost double the difference? I'm assuming the difference is caused by pfc.

 

[Soulkeeper]

I have two KAW meters
one failed on me after leaving it plugged in for a few months straight
now it reads 50% higher on everything watts, voltage, hertz

that said it was pretty accurate till it failed, and my newer KAW meter reads fine

 

[PhIlLy ChEeSe]

I have two KAW meters
one failed on me after leaving it plugged in for a few months straight
now it reads 50% higher on everything watts, voltage, hertz

that said it was pretty accurate till it failed, and my newer KAW meter reads fine

I was thinking they can be burned out, I never had one but when dealing with voltage, anything can happen to the meter!!! If it has a battery it could have popped a fuse, ETC.