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A 125VAC Kill-A-Watt has come to my hands, but in my country, the grid operates at 220VAC.

I know I can't use it as-is, but is it possible to modify it to be usable?

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You would need to open it up and see what is inside. Maybe you can change the transformer to work on 220VAC- But end of the day it only needs 12V/15V/18VDC to power the internal circuitrty (assumption) So break it open- make a few photos, search the internet for schematics.. or dump it in the bin – ppumkin Oct 3 '12 at 12:32
Thanks for the suggestion :) it is still in his wrapping, so maybe I'll try to sell it then – Jesús Oct 3 '12 at 13:57
The specs are clearly 125Vac max, WARNING: Do not exceed maximum ratings as detailed on label. They do not even show any UL labels on their website even though it appears to be intended for the American market. You might ask techsupport if you can adapt it ( and void the warrranty ) for your own use. techsupport@p3international.com – Tony Stewart Oct 18 '12 at 16:58
I suspect it is marketing invalid for EU and UK but they only cost $25 at NewEgg. I saw a CETL logo on the back with # 3140244. I wonder if anyone can find out more details? – Tony Stewart Oct 18 '12 at 17:11

2 Answers

up vote 1 down vote

Ask sales for availability of the 220Vac unit by email/ It shoukld be easy to adapt with the correct p/n component changes, an adapter cord pair and perhaps an MOV protection clamp with proper HV rated series line 1MOhm resistor.

I believe this may be the schematic for 220Vac using the same chip used in the 120Vac kill-a-watt. They are cheap,but how accurate depends on attention to many details. enter image description here

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up vote 1 down vote

The kill-a-watt unfortunately does it's own RMS conversion, and does not use a off-the-shelf power monitoring IC or anything.

Also, the controller IC is unfortunately, a epoxy-blob device, so it's not possible to easily reverse engineer it, or even determine what it is. The only IC I could look find the data sheet for in the kill-a-watt I took apart a while ago was a simple quad-op-amp (a LM2902).

Overall, I think it would probably be easier to build your own, rather then try to convert a existing kill-a-watt.

Anyways, no matter what you do, there is really no way to make the voltage readout work properly without a firmware change, so I can't see how useful even swapping some parts would be.

enter image description here

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Note the high-quality soldering job. It was like that from the factory.

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enter image description here

I did this tear-down a few years ago, and I've been just too lazy to actually post it anywhere.

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