GPO socket monitoring device

Introductions, general chit chat and off-topic banter.
Post Reply
User avatar
Gemini
Noobie
Posts: 24
Joined: Sat, 28 Jun 2008, 08:25

GPO socket monitoring device

Post by Gemini » Sun, 29 Jun 2008, 22:16

I came across this device while looking for something i cannot even remember now and thought it might interest a few people here.
latestbuy.com.au wrote: Product Specification

The Monitor My Power Meter allows you to monitor and measure the power usage of electrical appliances in real-time.

The Monitor My Power Meter is approximately 6.5 x 7.5 x 12 cm in size and requires 2 x LR44 batteries (included).

The unit can display line voltage, line current, line power, total electric quantity and total electric charge.

Technical Specifications:

    * Power supply: 250V AC 50Hz
    * Maximum load: 10A, 2500W
    * Measure voltage range: 210-301V AC
    * Measure voltage accuracy: +/-3%
    * Measure current range: 0.02-10A
    * Measure current accuracy: +/-3% or +/-0.03A
    * Measure power range: 0-3010W
    * Measure power accuracy: +/-4% or +/-10W
    * Accumulative electric quantity range: 0-9999.9kWh
    * Measure frequency range: 45-65Hz
    * Clock accuracy: +/- 1 minute per month
    * Power cost: < 2W
    * Operating temperature: -10C to +40C
http://www.latestbuy.com.au/digital-power-meter.html

Apparently, you can enter your local electricity rates and it tells you how much money you are spending on the fly.

Would be good to know exactly how much your EV costs to run   Image

antiscab
Senior Member
Posts: 2238
Joined: Mon, 26 Nov 2007, 05:39
Real Name: Matthew Lacey
Location: Perth, WA

GPO socket monitoring device

Post by antiscab » Mon, 30 Jun 2008, 03:04

yeh you can get one of those called an ms-6115 or something like that from jaycars. btw, the link is dead.

These things are WORSE than useless when it comes to measuring energy used to charge batteries.

The reason is these cheap meters measure 12 or so points on a sine curve to obtain its amplitude to determine rms value. Problem is, this does not work when the wave isnt sine.

Most chargers are switch mode power supplies that don't draw current proportionally to voltage (ie a sine wave). The result is a power reading 70% lower than it actually is.

I have one that tells me my scooter charger (irrelevant which of the 3 i use) draws 90w, while im getting 450w out of the dc side.

When looking for an energy meter for measuring how much your charger is drawing, you need to make sure it takes many samples per second (3000+). Or alternatively use an analogue kwh meter.

Matt

moemoke
Groupie
Posts: 115
Joined: Tue, 20 May 2008, 04:47
Real Name: Andrew Pugsley
Location: Moe, Victoria,

GPO socket monitoring device

Post by moemoke » Mon, 30 Jun 2008, 03:20

Matt is the 'cent-a-meter' that I have installed in the same boat

http://www.centameter.com.au/

I hope it goes backwards when I get the solar connected next week Image

antiscab
Senior Member
Posts: 2238
Joined: Mon, 26 Nov 2007, 05:39
Real Name: Matthew Lacey
Location: Perth, WA

GPO socket monitoring device

Post by antiscab » Mon, 30 Jun 2008, 03:37

i think it might be, but you never know. i havent used one personally though.
easy enough to test, put a switch mode power supply load through it and see if it shows the right amount of power (i assume it shows instantaneous power draw).

If switch mode power supply loads aren't a large portion of your energy usage on the circuit you put the cent-a-meter on, then i wouldnt worry about it. It should read correctly for all other loads. especially for all your major ones (fridge freezer washer oven etc).

have you had it installed for long? if you have compare its reading with your next power bill. it would be interesting to see how close it is.

Matt

User avatar
Tim
Groupie
Posts: 67
Joined: Tue, 08 Jul 2008, 03:54
Real Name: Tim
Location: Adelaide

GPO socket monitoring device

Post by Tim » Sat, 12 Jul 2008, 04:10

Those meters (in the first post, and the link works for me) are $39.95 at Jaycar too, saw them today.

OR... buy one on eBay like I did for ~$10 to 15 + $10 postage and handling. Identical item and brand.

Cheap enough for what most people want to see what pulls what outta the wall, and scare the hell outta the people who plug their plasma TV into it!

Tim.

drowe67
Groupie
Posts: 147
Joined: Fri, 18 Apr 2008, 20:14
Real Name: David Rowe
Location: Adelaide
Contact:

GPO socket monitoring device

Post by drowe67 » Fri, 26 Sep 2008, 01:16

Hi Matt,

My Jaycar MS-6115 is giving reasonable results when charging my EV. I have 12 Jaycar MB-3612 chargers, and on starting it measures a big spike of around 3kW (expected turn on transient), then settles down to around 1800W, reducing as the batteries charge.

The MB-3612 chargers are rated at 12A, and I have measured about 10-12A with a heavily discharged battery, tapering off as they charge.

So power output is around 12V x 10A x 12 = 1440W, if the chargers are 85% efficient as per spec thats 1700W at the wall, close to what I see. I haven't measured both input and output power at the same time, so these numbers are ball park, but there is a reasonable match.

Maybe the 12 chargers in parallel on the AC tames the current waveform?

Some time I will try both input and output power some time on a single battery and compare the kWH to the Electricity Meter if I can find a time when the house is quiet with no other big loads.

Cheers,

David


antiscab
Senior Member
Posts: 2238
Joined: Mon, 26 Nov 2007, 05:39
Real Name: Matthew Lacey
Location: Perth, WA

GPO socket monitoring device

Post by antiscab » Fri, 26 Sep 2008, 03:57

hi David,

more likely those chargers have harmonic distortion correction, so their current draw is more proportional of instantaneous voltage.
wiring switch mode power supplies without harmonic distortion correction actually makes the problem much worse.
I would consider those chargers to be of fairly high quality, as one would expect considering their cost.
its good to hear its working out for you.

for my own setup i now use KHW meters such as these:
http://cgi.ebay.com.au/ws/eBayISAPI.dll ... :IT&ih=007
far more reliably accurate than a ms6115, but as long as the setup works, its all good :)

Matt
Matt
2011 Blade Electron mk6
2007 vectrix - 145'000km
1998 Prius - needs batt
1999 Prius - needs batt

Post Reply