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Monitoring 240V AC Current Usage


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That will only show what the current is at 240v, it won't show the actual current drawn from the batteries at 12 volt.

I fitted a Victron BVM which shows whats actually going into and out of the batteries.

 

https://www.victronenergy.com/battery-monitors/bmv-700

That is what I measure but its not what the OP asked for

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Did you find them very accurate, Would be a handy way to see if you are improving the efficiency of a fridge by adding fans etc.

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I'd like to be able to see the current that my 240V appliances are using, eg the washing machine (on cold wash). Is there any reason why I should not just wire in one of these things in the 240V line from the inverter?

http://uk.rs-online.com/web/p/analogue-panel-ammeters/8861831/

 

I have one similar fitted as your question, different scale but does the job.

 

I also monitor the battery current and voltage as well.

 

Steve

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Did you find them very accurate, Would be a handy way to see if you are improving the efficiency of a fridge by adding fans etc.

Our fridge is 12 volt.

Originally got it to set our Vetus generator to run at optimum speed. Eventually replaced generator with Onan.

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It's much more useful to know the daily energy consumption in KWhr than the current. The current drawn by your washing machine will vary over an hour or two. The Maplin meter will tell you what the total energy used is per cycle. Similarly, your fridge may consume 2 or 3 amps when it's running, but you probably need to know how much is consumes, on average, per day. Kettles use a lot of energy, but only for a few minutes. It is smaller consumers, running for long periods, that .drain yer battery

Edited by mross
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The problem with a moving iron meter as you can see from the scale is they are not very accurate at low values. In the case of your meter it will be hard to read with any degree of resolution and precision much below 2.5 amps which is the best part of 600w.

Is that good enough for what you want???

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The problem with a moving iron meter as you can see from the scale is they are not very accurate at low values. In the case of your meter it will be hard to read with any degree of resolution and precision much below 2.5 amps which is the best part of 600w.

Is that good enough for what you want???

It'll have to be, I've ordered it!

It'll give me an idea of the load presented by combinations of my appliances, all of which specify a 13A fuse and a consumption of nnnnKthingies per year and nothing else that is useful.

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It'll have to be, I've ordered it!

It'll give me an idea of the load presented by combinations of my appliances, all of which specify a 13A fuse and a consumption of nnnnKthingies per year and nothing else that is useful.

They should have their wattage on the label somewhere.

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It'll have to be, I've ordered it!

It'll give me an idea of the load presented by combinations of my appliances, all of which specify a 13A fuse and a consumption of nnnnKthingies per year and nothing else that is useful.

 

No it will not, what it will give you is an instantaneous measurement of the items load and that will vary especially with a washing machine.

 

The washing machine may even have the rating of the heating element on the label. Subtract that from the maximum load and you have the cold wash answer.

 

As per Ditchcrawler, the labels will give you items maximum load (W/V = A)

 

Now you have ordered it, it may be more interesting to watch than the TV.

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On AC, watts = volts x amps x P.F. (power factor). On shore supply, power factor is about 0.8 to 0.85. But on inverter probably close to 1.0 when loads are resistive like incandescent lamps. It could be 0.7 if a motor is running.

 

edited to strike out nonsense

Edited by mross
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Power Factor has nothing whatsoever to do with the supply and everything to do with the load. An incandescent bulb or heating element, both being purely resistive, will have a PF of 1. A motor, being inductive, will have a PF <1.

 

Edited to remove now redundant quote

Edited by WotEver
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You are right! But power factor needs to be taken into account if OP wants to convert amps to watts or vice versa. I'll edit my post to strike through the offending sentence.

Fine. I've removed the quote too.

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If he is measuring ABOUT 3 amps on that meter its unlikely he will be able to see if it was 2.7 amps of 3.3 amps so I can see the power factor making much difference to the accuracy of his readings. If he was measuring a 100 amp with something a bit better it would be a different story.

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why do you refer to the OP when it's you? glare.gif

Is the load plugged into your inverter with a 13A plug, or is it hard wired?

Not sure. I'll consult my psychiatrist.

Yes & No. It is liable to change from one to the other or not in the near future. Why do you ask?

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