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Inverter quiescent current


blackrose

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I'm slightly confused about the quiescent current draw of my inverter.

 

With the inverter switched on and my mains selector switch set to "inverter" the quiescent current draw is about 0.7 amps on my 12v battery monitor. But if I switch the mains selector switch to "shore power" with the inverter still switched on the battery monitor shows 0 amps being drawn. Surely the quiescent current is still being drawn by the inverter even if there is no AC power being taken from it, or is that not the case? How can there be no 12v power drawn from the inverter if it's switched on? The lights and display are on but I guess the current draw for those are minimal.

 

This is a stand-alone 2200w PSW inverter not a combi if that makes any difference.

 

Also if I'm switching between shore power and inverter on my AC selector switch is it best practice just to leave my inverter switched on? If I want to switch a battery charger on I have to switch the inverter off first because my boat only has a single mains circuit.

Edited by blackrose
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Much will depend on the design of the inverter.  It is quite possible for the inverter to be built to detect the presence of 'foreign ' 240 V at its output and in consequence switch off the input stage.  This would be a good thing to do to protect the inverter as, if the inverter continues to produce 240 V,  there is not usually a mechanism for getting the inverter in phase with National Grid.  (Grid Tie inverters are different)   Being out of phase with the grid is not good for any electrical generator.

 

 I would double check my battery monitor against a DC  clamp meter if you have or can borrow one.  If the clamp meter also says there is no quiescent current with mains on then leaving the inverter on should be OK.  I assume you are not worried about battery drain if the inverter subsequently comes on as a result of mains failure.

 

N

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Thanks, I didn't know that's how the inverter worked. I'm 100% sure the battery monitor is correct but I'll check it with my clamp meter anyway. 

 

There's no possibility of the inverter coming on in the event of mains failure. When I'm on shore power the manual mains selector switch is set to shore power. There's no automatic switch over feature on either the selector switch or the inverter.

Edited by blackrose
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1 hour ago, David Mack said:

If your mains selector switch switches the boat's 230v wiring between the incoming shore line and the inverter output, then when you have the shore line selected there is nothing connected to the inverter output, so it cannot sense mains as @BEngo suggests.

 

Yes I understand that, but what I hadn't understood was why there was no quiescent current drawn when the inverter was switched on but inactive.

 

I'd just assumed that when it was switched on it would be drawing a quiescent current regardless, but that's obviously not the case.

Edited by blackrose
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2 hours ago, blackrose said:

I'm 100% sure the battery monitor is correct but I'll check it with my clamp meter anyway. 

 

If you are 100% sure then it does not need checking. Probably better to say 98% in this circumstance. 

 

I agree it is odd if an inverter uses no power whatsoever when switched on. 

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2 hours ago, magnetman said:

If you are 100% sure then it does not need checking. Probably better to say 98% in this circumstance. 

 

 

I was 100% sure the battery monitor is correct but I often check things to confirm what I already know, as I've now done. Probably best for you to speak for yourself.

Edited by blackrose
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7 hours ago, blackrose said:

 

I was 100% sure the battery monitor is correct but I often check things to confirm what I already know, as I've now done. 

This is not a logical position to hold.

 

Just saying (accurately).

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29 minutes ago, Col_T said:

Seems perfectly logical to me, as there are many things that change and / or wear over time,, meaning that what you once knew may not now be accurate.

Blackrose's original remark about this was "I'm 100% sure the battery monitor is correct but I'll check it with my clamp meter anyway".

 

His use of "I'm" and "I'll" seems to preclude any involvement of a significant time period in this case, so I think his later statement is illogical.

 

So in my view one of us is correct (me) while one of us isn't (you).

 

But perhaps I'm wrong - I suppose I have to be eventually - but then again, perhaps I'm not.

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16 hours ago, frahkn said:

This is not a logical position to hold.

 

Just saying (accurately).

 

I quite often hear/experience something which suggests that something I am 100% certain of may not be correct. If this happens, I usually check to discover that I was/am correct, and I remain 100% certain.

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If you are 100% sure of something being the case then this precludes the requirement to check it. The very fact you felt the need to check it means you were not quite sure which mathematically translates to less than 100 percent in terms of being certain it was the case. 

 

100 percent is a full container.  

 

Of course there are language issues around all this. Sometimes people say "I am one hundred and ten percent sure that is the case" so in some circumstances 100% may not actually mean a completely full container. 

 

 

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21 hours ago, frahkn said:

This is not a logical position to hold.

 

Just saying (accurately).

 

Why not? Lots of things are checked even though they're working fine.

8 hours ago, Col_T said:

Seems perfectly logical to me, as there are many things that change and / or wear over time,, meaning that what you once knew may not now be accurate. 

 

Exactly

8 hours ago, frahkn said:

Blackrose's original remark about this was "I'm 100% sure the battery monitor is correct but I'll check it with my clamp meter anyway".

 

His use of "I'm" and "I'll" seems to preclude any involvement of a significant time period in this case, so I think his later statement is illogical.

 

So in my view one of us is correct (me) while one of us isn't (you).

 

But perhaps I'm wrong - I suppose I have to be eventually - but then again, perhaps I'm not.

 

Well you're not making any sense at all to me! Your point seems more like a comment on lexical correctness rather than logic.

Edited by blackrose
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8 hours ago, frahkn said:

Blackrose's original remark about this was "I'm 100% sure the battery monitor is correct but I'll check it with my clamp meter anyway".

 

His use of "I'm" and "I'll" seems to preclude any involvement of a significant time period in this case, so I think his later statement is illogical.

 

So in my view one of us is correct (me) while one of us isn't (you).

 

But perhaps I'm wrong - I suppose I have to be eventually - but then again, perhaps I'm not.


Splitting hairs - Blackrose hasn’t said when he originally decided the battery monitor was correct, so he will check to see if it still is. There is, therefore, plenty of opportunity for a significant time period in this case. 😀

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5 hours ago, magnetman said:

If you are 100% sure of something being the case then this precludes the requirement to check it. The very fact you felt the need to check it means you were not quite sure 

 

While knowing the battery monitor is working correctly may preclude the requirement to check it that doesn't mean it can't be checked again if one so desires. That's where your logic breaks down because your basic premise and assumptions were incorrect.

 

I never said there was any requirement to check it. I was 100% sure that it was working properly, I was simply curious and wanted to see what the clamp meter read as I hadn't used it before.

 

I hope that's ok with you. Once again, it's probably best if you speak for yourself rather than trying tell me what I was thinking! 😏

Edited by blackrose
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10 minutes ago, blackrose said:

 

While knowing the battery monitor is working correctly may preclude the requirement to check it that doesn't mean it can't be checked again if one so desires. That's where your logic breaks down because your basic premise was incorrect. I never said there was any requirement to check it. I was 100% sure that it was working properly, I was simply curious and wanted to see what the clamp meter read as I hadn't used it before.

 

I hope that's ok with you. Once again, it's probably best if you speak for yourself rather than trying tell me what I was thinking! 😏

 

I talk to myself all the time. At least 70 percent of my day is taken up by talking to myself. 

 

I'm happy for you to check things when you are 100% sure but I am 110% sure it is not technically necessary.

We all have our faults. 

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1 minute ago, magnetman said:

 

I talk to myself all the time. At least 70 percent of my day is taken up by talking to myself. 

 

I'm happy for you to check things when you are 100% sure but I am 110% sure it is not technically necessary.

We all have our faults. 

 

If you can admit your faults you're halfway there...

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On 16/01/2023 at 22:37, magnetman said:

 

I talk to myself all the time. At least 70 percent of my day is taken up by talking to myself. 

 

I'm happy for you to check things when you are 100% sure but I am 110% sure it is not technically necessary.

We all have our faults. 

Just because someone believes 100% that something is ok, it does not mean they are correct, so checking is wise, also if they are correct they may wish to check from time to time to prove they are indeed correct to those that wish to question their claim.

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