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Old 19-06-2018, 12:41   #1
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Not really stray current, but still...

I don't know the proper term.

There's this breaker. Feeds the master bedroom. A couple of LEDs and a small fan.

All turned off, and the battery monitor shows a steady draw of 1W.

I have no reason to believe that there's a wiring problem inducing corrosion (this is on a steel boat. No rust on the hull, anodes wearing nicely).

1W is not important per se. But I'd like to figure out what's going on.

How?
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Old 19-06-2018, 20:41   #2
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Re: Not really stray current, but still...

Battery monitors are not often that accurate to begin with. Many have a "zero me" feature to calibrate them.

You'll need a DC ammeter you can put in circuit to know for sure there's no draw. But if you think it should be zero, I'd learn how to program your battery monitor and teach it what's what.
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Old 19-06-2018, 21:00   #3
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Re: Not really stray current, but still...

If there's one breaker for the master stateroom, the battery monitor is supposed to be showing ALL THE LOADS on all the circuits in the entire boat. That one watt could be coming from anything else anywhere on the boat.

If you want to find it, you kill ALL the breakers. If there's still a load, then you have to look for other loads, like a bilge pump sensor or perhaps the battery monitor itself, that are still connecting and drawing that one watt.

One a 12v electrical system, that one watt would only be an 83 milliamp load, which could be the memory on a car stereo and one other invisible tiny load. Maybe a couple of LEDs on the monitor or fuse panel.
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Old 19-06-2018, 21:13   #4
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Re: Not really stray current, but still...

The battery monitor probably draws over 1 watt itself.

1w is nothing. Less then 0.1a. I'd call that 0
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Old 20-06-2018, 11:52   #5
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Re: Not really stray current, but still...

You mean AMPS, Battery monitors display Amps not Watts, zero the gauge out if its a analogue, like already mentioned, one amp is not a concern.
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Old 20-06-2018, 12:42   #6
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Re: Not really stray current, but still...

Quote:
Originally Posted by Dougtiff View Post
You mean AMPS, Battery monitors display Amps not Watts
Well, my monitor displays Watts (and Amps). So, yes, I meant Watts.

Agreed that 1-2 Watts of parasitic current is not a concern. Still, it should be zero. And this isn't an artefact of inadequate measurement. If I toggle on this breaker, I see 1 Watt. Off and it is zero. Other breakers 0 on or off (when there is no load.

So, as I said, this one circuit appears to consume 1W whereas it shouldn't.

I'll eventually figure this out. On a rainy day
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Old 20-06-2018, 14:57   #7
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Re: Not really stray current, but still...

Measure with an analogue volt/ammeter for the real reading.
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Old 20-06-2018, 15:31   #8
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Re: Not really stray current, but still...

Quote:
Originally Posted by gauvins View Post
Agreed that 1-2 Watts of parasitic current is not a concern. Still, it should be zero. And this isn't an artefact of inadequate measurement. If I toggle on this breaker, I see 1 Watt. Off and it is zero. Other breakers 0 on or off (when there is no load.

So, as I said, this one circuit appears to consume 1W whereas it shouldn't.
Now you're starting to give us the important info. Before your concern didn't make much sense.

What shunt/monitor are you using? Is this a 12VDC circuit?

It could still be inadequate measurement, but you probably do have something parasitic in the circuit. How do you know the LEDs are turned off? How do you know the fan is turned off? How do you know that those are the only things on the circuit?
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Old 20-06-2018, 15:38   #9
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Re: Not really stray current, but still...

Since the 1W turns off when the breaker is off, I don't think it's a measurement error. Something is actually drawing close to 100mA on that circuit. It could be something like a dimmer on the cabin lights, an inverter that is not really off when not in use, or a USB adapter (or something else) plugged into a cigarette lighter socket. LED indicators should only draw a few mA, but anything that has one might draw more current for its standby mode.



You should be able to find it if you want, since it is not some stray current. However, you could just ignore it since it's not significant compared to your house loads.
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