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Old 10-12-2011, 03:50   #1
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Solar Panel Gauge Showing Charge at Night ?

Last night we were sitting on the boat, The battery banks during the day were at 13.8v . By 9:30 they were at 12.8, telling me there was nothing charging them at this point, (normal). I look at the gauges and it showed Solar was putting out 2.5 amps and wind gen was at 1 amp. I have never noticed this before.
Our set up is 3 AGM house batteries and 1 deep cycle starting/ back up battery.
We have 4 50 watt panels and an AmpAir 100 wind gen. It was a full moon and a little windy but ???? I dont believe that anything was generating power.
Any ideas or advice?
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Old 10-12-2011, 03:57   #2
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Re: Solar Panel Gauge showing charge at night?

The reading is obviously defective and you should disregard any SOC (state of charge) it is giving you.
What sort of meter do you have? Have You changed any of the wiring around the shunt?
Does the discharge side read OK?
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Old 10-12-2011, 05:22   #3
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Re: Solar Panel Gauge showing charge at night?

None of the wiring has been changed or altered. It has an ASC series regulator, On the panel it has two ammeter gauges for charging, one for solar one for wind. There is a digital read out gauge for battery charge on the panel as well as another Voltage gauge (looks like the ammeter gauges needle style) that has a selector switch to check each battery individually or altogether. There is no discharge gauge I am seeing. I will test this morning, I did have a wire I had to re zip tie under one of the panels 3 days ago but I did not manipulate the wire much, It pushes into the module underneath and it was only the ground, Not sure if this would have effected it, I will check what I can, I am average when it comes to 12 v systems, but some of the controllers, and regulators are new to me. I do have manuals for everything. I appreciate any help or advice that may speed up my progress.
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Old 10-12-2011, 05:46   #4
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Confirm gauges with Fluke multi meter.

cheers,
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Old 10-12-2011, 06:06   #5
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Re: Solar Panel Gauge showing charge at night?

Sounds like your charge controller has gone awry.
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Old 10-12-2011, 06:50   #6
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Re: Solar Panel Gauge showing charge at night?

Assuming the sun was gone by 9:30, I too would suspect the guages. Even if the controller wasn't working, there shouldn't be any charge coming through the panels at night. Definitely not 2.5 amps...
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Old 10-12-2011, 07:23   #7
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Re: Solar Panel Gauge showing charge at night?

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Originally Posted by callmecrazy View Post
Assuming the sun was gone by 9:30, I too would suspect the guages. Even if the controller wasn't working, there shouldn't be any charge coming through the panels at night. Definitely not 2.5 amps...
Correct so we could be looking at a discharge into the panels instead....

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Old 10-12-2011, 07:36   #8
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Re: Solar Panel Gauge showing charge at night?

The two separate meters will have separate shunts. Both meters going defective at the same is very unlikely. So it must be wiring that in common to both meters.
Trace the wires, it could be the ground or the + wire from the battery. One of these wires will have a poor connection, because the meters read very small voltage differences so a small amount of corrosion has a big effect.

A very advanced technique used by top electronic technicians is to wiggle the connections and see if there is any effect.

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Sounds like your charge controller has gone awry.
I want a charge controller that goes defective like that. 2.5A in moonlight fantastic.
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Old 10-12-2011, 07:43   #9
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Re: Solar Panel Gauge showing charge at night?

Could be an inductive voltage (phantom voltage) from proximity to a current carrying wire. Just a thought..
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Old 10-12-2011, 08:47   #10
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Re: Solar Panel Gauge showing charge at night?

All solar panel batteries will read ~13.8 if they are fully charged and good during the day, but will drop down to ~13.2-12.6 if you disconnect them.

If you have more than 1 solar panel, you need to have diodes to prevent the current from flowing back to the panels.

I can take a picture of my setup and post it on-line, send a PM reminding me if you'd like.
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Old 10-12-2011, 09:55   #11
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Re: Solar Panel Gauge showing charge at night?

Could be a bad ground connection.

On our previous boat with about 470 watts worth of solar panels we regularly measured 0.1 amps of charge from full moonlight.
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Old 10-12-2011, 11:39   #12
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Re: Solar Panel Gauge showing charge at night?

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Originally Posted by senormechanico View Post
On our previous boat with about 470 watts worth of solar panels we regularly measured 0.1 amps of charge from full moonlight.
So the lunar eclipse is reducing your solar panel output.


You will find this is an error in measurement. The zero adjustment of many ammeters is wrong and the difficulty measuring the small voltage differences in a shunt often give rise to these errors.

Moonlight is about a miliwatt per square meter. If your solar panels had 100% conversion the 6 square meters would produce 0.001x6= 0.006 wats or 0.006/12=0.0005 Amps. They are actually only about 15% so the current would be 0.000075 A by my calculations.
In practice solar cells designed for sunlight will not produce anything because the voltage will be well below the battery voltage.
It’s a full moon at the moment (the eclipse has just ended) and my solar controller shows the solar panel voltage is 1.0v and I suspect much of that is from my anchor light which is putting out more light than the moon.
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Old 10-12-2011, 12:33   #13
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Re: Solar Panel Gauge showing charge at night?

Any chance of you setting your alarm to wake up early enough in the morning to check battery resting voltage while still dark, on a night you switched off all 12 volt loads? Check your resting voltage before going to bed, switch off all loads, then after 8+ hours of darkness recheck resting voltage. If it has dropped, you have lost isolation from the panels during darkness.
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Old 10-12-2011, 12:50   #14
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Re: Solar Panel Gauge showing charge at night?

There have been a few posts about discharge from the solar panels at night.
I cannot see anything in the symptoms of the OP that are consistent with this.This problem would result in a very small discharge current.
The OP quotes the indication of a moderate and incorrect , charging current from both solar and wind.
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Old 10-12-2011, 13:12   #15
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Re: Solar Panel Gauge showing charge at night?

Quote:
Originally Posted by noelex 77 View Post
The OP quotes the indication of a moderate and incorrect , charging current from both solar and wind.
I agree, but some amp meters have trouble with currents the opposite direction, or the user is so used to read it for charge from solar that a minus-sign is overlooked (if digital meter). I reported this because I got fooled by it once myself

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