I feel I must start by saying I know very little about solar systems. I've had solar on previous boats, but I've never had an issue until now.

The solar array on my current boat was put in by the PO about 3 years ago: 2x 120 Watt panels, 30A MPPT controller, AGM house battery, plus a separately switched start battery. I added an extra house battery , taking capacity from 125ah to 250ah - didn't change any settings on the controller, but haven't had a problem with it in the 12 months since it was done.
Normally when I get aboard and turn things on, the digital voltmeter reads 13.1v. The last few times I've been on the boat I've noticed it down to between 12.5v - 12.7v. When Ive checked the controller, the solar input icon from the top left is missing from the display, and the charge light on the dual battery isolator is off.
I start up the engine to charge up a bit, and as soon as I shut the engine off, the solar input icon reappears on the screen and the light on the battery isolator comes back on.

This is what it looks like when I get aboard
note no solar input icon at top left

this is what it looks like with the engine running
no solar icon yet, but charging from the alternator (usually between 13.9v - 14.1v)

this is what appears after the engine is shut down
solar icon has now appeared in top left corner.

Also the charging light on the battery isolator will be off when I first check, will come on when the engine is started, and will remain on after engine shutdown

Then when i check the next morning - its back to square one, so I do it all over again, and it appears to work fine (at least for the rest of the day)

FWIW, bulk charge is set at 14.5v, float charge is set at 13.2v. Once I got the system reset and running properly again, (this is about the third time its happened) at 11:30am this morning (fine and sunny where I was), panel input was approximately 7.4A - 7.6A, with a bit of mast shadow moving across the panels.

It's like starting the engine resets the solar system or something, I really have no idea what's happening. I'm hoping somebody can interpret all of this for me and tell me what I should be looking out for, or if any components need checking/testing/replacing, or something.......I dunno....please help!

Thanks

12.5 - 12.7 is ok for a battery at rest, it appears the battery is fully charged and the controller is doing its job and not charging it anymore.
How long between visits ? Do you leave anything on when your not onboard ?

Thanks woko, I guess I'm just used to seeing 13.1v displayed every time I get aboard since I've owned her. I was told maybe the controller was stuffed and I was getting reverse current loss, I have seen it as low as 12.4v.
I use this for reference
so thought i was not getting a good charge anymore - only 75-85%. Is this table accurate? or am I needlessly panicking?

Between visits- I'm aboard 1-2 days every week, plus one day on a weekend with an overnighter once or twice a month.

Do I leave anything on- no, everything is shut down before I leave the boat - the house and start batteries are on separate master switches.

Hi AzureF305
I too know very little about solar charging but a question for those that do.

(All things being equal as batteries drop away over time)
At this time of year would less sun light hours and sun lower in the sky (maybe different prevailing winds that might position boat on swing mooring and panels away from sun) account for a drop in charge status?
Then next summer it's back to normal?

Hi Craig,
Damn good question!
I like to know too, I'm sure that would save a lot of anxiety (I can get a bit OCD about things sometimes)

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Craig66 said..
Hi AzureF305
I too know very little about solar charging but a question for those that do.

(All things being equal as batteries drop away over time)
At this time of year would less sun light hours and sun lower in the sky (maybe different prevailing winds that might position boat on swing mooring and panels away from sun) account for a drop in charge status?
Then next summer it's back to normal?

Like the rest of us I too know very little about Solar panels. I think you questions are very good.

Less sunlight hours would effect charging hours. Especially as being in summer would add an additional 2-3 hours of charging time. A way to test this is to figure out how any amps your solar panels are giving every hour they are charging and add 2-3 hours worth of charging to your answer and see if it adds up.

As for the prevailing winds question. A way to test this is to see where you boat sits on prevailing winds (and on different tidal stages). See whether there is anything blocking your solar panel.

PS I have no idea whether a more intense (UV) summer sun has anything to do with more power the solar panels would be getting. I do know after 25 degrees your solar panels are less efficient. So I presume not.
Regards,
Mick

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AzureF305 said..
Normally when I get aboard and turn things on, the digital voltmeter reads 13.1v. The last few times I've been on the boat I've noticed it down to between 12.5v - 12.7v. When Ive checked the controller, the solar input icon from the top left is missing from the display, and the charge light on the dual battery isolator is off.

IMO something is not right - if the sun is out you should be getting 13.1v if you have nothing drawing from the battery. It seems it doesn't want to kick in just with the solar.

MPPT controllers are dirt cheap these days & there are a wide variety of them, I would be getting another one & keeping the old one as a spare. Another option, not cheap, is to go to a BCDC system - I've just converted to a RedArc battery charging system that has an MPPT controller built in & I'm extreemly impressed ( www.redarc.com.au/dual-input-50a-in-vehicle-dc-battery-charger )

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Craig66 said..
(All things being equal as batteries drop away over time)
At this time of year would less sun light hours and sun lower in the sky (maybe different prevailing winds that might position boat on swing mooring and panels away from sun) account for a drop in charge status?
Then next summer it's back to normal?

I, too, know very little about solar charging, BUT I do know with these continuous days, we are having now, of no sun & rain & little wind & running my fridge etc I will have to go to my boat & bring the batteries back up a decent level either by going for a run or running my battery charger from the gen or shore power.

With the shorter days of winter if the sun is out I will still have enough to keep the batteries charged - in summer the extra input is wasted.
In my case, on a swing mooring, I don't think the different prevailing winds have any effect.

I've always worked off this table - I wonder which one is correct!!

battery voltage is a very rough measure of SOC, so none of the tables are really "correct"...

Hi Azure,
Looks like you've got the same solar controller as me (MP-3735 Powertech from JAYCAR).
From your top photo. You have a moon icon in lower right hand corner - this indicates the unit is in 'Night' mode, and from the manual:
"If solar array can not provide current or the current is less than 1 Amp for 5 minutes or more, the controller will switch to Night mode "
So it would seem when you arrived at the boat and had the status as per your top photo, there had been insufficient solar voltage to provide more than 1 Amp charging current, so the unit has switched to night mode.
Apparently, starting the engine and thus temporarily increasing the battery voltage causes the controller to switch to 'Day' mode and begin charging - albeit at very low current as indicated by the Charging Current Volume icon.
Under the conditions you describe, I'm guessing the unit will eventually revert to Night mode unless the solar energy improves to a level that charging current greater than 1 Amp can be maintained.
Here's my take on your situation - you either have insufficient solar energy to the panels to keep your batteries charged, or there is a problem with your solar panels.
Assuming your panels are squeaky clean (no dirt, bird poop, etc), and on the correct angle for your latitude, and not shaded, the most likely cause of your problem is - it's winter!
regards,
allan
ps: pretty extensive experience with solar, chargers, etc.

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AzureF305 said..

Also the charging light on the battery isolator will be off when I first check, will come on when the engine is started, and will remain on after engine shutdown

This is normal, the isolator has a delay in it and the battery volts take time to decay - typically keeps the batteries connected for say, up to 15-20mins. Or if the panels are charging the isolator will keep it connected until the solar stops charging.

Note that During this time if you start the motor you will be starting with both batteries in parallel.

On a sunny day, even in winter, with no loads, 240Watts of good (with no shade) solar panels should bring a 250ahr battery up to the bulk charge volts and then hold float by the end of the day.

Are you running any thing else on the system when you are away ?

A

Thanks Lazzz, Allan and Andrew, - each of you have touched on things that have been bothering me.

Lazzz: "IMO something is not right - if the sun is out you should be getting 13.1v if you have nothing drawing from the battery. It seems it doesn't want to kick in just with the solar."
- I agree completely and this is what's troubling me the most.
"With the shorter days of winter if the sun is out I will still have enough to keep the batteries charged - in summer the extra input is wasted.
In my case, on a swing mooring, I don't think the different prevailing winds have any effect."
- Same, at least it made no difference last winter anyway.

Allan: "this indicates the unit is in 'Night' mode, and from the manual:
"If solar array can not provide current or the current is less than 1 Amp for 5 minutes or more, the controller will switch to Night mode "
So it would seem when you arrived at the boat and had the status as per your top photo, there had been insufficient solar voltage to provide more than 1 Amp charging current, so the unit has switched to night mode."
- I read this too, but after I had 'woken up' the system i scrolled through the the screens (page 4), and it showed a charging current of 7.4-7.6A , so I don't know how the controller thinks it's getting less than 1A and not switching out of night mode in the mornings. I keep thinking that this is the major problem, it won't switch out of night mode.
-also, the pics were taken the second day I was aware of this so when I started the motor to 'wake' the system I was testing a theory and only had the motor running for less than 30secs to see if it would trip the system - that seems to have happened but I don't know why this is.

Andrew: "Or if the panels are charging the isolator will keep it connected until the solar stops charging."
- That's what I normally see. Every time I've checked it during daylight hours the light has always been on, and it's always off at night, but then will come on automatically with the solar system the next morning.
"On a sunny day, even in winter, with no loads, 240Watts of good (with no shade) solar panels should bring a 250ahr battery up to the bulk charge volts and then hold float by the end of the day."
- Agreed, that's exactly what I have come to expect. When I am on the boat overnight I can run fridge (runs for 8mins (av) in 60min cycles) and all lighting etc all day and all night. In the morning the battery will read a bit lower but the solar automatically kicks in and usually by lunchtime or so everything's back to 13.1v and on float for the rest of the day. Even for a 4-5 day trip it's the same.

I do keep the panels clean and everything is always shut off when I leave the boat - first at the panel, then house and start batteries have separate master switches which are always turned off.
Sorry it's such a long post, but
I'm still baffled