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  #11  
Old 07-18-2013
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Re: Solar charge controller question

Yes. The Controlador de carga de 15A (12V/24V) MorningStar – ProStar PS-15 is a good PWM controller. I believe it may be the most popular one worldwide.

Here's a bit more info: Morningstar Corporation » ProStar

Bill
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  #12  
Old 07-19-2013
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Re: Solar charge controller question

Thanks Bill. I was just down at the boat and I can't figure out if the problem is the controller or the panels (or something else). Under the (winter) midday sun I measured 13.5 volts arriving at the controller from the panels. I would have expected more. The controller was sending only 12.9 volts to the battery. It seems to be charging the battery, but not as much as I think it should. I wish I knew more about solar charging ....
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Old 07-19-2013
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Re: Solar charge controller question

That may or may not indicate a problem, depending....

- on the rating of your panels (wattage and OC voltage)
- on the wiring and connections
- on how well the controller is functioning
- on how accurate your voltage measurements are
- on the size and state-of-charge of your batteries

etc., etc.

First thing I'd want to do is find out how much amperage the panels are putting out to the controller, and how many amps the controller is putting out to the batteries.

Easiest way to do this is with a clamp-on DC ammeter. Try to borrow one if you can, but you probably ought to have one aboard anyway for electrical troubleshooting. You can actually buy a good AC/DC clamp on ammeter like the Mastech MS2108 (not the MS2108A) for under $70 online.

That will tell you right away how much amperage is being produced by the panels and how much is going into the batteries.

Bill
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  #14  
Old 07-21-2013
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Re: Solar charge controller question

Bill, the panels are 65w and have a rated output of 18 volts. I've checked all the connections at the controller and batteries and all seem OK. I checked the voltage with 2 different voltmeters and both jibe. The 160amp house battery started the morning with 12.3v and went up to 12.6v by midday (and then it clouded over and started to rain). In sunlight I see the voltage of the batteries going up, but it seems not as much as before. Maybe I'm expecting too much from my panels. I wish I had a good battery monitor to measure amps in and amps out to know what is really going on. One thing I found a bit strange is there are 3 diodes (but only 2 panels). One of the diodes gives a different (lower) voltage than the others when I measure voltage arriving from the panels. I'm an electrical dimwit, but my electrician here thinks the panels are working. He was a bit confused by the diodes though. I must say I'm tempted to just get new panels and a controller, but the prices here are pretty high.
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Old 07-21-2013
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Re: Solar charge controller question

If the existing controller is a simple charge controller, there will always be a voltage drop in the regulator, and if that is 0.6 volts, I'd suspect that is perfectly normal and acceptable.

You have 130W of panels and some 2000W of battery, so you certainly go hook up the panels directly for a couple of hours, or a day, and see how that helps.

Diodes can be of different kinds for different purposes. Somewhere, in the panels or in the wiring or in the controller (that's 3 places) there should be one diode which prevents the batteries from discharging back into the panels during the night. If a system was just cobbled together, and there are two diodes (i.e. one in the charge controller plus a second in the wiring into it) then you've got two diodes serving the same purpose--but with two voltage drops, so the extra one in the wiring can and should be removed. There may also be "bypass diodes", one on each panel, so that if one panel is shadowed or fails, the other panel still puts out full power. Those would stay.
A lot of stuff can be "wrong" but still work well enough not to be noticed. Of course once it is 20 years old and the system isn't as robust...could be time for some housekeeping. A sketch of the whole system, showing what is where and accompanied by a description of the bits, could shed some light on all of this too.
Some peeking and poking, i.e. battery condition and capacity testing, separately from the other questions, probably also would help. The whole system has to be questioned, really, in order to figure out which pieces might be misbehaving.
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Old 07-23-2013
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Re: Solar charge controller question

Thanks Hellosailor. The system is indeed 20 years old. I suspect it may be on its last legs. I just had a thought about the diodes. There used to be 3 panels (one was damaged and removed), so perhaps each panel once had its own diode, thus explaining the extra diode now. I'm going to wait for a really sunny day and see how it charges. It may be that I am expecting too much from my charging system. Would my two 65w panels coupled with a simple controller (not MPPT) bring a 160a battery up to full 12.8v charge in one day of sun? My boat is all LED and I have no electric fridge. I believe my consumption is not more than a few amps per day, sometimes more when I use my stereo. In the morning my battery used to always show 12.5 or 12.6 volts and was back at 12.8 volts before dusk.
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Old 07-23-2013
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Re: Solar charge controller question

"Would my two 65w panels coupled with a simple controller (not MPPT) bring a 160a battery up to full 12.8v charge in one day of sun?"
That would depend on how far down the batteries were to begin with, among other things. Depending on your latitude and time of year, one full day of sun can equal 4-8 hours of full power output, so that's a 2x variation all by itself.

"In the morning my battery used to always show 12.5 or 12.6 volts and was back at 12.8 volts before dusk. " And then as batteries normally age, they will go from 12.7 or more commonly 12.6v at full, down to 12.4 or 12.2 max in a few years.

And that's ignoring measurement errors, as multimeters age they tend to go out of calibration, and the cheaper ones are sometimes off to start with. So, not trying to duck an answer but "it depends" on an awful lot of things and you have to verify each one in order to figure out the whole picture.
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Old 08-31-2013
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Re: Solar charge controller question

I just thought I'd provide an update on the situation.

I've been back to the boat a few times with my electrician since my original post and this is what we've discovered. The solar panels, which I thought were 65w each are, in fact, 43w each (the Seimens model number is 65, hence my assumption they were 65w). This discovery has lowered my expectations in terms of power charging. It turns out I have a total of 86w of panels. We were able to test them and they were putting out more than 16v in a late afternoon winter sun, so it seems they are functioning fine. The current solar charger, however, is only sending 12.8v to the batteries- and that seems to be the problem. I now believe the charge controller is confused about the battery state and is withholding charge thinking the batteries are full. I've bought a cheap Chinese 30a controller to replace the current controller and will install it next weekend. I'm certain the controller is the problem, but I'll know for sure on Saturday. I am already thinking about buying one big 140w panel to supplement my charging capacity (I have plenty of room for panels). This raises another question: can I hook up two 43w panels with a 140w panel on the same controller or do all the panels have to be of the same model or wattage? I actually think the two 43w panels will provide enough power for my current needs, but as I'd like to add an electric fridge later to replace my propane one, I think I could use the extra power. I'l get a good MPPT controller later on my next trip abroad.
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Old 08-31-2013
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Re: Solar charge controller question

Quote:
Originally Posted by copacabana View Post
I just thought I'd provide an update on the situation.

I've been back to the boat a few times with my electrician since my original post and this is what we've discovered. The solar panels, which I thought were 65w each are, in fact, 43w each (the Seimens model number is 65, hence my assumption they were 65w). This discovery has lowered my expectations in terms of power charging. It turns out I have a total of 86w of panels. We were able to test them and they were putting out more than 16v in a late afternoon winter sun, so it seems they are functioning fine. The current solar charger, however, is only sending 12.8v to the batteries- and that seems to be the problem. I now believe the charge controller is confused about the battery state and is withholding charge thinking the batteries are full. I've bought a cheap Chinese 30a controller to replace the current controller and will install it next weekend. I'm certain the controller is the problem, but I'll know for sure on Saturday. I am already thinking about buying one big 140w panel to supplement my charging capacity (I have plenty of room for panels). This raises another question: can I hook up two 43w panels with a 140w panel on the same controller or do all the panels have to be of the same model or wattage? I actually think the two 43w panels will provide enough power for my current needs, but as I'd like to add an electric fridge later to replace my propane one, I think I could use the extra power. I'l get a good MPPT controller later on my next trip abroad.

With only 80W of panel it will take you days to get to absorption voltage. You will probably not come up to 14.XX until 95% +/- SOC... The available current in this case dictates how long it will take you to get to an absorption voltage. You will be stuck in bulk for a long while and the batteries are dictating the voltage based on the available current, or lack there of, to raise the voltage...

Your electrician should understand this and should have clamped the output to confirm current. Your controller is working but don't expect 14.XX for a couple of days or more even with all DC loads off....

If you had 150A of current you'd see 14.XX fairly quickly but you have essentially a trickle charger for a quarter to a third of a 24 hour period, thus it takes time....

This video may help to explain the relationship between current & voltage...

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Last edited by Maine Sail; 08-31-2013 at 01:31 PM.
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  #20  
Old 09-01-2013
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Re: Solar charge controller question

Thanks for your reply and video Mainesail. I really appreciate your informative posts and your "how-to" site. Now, when are you coming to Brazil to help me kill the gremlins on my boat?

If I understood your post and video correctly, I will only see 14+ volts when the battery is charged and in float state. I always assumed I would see higher volts going in as it charged and the voltage dropping as it reached float state. Now I'm more confused ...

Perhaps I should just state the facts about my charging system and maybe you can tell me what's going on.

When I bought the boat it came with the current two 43w panels and controller and about 450a of cheap batteries all in one bank (and all of different sizes). One by one, the batteries failed and I removed them. At this time I changed everything to LED aboard and, after the last original battery died, I bought a quality 160a deep-cycle battery for my house battery and a 70a starter battery. The new batteries are a bit less than 2 years old now. They are on separate circuits (I charge them separately). After these changes I always saw high 13's or 14+ volts from the controller to the batteries on my voltmeter during the sunny hours. At sunset I would see 12.7 or usually 12.8 volts on my battery and a bed time maybe 12.5 or 12.6 volts. My electricity use is the LED lights and maybe an hour or two of stereo. Some months ago I started to notice the volts during the day were always under 13v and the battery didn't seem to be getting up to full charge. After a good motoring though, the battery would be bursting with charge and would hold the charge fine. When I close the boat I leave the panels charging the 160a battery and it usually sits for 2 weeks like that. Still, when I get back to the boat after 2 or 3 weeks I find the charger putting out 12.8 or 12.9 volts. As a test I tried leaving the 70a battery on the charger for 2 weeks and I also saw only 12.8v going to the battery from the controller. Now, my doubts:

I don't have an amp meter unfortunately. How can I find out if the battery is being charged?

Shouldn't the 86w of panels bring a 160a battery up to full charge over a few weeks?

Why did the charger always send 14+ volts during the day to the battery in the past and now only send 12+ volts?

Since I've already bought the new controller I might as well go ahead and install it on Saturday. I'll let you know what happens.
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Last edited by copacabana; 09-01-2013 at 08:54 AM.
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