Power Supply Problems - Help please

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BrendanChandler

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www.brendanchandleryachtdelivery.co.uk
<span style="color:blue"> I have 2 Solara 85w solar panels on the boat. The first feeds its power to the second and then both feed power down on 2 core cable to a Prostar 15 solar controller.

I fitted these approx 3 years ago in accordance with the manufacturers instructions and have been very pleased with them until this week when the batteries (both heavy duty truck batteries installed in July this year and wired together) started to get low on power. Incidentally the reason that the batteries are wired together is that I do not have space for an additional starter battery. I carry a Power Pack as a backup in case I allow the power to drop too low to start he engine.

There has been almost no wind this week, so I could concentrate on the solar power.

Both solar panels show 20.2v at the output points on the panels.
The input wires to the controller show 20.1v when detached form the controller and show battery voltage when attached.

Today, a very sunny day the battery management system shows that the battery is receiving approx 3 Amps.

The controller is correctly set at type 3 battery, water filled.

I tried to connecting the input to the controller directly to the battery wires from the controller, bypassing the controller and the Battery Management system does not show a discernable difference, still about 3 amps.

As I type this, I notice that the voltage has now declined to 12.3 and with everything off, I am making 0.3Amp.

As you may gather, my knowledge of electrics is very limited.

Can I assume that the Solar Panels are ok because of the output voltage? Is it possible to gauge the Amps being supplied?

Can I assume that the Controller is ok as there was no discernable difference when bypassed?

If so, am I now looking for a power leak rather than lack of input and if so, where and how should I begin this process?

Help!!!
I am preparing for another Atlantic Crossing. The scurvy dogs will be even more revolting if they don’t have their Gin and Tonics cold!!

Thanks

Brendan </span>
 
With the panels connected to the controller you get 20 volt at the panel, but battery voltage at the contoller ? If so a resistive connection.
What happens if you connect one panel direct to the battery ? then the other panel, this will show if they are ok or not.
You can also try disconnecting the solar panels, does the monitor show any drain, if not then you are not loosing power that way.

Brian
 
The 20 volts is the open- circuit voltage of an illuminated panel ( or more in parallel) as soon as you connect, the voltage drops. I would go for a duff connection at the second array ( the one where the wires from the first array join it and go on into the boat) The arrays will perforce be outside in the sunshine and also the salt air. Go through all the connections methodically, re-installing the system. Then you will get another three years before having to repeat the excercise. You can measure across a joint - you should get no voltage. If you get any there is a problem with it.
 
Where are you at the moment? And what is the orientation of the panels to the sun?

It is hard to give much advice without knowing a lot more about your usage of the batteries, but from what you say there may not actually be anything wrong.

There seems to be no reason suspect the controller. The output from the panels seems a little low but not necessarily unreasonable if they are not in the ideal orientation.
 
<span style="color:blue"> With the panels connected to the controller you get 20 volt at the panel, but battery voltage at the contoller ? If so a resistive connection.
When I test the wires as they reach the Controller, but are not attached to the controller, I get 20v but when they are attached to the controller, I get battery voltage. What is a resistive connection and what do I do about it?

What happens if you connect one panel direct to the battery ? then the other panel, this will show if they are ok or not. I do not know. I will try and report back tomorrow. What should I hope to find and what does it mean?
You can also try disconnecting the solar panels, does the monitor show any drain, if not then you are not loosing power that way. Power loss at night seems not unreasonable but this is starting with a low voltage because of charging problems. </span>
 
Hi Billjratt
<span style="color:blue"> I disconnected the panels and remade the joint on the second panel. They are a spring loaded connection and in my ignorance, nothing like a screwed connection. I will do so again see whether I can replace the connection but cannot see how it can be done. Will try.
Thanks for suggestions</span>
 
If voltage drops to battery voltage, joints are probably ok, i.e. if faulty you would see a high voltage at the panels.

By linking each panel to the battery, you by-pass everything, see what the monitor says as to charge, you may just have a faulty panel.

By disconnecting panels, turn off all loads, the monitor should show if you have a drain causing your power loss.

May be worth disconnecting a battery in turn, and check charge, simple tests to point you in a direction, you need to find an area for the fault at the moment.

Brian
 
By chance I was doing a test today with my Solara 225M (56watt) panel. South of Rome in a marina with panel mounted flat on the deck. I had a 40 Watt car lamp bulb for a load and was measuring after the regulator and without a connection to the battery (just the lamp as a load).

Around 13:00 local time I was getting a current of 2.1 amps, this was quite constant for a couple of hours until a shadow from the mast of the boat next door cause amps to drop to about 0.45A. When the sun move around a bit the current came back up to 1.97A. From about 14:30 local the current was continually dropping until at about 16:30 it was down to 0.34A!!!

So, there a couple of points here:

The panel will only give 56Watts at the rated open circuit voltage: in my case 19.6 volts (if I remember correctly). Thus in IDEAL conditions I can expect about 3Amps at 20 volts. This 3 amps will give me 36watts at 12 volts. In fact around mid-day solar time I was only getting around 2 amps due to panel not orthoginal to the sun and also due to atmospheric losses which will depend on humidity in air, distance through atmosphere in direction of sun e.t.c.

At this time of the year I would guesstimate that you will only be getting about 2/3 of the rated current for about 3 hours of the day, if your panels are well orientated and with no shadows; for the rest of the time you will be getting a lot less.

So, a couple of suggestions: are you sure there are no shadows? Are the panels orientated toward the sun throughout the day? The actual power that you receive will be a lot less than you think.

If I can help with any comparitive measurements let me know, I have some spare hours this week.

Alan.
 
[ QUOTE ]
Today, a very sunny day the battery management system shows that the battery is receiving approx 3 Amps.


[/ QUOTE ]

Brendan,

you havent said how many Amps you have been getting on a regular basis previously.....

I dont know anything about these things, but I am sure the above info would be handy.

e.g. if you have been getting 10 or 12 Amps, and now only 3 Amps, thats a big difference, but if you have been getting say 5 Amps, it's not such a big difference.
 
The output seems a little low but not ridiculously so. I think Solar panels are rated at an output of about 16V, so the very best an 85W panel will give is about 5A - and that would be with the panel angled directly towards the sun at midday. Mount the panel flat and you could halve that even in the Canaries

If possible try connecting each panel in turn individually through the controller and see what output (in Amps) that gives. You should also record and tell us what voltage you were seeing at the battery when you were getting 3A current.
 
I would suggest that perhaps one or both the batteries are the source of the problem. Do check first that each solar panel is giving similar current as already suggested. One may have bad connection.

You should disconnect one battery and charge it as best you can then load it to several amps while monitoring volts to check for capacity. Do the same with the other battery.
You should be able to discharge something like 50% of the Amp Hour rating of the battery at near 12 volts. olewill
 
I had a similar problem on an otherwise faiult free solar/battery installation.
After much huffing and puffing I found a perfect looking three pin so called marine quality plug and socket has 20 volts one side from the panel array and 3 volts when coming out the socket. Tried cleaning both plug and socket, without avail and replaced with another make.
 
Hi All,

Thanksfor suggestions.
I did remake all junctions as well as possible. The attachment to the solar panel is with a spring hiolding the wires in place which I was suspicious of. I fiddled about and remade some connections with screw choc boxes and got better results.

Does anybody know whether a small shadow on part of one panel would have the effect of reducing the amperage by say 65%?

I think that I was getting perhaps 7 amps. Even though I am in Canaries, it is getting late in the year. Perhaps that and a small shadow are the reason.

I was getting almost 3 Amps from one today but the other had a shadow from one source or other all afternoon. I will have to try getting out of bed tomorrow morning and test then.

I am fairly certain that I am not leaking power.

Brendan
 
Short answer to your question: "YES" . Also the time of the year and the time of the day will be very influential.
As I said in my earlier mail, just a shadow from the mast of the boat next door knocked my current down from 2.1 amps to 0.45 amps. On my panel it seems to depend which part of the panel is in shadow as to how bad the effect is.

Alan.
 
From what I recall some panels do suffer a very large reduction in output if there is a shadow across it - I have an idea that amorphous silicion panels suffer more in that respect than poly/mono crystaline panels.

3Amps from a single panel is pretty much what I would expect.
 
Theoretically the max amps should be about 14 at noon with unbstructed sun - that means no shadows from masts or even ropes depending on the angle. If you cast a shadow across the panels you get a different reading than going along them. Are they clear? Can you measure at the cells under load? If they're dragged down to battery voltage (plus 0.6v or so for the controller) then they should be trying to push amps into the battery bank. Are any of the connections getting warm? If so they are costing power. Maybe only one of your arrays is working, try each sparately.
 
Sorry Billjrat, not trying to be picky, but max current will be :

85W times 2, divided by 20 volts (not 12) = 8.5A.

Don't want Brendan trying to find amps that are not there!!

Alan.
 
If you get 20 volts across the battery you've got real trouble!!
Although the open-circuit voltage is that high, it falls to the battery voltage when connected. If you want to be really picky it should max-out at about 14.8v for wetcells so split the difference, but it ain't pumping amps by that time - the batteries are almost full. It only pumps amps while the batteries are low, so the 12volt reading is valid.
 
In your post you said:

"Theoretically the max amps should be about 14 at noon with unbstructed sun "


I guess you meant volts; in that case I agree with you.

Alan.
 
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