Does my solar panel have a regulator?

Amari

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I have a rigid solar panel mounted on a stern gantry. Probably many years old. Boat instructions written by previous owner x3, 10 years ago, states ''always switch off solar panel when leaving boat'.
There is a 'quad-cycle' management system which shows 2amp charge from the panel on a sunny day (Turkey). Would be nice to leave panel on to top-up batteries in our 2 month absences. How can I tell if there is a regulator to prevent overcharging? Thanks
 

Danny

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If there's a regulator then when the batteries are fully charged you should see the charging current drop right down, even on a sunny day.

If you have a multimeter check the voltage across the battery terminals when you know they are well charged. If the voltage is above 13.5v (when the sun's out) then I'd suspect you have no regulator. Make sure you have no electrical or electronic equipment turned on (apart from the solar panel) when doing this test.
 

Amari

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Thanks Mainmarine. I didn't want to duplicate existing (if any). Will any of-the-shelf regulator suffice or are there different sizes/types?
Do I just snip the cable anywhere along its length and fit it?
 

Appleyard

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Giles we leave our boat for 2 months in the summer and 6 months in the winter,in Greece ,there is no need whatsoever to "top up" the batteries during thae time you are away,provided the batteries are in good condition. Simply fully charge them up before you leave and completely disconnect the leads from the terminals,and clean and dry the battery surfaces. There should be little or no loss when you return. We have done this for two years now and the batteries remain in a good state of charge in our absence. There is a lot of rubbish talked about batteries,.If you have good quality batteries and don't discharge them too much they will easily hold their charge for a long time. I am speaking from experience.
 
G

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There are 2 types of solar panels the self regulating type that has only enough cells to make it to 13 or so, volts and the non-self regulating that are normally 21V open circuit. What does it say on the back of the panel?

"disconnect the leads from the terminals" However. if you do not, then note that our mastervolt battery monitor plus the boat alarm uses up 50AH in 2 months.

Just the alarm lasted 6 months on 75AH.
 

shamrock

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My panels had no regulator, and I was told that if the charging current is less than 1% of the battery capacity, it's not needed. i.e. with 900ampHr of batteries, 9amps from the panels should be OK.

However, the panels can put out a little more than that in peak conditions, and 9amps seemed a lot to me for a 'trickle charge' so I fitted a regulator anyway, got a 'Fox 100' regulator from Foxes in Ipswich for a little under £50 and it'll deal with up to 16A. Seems to work fine.
 

William_H

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Shamrock is right in saying that the small solar panel large battery does not need a regulator.
I have never heard of "self regulating solar panels" all that I have every encountered can generate 18 volts or more with no load.

A solar panel current is related directly to its area. So a panel about 40cms by 30 cms is rated at 10 watts or gives about 1/2 amp.

A large solar panel say 80 watts or 5 amps is about 1.5 metres by .6 mtre ie quite big and heavy.

So if you typically have 200 AH battery connected then up to 40 watts can be connected permanently without a regulator while a larger panel should have a regulator.

So you need to figure out how many watts your panel generates. If it is a 2 amp ie 40 watt panel then a fairly large battery will have no problems without a regulator.

You need to know which and how many batteries are connected to the solar panel. I disagree with Danny in that solar panel current is usually so low that a voltage check may not be conclusive. Disconnect each battery lead and check the current into it with a multimeter. Or disconnect all batteries except one and check current on your "quad cycle" then disconnect that battery and connect another. You will probably get 2 amps into one or all batteries.

So once you know which batteries are connected to the solar you can estimate the battery capacity. About 100AH for 20kgs of battery.
It may be that the original owner didn't like any power left connected to anything while he was away. otherwise there is no reason to turn solar off while absent provided it has suitable fusing.
olewill

Don't rush to buy a regulator
 
G

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Solar cells have a squarish Voltage Current characteristic that means as the volts rises the current falls off dramatically.

So using 32 cell arrays (probably with an integral blocking diode) it is very hard to overcharge a 12v Battery. The currents are so small when the battery is at its charged voltage.

With a 36 cell array there is another 2v of head room and they need regulators.

It like the difference between a trickle charger and a 3 step charger. The 36 cell arrays are for fast charging and the 32 arrays are sold for remote monitoring installations and to yachts for trickle charging.
 

Danny

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[ QUOTE ]
I disagree with Danny in that solar panel current is usually so low that a voltage check may not be conclusive.

[/ QUOTE ]I agree with that, Olewill. Maybe I should have said: On a really sunny day with well charged batteries and no load - if you don't see a voltage across the battery terminals above the 'float' level then either you have a regulator or the solar panel is small enough with respect to your batteries that you probably don't need one.
 
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