Solar panel..leave it connected or not?

Alfie168

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I'm recommisioning the electrics having repaired the solar panel connection and bought a new battery. (I've never used them up to now)

Can I leave the solar panel connected..its about 15w..or should I disconnect. There is a 'box' on the system, but I don't know if its a regulator or just a box to stop the panel draining the battery (Its all in german)

I'm new at solar panels and batteries

Tim
 

VicS

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[ QUOTE ]
There is a 'box' on the system

[/ QUOTE ] Maybe just a diode to stop a small drain on the battery during darkness but that would only be a smallish encapsulated integral component.

if it is a biggish box ie several cms then it is more likely to be a regulator.

A voltmeter and bright sunlight might enable you to decide which. Expect the open circuit volts if not regulated to rise way above the 14v you would expect if regulated.

If not regulated then 15w is a bit too much to leave permanently connected unless you have a fairly large battery bank, say in excess of 120ah
 

pappaecho

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The thing that stops the current draining back from the battery to the solar panel is called a blocking diode and is usually tiny. Solar panels can potentially overcharge the battery, but in my experience there has to be a lot of direct sun about.
I would suggest that you measure the battery voltage, and leave it connected via the "box" for a few days. If the battery voltage goes up to about 14.0 to 14.2 volts and then stops then the box is a regulator. If it goes on rising then it is not. If not you can get regulators from Maplin for about £20
 

Billjratt

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your profile doesn't say where you or the boat is -assume UK. 15watts is very small and unlikely to fry a battery that is running standby circuits and navtex etc. - especially in our gloomy part of the world. Leave it connected and use a voltmeter to check the battery when you come aboard. (cheap digital multimeter will do) if it gets past 13.5 you'e lucky. 14.5 would be a concern for over charging.
 

jonathankent

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I've got 2 old small panels which produce around an amp at best, but still bring the battery from 12.2v to 13.8v in a day. I've installed a regulator just to be sure no overcharging - they are less than £20 anyway... is it really worth the risk??
 

Alfie168

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Its a very very basic electrical system on a Dehler trailer sailer, but all the components seem reasonable quality, and the previous..long dead battery was a very expensive german Gel battery 85Ah so I'd be fairly sure the "box" which measures about 8cm x 5cm is a regulator including a blocking diode.

I'm resurrecting the electrics as the boat has no instruments and I'm installing a NASA Clipper Duet and I may want to upgrade the nav lights next winter (currently only a masthead white in view of short length of yacht).

I'l get it going and stick the mutilmeter on it and see what goes..when i get the chance

Thanks

Tim
 

jonathankent

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In that case, you won't have very much power draw at all... the duet will be mA, and nav lights, depending on bulb, will only be <1A each aswell.

Depending on how often you intend to use the boat, 15w will be quite adequate to charge during the week for this use at the weekend.

What size battery do you intend to replace the dead one with?
 

William_H

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Assuming you new battery is about 85AH capacity. I would suggest in UK especially if you aree on a swing mooring then the solar panle is unlikely to ever overcharge your battery. So I am in favour of no regulator. In my experience blocking diodes are fitted at the solar panel and usually therefor not easy to find/identify.
In my checking also I have ever measured any leakage current in dark from abattery to a panel when I know there is no diode. Anyway the experts say hyave a diode so have one.

So yes have the solar panel connected permanently.(fit a fuse near the battery) No contrary to papaecho I don't think you would ever see a voltage more than 14 volts. Overcharge is most likely to be indicated by using excess battery water (if you can see and repalce it).
good luck olewill
 
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