How to check polarity on a hook up?

[peter2407]

By hook up I mean the invariably blue female/male connectors found on marinas and boats. This project is to use an 80w solar panel to charge/top up my batteries. The panel has -ve and +ve marked cables going to a "hook up adapter" (term?). My intention is to store this in the lazarette locker while sailing, and when i am done and tidied away, to then put out on the deck/cockpit area to charge the batteries. The set up i intend to use is: male hook up adapter to the female on the solar panel, with a cable running inside the boat, to the battery compartment with the regulator in place there, and the cable would then be terminated by crocodile clips on the starter battery. Questions:

What is wrong with this approach?
How can I tell -ve from +ve? Convention? Ie -ve is always on the left if the earth pin (term?) is top dead centre? Volt meter?
Can I use regular domestic power cable leads?
Other than checking voltage before I leave, and then again when I return, how do I know power, however insignificant, is on its way?
Position of panel? Is it worth trailing a cable onto the fore deck to avoid shadow from the boom? I am on a fixed pile river mooring, and generally moor her in a heading of 280. Flat or angled?

Thanks in advance as always.

 

[Mistroma]

It sounds as if you are talking about using a blue 16A AC connector with a 80w solar panel. If you open one up you will see that the connections are marked L live, N neutral and E earth. However, your panel is putting out DC and it would be a bad idea to use 230V AC connectors with a 12/24V DC system.

1) Someone could plug in 230V supply at some point and put that into your panel
2) It's a bulky unit and able to handle 16A (the panel will only output ~6A at best)

I'd suggest using a waterproof connector designed for DC. You could Google Bulgin Bucaneer connectors to see what I mean.

I looked at your profile but couldn't see anything to indicate your location even approximately (Australia, Europe etc.). The optimum direction and inclination will vary with location and time of year. You could look at something like http://solarelectricityhandbook.com/solar-angle-calculator.html

 

[peter2407]

Thanks. The blue connector was already on there, as I bought the panel from a Forumite who already had this rigged up on his boat. Are the blue connectors AC only?

 

[prv]

Are the blue connectors AC only?

They'll physically work with DC, but it's a really, really bad idea. One day someone will plug a shore power cable into it, explode your batteries, and possibly electrocute someone.

Pete

 

[Mistroma]

They'll physically work with DC, but it's a really, really bad idea. One day someone will plug a shore power cable into it, explode your batteries, and possibly electrocute someone.

Pete

Agree completely. I was going to mention putting 230V direct to batteries until I spotted that OP said female connector went to the panel. So connection to batteries would actually be a male and not likely to have AC fed into it (plenty of scope for shorting out the pins though). I edited the post I'd started to mention putting AC to the panel.


However, a bad idea as you say. I can't see any reason to choose these connectors for this task (unless you are far from civilisation and only have these parts). I was very surprised that another forumite had sold OP the panel with a 16A 230V connector already fitted.

 

[VicS]

As said above it would be bad practice and potentially dangerous to use the blue or yellow plugs and sockets used for 230 or 110 volts for your 12 volt stuff, quite apart from being unnecessarily large and heavy.

Use the Bulgin connectors suggested or the ubiquitous "Driplugs" http://driplug.com/products.html which are rated at 10amps and suitable for use only up to 50volts. 2 pin ones probably suit your needs

Use a voltmeter to identify positive and negative when necessary.

If David2452 joins the discussion take note of what he says ... it is his profession.

Flat is the probably the best compromise, unless you can tilt to face south (ish) assuming you are in the northern hemisphere

An 80 watt solar panel will require a regulator. I suggest you get one that shows the output, preferably in amps, but at least with LED indications of charge status. PWM (or MPPT) type for best performance.


The wiring will need to be heavy enough to avoid excessive voltage loss and will therefore depend on the total length. Loads of calculators available on line but be sure you use one that stipulates if its based on total positive plus negative wire length or just the cable run distance.