winter solar

[dougg]

As with a lot of other cruisers we will be leaving our boat unattended in a marina for 5-6 months over winter.

My question is do the majority of people leave the shore power conected or disconnected?

I underdstand it is better for the batteries to be kept upto "float"

We have solar which would keep the house batteries topped up, but what about the batteries for the engine and the bow thruster?

 

[johnalison]

I have done both in my time. For the last couple of years I've left the solar panel to keep the service batteries up, which it does well, and because it isn't connected to the engine battery, I put the mains charger on for a few hours every six weeks or so. Not very scientific I'm afraid, but it seems to work.

 

[maby]

Well, you certainly want to arrange some form of trickle charge to keep your batteries in good condition. A moderate solar panel should be good enough even in winter weather provided it's a polychrystalline type - the others can produce more output in ideal conditions, but only the poly will work in poor light and with shadows across the panel.

Alternatively leave it on shorepower, but hang an auxilliary anode over the side - six months on shore power will take a big bite out of your anodes!

 

[johnalison]

six months on shore power will take a big bite out of your anodes!

Not on the hard standing it won't!

 

[maby]

Not on the hard standing it won't!

Quite true - since the OP referred to " unattended in a marina ", I assumed in the water, but you are right - it's not a safe assumption...

 

[VicS]

Alternatively leave it on shorepower, but hang an auxilliary anode over the side - six months on shore power will take a big bite out of your anodes!

Plenty leave the shorepower connected all the time ( with the boat in the water). What is essential is a galvanic isolator ... and that applies even if the shorepower is not actually in use but simply plugged in.

 

[dougg]

Thanks for the replies, and yes i did mean in the water.

We have a 4 inch square ( approx ) thing called a battery isolator, im pretty sure it distributes the charge, wether it be shore power or alternator, to each set of batteries but also keeps them isolated from each other.

Question 1. Am i correct in thes assumption?

Question 2. If I conect the solar to the input of this unit will it keep them all topped up? assuming there is enough day / sunlight.

Thanks

 

[maby]

Thanks for the replies, and yes i did mean in the water.

We have a 4 inch square ( approx ) thing called a battery isolator, im pretty sure it distributes the charge, wether it be shore power or alternator, to each set of batteries but also keeps them isolated from each other.

Question 1. Am i correct in thes assumption?

Question 2. If I conect the solar to the input of this unit will it keep them all topped up? assuming there is enough day / sunlight.

Thanks

It's difficult to be specific without seeing it, but I would tend to assume that it is a simple diode isolator to avoid one battery discharging through the other. If so, it would probably also block your solar charger connected as you describe. I fitted a simple solar panel charge regulator - about £20 from Maplins (http://www.maplin.co.uk/dual-16a-solar-charge-regulator-266145) which was very successful. it will split the charge intelligently between two batteries and will protect the battery against over-voltage charge - though that is not likely to be a problem unless your solar panels are quite large.

 

[maby]

Plenty leave the shorepower connected all the time ( with the boat in the water). What is essential is a galvanic isolator ... and that applies even if the shorepower is not actually in use but simply plugged in.

The barrier potential of many galvanic isolators is a bit low for effective protection. I've seen anodes in our marina get heavily erroded in a few months on shore power. It's so easy and cheap to dangle an auxilliary anode that it simply makes sense.

 

[barnaclephill]

unattended in a marina for 5-6 months over winter.

We have solar which would keep the house batteries topped up, but what about the batteries for the engine and the bow thruster?

I have a swing mooring, but had a jetty berth for about 5 years, without power. I use a solar panel and regulator (depending on panel size) for both my house battery and my engine-start battery. A 40W panel for the house battery, and a 10W panel which does the engine starting and one bedlamp, on separate circuits. They keep things topped-up, are always available, even when on cruise.

Sealed LA batteries would be better for an unattended boat than batteries whose electrolyte could evaporate, not as great a problem in winter, but in summer it is more relevant.

 

[Haggsinnorway]

I leave my solar panel connected to the "House Battery" and take the engine battery home where it stays on-charge with an intelligent battery charger. So far I have not had problems at the start of a new season.

 

[dougg]

Yesterday I connected the output from the solar to the input of the battery charge splitter box, to evenly distribute the charge between the 3 seperate batteries/banks. It doesnt work.
So have put it back where it was. I guess the answer is to hope for the best with the engine and thruster batteries.

 

[Haggsinnorway]

Dougg
My understanding is that if you are charging more than one battery with a solar cell then you need a "multi-outlet solar cell control box" One line in from the solar panel and then a line out to each of the batteries, each battery having it own connection to the regulator.

I don't think you should be combining a battery charger with the solar cell.

You should have a solar cell control box (regulator) if you have installed a solar panel, regardless in order to protect your battery from over charging. The salesman should have asked how many batteries you intend to charge and sold you the correct control panel.

Hope this helps.

 

[maby]

Dougg
My understanding is that if you are charging more than one battery with a solar cell then you need a "multi-outlet solar cell control box" One line in from the solar panel and then a line out to each of the batteries, each battery having it own connection to the regulator.

I don't think you should be combining a battery charger with the solar cell.

You should have a solar cell control box (regulator) if you have installed a solar panel, regardless in order to protect your battery from over charging. The salesman should have asked how many batteries you intend to charge and sold you the correct control panel.

Hope this helps.

And, as I pointed out earlier, maplins sell a perfectly functional module for about twenty quid...