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Question Will Solar Panel Trickle Charge Battery?

Just bought my first real boat. Ericson 29. Couldn't afford to be in a regular dock so I settled or a star dock. Which means I don have electric. I've been told that there are permanent solar panels that can be installed on the deck to tricle charge my battery.

After some brief research I haven't found any useful literature. Any suggestions. Does anyone rely on these? I don't plan to use battery power hanging out at the dock.
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post #2 of Old 06-26-2014
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Re: Will Solar Panel Trickle Charge Battery?

When we had our 22 footer the PO installed a small solar panel attached to the cockpit seat (we could sit or stand on it) that was used as a trickle charger. We never had a problem.

It will depend on how much you need to keep charged.

Donna


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post #3 of Old 06-26-2014
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Re: Will Solar Panel Trickle Charge Battery?

It depends upon the type and size (Ah capacity) of you batteries, but you'll probably need a larger solar panel than just one of the those little "trickle chargers" (along with a good charge controller). Most of the panels marketed as such are between 1 and 5W. I have a total of 275 Ah of batteries on my boat (2 x 225 Ah 6V golf cart batteries and a 50Ah 12V reserve battery), and a 20W panel is just about right for keeping everything "topped off". If you have a smaller total Ah capacity, particularly if you are using AGM batteries, you may be able to get away with a 10W panel. But I wouldn't count on anything below about 10W having enough output to avoid the consequences of long-term undercharging of your batteries.

EDIT:
The rule of thumb is that wet cell batteries lose about 1% of their charge per day (AGM batteries self-discharge at a rate of only about 10 or 20% of that, or about 0.1 to 0.2%). So, discounting that a small part of the total battery capacity on my boat is in the form of AGM, that means that I need to supply about 3Ah a day (rounding to the nearest whole Ah) to maintain the batteries. A 20W panel, in a fixed position on the push-pit rail, can supply slightly more than 1 amp at charging voltages, or about 5 to 7 Ah per day (a bit more on a sunny summer day, quite a bit less on a stormy winter day). Allowing for various inefficiencies in the system, and counting on the system having to "catch up" after cloudy/stormy days, that works out to be just about the right size.

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post #4 of Old 07-16-2014
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Re: Will Solar Panel Trickle Charge Battery?

Check out aurinco.com. They have a decent breakdown of what you'd need based on what you want to run in their "education" section.
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post #5 of Old 07-16-2014
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Re: Will Solar Panel Trickle Charge Battery?

Since you are at a dock instead of at a mooring you may want to look into a dock mounted solar panel. We did this with a now sold boat and it worked fine. It was a lot simpler and easier than trying to figure out where to mount a solar panel on the boat that was also easily removable while sailing.

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post #6 of Old 07-16-2014
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Re: Will Solar Panel Trickle Charge Battery?

My setup (panel and charge controller) is from Northern Tool, has worked well. The panel is flexible. The rigid one I had got blown off the boat and smashed during the winter when boat was on jack stands.
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post #7 of Old 07-16-2014
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Re: Will Solar Panel Trickle Charge Battery?

Quote:
Originally Posted by Puddin'_Tain View Post

The rule of thumb is that wet cell batteries lose about 1% of their charge per day (AGM batteries self-discharge at a rate of only about 10 or 20% of that, or about 0.1 to 0.2%). So, discounting that a small part of the total battery capacity on my boat is in the form of AGM, that means that I need to supply about 3Ah a day (rounding to the nearest whole Ah) to maintain the batteries. A 20W panel, in a fixed position on the push-pit rail, can supply slightly more than 1 amp at charging voltages, or about 5 to 7 Ah per day (a bit more on a sunny summer day, quite a bit less on a stormy winter day). Allowing for various inefficiencies in the system, and counting on the system having to "catch up" after cloudy/stormy days, that works out to be just about the right size.
Actually the loss rate is more like 2%per month not 1% per day
I use a sun force 5 watt unit on my islander works great all I do with my battery is charge my cell phone and occasionally use running lights my cabin lights and my anchor light are all independent solar units.

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Re: Will Solar Panel Trickle Charge Battery?

Do you have refrigeration? That is the big energy hog if you plan on leaving it on, but not insurmountable for a solar panel. Otherwise likely a small panel will do, unless your boat leaks a lot, but we are not talking old wood boat, so you should be OK.

edit:

Also if you go with LED interior and navigation lighting you can really reduce your daily use a lot. How often do you plan on being on the boat? Do you have an inboard with charger?
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Re: Will Solar Panel Trickle Charge Battery?

Quote:
Originally Posted by newhaul View Post
Actually the loss rate is more like 2%per month not 1% per day
I use a sun force 5 watt unit on my islander works great all I do with my battery is charge my cell phone and occasionally use running lights my cabin lights and my anchor light are all independent solar units.
Hmm..

I went back and looked it up again, and the actual rate is about 1% per week. However, the rate of discharge is temperature dependent. So, "your milage may vary".

I used to have one of those 5W panels on the push-pit of my boat, and it couldn't quite seem to keep up; the batteries always seemed to be at about 80 or 90% charged. But, since my boat points south (more or less) in her slip, the mast is probably shading the panel for part if the day. In any case, with the 20W panel I use now the batteries seem to be much "happier".

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post #10 of Old 07-20-2014
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Re: Will Solar Panel Trickle Charge Battery?

The very small panels described above are pretty useless, mostly designed to leave on the dash of a car to keep the battery from losing too much.

Best to get a panel of 20 to 30 watts for maintaining and if actual charging after a sail is involved get one over 50 watts. And any panel that is worthwhile needs a controller - regardless of what you read on the internet.

Brian
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