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Ignorant solar panel and battery questions

Jan 19, 2010
9,999
Hunter 26 Charleston
It's the "cigarette lighter" style outlets we have now. We don't have real "shore power" with 110-style outlets and a port on the outside of the boat. I assumed I could plug phone chargers into them since I can do that in a car. Is that not true?
Yes you can charge your phone that way. Or iPad...
 
Sep 13, 2021
61
Hunter 240 Lake Jacomo
I stand by my assertion about the 20 watt . I understand that you need to resupply the amperage used . However , you folks with 30 foot and bigger boats seem to have forgotten a basic premise. There is no convenient place to mount 100 watt panels on a 24 foot boat !
Renogy lists a 100 watt panel having the dimensions of 42"x20" x1.5" . That's roughly 4 feet by 2 feet . Are you mounting this on the hatch where it is constantly being moved back and forth? In front of the mast where it is likely to be stepped on when ever someone goes forward to anchor or bring down the jib or attach a dockline ?
I'm speaking from practical experience . Yes in a perfect world , throw a 100 watt solar panel on top of a rigid bimini . Out of sight out of mind .
Yeah, the space issue is valid. My plan was to buy something flexible that I could move around as needed.

Something like this, maybe, with a controller for safety's sake. It's only 20x26.

 
Jan 11, 2014
7,827
Sabre 362 113 Fair Haven, NY
I stand by my assertion about the 20 watt . I understand that you need to resupply the amperage used . However , you folks with 30 foot and bigger boats seem to have forgotten a basic premise. There is no convenient place to mount 100 watt panels on a 24 foot boat !
Renogy lists a 100 watt panel having the dimensions of 42"x20" x1.5" . That's roughly 4 feet by 2 feet . Are you mounting this on the hatch where it is constantly being moved back and forth? In front of the mast where it is likely to be stepped on when ever someone goes forward to anchor or bring down the jib or attach a dockline ?
I'm speaking from practical experience . Yes in a perfect world , throw a 100 watt solar panel on top of a rigid bimini . Out of sight out of mind .
I am well aware of the limitations of a smaller boat having spent most of my time on boats in the 22-30 foot range. For OPs intended use, a 50 watt panel would be sufficient. It should come in at about 20" x 20". A panel that small could be mounted on the stern rail. Or the OP could put 2 20 watt panels in parallel to achieve about the same amount of power.

As on most things in sailing, there are more than one way to skin a cat. The important message is get enough power to actually do some good, be it one 50 watt panel or 2 20 watt panels or some other combination.

And for the record, bigger boats also run into size limitations. The answer for any given boat will involve space, power needs, budget, other charging sources, and needs. The panels I have just barely meet my needs, however budget and space limited the addition of another panel or larger panel.
 
Jan 4, 2013
252
Catalina 270 Rochester, NY
My 30 watt panel is 24.5 x 14.1 x 1.7 inches and stores in my cockpit locker while sailing and sits on a cockpit seat while away from the boat. How much simpler than that?
 
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Jan 19, 2010
9,999
Hunter 26 Charleston
Yeah, the space issue is valid. My plan was to buy something flexible that I could move around as needed.

Something like this, maybe, with a controller for safety's sake. It's only 20x26.

I mounted mine on the mast crutch pole.... and then just left it installed all the time. I also have my GPS and VHF ant. there (see pics)
1633707167281.jpeg
 

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Jan 11, 2014
7,827
Sabre 362 113 Fair Haven, NY
Yeah, the space issue is valid. My plan was to buy something flexible that I could move around as needed.

Something like this, maybe, with a controller for safety's sake. It's only 20x26.

Controllers are needed to lower the voltage delivered to the battery. If you look at the specs for the panel, you'll see that it puts out 22.6v which is roughly 8 volts above the recommended Constant Voltage charging voltage for most batteries. This will cause the batteries to "boil" the water out and kill the battery.

The controller takes the high voltage (22.6v) and low amperage output and converts it to a lower voltage with higher amperage (Ohm's law strikes again!) needed to appropriately charge the battery.

Flexible panels have advantages and are most useful for mounting over gently curved surfaces.They are however more delicate than rigid panels and are more subject to mechanical failure, i.e., broken circuits than a rigid panel. If used as a portable unit, think about adding a more rigid backing plate to prevent flexing and bending, a piece of ¼" plywood would increase the rigidity.
 
Mar 2, 2019
210
Oday 25 Milwaukee
My 30 watt panel is 24.5 x 14.1 x 1.7 inches and stores in my cockpit locker while sailing and sits on a cockpit seat while away from the boat. How much simpler than that?
Ah . .you have a single 30 watt panel roughly 2 feet by 2 feet . simple enough . 3 panels to get close to 100 watts and you now have 6' of panels and three cords to contend with. That's exactly why I mounted ours out over the back of the stern rail . In full sun and out of the way . I also lease a 20 watt in the cockpit seat . Problem there is bird poop and leaves seem to collect on the horizontal surface. Even out on a mooring on Lake Michigan several blocks from shore . The original poster was simply looking for a way to keep his battery full while on a mooring. He has all week to let the solar panel recharge the single battery . His usage is minimal.
 
Sep 13, 2021
61
Hunter 240 Lake Jacomo
Controllers are needed to lower the voltage delivered to the battery. If you look at the specs for the panel, you'll see that it puts out 22.6v which is roughly 8 volts above the recommended Constant Voltage charging voltage for most batteries. This will cause the batteries to "boil" the water out and kill the battery.

The controller takes the high voltage (22.6v) and low amperage output and converts it to a lower voltage with higher amperage (Ohm's law strikes again!) needed to appropriately charge the battery.

Flexible panels have advantages and are most useful for mounting over gently curved surfaces.They are however more delicate than rigid panels and are more subject to mechanical failure, i.e., broken circuits than a rigid panel. If used as a portable unit, think about adding a more rigid backing plate to prevent flexing and bending, a piece of ¼" plywood would increase the rigidity.

I have a friend willing to sell me this:


I may give it a try first and see if it's reasonable to store on the boat. Seems kind of big.
 
Sep 13, 2021
61
Hunter 240 Lake Jacomo
I have a friend willing to sell me this:


I may give it a try first and see if it's reasonable to store on the boat. Seems kind of big.
This may end up being too big/heavy/clunky for my situation.

If I wanted a flexible, easy to store 50watt panel and an appropriate controller, what brands should I consider?

Are the folding ones any good? That seems really appealing.
 
Aug 10, 2020
344
Catalina C25 Rocky Mount
After all that information.... I have a catalina 25. One battery and similar power usage. I have no shore power and sail at least once a week.
I use a $35 50w panel and charge controller off of ebay. I always have 12-13.5v even after sailing at night and running cabin lights. It was worth every penny.
 
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Jan 11, 2014
7,827
Sabre 362 113 Fair Haven, NY
This may end up being too big/heavy/clunky for my situation.

If I wanted a flexible, easy to store 50watt panel and an appropriate controller, what brands should I consider?

Are the folding ones any good? That seems really appealing.
The solar industry is still the wild west, with few standards and lots of hype. It is probably better to choose a retailer than a brand.

EMarine and Alt-E have been reliable. You don't need high end Solbian or Solara panels, but you do want to avoid really cheap stuff on Amazon and eBay. As you narrow down your search look at the Open Circuit Voltage (Voc), the higher the better and look panel efficiency ratings, the higher the better regardless of rated output.
 
Nov 30, 2020
67
Macgregor 22 Dania, FL
One thing that hasn't been mentioned: Please crank the engine every morning with the electric starter and let it run for say five minutes. That way if you do need the rope starter it will be easy.
 
Sep 13, 2021
61
Hunter 240 Lake Jacomo
Is your motor an outboard? Does it have an alternator? How much do you motor when you go for a sail?

We also need to know more about the batteries…specifically type (lead-acid, AGM, ?) and size or Amp-hour capacity.

You seem to have modest power consumption needs, but to size a solar panel, we need more specifics…but it sounds like a modest solar setup would work for you.

Greg
I took a look at the battery last night. It's a NAPA Marine 8240. 550 CCA, 675 CA, 120 RC, BCI No. 24
 
Dec 19, 2006
5,731
Hunter 36 Punta Gorda
If you think you might do over nighters more than invest in a second deep cycle battery and a start battery
as backup and if you plan on doing more over nights in future than look into solar and maybe 2-6 volt deep cycle ashouse bank and a second battery for start battery and build up from there depending how much cruising for more days out on water with shore power added as needed.
Nick
 
Jan 7, 2011
2,911
Oday 322 East Chicago, IN
I used to use 2 group 27 deep cycle batteries, and I would isolate one of the batteries during overnight stays so I always had juice to start the engine.

This year, I upgraded to 2) 215 ah 6-volt GC batteries in series.

C517E2F2-51EC-4B94-AE75-C5FDA96C7472.jpeg

I don’t yet have an engine start battery set up, but I did install one of these Renogy battery monitors..
005341EC-5ACD-434A-8E8F-BC0CA73D79BC.jpeg

Very comforting to see ins and outs to the battery bank and have the monitor calculate remaining capacity and hours of use.

i do hope to add a dedicated start battery to the system next year, but this has worked great for my normal day sailing and an occasional 2-night sailing weekend on the hook.

i did turn my fridge off (put a frozen Gallon jug of water in the fridge and a few frozen water bottles in the freezer to keep things cold…

Greg