*** recharging batteries with solar pannels ***

[gabrielwk]

Hello all. Gabriel here posting for the FIRST TIME :smt021

As a new boater, I'm learning the best possible way, making a million mistakes and solving problems that I could have prevented if I had known I was doing something wrong. This of course, is the most expensive way!!!

In any case, my latest problem is electrical. My engine would not start every other weekend (thank Gd for BoatUS and SeaTow). I got stucked in Miami, Key West, and Buttler Chain Lakes (Orlando). I finally researched and realized that my 2 batteries (they were different brands and installed at different times) may not be good and replaced them both. I cannot believe the difference. Now the engine starts so fast and strong that I just cannot believe it took me so long to figure it how.

I use the boat only on weekends and run it for short distances, so I have learned that I do NOT have the alternator running long enough to recharge them. Furthermore, once I reach my destination, I keep the radio running for hours while I hang-out with my friends and family.

To solve the problem, I purchased a Solar Panel (Sunforce 50022). Instructions indicate that I could plug it into the cigarette sucket. So here go my questions:
1. Do the bateries need to be BOTH on?
2. Just one?
3. Neither?
4. Can I have the radio on (actually it would be an IPod running from my Fusion system) while recharging?


I cannot find the answers to this enigma anywhere.

Thank you for your help!!!

By the way, if you have a Sunforce 50022 (or similar), I have come up with a bracket system that allows you to attach it to the rails of the boat (and remove it when not needed) and point it to the sun very easily without the need to screw it into your boat. If it interests you I can explain to you how you can do it yourself and avoid making holes into your boat.

 

[fc3]

That's a 5 watt panel, which is about 400 milliamps. You will be drawing more power to run the stereo system than that panel will output. Or look at it this way, 12 hours of charging will put enough power into the batteries (assuming 100% efficiency) to power 6 10 watt cabin (I'm guess that's what you have) lights for an hour.

I don't think this is the answer to your problem. You need a much, much bigger panel.

Best regards,
Frank

 

[JediJD]

To solve the problem, I purchased a Solar Panel (Sunforce 50022). Instructions indicate that I could plug it into the cigarette sucket. So here go my questions:
1. Do the bateries need to be BOTH on?
2. Just one?
3. Neither?
4. Can I have the radio on (actually it would be an IPod running from my Fusion system) while recharging?

Welcome aboard.

I'm thinking yes, no, no and yes you can have it on...but the system will be discharging so the time will be limited. Someone will give you the exact math, but my quick guess is that you could probably get as much juice from running the engines (and alternators) for thirty additional minutes than you could in several hours with the solar panel.

 

[gabrielwk]

Wow, now I'm really confused. Everything I researched in the Internet about the solar pannel I purchased (Sunforce 50022) says that is perfect for this type of application. Even the salesperson at West Marine told me so.

Do you think if all electronics are OFF it would at least help keep the charge in the batteries? and again....Should the batteries be on or off while charging with the solar pannel.

Thank you!!!

 

[fc3]

Five watts is five watts. Actually, charging voltage is 13.6 or so. So applying Ohm's Law we have 5W / 13.6V = 368 milliamps. Figuring on 12 hours of sunlight a day gives 4.4 amp/hours of charge. Average group 27 deep cycle battery is about 100 amp/hours of capacity. Now do you see the problem?

 

[electricaldoctor]

Do you have an onboard 120 volt battery charger that is left on during periods of non boating use? Do you dry slip your boat? If so, a solar panel(s) scenario would be a great option to top up your batteries during the week. I agree with the others that they cannot have any possible chance to stay ahead of your power draws while on the hook. Without knowing how your boat is wired, I don't know how to comment about where your battery switch position should be located during the week. What position does it have to be in when using the onboard charger to charge both batteries?

~Ken

 

[gabrielwk]

FC3, I do see the problem now.....Like I said on my first post: I'm learning the hard way, and it's getting expensive :grin:

ElectricalDr, my boat is left in dry storage with no electrical input whatsoever. I do turn both batteries off before I store it though but when I use it, I don't run it long enough to fully recharge the batteries because the distances are short. I guess that is the main problem.

What I would like to try is:

1. Leave the boat for 1 week without any type of recharging (with both batteries OFF) and measure the batteries charge before and after.
2. Then put the solar pannel for another week and do the same measurements (with both batteries ON) to see if there is any difference whatsoever.

Do you think it's worth the try or you already know the answer?
What's the name of the device used to measure the charge in a battery?

Thank you!!!

 

[Loneranger]

I would conduct your experiment; however for comparison's sake most "trickle chargers" only put out 2amp/hr compared to your 0.4 from the solar panels.

Check out the link below to help with understanding state of charge and measuring. At a minimum you need a digital voltmeter, sometimes called a multimeter. Ideally you would also have a hydrometer to measure the specific gravity of each cell (assuming you have flooded cell batteries). Lastly you could get a true load tester but it would be more expensive and probably not worth the cost.

http://www.arttec.net/Solar_Mower/4_Electrical/Battery Charging.pdf

John

 

[cpt. sundancer]

way too small for your needs,i have 3 panels of the same size that i use on my trolling motor batt. on my 14 ft. boat. we camp on islands and beaches alot on the mississippi and we take our 260 sundancer and 14 ft fishing boat,use the 14 ft. to haul gear,make beer and ice runs and pick up guests with. i plan on installing a big panel for the 260 and connect to house batt. i have 2 batt. in small boat,one for motor and lights and one for trolling motor,the total 15 watts seem to charge it well. it is connected to a solor charging controller that tells me batt.charge state and will stop any overcharge...just my 2 cents,good luck :smt001

 

[boatmailster]

using cig. lighter socket will not allow to charge your battery with battery switch off

 

[gabrielwk]

using cig. lighter socket will not allow to charge your battery with battery switch off

Got it. So I can have the batteries off if I connect the solar pannel DIRECTLY to the batteries, but they need to be on if connected to the cig lighter.

Thank you!!!