Solar Pannel for 1 battery
- Thread starter Scubajeep
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I have a similar set up to the one you are trying to do. I have 1 battery and a 40 watt panel. I have all the normal lights, a fan, and a stereo. I have never once had to plug in and charge my battery. Prior to switching all of my lights out for LEDs would leave my battery at about 50% after a whole weekend spent out. Now with the LEDs, if I don't use the stereo too much the power doesn't drop below 90%. This system works very well for me.
I have a Hunter 22 1983 with a 2007 6 HP suzuki with an alternator. The alternator is an opition that must be added but most smaller outboards have the opition. It cost me about $250 installed. the motor and my solar panel keep my boat powered just fine.
As others of said, the universal answer, "it depends," applies here. I have an h23 with only one battery, which I keep charged with a 5w solar panel. Excepting periods of multiday cruising with the kids, it has proved sufficient to keep the battery charged. The flip side is that I don't tend to use a lot of battery power. Light is a major consumer of power at our size range, and my wife and I prefer the mellow light of the kerosene lamp I installed a few years after buying our boat. We also have VHF, depth finder and a 12v socket for various appliances (TV/am-fm radio, vacuum cleaner, etc.).
As suggested above, analyze your likely energy use to determine how fast you're using power and how quickly you need to recharge.
As Ross noted, your area gets a lot of sun, so a charger can be expected to provide a decent amount of charge every day. I live in Oregon's Willamette Valley, at about 44.5 degrees N. latitude, with far less intense sun exposure.
Jim Kolstoe, h23 Kara's Boo
As suggested above, analyze your likely energy use to determine how fast you're using power and how quickly you need to recharge.
As Ross noted, your area gets a lot of sun, so a charger can be expected to provide a decent amount of charge every day. I live in Oregon's Willamette Valley, at about 44.5 degrees N. latitude, with far less intense sun exposure.
Jim Kolstoe, h23 Kara's Boo
I have used the 4.5 - 5 watt panel from icp solar on and off several boats over the years with real good luck. The first sailboat application had a VCR, two flat screen 12v TV's and a stereo, as well as cabin lights nav lights, anchor and steaming lights. With the exception of occasional deep charging, (the neighbor girls and the girlfriend had an all-day movie fest without my knowledge on one instance) the 5 watt panel was more than sufficient for weekend trailer sailing use.
A few years after that boat, I had a wooden motorboat that I kept at my dock in the water, and did not trailer. I had no shore power, and if any of you also have owned old wood boats, you know they leak. A lot.
That boat had a 1.5 amp (18 watt) panel connected to the main house battery via a charge controller. I had a separate 5 watt panel on my back-up starting battery, primarily as a battery maintainer. Even with the bilge pump running every 10-20 minutes, and no shore power, I was never in a situation where I had to revert to the back-up battery. The boat always started, the pump kept runnning, and everything was peachy. This went on for three seasons, until I sold the boat. The solar system was still performing flawlessly when I sold the boat.
As has been already stated, you need to size your charging system to your intended load and actual use. You may find after doing your use calculations that solar is not the answer for your particular needs. But if you primarily day sail, mainly on the weekends, with only an occasional overnight, and do not rely for the battery for too much other than interior lighting, music, and the occasional anchorng out, a solar panel can totally be the ticket.
This from one sailor who has had good luck with solar.
A few years after that boat, I had a wooden motorboat that I kept at my dock in the water, and did not trailer. I had no shore power, and if any of you also have owned old wood boats, you know they leak. A lot.
That boat had a 1.5 amp (18 watt) panel connected to the main house battery via a charge controller. I had a separate 5 watt panel on my back-up starting battery, primarily as a battery maintainer. Even with the bilge pump running every 10-20 minutes, and no shore power, I was never in a situation where I had to revert to the back-up battery. The boat always started, the pump kept runnning, and everything was peachy. This went on for three seasons, until I sold the boat. The solar system was still performing flawlessly when I sold the boat.
As has been already stated, you need to size your charging system to your intended load and actual use. You may find after doing your use calculations that solar is not the answer for your particular needs. But if you primarily day sail, mainly on the weekends, with only an occasional overnight, and do not rely for the battery for too much other than interior lighting, music, and the occasional anchorng out, a solar panel can totally be the ticket.
This from one sailor who has had good luck with solar.
I have a group 27 single battery and I have a 24 watt solar charger with a charge regulator in line. My electronics are quite simple. VHF, hand held GPS which I hook up to the cigarette lighter 12 volt attachment , running lights, cabin lights anchor light and electric start 9.8 with charging capability. This set up has proved more than adequate. My in-line volt meter rarely goes below 12.5 Volts.
>>ron <<
S/V Serenity
>>ron <<
S/V Serenity
What kind of a radio, music or VHF? An FM radiowith speakers will use around 1.5 amps per hour. If you use it for 8 hours you may use 12 amps of battery capacity. A VHF on receive mode will use around .5 amp/hour and on transmit mode around 5.0 amp/hour. If used for 30 minutes on combined modes you would have only used around 1.40 amps of battery capacity. What is the size in watts of the solar panel? Anything less than 20W will only give you 4-5 amps a day on the average. The light intensity fluctuates during the day and there are sunny and cloudy days so the average is usually calculated on a 5 hour a day basis over a 7 day period. The result is an average figure which does not guarantee you will get that on any particular day. You do not depend on the battery to start the engine so you have room to experiment and see what works and what does'nt. To better answer your question a small solar panel may keep your battery topped off when the boat is not in use but otherwise I would recomend it be charged at the end of each use. A single battery will mostly do, just get deep cycle, wet cell, group 27 . A deep cycle battery should not be discharged more than 50% of its capacity and a battery that is kept at 100% charge will last longer that one that is frequently left partially discharged over periods of time. Good luck.
You mean 12 AMP-HOURS... not 12 AMPS. 12 Amps is a measurement of current, amp hours is a measurement of battery capacity used. A 15 Watt solar panel will generally give you about five amp-hours of battery capacity, not counting losses due to charging inefficiency.
Converting AH to watts
The use of amp hours depends on sticking to one and only one system voltage. It also only works in DC circuits.
1 AH at 12 volts is not equal to 1 AH at 13 volts from a power (watts) or work (power X time) stand point because power is volts X amps and work is volts X amps x time. So while 1 amp flowed for 1 hour in each case the work would be 12 or 13 WATT HOURS respectively and the power would be, well 12 or 13 watts continuously respectively.
So at 12 volts we get; 1 AH = 12 watt hours
and
at 13 volts we get; 1 AH = 13 watt hours
Confused yet?
If I want to convert from AH to watts I also need to assume a time and voltage because AH is work and watts are power. Then you can say really dumb things like:
At 12 volts, 1 amp = 12 watts as long as you don't try to stick a time limit on it and
At 13 volts, 1 amp = 13 watts as long as you don't try to stick a time limit on it.
Which is pretty useless in understanding AH. But adding time back in just gets us back to equally dumb things like
At 12 volts, 1 Amp minute = 12 watt minutes.
and
At 13 volts, 1 amp minute = 13 watt minutes.
So when considering solar panels rated in watts for their amp houring
ability just divide the published watts by the system voltage (is that the charging or discharging voltage?) and you get the amps it will provide to the circuit. Then multiply by the time (in hours) that you can expect that kind of solar excitation and, presto, you have the AH that the panel can provide (at that voltage and in that time period). And don't forget the charging efficiency. This is a slightly different number,BTW, for each charging voltage (feel the headache coming on?) which is 14ish volts so to be correct we should actually use the charging voltage that YOUR BOAT uses.......and here is where we loose EVERYBODY.
So; unless you know that:
P=W*T&V=I*R&P=I*V...... and can accommodate the various charging/discharging scenarios which have voltages that very both during and among them you are going to be at the mercy of (to put a fine edge on it) those who can.
Those of us who have been on the site for a while can confirm that all it takes is a little time to arm yourselves with the basics and then apply it. It is not rocket science but is is certainly confusing when you don't know the rules. An analogy that I find helpful is; would you play poker with out knowing all the rules? That is a good way to loose a lot of $$$.
The rest of the story is AH is work and watts is power and you CAN NOT compare the two with out making assumptions about both the system voltage and the time that that system voltage (probably a varying one) is active.
The use of amp hours depends on sticking to one and only one system voltage. It also only works in DC circuits.
1 AH at 12 volts is not equal to 1 AH at 13 volts from a power (watts) or work (power X time) stand point because power is volts X amps and work is volts X amps x time. So while 1 amp flowed for 1 hour in each case the work would be 12 or 13 WATT HOURS respectively and the power would be, well 12 or 13 watts continuously respectively.
So at 12 volts we get; 1 AH = 12 watt hours
and
at 13 volts we get; 1 AH = 13 watt hours
Confused yet?
If I want to convert from AH to watts I also need to assume a time and voltage because AH is work and watts are power. Then you can say really dumb things like:
At 12 volts, 1 amp = 12 watts as long as you don't try to stick a time limit on it and
At 13 volts, 1 amp = 13 watts as long as you don't try to stick a time limit on it.
Which is pretty useless in understanding AH. But adding time back in just gets us back to equally dumb things like
At 12 volts, 1 Amp minute = 12 watt minutes.
and
At 13 volts, 1 amp minute = 13 watt minutes.
So when considering solar panels rated in watts for their amp houring
ability just divide the published watts by the system voltage (is that the charging or discharging voltage?) and you get the amps it will provide to the circuit. Then multiply by the time (in hours) that you can expect that kind of solar excitation and, presto, you have the AH that the panel can provide (at that voltage and in that time period). And don't forget the charging efficiency. This is a slightly different number,BTW, for each charging voltage (feel the headache coming on?) which is 14ish volts so to be correct we should actually use the charging voltage that YOUR BOAT uses.......and here is where we loose EVERYBODY. So; unless you know that:
P=W*T&V=I*R&P=I*V...... and can accommodate the various charging/discharging scenarios which have voltages that very both during and among them you are going to be at the mercy of (to put a fine edge on it) those who can.
Those of us who have been on the site for a while can confirm that all it takes is a little time to arm yourselves with the basics and then apply it. It is not rocket science but is is certainly confusing when you don't know the rules. An analogy that I find helpful is; would you play poker with out knowing all the rules? That is a good way to loose a lot of $$$.
The rest of the story is AH is work and watts is power and you CAN NOT compare the two with out making assumptions about both the system voltage and the time that that system voltage (probably a varying one) is active.
I hardly think that someone is going to hit my boat at night in 3' of water, Captain. It really depends on the size of your boat and where you anchor. I think that the boat captain really has to use his head when it comes to anchoring in certain areas. What about the guy who was floating out in the middle of Buzzard's Bay a few years ago at night, Striper fishing with no lights on, and another boat came along and slammed into him, killing him? If he'd have had some kind of a light on his boat at the time, he may be alive today. I understand that a lot of fisherman do this because they don't want anyone to know where their favorite fishing spots are. This to me is foolish!
I once came into an area at night in a fog near the Elizabeth Islands by Hadley's Harbor and anchored for the night. I had my youngest son with me that night and you can bet that I left my mast light on. It's only common sense.
Joe
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Yes, but jetskis and a lot of other small, relatively fast powerboats, can handle 3' of water without a problem.
For the past two years, I have used a MinnKota Endura 50 on my O'Day 19. I use four 6-volt golf cart batteries (GC-6 deep discharge - 2 banks of 12 vdc) that provide sufficient energy for my to use the motor over several days without needing a charge.
With this setup, I have motored around for several hours at #5 setting for a quiet harbor cruise. The batteries went from 100% charge to 80% charge.
The 12 volt trolling motors will not get you past 3 mph, but it is so convenient for docking and quiet motor sailing.
Check out the Yahoo Electric Boat forum and this link as a start:
groups.yahoo.com/group/electricboats/
www.mindspring.com/~jimkerr1/sebebts.htm
Somewhat interesting... I have a 20 watt panel/charge controller which is permanently mounted flat on the deck of my trailerable.
I recently picked up and mounted a LinkLite battery monitor in the boat http://www.xantrex.com/web/id/273/p/1/pt/5/product.asp
I lived for a long time just fine without one of these and mostly got it to get a better idea of how much power I am actually using. I picked up this one because it has very low current draw (uses only 9 ma) and seems to be a good choice for a low power system. The only thing I dont like about it is the meter display for current only has 100 ma resolution but oh well.
Anyhow, I have a car stereo in the boat and normally, car stereos have two 12 volt power wires. One power wire is where most of the current comes from and it also powers the memory (ie, chanel presets, ect). The second power line basically turns the stereo on or puts it in standby. I currently have the main 12 power wire connected to the battery all the time (so I dont lose presets) and the second power wire goes to my cabin power switch.
Turns out that my 20 watt panel looking straight up in Denver in January (also in my back yard with some shading from the house in the morning) will not keep up with the "standby" drain from the car stereo... The battery monitor has only 100 ma resolution but it shows the stereo standby at about 0.1 amp. Since this is on all the time, this would be 2.4 amp hours per day.
I looked at the current output of the panel at about 2 PM on a little hazy but sunny January day and it was only putting out maybe 200 to 300 ma. I then aimed the panel directly at the sun and the current about doubled. In the attached picture, you can see the angle I had the panel at looking directly at the sun - ie, the sun is awful low on the horizon. In my case, with the pretty anemic output of the winter panel, maybe Im getting 1.5 amp hours from the panel. But the dang stereo in standy is consuming 2.4 amp hours for a net loss each day.
So now I have to rewire the stereo so that the cabin power switch can completely turn off all power to the stereo (and lose all presets) and I will put in a "bypass" which will put the stereo only in stanby power (which I think will be fine during the summer and I wont need to mess with all the settings each time).
Anyhow, sort of interesting..
I recently picked up and mounted a LinkLite battery monitor in the boat http://www.xantrex.com/web/id/273/p/1/pt/5/product.asp
I lived for a long time just fine without one of these and mostly got it to get a better idea of how much power I am actually using. I picked up this one because it has very low current draw (uses only 9 ma) and seems to be a good choice for a low power system. The only thing I dont like about it is the meter display for current only has 100 ma resolution but oh well.
Anyhow, I have a car stereo in the boat and normally, car stereos have two 12 volt power wires. One power wire is where most of the current comes from and it also powers the memory (ie, chanel presets, ect). The second power line basically turns the stereo on or puts it in standby. I currently have the main 12 power wire connected to the battery all the time (so I dont lose presets) and the second power wire goes to my cabin power switch.
Turns out that my 20 watt panel looking straight up in Denver in January (also in my back yard with some shading from the house in the morning) will not keep up with the "standby" drain from the car stereo... The battery monitor has only 100 ma resolution but it shows the stereo standby at about 0.1 amp. Since this is on all the time, this would be 2.4 amp hours per day.
I looked at the current output of the panel at about 2 PM on a little hazy but sunny January day and it was only putting out maybe 200 to 300 ma. I then aimed the panel directly at the sun and the current about doubled. In the attached picture, you can see the angle I had the panel at looking directly at the sun - ie, the sun is awful low on the horizon. In my case, with the pretty anemic output of the winter panel, maybe Im getting 1.5 amp hours from the panel. But the dang stereo in standy is consuming 2.4 amp hours for a net loss each day.
So now I have to rewire the stereo so that the cabin power switch can completely turn off all power to the stereo (and lose all presets) and I will put in a "bypass" which will put the stereo only in stanby power (which I think will be fine during the summer and I wont need to mess with all the settings each time).
Anyhow, sort of interesting..
Attachments
Your problem isn't that the panel isn't capable of keeping up with the parasitic draw of the stereo, but that your installation pretty much guarantees the panel is going to be crippled in its ability to work properly.
ANY SHADOWS cast on a poly/mono-crystalline panel will have a very drastic negative effect on its output. You've mounted yours in what is a really lousy location, since from almost any angle, the panel will have MULTIPLE SHADOWS CROSSING IT. Don't blame the panel for a faulty installation.
A good 20 Watt panel should put out about 1.5 amps per hour during the middle of the day, provided it is aimed somewhat towards the sun. If you moved the panel to someplace it didn't have all those lines and such hanging over it, and tilted it, you'd probably get 6-7.5 amp-hours out of the panel, instead of the 1.5 amp-hours or so you're currently getting.
BTW, that looks a lot like the Harbor Freight 25 Watt solar panel I recently added to my boat, and I get 1.9 amps off it for most of the mid-portion of the day. But mine is mounted on the stern pushpit rail, and has no shadows crossing it.
ANY SHADOWS cast on a poly/mono-crystalline panel will have a very drastic negative effect on its output. You've mounted yours in what is a really lousy location, since from almost any angle, the panel will have MULTIPLE SHADOWS CROSSING IT. Don't blame the panel for a faulty installation.
A good 20 Watt panel should put out about 1.5 amps per hour during the middle of the day, provided it is aimed somewhat towards the sun. If you moved the panel to someplace it didn't have all those lines and such hanging over it, and tilted it, you'd probably get 6-7.5 amp-hours out of the panel, instead of the 1.5 amp-hours or so you're currently getting.
BTW, that looks a lot like the Harbor Freight 25 Watt solar panel I recently added to my boat, and I get 1.9 amps off it for most of the mid-portion of the day. But mine is mounted on the stern pushpit rail, and has no shadows crossing it.
Saildog, please post some picture of your stern rail mount. In my opinion, there are not a lot of good places to put a solar panel on a trailerable boat - maybe you found a good way to do it. I think we would all like to see some pictures.
With a trailerable sailboat, the solar panel is mostly about charging the batteries when your not using the boat. A 20 watt panel makes only a dent in my typical day usage. So you could mount the panel is some places which would be poor for sailing then just move the panel while your sailing.
My location is a compromise and I have to disagree with it being faulty because it meets my needs. During the winter, I really only need the panel to keep the battery charged since the boat is not being used (I typically work on the boat in the winter but then I have AC to the boat and a battery maintainer). Lets say I have 10% monthly self discharge of my 200 amp hour battery flooded cell bank (probably conservative since the boat/ battery is in a place with cold temps - ie, lakes frozen over). Even with my worst case panel looking straight up and in January with the sun way to the South, the 20 watt panel can keep up - as long as I have things which "leak" current such as the stereo completely turned off. As the sun moves back North and we get longer days, the issue of keeping the battery bank charged pretty much goes away.
During the summer (which I have two seasons experience with this panel - but only monitoring battery voltage), the sun is much higher in the sky with much longer days. During the summer, I use the boat typically one day per week and only charge the batteries with the solar. I probably use maybe 15 to 20 amp hours on a typical outing (I will have a better idea this summer with the battery monitor I just put in the boat).
Anyhow, I'm pretty happy with my "faulty" location but would like to see how you mounted the panel to the stern rail. You have a very different boat but still have the space limitations of a trailer sailboat
With a trailerable sailboat, the solar panel is mostly about charging the batteries when your not using the boat. A 20 watt panel makes only a dent in my typical day usage. So you could mount the panel is some places which would be poor for sailing then just move the panel while your sailing.
My location is a compromise and I have to disagree with it being faulty because it meets my needs. During the winter, I really only need the panel to keep the battery charged since the boat is not being used (I typically work on the boat in the winter but then I have AC to the boat and a battery maintainer). Lets say I have 10% monthly self discharge of my 200 amp hour battery flooded cell bank (probably conservative since the boat/ battery is in a place with cold temps - ie, lakes frozen over). Even with my worst case panel looking straight up and in January with the sun way to the South, the 20 watt panel can keep up - as long as I have things which "leak" current such as the stereo completely turned off. As the sun moves back North and we get longer days, the issue of keeping the battery bank charged pretty much goes away.
During the summer (which I have two seasons experience with this panel - but only monitoring battery voltage), the sun is much higher in the sky with much longer days. During the summer, I use the boat typically one day per week and only charge the batteries with the solar. I probably use maybe 15 to 20 amp hours on a typical outing (I will have a better idea this summer with the battery monitor I just put in the boat).
Anyhow, I'm pretty happy with my "faulty" location but would like to see how you mounted the panel to the stern rail. You have a very different boat but still have the space limitations of a trailer sailboat
Walt-
My boat is a trailerable.
The main reason I said the installation was "faulty" is that at almost every angle the sun will cast a shadow of the shroud and genny sheet on at least half the cells in the panel. That means that the panel will always be working a only a fraction of its capacity, due to the shadowing on the cells. This affects mono-crystalline and polycrystalline panels fairly drastically.
The panel on my boat is mounted on the port cockpit railing, as seen in this photo. The panel, a Harbor Freight supplied 25 Watt from Chicago Electric, measures about 16" x 31", and isn’t shadowed at all during the day. This panel is only mounted here during the winter storage period. During the normal season, it is mounted on the transom arch, which the mast rests on during the winter storage season.
I also have two much larger 130 Watt panels that are used during the sailing season, which are currently in storage.
My boat is a trailerable.
The main reason I said the installation was "faulty" is that at almost every angle the sun will cast a shadow of the shroud and genny sheet on at least half the cells in the panel. That means that the panel will always be working a only a fraction of its capacity, due to the shadowing on the cells. This affects mono-crystalline and polycrystalline panels fairly drastically.
The panel on my boat is mounted on the port cockpit railing, as seen in this photo. The panel, a Harbor Freight supplied 25 Watt from Chicago Electric, measures about 16" x 31", and isn’t shadowed at all during the day. This panel is only mounted here during the winter storage period. During the normal season, it is mounted on the transom arch, which the mast rests on during the winter storage season.
I also have two much larger 130 Watt panels that are used during the sailing season, which are currently in storage.
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