Solar-only battery charging on Sailboat w/o an engine...

I believe this 30' sailboat is in good shape when it comes to meeting it's 12v power requirements via solar only, but would like the experts to chime in with comments and suggestions.

The solar panels are high voltage custom made units used by a traffic control equipment manufacturer.

The 138w array = ten sets of three 4.6w panels, with a Morningstar SS10 controller.

12v DC system = Two 6v 200Ah deep cycle golf cart batteries.

24 hour energy budget = 60 Ah (includes 20% reserve). Most of the budget supports the controller, tiller pilot, VHF & SSB radios and inverter (there are no fancy appliances on this boat and the electronics are basic).

Shade is a factor when the rigging of the boat casts a shadow on part of the solar array. During the day, maybe an average of 10% of the array will get shaded at any one time. On occasion, deck temps might reach +100*F without convection when sailing downwind. And overcast skies might average 2 days out of 7 and maybe morning-to-noon fog on occasion.

Thoughts? Comments? Suggestions?
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Comments

  • BB.BB. Super Moderators, Administrators Posts: 30,494 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    You don't say where your are sailing... So just assuming 5 hours of sun per day and 12 volts system (this is a SWAG--put the change any numbers to match your actual conditions--0.7 derating is my experience with 3,500 watt panels on roof on 80 degree day):

    amp*hrs = 5hr*138 watts * 0.7 HighTemp derate * 0.95 charge eff * 0.80 batt eff / 12v= 30.6 amp*hrs per day

    Roughly, you are only meeting about 1/2 your power needed per day with the solar panels...

    Wind Generator--even this only gives 400 (33 amps) watts at 28 mph... You need at least 7 mph wind just to get it spinning:

    http://www.nwpwr.com/products/wind/air_x_marine.htm

    And/or a towed turbine... This one produces about 1 amp per knot through water (6-7 knots max effective tow speed?):

    http://www.ampair.com/homepages/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=5&MMN_position=9:9

    Regarding batteries, AGMs are about 98% (vs ~80% efficient for "wet" lead acid storage batteries) for charging... Also, AGM's (assuming that you are OK with the extra costs up-front) are probably much more suited for use as storage batteries for the average person... More efficient, no water to check/add, no leaks, accepts higher charger current (motor/dock power--means less time on generator), may have longer life in ocean/high vibration/typical maintenance environments.

    So--either go on a conservation kick, characterize power between at anchor (solar/wind) vs at sea (solar/wind/tow) power requirements. Ad small generator and "good" regulator for makeup power (30 amphour per day deficit)

    200amphr/30 amphr/day * 5/7 sundays/fogdays =~ 4.7 days of power before "external" charging needed

    Good web site for boaters by Jim earlier today/thread...

    http://www.amplepower.com/

    Is this kind of what you were looking for?

    -Bill "not a sailor or solar expert" B.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Solar-only battery charging on Sailboat w/o an engine...

    i'll agree with bill here in that you are falling at least 50% shy of your needs. i dissagree with a trailing generator as that is just an inefficient means of recovering some of the movement of the boat and thus slows the boat down. if you are stationary and have currents strong enough maybe i'll say yes to it then. get some more pvs and try to put them in a different place on the boat so as to not be in the shade when the others are.
    beware that the radios will suck much power from your batteries. just in receive alone you probably will use 2-3amps continuously between the 2 radios. my guess is the ssb will draw as much as 20amps in full power transmit and the vhf about 5-6amps in full power transmit.
  • System2System2 Posts: 6,290 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    From June to August, the boat will be sailed offshore, in blue water mostly, from SF to Hawaii then from Hawaii to Cape Flattery. The lat/lon box ranges from 20N to 45N and from 160W to 123W. Use of the tiller pilot can be adapted to the power available, and the radio will be in use for less than an hour per day. A battery operated GPS units and sextant will be the primary nav instruments, and battery operated VHF radios will be used to monitor Ch 16 24/7.

    The solar array will be exposed to sunlight from sun up to sun down. The conservative estimate of solar generated amps is the result of my lack of knowledge about the amount amps the solar array will generate in the first hours of the morning and last hours of the afternoon. Heeling of the boat is also a factor, but probably one that evens itself out in a 24 or 48 hour period. With regard to amps generated on overcast days, I reckon the panels will perform close to peak levels because they are particularly suited to operating in such conditions.

    Hopefully my thinking is reasonable.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Solar-only battery charging on Sailboat w/o an engine...

    i would give the system a trial run not far from shore for 4-5 days to see how it all works out. better to have something go wrong before the major voyage rather than during it.
  • BB.BB. Super Moderators, Administrators Posts: 30,494 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    Here is a short article about power for a sailboat...

    http://www.bayweekly.com/year01/issue9_40/lead9_40.html

    They are talking about ~34 amphrs (12 volts) per day--just running lights, may be a couple reading lamps and a tape player.

    I would suggest looking for LED powered navigation lights, or possibly CPF type lights for use in the cabin to save some power.

    The drag from a water turbine was stated to be upwards of 50 lbs. I guess that will be a trade-off between wind and hull speed as to when to toss it into the water... Also, they are talking about 80+ feet of line. Something you don't want to deploy in shallow water (like much of SF Bay / Delta).

    Regarding heeling of the boat/shading/less than optimal positioning of panels/sun--don't kid yourself. The panel's power output is directly proportional to the amount of light striking the surface (at right angle +/- 15 degrees or <5% loss). It will not average out--it all will cost you lost energy (and for the panels, depending on how they are wired, 10% shading can result in many times more loss of power. Same with overcast--A slight high altitude cloud layer may not affect output by much--but almost anything else will cut it by 1/3-1/2 or more (and you are already only feeding, roughly, 1/2 the required power without those drawbacks). The panels will likely not operate at close to peak levels because they will not always be operating under peak conditions--depending on latitude/season, having the panels flat vs Latitude +15 degrees (for Hawaii) can cost you 20% or more in lost power.

    Also, I gave numbers for summer +/- a few months... For winter, you can see, on average, about 1/2 of that amount of energy. That you are planning the trips for June-August... That is a help.

    Take a look at the "Red Book" link below and pick Hawaii or California for some sample data.

    http://rredc.nrel.gov/solar/pubs/redbook/

    I am not trying to "rain" on your parade--I just want to make sure that you have backup for your solar panels (and that backup could be a towed turbine, running an alternator/charger/small standby Honda eu1000i gen and a couple gallons of fuel, cutting back on non-critical power use, more batteries, etc.).

    Here is one site that may have USCG legal running lights (don't list current, but should be 50% to 80% less current use wrt to standard 1 amp per bulb running lights--I would guess):

    http://www.fourwinds-ii.com/lednavigation/lednavigation.htm#led

    For radios, your main VHF radio may draw 0.5 amps or more on standby... Get a second hand held VHF and it should draw only ~ 0.1-0.2 amps on receive... Leave the small radio on to monitor--only turn the full size set if you hear anything that needs to be monitored... Perhaps get a small hand held GPS (again, with low power DC connection) for basic open water navigation and track log... Use the fancy, hi-powered unit, when needed near port for navigation.

    If you are using an inverter--watch what loads you choose to run. Pick a low power laptop instead of desktop unit (you probably already are using a laptop just because of space requirements), etc...

    I will stop here. I am probably just typing things you already know better than I...

    Sounds like fun!
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    First off, thanks to all for the thoughtful and very helpful info. Please keep the comments coming if anything else comes to mind. One additional factoid seems worth mentioning...the reserve capacity of the battery bank is 105 hrs. Assuming the boat sailed for days with skies heavily overcast, how long would it take the aforementioned solar array to recharge depleted batteries once clear skies returned?
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Solar-only battery charging on Sailboat w/o an engine...

    with rough calculations i figure about 31hrs so with about 5hrs of full sun per day it's not hard to figure upwards of a week give or take a day or 2. this depends on cloud cover and the true hours per day of full sun and if it averages with the cloudy days at that 5hrs/day figure then you are looking at about 6 days. i don't recommend taking the batteries down to 100% dod as this not only takes away from the lifespan it also increases the chances of cells going bad ruining the entire battery. batteries aren't meant to routinely be 100% depleated. i know the batteries are only needed for a few months and in an emergency i'd depleat them, but i wouldn't have designed the system for having to do that with a long recharge time involved when lives could be in danger. now in an emergency you won't wait for a full recharge to use some for the radios and given the extended high drain possibility those batteries could get ruined very quickly.
    or maybe i'm just being too much the pessimist.
  • BB.BB. Super Moderators, Administrators Posts: 30,494 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    I see that Niel has posted while I am typing this up... I agree with him on his recommendations. And never plan your trip such that everything has to be exactly correct... I would count on a 50% safety factor, that, at least one major piece component can fail (solar charger or gen set--but not both) and have plans on how to survive if something does happen (no wind, mast failure in storm, -- only power for emergency radios--different standby power sources, turn off other loads, etc.). The emergency locater, required flares/signaling devices, and emergency food/water/medicines while waiting for rescue.

    I don't know know open ocean travel--but obviously--you DON't plan a 10 day trip and carry only 10 days of supplies (or electricity). Add missing word "DON'T"

    Again, I am sure that you have more experience than I in sailing--I just add the above because this is an open Internet forum and I don't know your, or other's, experience level.

    Back to what I originally typed:

    Reserve Capacity is that amount of time a battery can be discharged at 25 amps... For your batteries that would make the rating:

    25 amps * 105 hours = 2,605 amp hours --- probably not correct unless you have a 6,000 lb battery bank or an awfully large golf cart. :wink:

    More likely... the RC is in minutes for the batteries you describe:

    25 amps * 105 min / (60min per hr) = 43 amp*hours

    This is a pretty heavy load for a "small" battery--equates to a load on your boat of 600 amp*hours per day--or almost 10 times your average load of 2.5 amps... Batteries do not discharge linearly--i.e., discharge your bank at 2.5 amps and it may last 80 hours (200amphr/2.5amp=80 hours or 3.3 days). Discharge your battery 10x as fast and you will only get 43 amp*hours from the battery or 43/200 = 22% of it ability to do work. Please note, that you will still need to charge this battery bank for approximately 200 amp*hours worth of solar (or "low" current solar) to get its full capacity back.

    Your batteries are probably rated at the 20 hour rate (how many amps can be supplied for 20 hours) and the answer is 200amp*hr / 20 hr = 10 amps... Since your load is less than the 10 amp load, you will should get more than 200 amp*hours out of the battery. How much more, that is the Peukert factor... maybe 10% more (battery temperature, care, quality of charge, age, maintenance, etc. will probably make the 10% number less than meaningful in this discussion--keep at 200 amp*hours for following discussions). You can read about the Peukert fact here:

    http://www.vonwentzel.net/Battery/00.Glossary/

    OK, to answer the rest of your questions: 200 amp*hrs is full capacity of battery bank (when new and broken in). Many folks recommend not regularly discharging the batteries much below 50% so that the batteries have long life. If you store a 100% discharged battery for more a few handful of hours (and or recharge it over a longer period of time) you will permanently damage/ruin the battery. I will give both numbers below... Calculations based on 100% discharged and 50% discharged and suggest that you don't go much below the 50% discharge range except in an emergency (and you plan to replace your batteries).

    200 amp*hrs / 60 amp*hrs per day = 3.33 days until fully discharged (with no sun)
    1/2 of 200 amp*hrs / 60 amp*hrs per day = 1.66 days until 50% discharged (with no sun)

    Assuming from before that full sun, good boat/sun position, ~max sun on a warm day is 30.6 amp*hrs per day--no clouds:

    200 amp*hrs / (60-30.6) amp*hrs per day = 6.8 days until fully discharged (with full sun under load)
    1/2*200 amp*hrs / (60-30.6) amp*hrs per day = 3.4 days until 50% discharged (with full sun under load)

    The solar panels will never charge the battery bank unless the daily load is less than the charge current (per day) coming in from the panels... Assuming no load to recharge:

    200 amp*hrs / (30.6) amp*hrs per day = 6.5 days until fully charged (with full sun under no load)
    1/2*200 amp*hrs / (30.6) amp*hrs per day = 3.27 days until 50% discharged (with full sun under no load)

    Assuming that you need an anchor light (1 amp 12 volt standard anchor light, assume 24 hours per night) during recharge period and batteries are fully/50% discharged when "parked".

    200 amp*hrs / (1amp * 24 hrs/day) = 8.33 days until fully discharged or 4.2 days at 50% [email protected] sun
    200 amp*hrs / (30.6 amp*hrs - 1amp * 24 hrs/day) = 30 days until recharged or 15 days 50% [email protected] sun

    If you put a timer/photo cell or are there to turn light off during the day (assume 12 hours per night) and batteries are fully/50% discharged when "parked".

    200 amp*hrs / (1amp * 12 hrs/day) = 16.7 days until fully discharged or 8.3 days at 50% [email protected] sun
    200 amp*hrs / (30.6 amp*hrs - 1amp * 12 hrs/day) = 10.75 days until recharged or 5.4 days 50% [email protected] sun

    I used the full equations everywhere, so you should be able to adjust the numbers for your exact power needs and charging capacities/assumptions.

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    Bill, Niel...thanks for sharing your knowledge with me. And thanks for the new word in my lexicon...Peukert :-D Oh and thanks for being gentle with my goof about RC equaling hours rather than minutes.

    I don't have much experience with solar power, but do have thousands of miles of open ocean sailing under my belt, both racing and cruising on OPB's (O_ther P_eople's B_oats). Most of the sailing has been short-handed, meaning less crew than normally expected. In the case at hand, the passage from SF to Hawaii will be sailed solo by a friend, and the passage from Hawaii to Victoria BC will be sailed by me and my S.O. (she's also very experienced and used to Spartan, hands-on sailing).

    We are very keen on seeing what solar can do. The anecdotal stuff within the sailing community is all over the map. While sailing is the adventure we are preparing for, the boat with it's minimalist set-up give us a chance to learn first-hand about the true energy demands of the electronics on board and the actual power generation of a particular solar array. When we get home hopefully we will have some facts, figures and stories that will enhance the great body of knowledge you've already accumulated.

    I don't know if it's important or not, but the solar panels installed on the boat are better than the average panel found in the marketplace. They are specially designed to power traffic control lights and are found as far north as Alaska as well as in the Sunbelt. The owner of the boat is convinced that the output of the panels throughout the day is much greater than what is expected of panels usually found at retail. By this I mean, there is an expectation that peak output extends well before and after solar noon and the difference in output on sunny days and moderately overcast days is minimal.

    Personally, I'm not savvy to state-of-the-art developes in solar cell technology or panel design or whatever. I think counting on 6 hours of peak output is optimistic, and will probably bank on 4 hours per day sun or clouds and if I get more amps than expected in Week One, it just means I can increase my daily energy budget for Week Two. That probably means more reading for me, and more driving for Auto.

    We'll know much more for our passage from Hawaii to Victoria after our friend completes his trip from SF to Hawaii, although the two passages are very different sailing-wise...the latter hot, and downwind mostly while the former is much less warm, more clouds with very little wind hitting the back of either ear.

    Right now we figure the solar array is fixed at 138 watts, max. so based on your input, we shouldn't count on more than 80% of that for our peak output number. And I've arbitrarily picked 4 hours a day to arrive at 36.8 Ah per day from the solar array. With 200 Ah of battery power, our planning is based on half that amount, so we seem to have plenty of battery. We know what the rated amperage is for all the electrical stuff on the boat but what we don't know is what the actual Ah requirement will be for things like the controller, autohelm and SSB because we don't know exactly how much we are going to be using some of this equipment vs leaving it in standby mode. Until we do, we won't know how many amps will be available for the inverter, so battery power for the computer, etc. will be relied on for the first week.

    Hopefully, after the first week we'll know if 36.8 Ah of solar power is a good number, and we'll know if our use of the autohelm and radio is excessive or overly conservative. Week two, if anything will be less full of questions about our power requirements and hopefully more full of Ah. Week three is when we expect more clouds and some fog. Week four should be cut short by our arrival in Victoria.

    For us, total distance as the crow flies...2700 nautical miles. Estimated average speed over ground 5 kts, hopefully. The vessel is an Olson 30, which is a ULDB (U_ltra L_ight D_isplacement B_oat). It is a masthead, sloop rig, meaning it has one mast, a mainsail and foresail, which can be either a jib, genoa or spinnaker. Masthead means all sails are hoisted to the top of the mast, instead of a fractional rig which means that one or more of the foresails are hoisted to a point below the top of the mast.
  • BB.BB. Super Moderators, Administrators Posts: 30,494 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    B2S,

    Regarding the Solar Panels... You really need to identify the manufacturer and Model/Part Number of those devices... Because--I will tell you a couple paragraphs later... :-P

    First, there are several major types of solar panels. And they can use different materials GaAs (space craft use this material because it converts more of the sun to electricity per square inch than Silicon and it responds better to high temperatures and radiation exposure--but it costs 10x as much). It is unlikely that you have GaAs. Most terrestrial uses don't want to pay that much for more efficient panels, radiation is usually not a problem, so that leaves Silicon...

    In Silicon, the mono-crystalline and polycrystalline usually are thought to last longer in sun/under UV. The Amorphous types are usually cheaper to manufacture and may not last as long (and be physically bigger for same power ratings)--but they can be more flexible and resistant to vandals (vs. the crystalline types which usually have glass covers). Your panels may be of any of these three types. And, assuming that your panels are very weather proof, have been constructed in the last few years--they will have pretty much standard outputs and sensitivity to temperature (warm solar PV cells lowers voltage with lowers power output). Designed for Alaska or traffic lights, to me, would indicate there ability to withstand temperature extremes and, possibly, vandals--not really much in the way of special power outputs. Physics would indicate that any of these panels will operate about the same under cloudy sky's (i.e., lose 50% to 80%+ of their output).

    Now, why mfg and part/model number... If these are designed for traffic lights or a specific area of the world, they can have non-standard output voltages. If you us a standard PWM charge controller, the Vmaxpower of these panels usually has to be more than ~17.5 VDC. If the voltage is too low, the charge controller will not be able to fully charge your batteries. If the voltage is too high, it can damage the charge controller and it is a waste of energy (PWM charge controllers can't convert the power of a 35 vdc/5 amp panel any better than a 17.5 vdc/5 amp panel--even though the first panel is a 175 watt panel at twice the area and the second is a physically smaller 87.5 watt panel--to the batteries, they will both seem about 70 watts of charging power at full sun).

    In fact, reviewing your first post, you said that these are "solar panels are high voltage custom units" would worry me... If they are for 24 volt traffic light systems, then for your use, they would only be rated at 69 watts for you application--1/2 of what I assumed above. If they were for 48 VDC operation, only 35 watts.

    In the end, if you are trying to build a seaworthy solar PV panel system... I would be very tempted to dump the current panels and replace them with a single modern 130 - 180+ watt panel (or several smaller panels) rated for use with your type of controller (PWM or MPPT)--assuming that you have the deck area for it. The 30x 4.6 watt panels are just too small and numerous for a reliable system... There are 60+ electrical connections, many jumper wires, salt water, and many more edges of panels where water can leak in... Just not a basis for a reliable system. One panel, two connections, and you are done. If a connection fails, there is only one of two points to check/repair. You could lose 10-20% of your multi-panel system and may never know that it was operating with the failed panels without checking each one with a DVM.

    If this first solar system is for "fun", then go for it and see how it works (assuming that you have backup power--or don't need the power). Otherwise, I would have serious reservations about this system. There are many unknowns and potential weakness in the design (as much as I can tell from reading a bulletin board).

    By the way, you can probably just dry test your system anywhere (dock, anchor, etc.) right now... Just put a known load (couple small 12 volt lights and monitor the battery charge/usage). If it does not work in port, it is not going to work at sea...

    Take care,
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 30,494 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    2-4 of panels in parallel (or series if MPPT controller) may be the ticket--but I would still look for drastically differing sources of power... You may drop a tool and break one panel... You may have a boom fall and wipe out the whole array in a storm...

    I too have many thousands of miles of navigation... Light plane across the US (SF to NY to TX and back to SF) about 30 years ago--day time only, no generator, hand prop to start, and a single motorcycle battery for an hour or so of aviation radio and VOR navigation use over a few days (charged the battery every few days or so...)... Lots of dead reckoning (airspeed, compass and watch). At least I had a few land marks and could always get an emergency VOR fix if I needed one (rarely did that).

    In general, you can get away with very little power in normal situations (running lights at night are about all I can think of that would be required by the coast guard). But, it does pay to be prepared for emergencies.

    Changing out lighting to LED's can also save a bunch of energy... Start with conservation--then add batteries and charging capacity. And keep it simple.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    I will work on getting the actual OEM make/model info.  Meantime, here is a drawing.  I removed names and distributor ID's to protect the innocent.


  • BB.BB. Super Moderators, Administrators Posts: 30,494 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    Vpeak is 6 volts and Vopencircuit is 7.08 volts... As long as the arrays are 3 in series for 18 volts peak power and about 21 volts open circuit, these panels seem to match the requirements for the average 12volt battery bank PWM solar charger/controller. (IMHO).

    I don't think you need much more information... You may be able to look up the brand name/model on the Internet to see if anyone has reliability issues with the panels... But since you have them, I would probably not even worry about that (and you will probably not find much information anyway).

    One silly question... The drawing does not say one way or another... Is there a bonded/sealed glass sheet on top of the panels (i.e., factory sealed all the way around) or were these "raw" units intended to be installed in a secondary enclosure?

    I did not see any frame/mounting hardware so it is kind of hard to understand how they are installed on your boat. I would suggest that you check around the wires exiting the Panel's FR4 substrate and ensure that they are sealed and strain-relieved well with drip loops (prevent cracking of insulation and water migration into the wires and/or into the base of the solar panel itself).

    Personally, I would prefer fewer/larger panels with pigtails bonded to the panel. You can then used the attached weather proof connectors to route the connections inside to a protected space to parallel the rest of the strings together. (At USGS we would wrap with tape and paint 3M electrical sealent over the outside of the exterior connectors on shipboard connections like antennas and other electronic gear).

    But, you already have these panels and as long as they work for you--it is probably not worth the time and money to replace them until you have tested the rest of the system.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Patman3Patman3 Solar Expert Posts: 62 ✭✭✭✭
    Re: Solar-only battery charging on Sailboat w/o an engine...

    Born2Sail,
    I'm not sure what type of batteries you have, but if you don't have AGM type you should get them. After reading that vonwentzel stuff on batteries I quote:

    "Virtually no gassing under normal operating conditions: Unlike flooded cells, gel cells and AGMs are hermetically sealed and operate under pressure to recombine the oxygen and hydrogen produced during the charge process back into water. You find VRLAs in the bilges of high end yachts such as Hinckley, Hans Christian, Island Packet, etc.. Every boat benefits from a low center of gravity over the keel (good for righting purposes) and the minimal venting requirements make it possible.
    The ability to put VRLAs in the bilges (they can operate under water should you hole yourself) also lengthens their lives: For every additional 15 degrees of heat over 77 deg F, lead acid battery life (regardless of type) is cut in half (batteries self-destruct with time, you can only slow that process). Chances are, the bilges are the coldest place on board (outside the freezer) and the keel provides protection.
    VRLAs can operate in any orientation (although you may lose some capacity that way) and even if a container is broken, a VRLA will not leak. This is a feature particularly important to blue water sailors who may encounter survival storms - you don't want to coat the inside of your boat with sulfuric acid if you ever get rolled. Proper (heavy duty) battery restraints are a must, regardless of battery type. "

    Maybe you already saw that, if so sorry for redunancy.
  • System2System2 Posts: 6,290 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    I totally agree about the AGM batts. Hopefully, that mod will take place for all the excellent reasons argued for on this forum. Changing the batts is not going to be easy, however, because of space. As for positioning, the current batteries are well away from any water collection point in the bilge area, which is not a popular place for batts anyway.

    Speaking of batteries...as an aside, the 6v deep cycle batteries currently on the boat may not be golf cart batteries after all. It sounds as if they are OEM type batts used by the RV and marine industries. Here's what an online source had to say in response to an inquiry I made about having a hard time getting specs for the batteries in question...

    "What I have been able to find on the Powervolt VA-1055 is that it is a six volt (3 cell) marine storage battery with 105 minutes of reserve capacity at a 75 AH discharge rate at 80 degrees F and that it is a BCI CG2 size. Taken to account the Peukert Effect, this would translate to approximately 210 to 220 amp hours at a 20 hour discharge rate. What normally differentiate golf cart batteries for less expensive marine batteries is the plate chemistry and thickness of the plates. Golf cart batteries are normally wet Standard (Sb/Sb)lead-acid batteries and marine/RV batteries are normally wet Low Maintenance (Sb/Ca) lead-acid batteries with thinner plates possible made by Johnson Controls. I think your friend has less expensive wet 210 amp hour marine/RV batteries that is not in the same league as the true golf cart batteries, such as, Trojan, U.S. Battery, etc. or the wet Standard deep cycle batteries made by Surrette/Rolls, etc."

    IMHO (formed thanks to you all) the three strongest arguments for going with the AGM: (1) they take a charge quicker; 2-12v offer redundancy that 2-6v don't; gassing (even tho the PWM feature on the controller seems to mitigate this).
  • FrankFrank Solar Expert Posts: 54 ✭✭✭
    Re: Solar-only battery charging on Sailboat w/o an engine...

    AGM's are definitely the way to go. Supposedly AmpAir wind turbines are a lot quieter now and if I think that'd be a good investment. There's probably others out there now too. The older style wind machines drive us crazy when close to other boats due to their noise levels. I'd definitely spring for LED nav lights/bulbs and there's now LED cabin lights too (not sure who makes these but saw some earlier this year).

    I applaud your gumption to try this out. Not many boats w/o some type of auxilliary power these days...
  • BB.BB. Super Moderators, Administrators Posts: 30,494 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    B2S,

    If you are serious about power while sailing (duh... middle of the Pacific), I could suggest another reason to use two 12 volt AGM batteries...

    Set them up as two different circuits... You can still use one panel, two solar chargers (check that they are negative ground--Wind-Sun has said that they do this all the time), and wire each to a separate battery. Then wire the navigation lights, auto helm, GPS, emergency radio, one work lamp, to one battery ("A") (the fewer loads, the better) and all of your optional loads to the second bank ("B").

    Of course, you should probably have a switch to allow you to kill power to one charger or the other (i.e., all power to battery A). And the ability to run your critical loads from the alternate battery--if needed.

    This would allow you to monitor your usage, and keep the critical loads going as long as possible without having to monitor the loads like a hawk.

    Bank "A" loads:

    3x 0.30 amp 12v LED nav. lights x 8 hours per day (summer cruising). (guess--7.2amphrs/day)
    1x 0.10 amp VHF receiver (portable, low power) x 24hrs (2.4 amphrs/day)
    1x 3 amp load (2nd SSB radio, cab lights, GPS) x 1hrs (3 amphrs/day)
    ============================
    12.6 amphrs per day.

    If you want to use only 100 amphrs from the bank, that is good for 8 days of no sun.

    Your solar panel is good for ~30 amphrs per day (in full sun, good position). I feel that expecting 15 amphrs per day (on average over a two week period) is pretty safe. Even assuming 1/4 output (7.5 amphrs per day), that would give you an easy:

    100 amphrs / (12.6-7.5)amphrs/day = 19.6 days of battery/solar power from one bank (50% drain). ~40 days at 100% drain.

    You would still have 100 amphours (50% of 200amphrs) in the "B" bank to play with as you need...

    But, to be honest, I don't believe that you have much "extra" in the way of solar power available to charge that 2nd bank unless you have great weather and/or another charging source. And given that you wanted, at least, another 30-45 amphrs and, on the best of days, you will only have 15 amphrs per day for everything else...

    If you don't want a small generator (like a Honda eu1000i) with 5 gallons of gasoline. Then you would need one of those wind/water turbine units... The water towed unit is good for about 1 amp per knot (5 knots, 5 amps). Assuming roughly a 50 lb drag, and 4 knots, that would be 4amp * 24hours per day = 56 amphrs per day...

    Comparing a towed turbine at 4 knots:

    56amphrs / day * 12 volts = 672 watthours per day.

    Your solar system:

    30.6amphrs/day * 12 volts = 367 watthours/day (or even 1/2 or 1/4 of that in bad weather).

    Honda eu1000i running a battery charger...

    3.8 hours per tank * 900 watts * 75% (charger/AGM batt eff) * 5 gallons of fuel/0.6 galspertank) = 21,375 watthours/5 gallons of gas

    Or, 5 gallons of gasoline will, roughly, power 60amphours/day at 12 volts for:

    21,375 watthours / (60amphr*12) = 29.7 days (and you still have full batteries for a bit more time)

    Or, if you are running ~30amphrs of optional loads (PC, cabin lights, SSB radio, etc.), that 5 gallons would be almost 60 days on the water.

    Amount of generator for 30 days of sailing at 60amphours per day of all loads, no other power source (wind/solar/turbine).

    5 gallons * 3.8 hours/tank / [0.6gals per tank * 30 days] = 1 hours per day average generator run time to keep batteries full

    I am sure that you would not look forward to using a generator for several hours every other day or so... But it is really a trade-off between the power you Need vs Want, and how you wish to generate it (sun/wind/water/gasoline).

    The water turbine sounds nice--but but it would add days (if not a week or more) to your trip... If you were careful with your power use and really conserved, you could probably get by really nice with using the solar + towing the water turbine for only 6-12 hours per day (average sun)...

    Interesting problem--what are you thinking about?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    What am I thinking about? For sure a whole heck of a lot more thanks to this forum :lol:

    Seriously, much will depend on how things go for our friend on his sail from SF to Hawaii. Assuming things work "close" to plan, I'm developing connections in Hawaii so we can install 2 hefty 12v AGM's and possibly an EU2000i gen off another boat in the Islands that's not being sailed much anytime soon (ship the gen back when we're done).

    As for developing the two-circuit idea. I don't think there will be the time or the enthusiasm for such a mod. Again, the sail from SF to Hawaii will go a long way in determining how much bolstering of the electrical system falls into the manditory and the optional job-jars.
  • System2System2 Posts: 6,290 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    Here are a few pics of the panels that have been on the boat and performing well for about a year or more. These panels are mounted permanently. They are remaining on the boat as part of the total array. The additional panels will be on rubber mats and intstalled as temporary fixtures, via well designed temporary attachments :wink:


  • System2System2 Posts: 6,290 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    More...

  • FrankFrank Solar Expert Posts: 54 ✭✭✭
    Re: Solar-only battery charging on Sailboat w/o an engine...

    Thanks for the pics. Is the panel in the top shot mounted on a hatch cover? How about the next two: looks like aft near some stanchions? BTW, I think you can make this work, especially if you can pickup a "drag along" generator. Small penalty in sailing speed but you can keep the batteries charged. Maybe you mentioned this already but the post is getting too long to reread...

    TIA
  • System2System2 Posts: 6,290 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    The panels are mounted on the deck (transom area). There are 2 sets of 3 solar panes, one set on either side of the hatch cover that leads to the stern lazerette. In a previous post, I mentioned my effort to line up a portable gen if the sail from SF to Hawaii suggests, even a little bit, tha we go to Plan B. Right now, we might have access to a Honda EU1000i. I don't think that'll do the job, so I'm still looking for an EU2000i or the like. We have a sailing friend on Oahu who is checking around the island.
  • System2System2 Posts: 6,290 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    The race from SF to Kauai started on Saturday. Both the skipper and the boat are doing better than good. People interested can follow the progress of Foolish Muse by going to http://www.sfbaysss.org/TransPac/transpac2006/index.html

    Work on the solar array was completed at SFYC the week before the race. Here are some pics taken by a friend.


  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Solar-only battery charging on Sailboat w/o an engine...

    hey i wish them all of the luck in the world on this journey. i guess you'll stay on shore, am i right? tell of the final decissions on what all is there for power.
  • System2System2 Posts: 6,290 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    Foolish Muse is being solo sailed to Hawaii. ETA is +10 days. The two of us arrive in Hawaii a few days later and plan to double-hand Foolish Muse back to Victoria. Our depart date is 7/12, followed by Dogbark departing for Puget Sound about a week later. She cover our distance in about half the time it takes us. If the solo sail to Hawaii is challenged at all by an AMP deficit, we'll have a new batts/generator Plan B option(s) in place if needed. And even if we don't set sail with Plan B items, we'll talk to Dogbark about carrying Plan B stuff as our Plan C :wink:
  • FrankFrank Solar Expert Posts: 54 ✭✭✭
    Re: Solar-only battery charging on Sailboat w/o an engine...

    I like the mounting job. Can you walk on those panels okay?

    p.s.: good luck!
  • System2System2 Posts: 6,290 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    Yep, so far no harm has been done when the panels are walked, or more likely, kneeled on. Such treatment is kept to a min., obviously, except when we want to sit back on the transom at night. When we do, we'll use a pad, and as a habit we always wear shorts with no hard parts like zippered pockets, etc.

    BTW, a recent log entry by one of the other competitors in the race stated that Foolish Muse has power but is rationing electrons because the overcast has persisted since the beginning of the race on Sat. The batt bank has a reserve of 105 mins. Satellite images indicate a sizeable patch of clear sky ahead. Hopefully Sol will show himself for a good long time.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Solar-only battery charging on Sailboat w/o an engine...

    yes, i know the feeling after getting all of this rain in the east for days on end. record floods are occuring in many areas.
    crewzer,
    are you fairing ok down there as i forgot to ask you in the pm?
  • System2System2 Posts: 6,290 admin
    Re: Solar-only battery charging on Sailboat w/o an engine...

    Qwik Update...Foolish Muse is doing quite well after a period of light winds. This edition of the race is turning out to be one of the slowest. ETA is now Saturday, so it will be 2-weeks for the solar-only sailboat from Victoria BC.

    As for his delivery crew...we've decided after much noodling and budgeting to buy a Honda EU1000i generator to take with us. It's small and light enuf that we can pack it in a gear bag and check it as luggage. Because it's brand new, we don't have to pickle and ship anything as hazardous stuff.
  • BrockBrock Solar Expert Posts: 633 ✭✭✭✭
    Re: Solar-only battery charging on Sailboat w/o an engine...

    Let us know when you leave and get back safe! I used to deliver boats in the Chicago - Mackinaw race, get them one way or the other, very busy for about 2 weeks before and after the race. But that was only on our small Lake Michigan, I can't imagine running to Hawaii in a boat that small, heck that would be small for the Mack run. Impressive!
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
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