Solar or Wind???

Sumner

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Jan 31, 2009
5,254
Macgregor & Endeavour 26S and 37 Utah's Canyon Country
Well.. just pointing out that when I see the pictures of Sumner’s solar panel on the back of the boat and that gas generator.. I cant help to think to myself that if he did get rid of the fridge, he could get rid of that generator and probably get by with 50 watts of solar (I said ½ earlier, should have said ¼).

But.. I know Sumner likes having that fridge and doesn’t mind the tradeoffs.

Regarding the battery capacity, we should also be considering how deep the batteries get cycled. If you look at the ratio of daily amp hours used to battery capacity, in the case for Chis’s boat, its probably about 20 / 160 = .125 I.e., for Chris, his daily use is about 12.5% of the battery capacity.

For Sumner case, I think he said he uses 35 + 9 + 10 = 54 amp hours (fridge + cpap + computer). ...
I can't understand why us having a fridge is such a big deal to you Walt. I could care less that you don't have one.

I've said over and over in this thread and others that 1 battery is probably all most people need. I'm just offering suggestions for those few that want to do things a little different. It was you that put us on to using two 6 volt batteries vs. one 12 volt battery and as of now we still haven't done it since the 12 volt batteries haven't given out.

We never did let the batteries go below 50% because we did have that ugly generator hanging off the back of the boat and also for one fact you didn't account for. We don't discharge and then re-charge entirely as your scenario suggests. The fridge is off at night, coasting and is on during the day when the panels are producing.

If you were to read the first page on our site....

As you read through the mods we have made to our Mac please keep the following in mind. First this is our first sail boat and we had never sailed until we bought the Kera-Jane in the spring of 2009. We are moving into our late 60's so we are setting the boat up for easy handling on the water and trailer and also for extended cruises of over a month, sometimes not resupplying on the water for over 3 weeks. We anchor almost every night, so good anchoring equipment and shore lines have become a top priority for us.
We are explorers more than sailors. This boat is our Jeep on water combined with the hauling ability and comforts of the Suburban that pulls it down the highway. It is meant to take us about any place on inland and coastal waters in some comfort and hopefully safety. Some of the mods have certainly hurt the sailing performance, but that is OK as we are retired and in no hurry.
With that in mind hopefully some of what you find here will help you or someone to some degree with "your goals and wants" in mind,
Sumner and Ruth
...it might become a little clearer what we have a sail boat for.

I often receive e-mails from people saying that at some point they too would like to do some extend trips/exploring with a boat also and appreciate what we have done to our boat and would like to do something along the same lines.

The more I'm on some of these boards the more I realize why people lurk and don't post or just quit altogether. I've cut back my participation here and probably will a lot more. I tried to make my posts constructive, sorry if I failed and I don't see the point in your questioning our decision to do having the fridge and other things that make our trips more enjoyable,

Sumner
 
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walt

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Jun 1, 2007
3,511
Macgregor 26S Hobie TI Ridgway Colorado
I hope I didn’t pass judgment on your setup in the previous post (I didn’t think so, my apologies if it was taken that way) as I completely respect anyone’s decision on the tradeoffs they make in what they buy and how they set things up. I own a Macgreggor – some would pass judgment on just that decision alone but the boat I have pretty closely meets what I need.

If I noted some tradeoffs you made putting in a fridge on a boat this small (26 classic), hopefully you find that fair, worthwhile discussion and useful to others.

Back to the thread - and discussing staying out longer with higher energy needs..

Lets assume a fridge takes 35 amp hours per day to run (Sumner’s number – Ill assume it’s fairly accurate). Just considering the fridge only, if you run this off golf cart batteries which have 225/2 = 113 amp hours available, the fridge alone can deplete your normal available charge in about 3 days. Add in other loads and the margin is less. About the minimum solar you need to support the fridge is 100 watts (this number could vary all over the place depending on a lot of thing). You will sometimes go for days with weather that could reduce the solar output to almost nothing so you need to bring along something such as the gas generator Sumner has (uses an auto alternator so can supply a lot of current at 12 volts assuming the batteries can accept the charge). So your tradeoff is say 100 watts of solar (in addition to what you need for everything else) plus a gas generator. Some will find that acceptable for not having to buy ice every few days, some would not want that, just depends. Normally you may not need to run the generator much at all - but you still need to bring it along just in case. Or.. dont bring the generator and just buy ice when the solar output is low. Or.. add extra battery capacity. I have never sailed a relitively small boat with a relitively large solar panel array way to the rear but suspect that it does affect the way the boat sails and turns - another tradeoff that may be important to some, not at all important to others. The big solar array back there probably does reduce the swinging at anchor however - which is a good thing.

Could you make a 110 V generator work (such as the Honda or Yamaha 1000 or 2000 watt ones work for keeping the fridge cold? I don’t think you can use that type of gas generator to charge batteries directly (??) and probably dont want to run it continously direct AC to the fridge so you would need an AC to battery charger. Just as an example, say you found one that could charge at 30 amps. 30 amps would require a battery large enough to accept that much charge and also would need to be operating in the bulk charging range (between 50 to 90%). We need 35 amp hours for the fridge so if you actually could get 30 amps into the battery, you would only need to run that generator for a little over one hour per day. A 1000 watt generator would fine for this as in this case, the power to the load (battery) is only 30*13 = 390 watts plus some overhead. I’m not sure how quiet these end up being on the water but if they really are quiet, this would not be all that bad and the 1000 watt generators don’t weigh that much. How large of a battery do you need to be able to accept 30 amps for over an hour I don’t know. You would also be cycling the batteries fairly deep. I suspect that two golf cart batteries may be a little too small because of the acceptance– but am not sure.
 

walt

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Jun 1, 2007
3,511
Macgregor 26S Hobie TI Ridgway Colorado
Another option on the fridge..

When I have more time, I would like to use the 26 classic to explore places such Puget Sound and the San Juan islands. We might be using the boat for up to three weeks. That area has a lot of marina's with AC power so I would plan the trip to spend a majority of the nights in a marina, mostly using the boat to day sail (and sail between marinas) and as a place to sleep.

For this trip, an ice chest (in my opinion) works just fine but a fridge would be a luxury although I’m not sure about the $500 plus cost just for the fridge. In this case, most of the fridge charge would come from marina AC and I may need to upgrade the 5 amp charger I have to maybe 10 amp since I would only be charging at night.

But I could also spend several nights camped out in the boat every once in a while and let the batteries get depleted a little. Since you don’t have a lot of margin with just two golf cart batteries (3 days margin - and that is not counting any other loads I have on the boat which may bring the margin down to really only 2 days) a way to accurately keep track of the battery state is useful (like the Balmar battery gauge or a battery monitor). If the batteries did get down too far, I’m assuming that it’s no problem to put a bag of ice in a fridge and shut off the power for a while until you get the charge back up. I may actually do this in couple years from now when I hope to have the time.
 
Feb 6, 1998
11,665
Canadian Sailcraft 36T Casco Bay, ME
Always keep in mind that the real usable capacity, once more than a day away from shore power charging, is 30-35% of a lead acid batteries total capacity or 50% SOC to 80-85% SOC....

So a 100Ah battery, in the real world, only has 30-35Ah's of truly usable capacity when off cruising. This is due to current limitng and battery acceptance rates dropping rapidly once at absorption voltage.
 

walt

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Jun 1, 2007
3,511
Macgregor 26S Hobie TI Ridgway Colorado
just out of curiosity.. if you put a bag of ice in a small electric fridge, how hard is it to get the melted water out? Is there a drain like an ice chest has so this would not be a big deal?
 

walt

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Jun 1, 2007
3,511
Macgregor 26S Hobie TI Ridgway Colorado
charging, is 30-35% of a lead acid batteries
For my marina hopping fridge idea (spending most nights pluged into AC but with a fridge), this 35% probably still applies.

So with the fridge and my daily normal use of about 15 amp hours, my total daily use with the fridge would be about 35 + 15 = 50 amp hours.

If my 2 golf cart battereis were new, I would have a 35% capacity = 75 amp hours. So I would use up the capacity in only 75/50 = 1.5 days.

The fridge would still be nice given that I would spend maybe 75% of the nights in a marina plugged into AC. But if I were to anchor out for a couple nights, shutting off the power to the fridge and bringing a bag of ice would probably be the best plan (no gas generator for me..).
 
Feb 6, 1998
11,665
Canadian Sailcraft 36T Casco Bay, ME
For my marina hopping fridge idea (spending most nights pluged into AC but with a fridge), this 35% probably still applies.

So with the fridge and my daily normal use of about 15 amp hours, my total daily use with the fridge would be about 35 + 15 = 50 amp hours.

If my 2 golf cart battereis were new, I would have a 35% capacity = 75 amp hours. So I would use up the capacity in only 75/50 = 1.5 days.

The fridge would still be nice given that I would spend maybe 75% of the nights in a marina plugged into AC. But if I were to anchor out for a couple nights, shutting off the power to the fridge and bringing a bag of ice would probably be the best plan (no gas generator for me..).
If you can plug into a marina every night then your usable capacity becomes 50% as opposed to just 30-35%. This of course if your charger is big enough to fill the batteries on 10+ hours...
 
Aug 7, 2011
496
MacGregor 26S Lakeland, FL
So let me ask...does a battery recharge "properly" when charged at a slower rate than the normal "bulk charge"? For example, we plan to overnight on the weekends, and the boat will sit idle (mast up on the trailer, we hope) the rest of the week. I was thinking that a small solar panel (with charge controller) that could be set up on the boat while on the hard could charge the battery after we put the boat up Sunday afternoon, and keep it topped up until we launched the next Friday evening or Saturday morning. If the charge was slow, would that be "bad" for the battery, or is it just that it will not recharge as fast as it could if we had a bulk charger? (We wouldn't care about the speed of recharge at that point)
 

walt

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Jun 1, 2007
3,511
Macgregor 26S Hobie TI Ridgway Colorado
I cant tell you if its good or bad for the batteries but that is exactly what I do. I have a 10 watt panel on the boat through a PWM charge controller. when I get done with a sailing trip, just leave the boat. My case is a little different in that I leave the boat for a lot longer than 1 week.

I use a PWM controller mostly because my solar is all fairly low power but one benifit to this is that I have no loss in efficiency by connecting up an additonal 40 watt panel to the 10 watt panel - since both panels just end up at the battery voltage no matter what.
 
Feb 6, 1998
11,665
Canadian Sailcraft 36T Casco Bay, ME
So let me ask...does a battery recharge "properly" when charged at a slower rate than the normal "bulk charge"? For example, we plan to overnight on the weekends, and the boat will sit idle (mast up on the trailer, we hope) the rest of the week. I was thinking that a small solar panel (with charge controller) that could be set up on the boat while on the hard could charge the battery after we put the boat up Sunday afternoon, and keep it topped up until we launched the next Friday evening or Saturday morning. If the charge was slow, would that be "bad" for the battery, or is it just that it will not recharge as fast as it could if we had a bulk charger? (We wouldn't care about the speed of recharge at that point)
If the time between charges to "full" is too slow then the battery can still sulfate. That said deep cycle batteries to like a slower charge, just not too slow. A lower current charge can penetrate deeply into the plates. This is why you see most golf courses charging at about 8-10% of capacity.. On boats we need to fast charge or we deplete capacity so everything is a trade off. A mix of high current in bulk then a finish charge by solar seems to extend battery life compared to just fast charging via alt only but this likely has the most to do with actually getting the batteries full...
 

walt

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Jun 1, 2007
3,511
Macgregor 26S Hobie TI Ridgway Colorado
Regarding the fridge idea I was looking at..

I know my wife would love the electric fridge and one thing I really like about it is that all the space in the fridge is usable unlike an ice chest where a good portion of the area is taken up by ice. However, the fridge requires much higher power than anything else on the boat and while I thought my two golf cart batteries were over kill for my current use, they may be a little under capacity for a fridge given that the fridge alone could deplete the bank in a couple days. With a big solar array, you could do like Sumner does and mostly run the fridge when the sun is shining but on the trip to the Puget sound area (partly going there to visit family), I am guessing it might be common to go for long enough times with no solar to where you need some sort of high current charging system. Larger boats have this built in (alternator on the engine) but on our small trailerable boats, the outboard is not adequate to support the fridge (I would need to run the outboard about 7 hours a day to maintain the fridge) so you either are tied to a marina with power or you need a high current charging system like Sumner has. Or.. you end up putting ice in the fridge every once in a while and as far as I could tell from reading the manual, they don’t have a drain like an ice chest does – not really designed for putting ice in. If I’m going to end up putting ice in it anyhow, might as well stick with the ice chest.

So.. the fridge would require too much modification to the boat for just the one trip I was thinking about. My normal use of the boat would just make the fridge a hassle (marina day sailed, generally no AC power) so I would end up changing back to an ice chest after the trip.

It also looks like Sumner has a good setup for using a fridge but it also shows the overhead required. I think you need both the large panel array and unless you put in a considerably more than two golf cart batteries, you also need some sort of high current generator since two golf cart batteries are really only a couple of days away from being depleted if weather conditions shut down the solar.

Interesting to look at the details.. I think I do need an auto pilot for that trip however.
 
Aug 7, 2011
496
MacGregor 26S Lakeland, FL
If the time between charges to "full" is too slow then the battery can still sulfate. That said deep cycle batteries to like a slower charge, just not too slow. A lower current charge can penetrate deeply into the plates. This is why you see most golf courses charging at about 8-10% of capacity.. On boats we need to fast charge or we deplete capacity so everything is a trade off. A mix of high current in bulk then a finish charge by solar seems to extend battery life compared to just fast charging via alt only but this likely has the most to do with actually getting the batteries full...
So are you suggesting that this would be a less desirable setup, or just that it may ultimately cause my battery to die a little sooner (longevity)?
There's no reason I couldn't pull the battery out once every six months or so and hook it up to a desulfation charger and give it a renewal, if the simplicity of the system means the boat gets a lot more use...would that work as a plan?
 
Aug 7, 2011
496
MacGregor 26S Lakeland, FL
I cant tell you if its good or bad for the batteries but that is exactly what I do. I have a 10 watt panel on the boat through a PWM charge controller. when I get done with a sailing trip, just leave the boat.
Great...glad to know I'm not out in left-field!
 
Feb 6, 1998
11,665
Canadian Sailcraft 36T Casco Bay, ME
So are you suggesting that this would be a less desirable setup, or just that it may ultimately cause my battery to die a little sooner (longevity)?
There's no reason I couldn't pull the battery out once every six months or so and hook it up to a desulfation charger and give it a renewal, if the simplicity of the system means the boat gets a lot more use...would that work as a plan?
It is certainly better than nothing at all. In an ideal world a battery would be 100% recharged after each discharge. On boats we don't often have this luxury so we accept the life we get from our banks. Best practice is to get the batts 100% charged as soon as possible after each discharge, reality is, do the best you can... Try to size the panel to get them back to full in about three days and you're doing okay..
 

walt

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Jun 1, 2007
3,511
Macgregor 26S Hobie TI Ridgway Colorado
I can anwswer one question - do I want to answer your question? Nope:D
 

walt

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Jun 1, 2007
3,511
Macgregor 26S Hobie TI Ridgway Colorado
Since this is a somewhat of a battery thread..

I replaced the battery in my 15 foot dingy yesterday. The battery is located just in front of the mast (low as possible where it helps with ballast) and the cubby opening is very tight. Last winter I put in the access hatch shown in the attached picture and made a terrible job of removing the battery now fairly easy.

The battery is a single group 24 and it lasted for about 3.5 years. I have used this boat a lot, probably 20 to 40 times each season and it’s mostly with the 30 pound thrust trolling motor. I mostly use the trolling motor to get in and out of the dock but also usually like to zip around the lake a little at the peak speed of 3.4 mph. So I’m probably averaging about 20 minutes at about 25 amps each session plus powering the GPS/depth finder and a computer speaker stereo. The battery is always charged with a Guest charge pro 6 after each sailing session (plugged into AC).

When the battery is worn out, I can tell that when I use the trolling motor, the voltage drops a lot more than when the battery is fresh. When I get home, I plug the boat in to charge it and even though I know I’ve run the battery down some, the charger goes to float mode very quickly and limits the charging - so it also doesn’t charge very well. This all looks similar to if you added a resistor in series with the 12 volt lead (battery internal impedance likely is much higher now then when new).

The second picture is the boat this morning.. no sailing today.
 

Attachments

May 4, 2005
4,062
Macgregor 26d Ft Lauderdale, Fl
...snip...
Could you make a 110 V generator work (such as the Honda or Yamaha 1000 or 2000 watt ones work for keeping the fridge cold?
-I'm not sure if I posted this in this thread, but one option is a lawnmower sized 4 stroke engine and a 1 wire alternator. (direct 12v charging)

Sumner built one for the mac, and think he's happy to have it.

you can get some pretty large alternators, but the typical altenator is 60 amps. I think you can go up to 150amps...

http://theepicenter.com/tow082099.html


-I've also seen some backyard hacks of an outboard flywheel connected to an alternator... most look very dangerous, with exposed flywheels and belts... but its been done and has worked for some....
 

walt

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Jun 1, 2007
3,511
Macgregor 26S Hobie TI Ridgway Colorado
Yep.. a high current generator like that is probably necessary if you want an electric fridge and have the possibility of multiple days of cloudy weather and are away from a marina with AC. However, on these smaller trailerable boats (which dont have high charging capability built in like on a larger boat) the big gas generator is also completely not needed if you can "live" with just an ice chest.

I think Sumner has a good description also of how he did his on his web site somewhere.