Actual power budget of cruising monohull?

[MarkJ]

I agree with Suijin. No generator needed. I have used my engine for electricity for less that 10 hours in the last year. That's less than 1 hour per month.

Originally Posted by tomfl

With 420 watts of solar charging a 430 amp hour battery bank I normally am dumping power after 10:00 AM on a sunny day; at which time I charge my computers, camera batteries, other toys, and sometimes use my electric rice cooker or other 120 volt toys.

I think this 1 paragraph sums up many "rules":
Solar panels wattage should roughly equal house battery amp hour capacity.
You should be 100% full by 12 noon or 1pm. (10am is very good)
You get to know your system and know when it should hit 100% or you can 'feel' the problem.
Only charge battery operated stuff when you are 100% and just wasting sun.
Use your high draw stuff last.

[skipmac]

Originally Posted by Cheechako

With a small refrig box and refrigeration, I'm gonna say 100-120 ah per day.

Assume your talking total power budget and not just the fridge. If total power I think that would be in the ballpark. Maybe more if underway with AP and nav electronics running, less at anchor.

[a64pilot]

Originally Posted by MarkJ

You should be 100% full by 12 noon or 1pm. (10am is very good)
You get to know your system and know when it should hit 100% or you can 'feel' the problem.
Only charge battery operated stuff when you are 100% and just wasting sun.
Use your high draw stuff last.

If you are to believe Mainsail, it is not possible with lead acid batteries to be 100% "full" by noon, much less by 10 AM. In fact if he is to be believed, your not going to be 100% "full" by sunset, with an average aged bank, on an average day.

The charge acceptance rate of a lead acid battery bank makes fully charging by noon impossible, it has nothing to do with how much Solar you have, it is a limitation of the battery, and the number of hours of usable sunlight.

I have a tendency to believe his hypothesis, I have reviewed everything I can of his on this subject and cannot find any flaws in it. I have also watched how my bank behaves with unlimited power available from Shore Power and can attest that I cannot get to 3 amps at absorption voltage from good light until Noon. I have a 660 AH Lifeline bank and 100% full is .5% or AH capacity charge at absorption voltage, and I have 185 amps of charger

You can't get to 100% full very often if at all on Solar alone, this means you need to have another source of power, or accept the reduced life of short cycling the bank. Which is another viable option, some I believe just work it into the budget and say every other year we are buying a new bank of golf cart batteries, I'm not driving myself crazy, obsessing over batteries.
Life-Po being a very likely wild card, there you don't need or want to get to 100% charge, in fact you don't want to.

[s/v Moondancer]

While I would happily live on Mark's energy budget and have lived and cruised on much less...I have a wife who has sailed 40,000nm with me and she has other requirements!

Nell's 60th birthday was celebrated 800nm miles off-shore and we and 3 friends had shrimp, filet minion and homemade ice cream! While running the geneator each evening Nell runs the washing machine and our watermaker makes 35 gallons per hour as she does the washing and I drink a G&T with ice made on the boat.

It all comes down to your chosen lifestyle both at sea and at anchor?

As for an energy budget...All the solar you can fit backed up by a genset or Honda 2000.

[Cheechako]

Originally Posted by skipmac

Assume your talking total power budget and not just the fridge. If total power I think that would be in the ballpark. Maybe more if underway with AP and nav electronics running, less at anchor.

Yep... total power. But is about what I experienced in the Caribe mostly at anchor. (best estimate only) Even if your refrig unit only averages 3 amps per hour, that's still 72 in 24 hours, just for the unit.
A lot of AP use while moving would add to that I imagine.... although I often end up motoring some anyway...

[a64pilot]

Originally Posted by s/v Moondancer

It all comes down to your chosen lifestyle both at sea and at anchor?

Yep and I have been married to my wife for 35 years now, and I know she does not like camping, but then neither do I anymore

[robert sailor]

Repairing gensets have got to be in the top 6 issues on many cruising boats. Over the years I have just come to the opinion that they can't be relied upon in the boon docks. Your fine in areas like the Caribbean as there are plenty of people that can make repairs but it just seems when you need them the most they die. If you start out with a brand new one it certainly helps.

[MarkJ]

Originally Posted by a64pilot

If you are to believe Mainsail, it is not possible with lead acid batteries to be 100% "full" by noon, much less by 10 am...

I'm not driving myself crazy, obsessing over batteries.

I respect immensely everything @Mainesail says. However I am living 'out here' and he is not. We talk about problems with a slightly different viewpoint, I from the lay-person side and him from the technical.

My boat has been running under solar for 8 years cruising now. I added wind 3 years ago. Its great at night.

My system works. Its not to say another boat won't prefer another system.

However I do think people who are jotting up their boats should be extremely careful of technology the chandelries refuse to sell: LiPo batteries is one. Why don't they sell them? One chain told me they just are not satisfied with them enough to risk selling them and have customers feel ripped off.

So I do the low technology way I want. I don't want the obsession or stress, I want what I have which is as bullet proof as it gets on a boat.
No, I will not have golf cart batteries! I refuse to go from 17 volts to 6 volts to 12 volts in double the number of blobs as 12v batteries.
By the same token I won't have a 24v system.

Other more tech savvy folks may do what they like, but I have finished my 9th full year cruising. I am still here. I must be doing something right

That's why my advice is as it is. Its MY advice
I don't think its incompatable with MaineSails advice, I just think mine can come from another viewpoint at times.

Btw, if you think LiFPo batteries and any good, have a look at the thread where a guy in St Martin needed to get a replacement one shipped in from the USA. What the hell would you do in the middle of the Pacific?
Go with the old technology untill the new stuff has spiders webs on it
Old, tried and true, leads to less stress. and tgats what cruising is meant to be about

[Sputnik]

......of course using what is available in modern kit is also key:
LEDs
Fridge or freezer with thru hull cooling element is about 40% more efficient apparently.
Autopilot will also be a big consumer depending on sea state.
Solar panel that you can walk on fixed to the deck are a great idea. Fitted close to the mast to reduce clutter on the deck is the best place, also flexible ones on the top of the bimini or spray hood.
Buy the best solar panels you can afford, again, efficiency can vary.
Wind generators are usually a PITA for noise.
Neil

[robert sailor]

Originally Posted by Sputnik

......of course using what is available in modern kit is also key:
LEDs
Fridge or freezer with thru hull cooling element is about 40% more efficient apparently.
Autopilot will also be a big consumer depending on sea state.
Solar panel that you can walk on fixed to the deck are a great idea. Fitted close to the mast to reduce clutter on the deck is the best place, also flexible ones on the top of the bimini or spray hood.
Buy the best solar panels you can afford, again, efficiency can vary.
Wind generators are usually a PITA for noise.
Neil

Real world difference between a keel cooler type of fridge and water cooled isn't even 10% in efficiency much less 40%. If you install solar panels directly to the deck your asking for trouble, to my way of thinking it's the second best idea to have ever been put out there. First of all your making holes in your deck, secondly if you install those semi flexible panels to your deck you better plan on leaving there forever because there is so much heat put off by those panels that they will cook the gelcoat on your deck until it's brown and full of small cracks. Stick to your bimini and spray hood location, much smarter.

[a64pilot]

I'm not abdicating Life-Po, I'm not running them myself.
However, way I see it, assuming all or most of the hype is true, they may be a game changer. The way I see it now, they are a Science experiment, requiring a Scientist to run it. I want a turn key solution, that I don't believe exists yet.
Like the Firefly, it may also be a game changer.
Hopefully by the time my current bank dies, I will have a better idea on which way to go.
I see nothing wrong with golf cart batteries, if they would fit in my boat I would have gone that route, but without major surgery, they won't fit (too tall)

[a64pilot]

There is no real difference in efficiency of air or water cooled refrigeration, you would think there would be, but there isn't, yet marketing wise people will believe there is, so therefore it sells

[noelex 77]

It is very hard to determine a realistic average power consumption.

If I can give you an analogy, it is like asking how much money is needed to live. People in a third world country might give an answer of less than a dollar a day, but people in the developed world would scoff at such a number as ludicrous.

In a earlier cruising yacht we had 46w of solar and almost no other means of power generation, but my wife and I cruised happily for months at a time. Our latest yacht has over a 1000w of solar.

Will we use and be able to do more with extra power. Of course . Life is better with lots of power. Is it essential? Obviously not.

It is important to realise that if you use power you must generate power or spend time in marinas. Yuk . Power usage has drawbacks, not just advantages. A large solar array is ugly and generates windage. Generators are not very reliable and you will spend time fixing problems rather than enjoying the beautiful anchorages, etc, etc.

There is no perfect or even correct answer.

My advice would be to try and live with what can be generated by solar power. Solar is very reliable and requires no maintenance. If you are desperate for more, add wind.
If you will only be happy with more power, install a generator.

Simple .

[Paul L]

Originally Posted by a64pilot

If you are to believe Mainsail, it is not possible with lead acid batteries to be 100% "full" by noon, much less by 10 AM. In fact if he is to be believed, your not going to be 100% "full" by sunset, with an average aged bank, on an average day.

The charge acceptance rate of a lead acid battery bank makes fully charging by noon impossible, it has nothing to do with how much Solar you have, it is a limitation of the battery, and the number of hours of usable sunlight.

I have a tendency to believe his hypothesis, I have reviewed everything I can of his on this subject and cannot find any flaws in it. I have also watched how my bank behaves with unlimited power available from Shore Power and can attest that I cannot get to 3 amps at absorption voltage from good light until Noon. I have a 660 AH Lifeline bank and 100% full is .5% or AH capacity charge at absorption voltage, and I have 185 amps of charger

You can't get to 100% full very often if at all on Solar alone, this means you need to have another source of power, or accept the reduced life of short cycling the bank. Which is another viable option, some I believe just work it into the budget and say every other year we are buying a new bank of golf cart batteries, I'm not driving myself crazy, obsessing over batteries.
Life-Po being a very likely wild card, there you don't need or want to get to 100% charge, in fact you don't want to.

I'm with MarkJ on this. I think Mainesails analysis is a bit skewed to the negative side. I have Rolls AGMs and on a sunny day the charge sequence gets down to 3 or 4 amps at 14.7 by late afternoon. This means that from noon or 1 on there's a spare 20amps to use for other things. This doesn't occur everyday, but it occurs enough to keep the batts happy.

[robert sailor]

We have a Morningstar controller for our solar power which is 410 watts. Our service battery bank is approximately 400 amp hours leaving us 200 usable. If we get decent sun the batteries will go into the float stage around 12 noon to 1:00 pm and after that we can make water if we choose to. I try to equalize them every 4-6 weeks. The 4 year old Trojan lead acid batteries are still showing very healthy signs and because they are never deeply discharged I expect to get another 2 or 3 years out of them, with a little luck.