Electrical resiliency for Atlantic crossing

[StuM]

Originally Posted by admiral 31

btw I have nearly 600 amp of battery power & 250 watts of solar, it is needed to run everything, on my sailboat!

Is that CCA?


I suspect you have 600 Amp hours of battery energy.

[conachair]

Originally Posted by Mediator

and (most likely) a Monitor windvane before we depart, which will significantly improve our electrical resiliency.

Least you can still keep the boat moving when the batteries do die.

[CassidyNZ]

Originally Posted by conachair

Least you can still keep the boat moving when the batteries do die.

I never make allowances for when the batteries die. I prefer to do what I can to make sure they don’t

[conachair]

Originally Posted by CassidyNZ

I never make allowances for when the batteries die. I prefer to do what I can to make sure they don’t

Going long distance cruising they will die

When they do it happens quickly.

And if you're unlucky it might be a very long way to find some decent new ones.

[john61ct]

Yes personally I would only want comfort to suffer when the electricity goes out, not allow it to threaten our survival.

Even if it means learning how to use a sextant and stocking hardtack and beef jerky.

[Adelie]

Originally Posted by Mediator

I'm preparing my boat for an Atlantic crossing (northern route) next summer. Lately I've been thinking about our electrical resiliency and I'm curious to hear from others who have made ocean crossings.

We have about 1kw of battery capacity supported by 350w of solar panels and our engine with a single alternator. Navigational equipment, electric autopilot, fridge, and freezer are our largest electrical loads. With normal sunlight, we will deplete our battery bank in about 5 days if we don't run the engine on a passage.

I consider our engine (1988 Perkins 4-108) to be fairly unreliable. If it fails halfway through the trip, or if the charging equipment related to the engine fails, then we will have to choose which electrical systems to sacrifice to maintain power for the remainder of the voyage. We would most likely turn off the fridge and freezer, some of our nav equipment, and hand steer during the day. That should reduce our electrical draw enough to run our critical systems with solar alone.

How long could you maintain electrical power without your engine? Is this an acceptable level of risk? We will install a second alternator and (most likely) a Monitor windvane before we depart, which will significantly improve our electrical resiliency.

Thanks as always to this great community

Your system sound fine.

In the afternoon when the batteries are approaching full and not all the solar is being used you should set the fridge and freezer colder. At sunset return settings to normal. There will be no draw thru the early dark until internal temps rise back to the normal setting. You will be using power that would normally go to waste and eliminate that draw for part of the day.

Are the fridge and freezer separate or part of the same system? If separate you could turn off one (I would vote for fridge) and just run the freezer if engine power is lost.

Learn to use the wind vane, no electric draw and more durable than an autopilot. Reserve the autopilot for low wind or downwind sailing.

What do you mean by 1kW capacity? 1kW is a rate of energy delivery. Here people normally think of battery capacity in terms of amp-hr at 12v or in Watt-hours. How many amp-hr of battery capacity do you have and what voltage.

[steve77]

Originally Posted by Mediator

Sorry, I meant to say 1000amp/hr. To be exact, it's 985amp/hr without including the starter batteries. My mistake.

Our engine has a mount for a second alternator that was clearly utilized at some point, which is why I'm tempted by the idea. It seems like an easy modification.

Sounds like it's time for me to create a real energy budget. I've been putting it off for some time now. I have a good idea of general electrical load (both at anchor and underway, and yes it is significantly higher while on passage) but I've never actually tested or calculated the amp draw of each piece of equipment.

More solar might not be a bad option. We certainly have the space for it.

Sounds to me like you're on the right track. You have a large battery bank and that gives you flexibility.

I have never run two alternators on an engine, so I can't speak for that. If you already have the mount and pulleys for a second alternator then perhaps mount a Balmar or equal with a regulator there and take the belt off of your existing alternator. If you lose the Balmar, then your existing alternator is already mounted as a spare. But I highly recommend you upgrade your alternator with a good regulator.

If you have space for more solar then that is an excellent place to start. When you get your energy budget prepared it will help you size your panels to address your energy deficit. And don't forget a good battery monitor as part of your whole battery charging and maintenance system.

Don't disregard what I said earlier about engine reliability. There are lots of very good reasons to visit Europe and the Med but the sailing conditions are not one of them. You will most likely motor more than you think. Get your engine in top condition with a properly regulated alternator and you will have that as a good fallback charging system to your solar panels.

Crossing to Europe brings a lot of challenges, and there were two major surprises for me - 1) The amount of motoring that we do, and 2) the amount of time spent in marinas instead of at anchor. Be sure and include both of those in your planning for crossing to Europe.

Cheers!

Steve

[belizesailor]

Originally Posted by john61ct

Yes, watts or kW is not storage capacity, but instantaneous flow rate.

Otherwise, simple math, A * V = W, or Ah * V = Wh

1000Ah if a 12V bank, call it 12.5V average,

so 12,500Wh or 12.5kWh

Yes Ah is a better unit, but only when the voltage is obvious and consistent.

Related note for OP. Your notation 1000amp/hr, I assume is meant to convey "amp hours" not "amps per hour" as the "/" would imply. The more common notation for "amp hours" is simply "Ah" as John uses above.

[john61ct]

Yes, and consumption over time is Wh or Ah per time period.

Amps per hour or watts per hour is IMO just confusing to the point of meaningless.

So "while the compressor is running the unit uses 185W / 15A, and average usage in 70° weather is 800Wh / 65Ah per 24 hours "

[StuM]

Originally Posted by belizesailor

Related note for OP. Your notation 1000amp/hr, I assume is meant to convey "amp hours" not "amps per hour" as the "/" would imply. The more common notation for "amp hours" is simply "Ah" as John uses above.

<Pedant Mode On>
In full, it's "10 ampere hours", it's symbol form is "10 Ah".

"amp hrs" is commonly used as an abbreviation, but as BS points points out amp/hr and other such forms with a "/" or "per" is totally incorrect.



Note the capitalization,spacing and lack of plural in the symbol form.


https://www.nist.gov/pml/weights-and...g-metric-units

The names of all units start with a lower case letter except, of course, at the beginning of the sentence. There is one exception: in "degree Celsius" (symbol °C) the unit "degree" is lower case but the modifier "Celsius" is capitalized.


Symbols: Unit symbols are written in lower case letters except for liter and those units derived from the name of a person (m for meter, but W for watt, Pa for pascal, etc.).

A space is used between the number and the symbol to which it refers.

Symbols for units are never pluralized

[Pete7]

Originally Posted by StuM

<Pedant Mode On>

Symbols: Unit symbols are written in lower case letters except for liter and those units derived from the name of a person (m for meter, but W for watt, Pa for pascal, etc.).[/I]

<Pedant Mode On>

I thought litre came from the French language, it is an SI measurement of volume. However, we do allow 'Mericans some leeway with their odd spellings.

Pete

[GordMay]

You may also be interested in this thread ➥ http://www.cruisersforum.com/forums/...ay-220905.html

[StuM]

Originally Posted by Pete7

<Pedant Mode On>

I thought litre came from the French language, it is an SI measurement of volume. However, we do allow 'Mericans some leeway with their odd spellings.

Pete

From the same NIST page:

NIST guides use American spelling. All units and prefixes should be spelled as shown in this guide. Examples: meter, liter, and deka, NOT metre, litre, and deca.

For the rest of the world, it's is indeed litre.

And we should all abbreviate with a capital "L".


But it's not a SI Unit. Its a "non-SI unit accepted for use with SI", the same as "hour"

[Dockhead]

Originally Posted by steve77

Sounds to me like you're on the right track. You have a large battery bank and that gives you flexibility.

I have never run two alternators on an engine, so I can't speak for that. If you already have the mount and pulleys for a second alternator then perhaps mount a Balmar or equal with a regulator there and take the belt off of your existing alternator. If you lose the Balmar, then your existing alternator is already mounted as a spare. But I highly recommend you upgrade your alternator with a good regulator.

If you have space for more solar then that is an excellent place to start. When you get your energy budget prepared it will help you size your panels to address your energy deficit. And don't forget a good battery monitor as part of your whole battery charging and maintenance system.

Don't disregard what I said earlier about engine reliability. There are lots of very good reasons to visit Europe and the Med but the sailing conditions are not one of them. You will most likely motor more than you think. Get your engine in top condition with a properly regulated alternator and you will have that as a good fallback charging system to your solar panels.

Crossing to Europe brings a lot of challenges, and there were two major surprises for me - 1) The amount of motoring that we do, and 2) the amount of time spent in marinas instead of at anchor. Be sure and include both of those in your planning for crossing to Europe.

Cheers!

Steve

The original topic is a very interesting one, and this is a very good post.


We faced something similar last year when we sailed to Greenland, being far from civilization and very dependent on different systems, including electrical power which on my boat is mission critical.


We have more redundancy than you with a larger boat -- two alternators on the main engine, heavy duty diesel generator -- but still I was nervous about it and considered adding a suitcase generator as an emergency backup.


If I were the OP, I would definitely add the second alternator and separate the engine start system including its battery completely from the house electrical system. This configuration is very robust and simple, with fewer points of failure, and the second alternator can be a proper heavy duty one designed to produce bulk power. A large battery bank like that needs a large alternator to charge it. If one alternator fails, you can interconnect the systems one way or another and limp home.



Obviously adding solar brings great benefits as well, but you have to be careful about windage, and exposure to breaking seas. I don't have solar on my own boat at all because of these concerns.


I agree with Steve about main engine reliability. I think that's also mission critical; I would not leave home without a main engine which I considered more or less bulletproof.


A small suitcase generator like a Honda 100eu would be a very good thing to have as backup.


Don't forget spare parts. I carried an entire spare alternator with me last summer and I recommend this. And lots of belts, regulator, and extensive electrical kit. Spare battery charger too.

[belizesailor]

Esp w 1 engine, a small backup gen is a good idea. I recently crossed the Atlantic on a catamaran...we had 2 engines/alternators, ~500W of solar, wind gen, and a small Honda (1000W, IIRC)...so the odds of us not having a charge source was slim.

We had excellent solar & sailing conditions all the way....no more than 3 days of motor sailing.