Aircon at Anchor

[s/v Moondancer]

Rodeo,

We always knew it was possible but not think anybody was that crazy.

What is the weight of the batteries and do they effect sailing performance, specificly does the bow dive going to windward in a seaway?

What is the amp hours of the batteries and how much does the solar and wind put in per 24 hrs?

What is the voltage of the batteries after 8 hours of A/C?

Congratulations on making it work.

[RodeoClown]

Guys-

As I indicated... I am new to sailing but am neither ignorant nor arrogant.

I appreciate all the advice I have received to another posting and was merely responding to a question on something, as a newbie, I have worked through...

I am not a technical guy but hire—-and rely on—-people to give me sound advice.

I am neither a “weekend warrior “ nor do I live on my boat and cruise around the world. I am a regular guy with the means to make things right.

I am not interested in debating whether I am FOS or not. I am sure I could probably figure out what the math is on my solar panels, wind generator, and alternator. That is not gonna happen. What I can tell you is: I have made multiple overnight trips on a long weekend in the Indian River and have run the air conditioning to the point that I needed to turn it off in the middle of night because I was too damn cold. I know that when bring it back to the house and connect it to shore power that the batteries, at some point, will become fully charged. Additionally, I have taken the boat on an eight day trip that was both a combination of marina/shore power, anchoring, and mooring and the battery bank performed without problems and me and the two other guys spent more time complaining about the meat locker (e.g. cold) versus the heat, humidity, and mosquitoes.

My ego is not that big that I am going to be offended by somebody asking me questions; however, if you want me to deliver to you the math on whether this really works or not, I am really not interested.

I know this is probably heresy for the sailing community, but I have a Beneteau M 38 1991 equipped as advertised and if you want to private message me I will send you pictures and give you the contact of both my electrician and the Yanmar distributor who installed the smart relays and alternator and they can tell you how to do what I did.

With respect to a few questions regarding the batteries in the V berth. The question is not so much the “stink” of acid-lead batteries, but rather, the risk of hydrogen accumulation in a closed space that poses an ignition and explosion risk. This is something, obviously, that was considered and I have an exhaust fan that is hardwired and is running continuously in that space. Additionally, I even considered installing a hydrogen gas monitor; but, for now, I elected to mitigate this by keeping the V berth space open when not in use. Very specifically, when I get up in the morning, I lift up the mattress and the laminated plywood to dissipate any potential gas. At night, just before going to sleep, I lay everything down. The space is enclosed, while traveling, for maybe 6-8 hours.

I also concede that I am a “coastal“ sailor. So it is certainly possible that the V-berth battery bank is not fully charged after motoring out from the marina in the morning (one hour) and also motoring into the next anchorage/morning/marina at night. If you are one of these exceptional sailing around the world 17 times sailors then the solution that I have devised for my “weekend warrior” self and what I want for me and my boat is probably not for you.

Like I said, I am new to this forum and appreciate the input of other individuals.

I’m not here to get into a pissing contest; on the other hand, I have created a system that works for me and would be more than happy to share information with those who are genuinely interested in a dialogue and not measuring the size of their decks (spelling corrected to protect the innocent and whoever is monitoring this posting).

Like I said, I am more than happy to send, via private message, pictures of all 10 of the golf cart batteries in the V berth, the four (4) house and one (1) starting batteries, the water tank that is currently sitting up in my attic, the inverter, the high output alternator mounted to my Yanmar, the two (2) Air conditioning units with condensation discharge pumps, the smart relays, wind generator, solar panels, and all of the other stuff...

I am not smart, good looking, nor even an average sailor but I do know the value of well thought out and integrated systems and surrounding myself with people much smarter than I am both electrically, mechanically, and as sailors.

IMHO...

David

[Dockhead]

Originally Posted by RodeoClown

Guys-

As I indicated... I am new to sailing but am neither ignorant nor arrogant.

I appreciate all the advice I have received to another posting and was merely responding to a question on something, as a newbie, I have worked through...

I am not a technical guy but hire—-and rely on—-people to give me sound advice.

I am neither a “weekend warrior “ nor do I live on my boat and cruise around the world. I am a regular guy with the means to make things right.

I am not interested in debating whether I am FOS or not. I am sure I could probably figure out what the math is on my solar panels, wind generator, and alternator. That is not gonna happen. What I can tell you is: I have made multiple overnight trips on a long weekend in the Indian River and have run the air conditioning to the point that I needed to turn it off in the middle of night because I was too damn cold. I know that when bring it back to the house and connect it to shore power that the batteries, at some point, will become fully charged. Additionally, I have taken the boat on an eight day trip that was both a combination of marina/shore power, anchoring, and mooring and the battery bank performed without problems and me and the two other guys spent more time complaining about the meat locker (e.g. cold) versus the heat, humidity, and mosquitoes.

My ego is not that big that I am going to be offended by somebody asking me questions; however, if you want me to deliver to you the math on whether this really works or not, I am really not interested.

I know this is probably heresy for the sailing community, but I have a Beneteau M 38 1991 equipped as advertised and if you want to private message me I will send you pictures and give you the contact of both my electrician and the Yanmar distributor who installed the smart relays and alternator and they can tell you how to do what I did.

With respect to a few questions regarding the batteries in the V berth. The question is not so much the “stink” of acid-lead batteries, but rather, the risk of hydrogen accumulation in a closed space that poses an ignition and explosion risk. This is something, obviously, that was considered and I have an exhaust fan that is hardwired and is running continuously in that space. Additionally, I even considered installing a hydrogen gas monitor; but, for now, I elected to mitigate this by keeping the V berth space open when not in use. Very specifically, when I get up in the morning, I lift up the mattress and the laminated plywood to dissipate any potential gas. At night, just before going to sleep, I lay everything down. The space is enclosed, while traveling, for maybe 6-8 hours.

I also concede that I am a “coastal“ sailor. So it is certainly possible that the V-berth battery bank is not fully charged after motoring out from the marina in the morning (one hour) and also motoring into the next anchorage/morning/marina at night. If you are one of these exceptional sailing around the world 17 times sailors then the solution that I have devised for my “weekend warrior” self and what I want for me and my boat is probably not for you.

Like I said, I am new to this forum and appreciate the input of other individuals.

I’m not here to get into a pissing contest; on the other hand, I have created a system that works for me and would be more than happy to share information with those who are genuinely interested in a dialogue and not measuring the size of their decks (spelling corrected to protect the innocent and whoever is monitoring this posting).

Like I said, I am more than happy to send, via private message, pictures of all 10 of the golf cart batteries in the V berth, the four (4) house and one (1) starting batteries, the water tank that is currently sitting up in my attic, the inverter, the high output alternator mounted to my Yanmar, the two (2) Air conditioning units with condensation discharge pumps, the smart relays, wind generator, solar panels, and all of the other stuff...

I am not smart, good looking, nor even an average sailor but I do know the value of well thought out and integrated systems and surrounding myself with people much smarter than I am both electrically, mechanically, and as sailors.

IMHO...

David

Ignore the noise. It's very interesting what you have done, and thanks for posting about your experiences. I wouldn't have done it myself, if for no other reason than I would not want to add all the weight in the bow of a relatively light boat, but everybody has his own priorities. You've done something few have done and your experiences will be valuable for some

[svHyLyte]

Originally Posted by Dockhead

Ignore the noise. It's very interesting what you have done, and thanks for posting about your experiences. I wouldn't have done it myself, if for no other reason than I would not want to add all the weight in the bow of a relatively light boat, but everybody has his own priorities. You've done something few have done and your experiences will be valuable for some

Hear! Hear!

If your installation works for you and you're happy with it, good for you. The "shared" information is/will be useful for some. The rest of the commentary merely static.

[thinwater]

Rodeo clown is NOT crazy. I just don't think it is a good idea, that said...

I have run my 12K Dometic Turbo off the batteries several times for up to 2 hours during the day when I inadvertently unplugged from shore power to do something. That was off 3 group 27 batteries and did not take them below 50%. The unit is very low draw for the size and has a fairly soft start. Also, once the boat is cooled down, particularly at night, we are not talking about a 100% duty cycle; it will run only 1/3 of the time with no sun load and a cool boat.

So I believe he is telling the whole truth. There will be a lot of recharging to do, but remember that 50% duty cycle--it may no be as much as you think.

[Colin A]

Of course it can work just takes a whole lot of battery power. With Lithium I expect we will see it more.
Looks like a 12k BTU unit will pull 1320 watts running (not start up) and he has around 17280 watt hours of power (at 100% discharge) so figuring not 100% run time it will run it quite a while. I'm guessing he has about 600 lbs of batteries. I saw a NMC lithium pack marketed to commercial marine applications the other day that packed 18KWH into 313 lbs.
Another tact I have seen a few times now is to install a state room only 5-6k btu unit and run off batteries just at night. Saw a small trawler with a setup like that for the state room this summer.

[skipmac]

Hi RodeoClown,

Clearly several of the replies the poster did not read your original where you clearly stated you had already done the installation and were using the air con on the batteries.

Just to analyze the setup I thought I would do some math.

10 X 6V golf cart batteries I assume GC2 or similar so you have about 650 lbs of batteries at a cost of about $1000. The 10 batteries should give you about 1125 amp hours total capacity which if used conservatively would give you about 600 amp hours usable.

12 kBTU air con should average 8-10 amps so guestimating 800-1000 amp hours over an 8 hour run. Even starting will 100% charged bank that's putting a pretty big hit on the system. Didn't notice if you mentioned how much solar and wind but based on the size of your boat I would guess max of 30-40 amp from both combined. So maybe 200-250 amp hours max back into the batteries from wind and solar. That leaves around 600-800 amp hours you need to put in from the engine or shore power.

Unless I'm missing something I don't think you can run your air con more that a day without plugging in or running the engine non stop. I also don't expect you will get really long life from the batteries.

Basically if this serves your needs then you have made it work but I don't think it would be practical for most boaters.

[smac999]

Originally Posted by skipmac

Basically if this serves your needs then you have made it work but I don't think it would be practical for most boaters.

most boaters use their boats a few times a year for a weekend. probably 98% of the 10'000s of boats in my city... so it would work great for most boaters

[StuM]

Originally Posted by skipmac

12 kBTU air con should average 8-10 amps so guestimating 800-1000 amp hours over an 8 hour run.

That's assuming a 100% overnight duty cycle.
It depends on how low you turn the thermostat and where you are anchored.

That could be the case in the tropics if you want to freeze your n*ts off in the early hours of the morning, but 30-50% would be more realistic in many cases so, 300-400Ah?

[OzePete]

Here is something to think about if it's only a small cool sleeping area you require: Store energy as ice! Thermal energy, then use this energy at night to cool your cabin.
Here is how its done:
Water as it phase changes (freezes) 'stores' 80 watts per litre, add another 10 watts for specific storage and each litre can provide 90 watts of cooling. So lets say a water tank of 80 litres is well insulated and say two refrigeration evaporator coils are located within and each is coupled to a 3.5cc codensing unit. A total of 6300 watts (about 20000BTU) can be stored. (90% ice)

A third coil is installed as a loop within the tank through which a brine or glycol mix (with a very low freeze point), can be cycled via a switched pump, to a switched fan - coil unit located in the area to be cooled, then back to the coil to re-cycle again.

These refrigeration units are then programmed to run when-ever the battery power supply exceeds xx volts or when-ever there is an abundance of electrical energy available.

So what happens?
When the battery bank sees a voltage greater than xx, the two refrigeration units (in sequence) start up and commence to refrigerate (phase change) the stored water.
The refrigeration needed to phase change (freeze) 90% of 80 litres is >6300 watts. Each 3.5cc compressor unit running a minus 5C evaporator will remove approx 350+ watts or 700+ watts per hour combined.

Note: Storing phase change 'eutectic thermal energy' requires less than half the weight that batteries would be, to provide the same amount of refrigeration and never needs replacing and is not dangerous.

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems

[belizesailor]

Originally Posted by svHyLyte

Hear! Hear!

If your installation works for you and you're happy with it, good for you. The "shared" information is/will be useful for some. The rest of the commentary merely static.

+1. Its all about what works for you and your situation. In your case, multi-day trips with some mix of marinas and shore power and it all works out. I assume you have a big ass shore powered charger too?

Me, Im probably gonna pull my long unused AC units out next season and maybe put another water tank in the space. [emoji6]

[RodeoClown]

Thanks skipmac for the math.

I run the A/C only at night with the thermostat usually at 79 degrees. Takes enough of the ambient humidity out of the cabin and cools sufficiently to make sleeping quite comfortable. As a coastal sailor, recharging batteries through motoring, wind, solar, and marina/shore power hasn't been an issue.

[skipmac]

Originally Posted by StuM

That's assuming a 100% overnight duty cycle.
It depends on how low you turn the thermostat and where you are anchored.

That could be the case in the tropics if you want to freeze your n*ts off in the early hours of the morning, but 30-50% would be more realistic in many cases so, 300-400Ah?

When I had my boat on the hard doing a refit I put a 12,000 BTU home air con in a hatch to keep cool(er) during FL summers. I kept the thermostat at the min temp, max cool setting. The unit didn't run continuously but as I recall 80-90% duty cycle and that kept the main cabin and forepeak (but not the aft cabin which was just less hot) tolerably kind of coolish; very far from freezing any body parts. This was daytime so the hottest time but also mostly shaded under a couple of large oak trees. Making a wild guess I would speculate that it would keep the interior cooler at night and run at a slightly lower duty cycle.

So I based my guestimates on that personal experience which if not worst case was at least a very bad case scenario. So perhaps my numbers were on the high side and a bit lower might be more accurate. Would be very interested to get some hard numbers from the OP.

[skipmac]

Originally Posted by smac999

most boaters use their boats a few times a year for a weekend. probably 98% of the 10'000s of boats in my city... so it would work great for most boaters

Quite true in my area as well. However, I doubt that most boaters IF they even had the space (the OP had to remove a water tank), would want to spend $1000 and add 650 lbs of batteries to their boat.

[skipmac]

Originally Posted by RodeoClown

Thanks skipmac for the math.

I run the A/C only at night with the thermostat usually at 79 degrees. Takes enough of the ambient humidity out of the cabin and cools sufficiently to make sleeping quite comfortable. As a coastal sailor, recharging batteries through motoring, wind, solar, and marina/shore power hasn't been an issue.

Hi RC.

That is similar to my experience with a 12k window unit on the hard; reduced the humidity dramatically, the temp to tolerable and that was during the day, FL midsummer with temps 90F or more (that's 32C or more for the metric crowd ). I think at night it would have been much more efficient and able to cool down a lot more on a higher setting.

So have you ever measured the total amp hours used overnight?