Understanding battery consumption on mooring/anchor

[nmcafee]

So, am trying to understand what life on the mooring, or anchor will look like on our future boat. Am targeting either a ~55 foot Hatteras or a Sea Ray 550 Sedan Bridge. I love the sedan bridge helm but prefer a standup engine room you can find on the Hatteras.

Question is......If I have a 17kW generator and a battery bank. Want refrig and lights and power for computer to be always available. Want AC to be available at night. The generator charges the batteries, how much life do I have on the batteries? Will the generator be running all night if I am running the AC?

I am budgeting 1g of fuel per hour of generator, I just don't have a clue how many hours it will need to run per day. 1g of fuel x 24 hours gets to be real money pretty quick.

Have tried to google but just must not be using the right terms.

Nathan

[Woodland Hills]

If you want a/c at night you will need to run a generator.

We run our 63’ Hatteras’s 110v loads at night on our inverter bank, this includes the Bosch refrigerator, the chest freezer, the TV’s, the lights(led), fans, etc. the head pumps and other lights are 32v as are the bilge pumps and freshwater pump.

We are able to go overnight on battery without getting below the mid-70% range on the inverter and the mid 90% on the 32v house bank. Remember that if you often discharge your lead acid batteries below 50% you will do permanent damage to them.

To recharge we run a generator for about 3 hours in the morning and a couple of hours in the evening when we cook. We run it longer when we make water and do laundry.

Don’t forget that you will have to do a generator oil change every 100 to 200 hours depending on make and model. If you run it 24hrs a day that’s every 4 to 8 days.

[Manateeman]

Hi. It’s very difficult to answer your question without knowing the electrical consumption onboard. Each item uses x amps per hour you run. For example, how many air conditioners, what kind of insulation does the boat have, where are you cruising. Refrigerator, water maker, at anchor or dock bunny.
Please provide more info. For example. 2 manatees = I case lettuce + two cases beer / day = 150 amp hours at 24 volts.
Happy trails to you.
Mark and his well cared for manatees

[Sailmonkey]

Budget 1.3-1.5 gph, plus maintenance.

The generator will run all night for your AC. Especially if your cooling the whole boat.

The battery bank required to run a boat like that for any real amount of time will make the 1gph figures seem like a rounding error

[a64pilot]

If you want to run AC and everything off of batteries and then charge the batteries with the generator, it’s going to take a really huge battery bank, and a few really large chargers.

Now it will take 6 hours to fully charge a battery, it will take 6 hours to charge one battery or 100 batteries, of course if you have 100 batteries, it’s going to take 100 times as much charge current as one, but it still will take 6 hours.

This is lead acid batteries, lithium is a different animal.

So your going to run your generator 6 hours a day or you will be short cycling the batteries.

Most likely you will get 5 years out of a battery bank if it’s sized correctly and taken care of.


Now I’m going to go out on a limb and guess that you don’t have $10,000 or so to set up an electrical system, so your going to have to do what everyone else that lives on a big powerboat on the hook does, and that’s learn to live without AC and many other electrical devices and run a Honda suitcase generator during the day and run off of the battery bank at night.

It’s all driven by what is sustainable expense wise, to replace that generator is what maybe $15,000 or more?

[rslifkin]

If you can live without A/C overnight, keeping power consumption down enough that a reasonable quantity of batteries and solar will keep things powered isn't hard.

In my case, I plan for a short generator run in the morning for breakfast and a slightly longer one in the evening to make dinner and hot water for showers. As long as I don't spend more than 2 - 3 nights in the same place, I don't have to plan generator runtime just for battery charging.

Once I add solar and an inverter, I'll be able to drop the morning generator run most days and just run the coffee maker on battery/inverter. The evening generator run will stay to power the water heater, stove, and other high demand devices, so my average daily generator runtime while away from shore power will drop from around 1.5 hours to something like 45 minutes to an hour depending on what's for dinner that day. And an appropriate amount of solar will mean that I could stay in the same place for a week and I'd only need to run the generator for battery charging if we got a bunch of cloudy weather.

Realistically, there's no way to answer what it'll take to power the boats you're looking at without knowing what stuff you want/need to keep running all the time vs just using occasionally, etc.

[Woodland Hills]

Originally Posted by a64pilot

If you want to run AC and everything off of batteries and then charge the batteries with the generator, it’s going to take a really huge battery bank, and a few really large chargers.

Now it will take 6 hours to fully charge a battery, it will take 6 hours to charge one battery or 100 batteries, of course if you have 100 batteries, it’s going to take 100 times as much charge current as one, but it still will take 6 hours.

This is lead acid batteries, lithium is a different animal.

So your going to run your generator 6 hours a day or you will be short cycling the batteries.

Most likely you will get 5 years out of a battery bank if it’s sized correctly and taken care of.


Now I’m going to go out on a limb and guess that you don’t have $10,000 or so to set up an electrical system, so your going to have to do what everyone else that lives on a big powerboat on the hook does, and that’s learn to live without AC and many other electrical devices and run a Honda suitcase generator during the day and run off of the battery bank at night.

It’s all driven by what is sustainable expense wise, to replace that generator is what maybe $15,000 or more?

I’ve never seen a big powerboat running a suitcase generator. Express cruisers in the 30’ to 40’ range and sailboats, but never a powerboat over 50’. Not to say it’s never happened, just that it’s been very rare in my experience. How would one go about connecting a Honda 1000 to a 50’+ powerboat? Through the 30a or 50a shore power cord, or with an extension cord to the device?

You say it takes 6 hours to charge a battery. Is that to charge to 100% or until the end of float charge? We normally charge until the Victron monitor shows 100% twice a day and until it shows under 1a draw once or twice a week, the first takes about 3 hrs and the latter around 6hrs. Of course the times vary according to the depth of discharge: the other day the charger breaker popped and we got down to 44% before I noticed and that took a lot longer to get up to 100%.

[tarian]

Remember agm batteries charge faster than liquid lead , this is another thought process so 6 hours charge for liquid is not the same as 6 hour charge on agms

[TBear60]

If you're really serious about this, you may want to look into solar panels. This way you can top off your batteries without the noise and fumes from a genset. Pacific Yacht Systems from BC, Canada, has a great website and tutorials about using Solar Panels. They claim to be able to run AC, watermaker, pumps, Frig, etc for as long as two weeks without turning on a generator. Of course this is in the Great Northwest where summer daylight goes to 10pm and there's no cloud cover all summer. Still, something to look at to augment your generator! Good luck.

[rslifkin]

Originally Posted by tarian

Remember agm batteries charge faster than liquid lead , this is another thought process so 6 hours charge for liquid is not the same as 6 hour charge on agms

AGMs can be bulk charged faster when they're fairly low on charge. But as they approach full, their charge acceptance drops off much like flooded lead acid. So they may be a little faster to get from 50% to full, but it's not a lot faster.

[tarian]

Originally Posted by rslifkin

AGMs can be bulk charged faster when they're fairly low on charge. But as they approach full, their charge acceptance drops off much like flooded lead acid. So they may be a little faster to get from 50% to full, but it's not a lot faster.

But faster as in my original post , how much faster I will leave to the boffins that like to calculate such numbers

[waterman46]

As mentioned by many, take AC out of the picture when not running generator or at the dock. The power demands on an inverter and batteries would be horrendous. We find that a few small fans are all we need to be comfortable in the tropics.

For the rest of it, you won't know your actual consumption needs until you get the boat and stay a few days on it. Be sure to have an Amp-Hour meter on your house battery bank so you can get actual numbers instead of guessing.
Charge batteries in the morning, then run everything you would normally run during a 24 hour cycle, including refrig and freezer but NOT AC, from the batteries for 24 hours. Read AH meter. Repeat several days, reading Amp-Hours each morning before starting the charger.

Only after that will you know your power budget. You'll know if your battery bank and chargers are up to the task. You'll know how long it takes to re-charge batteries so that's your generator time - use AH meter to know when all those AH have been replaced back into the batteries. You don't have to go all the way to float mode every day - a cycle of 85% AH down to 35% remaining AH can be used most days, but, very important once a week you should fully charge batteries to float mode - this will take more generator time.

[cal40john]

Originally Posted by tarian

Remember agm batteries charge faster than liquid lead , this is another thought process so 6 hours charge for liquid is not the same as 6 hour charge on agms

The charge time is only slightly faster as the time spent in bulk charge is a minor part of the total charge time, and then only if you have the capability of charging at a greater than .25C charge rate.

https://marinehowto.com/how-fast-can...ry-be-charged/

[waterman46]

Originally Posted by TBear60

If you're really serious about this, you may want to look into solar panels. This way you can top off your batteries without the noise and fumes from a genset. Pacific Yacht Systems from BC, Canada, has a great website and tutorials about using Solar Panels. They claim to be able to run AC, watermaker, pumps, Frig, etc for as long as two weeks without turning on a generator. Of course this is in the Great Northwest where summer daylight goes to 10pm and there's no cloud cover all summer. Still, something to look at to augment your generator! Good luck.

AC in the Canadian PNW, what a joke! The reverse cycle for cabin heating would be the only use for that. Up there you can cool your refrigerator with ambient sea water temperature.

[Manateeman]

Woodlawn Hills. Am I correct you have two 21 kw gen sets and you run one of them say...6 hours per day ? Which translates to how much diesel per month just kinda very warm not brutal heat ? Two people on board?
Running a total of 60,000 btu air? No solar correct?
I’m very interested in the numbers for a friend.
Sincere thanks.
Mark