House banks, whatcha got, whatcha want?

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Sea Word

Senior Member
Joined
Jun 4, 2017
Messages
178
Location
USA
Vessel Name
SARAH TOO
Vessel Make
40’ beer can
I’m designing a power system from the ground up. It will be a little non typical in a few ways. Mainly that I don’t want to ever use shore power OR generator. It will be 100% solar run, hopefully, and I’m trying to get a feel for what people actually need for AH capacity on their boats. Also, I see some people use an 8D for a starting battery. Why the heck would anyone use such a large batt for starting? Seems overkill for dedicated engine batt. Anyway, here’s the equipment list:

Typical systems for a 40’ live aboard regarding lights, fans, iPads, water pumps etc.
Diesel furnace and water heaters, we may even use the boiler for some sort of improvised hot tub
Dorm fridge, and possibly a chest freezer too for long trips.

All the above (except the water heater and furnace) will be powered by a full time inverter on AC. The inverter has a 1w idle current draw.

Roof solar: I’m fitting 1200w panels.

SO, how much AH storage would be a good goal? I’m thinking that I’ll try to use sealed lead acid, running at 24v bank. My initial thinking is that around 400ah@24v would be enough for us and allow rom for bank degradation in coming seasons, but I also don’t want to go below 50% DOD, so that’s really only an effective capacity of 200ah, and if you figure 24% degradation over a few years now we are down to 150ah usable and that feels a little light to me. Should I just bite the bullet and up the capacity from the start or ? We have plenty of room in the engine room, so that’s not a worry.
 
I see you're in the Pacific Northwest. How many days in a row are you prepared to go without the sun recharging your batteries?

Ted
 
Are you proposing the equivalent of 4 8Ds for your battery bank? Is that all house? What do you plan for a start battery? Do you have one or two main engines? Is there already a boat or are you in the theory planning stage?
As to an 8D for starting a perhaps 6L diesel, I can`t tell you the thinking behind it but Onan recommend an N150(?6D) for starting a 3cyl Kubota engined genset. It has to preheat as well as start so maybe that`s why,it`s a lot of battery but I do it because it`s what Onan says to do. What size battery is advised by the mfr of your (?intended) main(s)?
O C Diver raises a good point. From my limited experience of PNW, going without a genset, in "Yes Minister" terms, is "courageous".
 
Would be good to know your expected daily consumption. And if you want to be 100% “ off the grid” you ought to consider adding a wind generator.
 
Well even on cloudy days you still get solar watts, but I dont know how many it’s true. Yes the boat exists but it’s quite spartan, the systems most boats have that I’d be replacing were never installed on this craft. So, that’s good and bad. At least I’m not having to suffer with inferior old crap, but it means I have to create new systems now.
I may find that I need a genie. I may decide that I can’t live without AC, and I have room for one, so that is almost a likelihood . However since we are living on the hook and I’d rather not run gen everyday the goal is to not need it under normal circumstance, and given the efficiency increases in solar in recent years, coupled with the large area of available space it seems like it should be possible.

For batteries I’m looking at either L16 style 6v or another 12v style that I don’t know the form factor name for. A fellow here has them for a very good price. They are 188ah@12v, 130lb each, 15yr rated life and he wants 150$ ea for them. So 4 of those would be 380ah@24v. But I may get 6 of them if we decide that we need more cap than 380ah, that would boost it to 570ah. Again though at 50%DOD that’s only 285ah usable.
The boat has twin baby 4cyl Isuzu’s and I’d likely just keep an automotive started batt for them with a simple maintenance trickle charger.
 
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I think that to get where you want to be, you need more battery than 380(@24v). So six rather than 4, but you can add later. There is a boat on my marina who ditched the genset and went for a massive panel array which seems to work with more batts where the genset was. What ccs and hp are the "baby" Isuzus, what size are the alternators?
A wind generator too is a good idea, if it ain`t sunny it`s probably blowing.
 
I don't think wind generators are much good.
Most cruisers tend to travel downhill, so wind is reduced
Most cruisers tend to anchor behind something, so again, wind is reduced.
Plus, they are bloody noisy.

.
 
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Yeah I don’t want the wind turbine noise. And here in Portland it’s actually not very windy at all. It’s nice that way. I’ll have to do some math and see what I think we could gain on a cloudy day. If we can’t even top up the mid size battery then there isn’t much point in over sizing it without adding panels, which I could do. There’s another large roof area we could fill but rather than do that I’d probably just opt to shut down the electrical loads instead while we are off boat, or resort to getting a gen.
 
I live in Coastal BC, Vancouver Island, so pretty much your weather. My philosophy is a little different considering our not always sunny climate. In southern regions, solar is the go to and everyone in our region copies this advise. But in my opinion, your first go to should be Efoy (preferably the 210), that coupled with a decent alternator and in my case 4 Firefly batteries, I have ample power on the hook away from shore power. This recommendation is based on off season boat cruising.

I have added Efoy first, if for some reason I have a critical shortage of power, then I might consider solar. But I know the Fireflies are like Lithium and take a quick charge and can be taken down to 20 % which many do regularly. My refiter installed a large solar system in another boat, only to get a call from the guy when he was in Desolation Sound during a week of rain wondering why his solar unit wasn't generating enough power.
 
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rsn48 said:
I live in Coastal BC, Vancouver Island, so pretty much your weather. My philosophy is a little different considering our not always sunny climate. In southern regions, solar is the go to and everyone in our region copies this advise. But in my opinion, your first go to should be Efoy (preferably the 210), that coupled with a decent alternator and in my case 4 Firefly batteries, I have ample power on the hook away from shore power. This recommendation is based on off season boat cruising.

I have added Efoy first, if for some reason I have a critical shortage of power, then I might consider solar. But I know the Fireflies are like Lithium and take a quick charge and can be taken down to 20 % which many do regularly. My refiter installed a large solar system in another boat, only to get a call from the guy when he was in Desolation Sound during a week of rain wondering why his solar unit wasn't generating enough power.
Click to expand...
Wow I had no idea that those were a thing. That’s incredible. What a great way to replace a rattle box ICE genset. Are they very expensive?
 
Sea Word, I think solar is great and it is true that solar panels can be quite effective on overcast days. However, you have to take into consideration the length of the day as well. Portland is a bit further south, but our days are short for 1/2 the year. Your solar array will not be providing you will much during Oct-Feb.

When I replaced my battery bank, I ended up with 4 x L16 AGMs. The total rated size of that bank is 780Ah. I was very tempted to upgrade that 6 x L16s to give me 1060Ah but decided not to based on weight, cost, and the fact that my existing charger maxes out at 125amps. These AGMs like to be bulk charged at 20% of capacity (150amps for a 780Ah bank) and so it would be significantly undersized for a 1060Ah bank.

I added 365W of solar to my boat. I would like to have added more but that was as much as I could comfortably fit without some major construction on the flybridge. You are looking at adding over 3x that amount but even so I don’t think that would be enough to meet my power needs in the winter.

Using a fuel cell to supplement the power in the winter months would be possible, but in the long run I think you may find that much more expensive than a diesel genset. If you a sufficiently large house bank with a charger sized appropriately, you could run the genset at full load to put a lot of energy bank into a bank in a relatively short amount of time.

Do an energy audit to see how much power you actually will use. You can find graphs of how much sunlight you will get throughout the year and then calculate how much you will need in panels to get you there.
 
Good advice. It’s hard to really know the total energy used by speculation of course, because there are many variables especially in refrigeration needs. And even heating too in winter. A solar setup must be sized for the worst case scenario, which is in January. I suppose a gennie makes sense regardless of the setup.
 
I run a 48v inverter system. Smaller cables and batteries can be further away from the inverter. Everything on the boat is 120/240 ac except the nav lights, bilge pumps, emergency lights and nav equipment. What made a big difference to me was adding a 48v alternator to one of the mains. It keeps the 48v banks up while running without operating a generator. I may add a wind generator because my winter dock is in a high wind area and Many of the places I anchor have some wind. The noise won't bother me. I don't have solar but thinking about it. Also in the PNW.



 
If you end up installing a generator I’d consider a diesel DC model if battery recharging is its primary function. Lighter, variable speed, quieter and more efficient than a AC model.

John
 
While the Efoy looks interesting, they seem extremely expensive for their capacity (KW rating), the KWs produced per gallon of fuel is poor compared to diesel, and KWs produced per dollar of fuel is incredibly expensive. Saving the environment with one of these isn't for the financially challenged.

Ted
 
Well I stumbled on a sweet deal on these northstar 190ah batteries. They are 3mo old and taken out of some cell phone tower backup situation. They all had 12.8v so I couldn’t say no. I was going to get 6 but ended up not resisting the temptation to get as many as my poor little car could carry, which was 8. In fact, that’s a lot more than my car should carry, 1100lbs! So now the question is, do I use all 8 on the boat, or do I just use 6?
 

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Nice find. If it was me, I’d probably see if I could find room for all of them. 1,400-1,500Ah is a lot of juice. Just make sure that you find out exactly how those batteries should be charged and ensure that your charge controller can be configured for that.
 
Yes that’s a good point. And also that they will charge well in a 24v system.
They are AGM batteries.
 
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That is a lot of capacity. I recently added a couple so we are now at 1020. I haven’t spent Time on the hook yet since the upgrade, but I am thinking that will give us about 2 days in between Gen runs to charge. The amount you have seems like a lot for a Solar System to charge based on the system you are describing. Anyway, keep us posted. I am interested to hear how things work out.
 
Well after wrestling 6 of them (130lb) outnof the car, on to the dolly, down the beach, into the dinghy, and on board, I think 6 is the perfect amount lol! I dunno, it was a case of 6vs8 and if 8 lasts longer or does more for us then that’s worth the extra 200$ but if not, then I’ll save them for my van instead. Hard call, especially without ever having used the boat yet. We haven’t even slept on board once in fact.
 
Do the dirty work first. Sit down and figure the electrical loads.

W/O that everything else is just guessing..

Spend some time on the boat and see what you use and for how long. Go from there..
 
Thanks to the thoughtful previous owner, SCOUT has a 1600Ah@12V house bank fed by 1400W of solar, split into four banks:

16921-albums844-picture5219.jpg


16921-albums844-picture5220.jpg


Each bank is controlled by its own Victron MPPT controller. This protects a bit from shading by the dinghy, etc.

We have a huge 23cuft full-size two door and freezer drawer home fridge that draws nearly all the power we use on the hook (everything else pales in comparison).

Our typical daily consumption at anchor is about 200-250Ah (2400-3000Wh) with the fridge running and using the microwave, coffee maker and electric grill periodically, phone/tablet chargers, TV, lights, etc.

We average about 4500-5000 Wh generated from the ten solar panels on a full-sun day. By 2:00pm each day, the batteries are close to 100% SOC.

With this setup, we are fully self-sustaining --- without AC or water heater, of course. If cloudy, we can go about 3-4 days on the house bank alone. If sunny at least 1 out of every 2-3 days, we will never run out of power.

What do I want?

------- one of the newer mini 4kBTU air conditioners for the v-berth. (35A@12V when compressor running). Should be able to run an 8hr night (4-6hrs compressor time) on our current battery bank along with our other loads?:angel::angel::socool::socool:
 
Sea Word said:
Yeah I don’t want the wind turbine noise. And here in Portland it’s actually not very windy at all. It’s nice that way. I’ll have to do some math and see what I think we could gain on a cloudy day. If we can’t even top up the mid size battery then there isn’t much point in over sizing it without adding panels, which I could do. There’s another large roof area we could fill but rather than do that I’d probably just opt to shut down the electrical loads instead while we are off boat, or resort to getting a gen.
Click to expand...

If you haven't already been asked for or done so [I've only read to post 8 so far]...

Can you please supply photos of boat as well as areas for solar panels and areas for batt bank?
 
I have a 900 AH wet cell bank. My largest hourly consumer is refrigeration. After swapping out the Norcold for a high efficiency appartment refrigerator, consumption has probably been cut by 40%. The microwave and other cooking appliances are probably a distant 2nd. While I have enough battery storage for my cruising style (even with microwave use don't go below 80% of battery capacity), I would like to have 1,350 AH of wet cell capacity. The need isn't there to justify building a new battery box, etc., but I still want it. :)

Ted
 
Sea Word said:
I’m designing a power system from the ground up. It will be a little non typical in a few ways. Mainly that I don’t want to ever use shore power OR generator. It will be 100% solar run, hopefully, and I’m trying to get a feel for what people actually need for AH capacity on their boats. Also, I see some people use an 8D for a starting battery. Why the heck would anyone use such a large batt for starting? Seems overkill for dedicated engine batt. Anyway, here’s the equipment list:

Typical systems for a 40’ live aboard regarding lights, fans, iPads, water pumps etc.
Diesel furnace and water heaters, we may even use the boiler for some sort of improvised hot tub
Dorm fridge, and possibly a chest freezer too for long trips.

All the above (except the water heater and furnace) will be powered by a full time inverter on AC. The inverter has a 1w idle current draw.

Roof solar: I’m fitting 1200w panels.

SO, how much AH storage would be a good goal? I’m thinking that I’ll try to use sealed lead acid, running at 24v bank. My initial thinking is that around 400ah@24v would be enough for us and allow rom for bank degradation in coming seasons, but I also don’t want to go below 50% DOD, so that’s really only an effective capacity of 200ah, and if you figure 24% degradation over a few years now we are down to 150ah usable and that feels a little light to me. Should I just bite the bullet and up the capacity from the start or ? We have plenty of room in the engine room, so that’s not a worry.
Click to expand...

Sea Word - Check these guys out: revision marine - marine electric propulsionWelcome to ReVision Marine | revision marine They are literally leading the charge on what you're trying to achieve.

And here's a recent article about them: https://www.passagemaker.com/technical/pacific-powerhouse
 
Art said:
If you haven't already been asked for or done so [I've only read to post 8 so far]...

Can you please supply photos of boat as well as areas for solar panels and areas for batt bank?
Click to expand...


I’ll post some pics after I get them thanks. The roof area is about 10x10 ft approximately, and I could expand onto salon roof but I’m hesitant to because I’d rather keep that open for kayaks or sun beds etc. the engine room is absolutely spacious and I have room for as much battery as I could want. Twin baby diesels and outdrives have left us a lot of room to utilize for whatever. After the house bank is installed, I’ll probably get to making custom water tanks to maximize our fresh water cap. Since we live on hook fresh water is a big issue.

As far as using the boat and finding out my electrical needs, unfortunately this isn’t very possible because we are A: living on hook, with no dock in sight, and B: don’t have ANY house battery system installed whatsoever. This boat was never truly competed even though it’s 20 yrs old or more.
 
Moonfish said:
Sea Word - Check these guys out: revision marine - marine electric propulsionWelcome to ReVision Marine | revision marine They are literally leading the charge on what you're trying to achieve.



And here's a recent article about them: https://www.passagemaker.com/technical/pacific-powerhouse
Click to expand...



I think you need to start with an energy budget, even if it is an estimate. Next, convert all your requirements to watts. With 12, 24 and 110, you need to be talking units of work, in and out. And would be easier for all the contributors to be on the same sheet of music when we talk battery capacity.
The longer you want to spend at anchor, the larger the battery bank needs to be, regardless of the size of your solar. As to solar sizing, cover every square inch of space you can, and that’s your input capacity. Break them up into zones with separate MPPT controllers. Get professional help designing the system.
You go to bed one evening with batteries at 90%. Next few days are fully overcast. Figure 20% of max output from panels for 4 hours. The rest comes from your batteries. How many hours before you are at 50%? If you have room for all 8 of those batteries there is no reason not to install them. To put it another way, once you max out your solar, the larger the battery bank, the longer you can stay at anchor once you loose solar input.

Yes, solar panels put out on cloudy days, But don’t expect much on fully overcast days, maybe 20% of a sunny day. Sun angle makes a big difference so much less output in January; slant angle and shorter day. I get higher max output in Newport, RI in July than I do in the Bahamas in January.
Whether or not you will need a genset comes down to your options when you run out of stored power. If you can run back to a marina, great. If you can’t then what?

Best wishes
 
IMO - There is no reason to not have at least a small fuel powered gen set stored away aboard any boat. Even if it's just once every year or two it is reguired for some instance.


Charging batts after many overcast days could be one such usage.
 
I agree with your statements except that there comes a point where I say that I want to remain at anchor forever, and never run generator. This means my battery needs to only be sufficient to survive one day on the worst solar gain day we see, which is a Cousy day in January. If we operate at any loss at all, then we will need a genny at some point.
 
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