House battery recommendations

dlochner · Dec 5, 2022

Start with calculating the amount of energy that you will need to power your toys for as long as you will go without charging. Now double the amount of power you will use to stay above 50% of the capacity.

In order to charge the battery you will need to put back between 115% and 125% of the energy that you take out of the battery due to charging inefficiency.

Once you have those 2 numbers, we can start seriously talking about what kind and how many batteries you will need. You will have to find a place to put them and how you plan to charge them.

rgranger · Dec 5, 2022

@dlochner summed it up nicely.

I suspect the real energy hog will be the use of the inverter to power your dvd player. Inverters are inefficient as are dvd players. You might have better luck (and cost less) with an unlimited data plan and just watch netflix on your phone.

jssailem · Dec 5, 2022

We talk about an "Electrical Budget". Not all owners know what we mean. Here is an example from SailBoat Cruising.

https://www.sailboat-cruising.com/images/current.jpg

Boat Electrics; How to Calculate Your Daily Amp Requirement

This simple, if rather tedious, exercise in evaluating your boat electrics is necessary for battery bank sizing but the spreadsheet on this site will make the whole process a great deal easier.

www.sailboat-cruising.com

Scott T-Bird · Dec 5, 2022

Forget the power budget, what's your cost budget? (well, don't really forget your power budget) Usually space and cost are the primary limitations on a small cruiser like yours. Budget unlimited? Get as much 12v LiFePO4 ah as you have space for. I'd guess a pair of 12v 100 ah house batts will give you 150 ah true capacity before needing to charge for about $1,700 - $2,000? If you spend enough time charging on the dock, you probably won't need nearly so much capacity and can manage with the cheapest FLA deep cycle batts you can find, say a pair of Grp 27 90 ah batts for less than $200 at the other end of the cost spectrum. Most sailors will suggest that 6V golf cart batteries give you the most power at an economical purchase price.

But you haven't mentioned your charging sources other than a solar panel. It's a system and you need to tell us a lot more about your cruising habits, your charging regimen & existing system components, your cost budget & space limitations and most of all just a hint at what you might prefer before anybody can give you any meaningful advice. You might be thinking about golf cart batts or AGM for all we know. Give us a starting point ...

Tally Ho · Dec 5, 2022

I would get a couple of 6-volt golf cart batteries from Sam’s Club. They can give you 215 Amp Hours of capacity. I picked them up pretty cheap during one of their battery sales.

I have this set up on my O’Day 322 and I run a fridge, radio, VHF, cabin lights (LED), charge my cell phone and IPad, Sirius satellite receiver, auto pilot….for 2-3 days.

I am on shore power most of the time, so batteries stay charged most of the time.

Your needs may vary,

Greg

berner73 · Dec 5, 2022

Dlocner's comments are all spot on.

Curious - where do you keep the boat - meaning are you at a slip with shore power or on a mooring? That's a pretty extensive list of power loads if you expect to support all of it with a solar array that can fit on a 26' boat.

Kings Gambit · Dec 6, 2022

dlochner said:
Start with calculating the amount of energy that you will need to power your toys for as long as you will go without charging. Now double the amount of power you will use to stay above 50% of the capacity.

In order to charge the battery you will need to put back between 115% and 125% of the energy that you take out of the battery due to charging inefficiency.

Once you have those 2 numbers, we can start seriously talking about what kind and how many batteries you will need. You will have to find a place to put them and how you plan to charge them.

For most of us, I expect, this is an empirically determined value. That is, you know your power (and replenishment) needs after you’ve measured them over several iterations of use. My advice would be to build your capacity as you discover your needs. Adding up expected amp-hour demands versus supply, etc., is basically a “ball park” theoretical figure in my experience.

dlochner · Dec 6, 2022

Kings Gambit said:
For most of us, I expect, this is an empirical value. That is, you know your power needs after you’ve measured them over several iterations of use. My advice would be to build your capacity as you discover your needs. Adding up expected amp-hour demands versus supply, etc., is basically a “ball park” theoretical figure in my experience.

@Kings Gambit is of course correct that real data accurately measured over time will give a better estimate use and demand than an armchair exercise. I've done both and I'm currently involved in a project where we don't have access to experiential data as it is a new build. That's the problem the OP is confronting, he doesn't have the experience on this boat to base his use estimates on. So, he is really left with an armchair exercise.

There are some pitfalls with starting small and scaling up. Perhaps the largest is undersizing the system by a large factor which requires essentially rebuilding the system from scratch. Increasing the size of cables or adding a new fuse bank are not that expensive, however, undersizing the charger will lead to an expensive replacement as will undersizing the battery bank.

All sailboats have limitations, going through an energy audit is important to understand the boat's reasonable limits. Sure batteries can be added, solar panels can be added, and a suitcase generator can be added, but pretty soon the sailor will be wondering where to sit and the boat will sail like an overweight pig. Probably not the outcome any of us seek.

Kings Gambit · Dec 6, 2022

Well, it’s true that one has to start somewhere. A large boat with many systems will of course require greater power use than a small one with few. So, no one would start with one or two starter batteries and work up from there for the big boat. If you’re going to run AC systems from an inverter for many hours a day, plus 12 volt, then yes an a priori estimate would be wished for getting started. Continuous demand is more easily modeled than intermittent, ad hoc, demand. The OP mentions items that suggest intermittent use, not on all at once, etc.; perhaps not daily even. He might easily overpower with batteries ($$) beyond actual needs. The boat probably has an ice box; why a 12 v cooler? Can keep stuff cold for several days using block ice.

Hayden Watson · Dec 6, 2022

I have seen lots of spreadsheets and apps to work out an energy budget but have never been able to get one that came close to estimating my actual energy needs. My C30 came with a link-10 battery monitor which told me exactly how many amps I use. Because of that, I know that on average, I use 100Ah/day in good weather and 140Ah/day in cold weather. Both of the RV's I have purchased since then the first thing I did was to install a coulomb counter so that I could find my energy demands to better know what modifications I need. Spoiler, I am an energy hog.

Because of that, I built a DIY 560Ah LFP pack for my boat for about $750 and am awaiting delivery of two 480Ah drop in's for my motorhome.

dlochner · Dec 6, 2022

Hayden Watson said:
I have seen lots of spreadsheets and apps to work out an energy budget but have never been able to get one that came close to estimating my actual energy needs. My C30 came with a link-10 battery monitor which told me exactly how many amps I use. Because of that, I know that on average, I use 100Ah/day in good weather and 140Ah/day in cold weather. Both of the RV's I have purchased since then the first thing I did was to install a coulomb counter so that I could find my energy demands to better know what modifications I need. Spoiler, I am an energy hog.

Because of that, I built a DIY 560Ah LFP pack for my boat for about $750 and am awaiting delivery of two 480Ah drop in's for my motorhome.

There is value in estimating the boat's energy consumption both for planning the system and understanding the limited electrical resource there is on a boat and the cost to provide that energy. We who live on the grid are largely blind to the amount of electricity that we consume any day much less at any moment. How many times a day do you look at your electric meter at home to see how much power you are using? How often do you do that on the boat? However on a boat with limited energy knowing that the refrigerator is drawing 5 amps for 45 minutes of each hour is important. Or knowing that it takes 10 amphours to run a DVD player and TV for a couple of hours while a tablet will only consume 2 or 3 amp hours in the same time period.

An energy audit is as much an awareness exercise as it is a planning exercise.

Kings Gambit · Dec 6, 2022

I once found myself driving slowly behind a camper truck going up into a campsite in the High Sierra loaded with everyday stuff inside and out. The friend with me made the comment. “Taking it all with him to get away from it all!”

The folks near you who are there to get away from it all likely will not appreciate a portable generator running to power a stereo and DVD player (and other) on a boat that will be surrounded by lights, and that can be seen and heard pretty far away in an otherwise remote or pristine location. Perhaps just go out primitive a few times; see what gives with that.

dlochner · Dec 6, 2022

There is a distinct difference in the culture of powerboats and sailors especially as they head to anchorages. Go into any anchorage populated primarily by sailors and the anchorage will be quiet, stereos are turned down, generators (if running) are well muffled and not run during the night or in the morning.

Anchorages mostly populated by powerboats, a whole different story. It is party city with music blaring over the generators and lots of lights. This is annoying to sailors and to the people on shore.

Noise carries a great distance over water especially the booming bass that seems so favored. There are consequences especially around lakes with many vacation homes. Local municipalities start setting rules about when and where boats can anchor and they get enforced.

As you plan your entertainment center, please be considerate of those around you who may not share your tastes in music nor appreciate the noise emanating from a generator while sitting peacefully in their cockpits enjoying the sunset.

jssailem · Dec 6, 2022

artleyt115 said:
I made the post for battery recommendations, I've kinda gotten everything but that. I don't want to come off rude but we are pretty off topic.

Art... you ask a question.. Battery Recommendations. It sounds so simple.

Install 4 Trojan batteries..

Trojan T-105 GC2 6V 225Ah Deep Cycle Flooded Lead Acid Battery

Will they work for the type of system you believe you want/have? I have No idea.
The important information we asked, i.e. battery energy budget, charging systems, etc

You choose to ignore or fail to reply to the additional information member boat owners have asked.

Batteries on a boat are a system not a single purchase item. It is ok if you want just an answer rather than avail yourself of insight earned from making mistakes.

What I do know is that the above batteries serve a large number of boaters. They are not "cheap" and in order to get the best life for the money spent you will want to integrate them into a power system.

Kings Gambit · Dec 6, 2022

artleyt115 said:
So I don't want to say you're assuming what I plan to do with my sailboat but I don't plan to be a nuance to other boaters. Not only is the genny I have is quiet (mainly because I don't want to hear it) I know not everyone wants to hear my music. I made the post for battery recommendations, I've kinda gotten everything but that. I don't want to come off rude but we are pretty off topic.

Forgive us. You’ll discover for yourself. Boaters may not see themselves as a nuisance in a anchorage; only enjoying the surroundings in their own way. But just FYI. A “quiet (portable) generator” can be heard over water on a still night much farther away than one might think. If I can hear it, then it’s not “quiet” enough as far as I’m concerned. “Quiet” is basically a sales pitch; “oh it’s quiet!” That’s much different than, say, a “silent” device.

If you want a lot of battery capacity, get 4 true deep-cycle, 6-volt golf cart batteries and wire them in series-parallel to get two 12-volt sets with around 400 + total amp-hour capacity, and a separate starting battery. That would probably get you through a long weekend w/o having to charge much, if any, on site.

House battery recommendations

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SBO Weather and Forecasting Forum Jim & John

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SBO Weather and Forecasting Forum Jim & John

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