House batteries

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BillyK

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I'm setting up a house bank in my boat and already have the things I want on it separated from the things needed to operate the boat. I figure a total of 63 amp hours if everything was running for an hour, which will never happen. I don't know the start up amps of a 15kw Onan diesel generator, so that will have to be added to the total. I have an existing battery charger which has a third + to charge this bank. How many of what kind of battery would you install for this load.

Things on the house battery bank and total amps

Bilge pumps - 9
Shower sumps - 4
Vacuflush - 18
Generator - ?
Lighting - 30
Total - 61 = generator

Thanks,

Billy K.
 
You may want to find a good site regarding batteries, Amp Hrs, etc. I'm sure you can "Google up" a site. That will give you good info.
Good luck,
Ron
 
Amp hours vary widely from manufacturer to manufacturer but let's make some assumptions. A 27 series battery has about 85 amp hours [42 usable] A 31 series battery has about 100 amp hours [50 usable] a 4D battery has about 150 amp hours [75 usable] and an 8D battery has about 200 amp hours [100 usable].

The question is: How long do you need to run you electrical devices between charges? Bilge pumps probably shouldn't be running very much at all. Shower sump only during showers and even then not continuously. VacUflush, maybe once an hour for a minute, tops. Lighting, 30 amps per hour. How about a refrigerator, bait pump or stereo and TV? Anyway, based on your real world usage a 31 series battery should last you around an hour an a half or so. 50 amp hours divided by your expected usage of 33 amps per hour. An 8D battery would last around 3 hours.

Is this in the ballpark of your usage and expectations?
 
I do not know that I would put bilge pumps on the house bank. I do not know this, but my intuition tells me that bank has more chance of running down than the operating bank.

George
 
Your generator should really have its own battery, not share the house bank. Or at th very least it could share a start battery with one of the mains.
In any case you can't measure cranking get in amp Hours like regular house loads.

Bilge pumps, Vacuflush etc can't be measured like that as they don't run non stop. How an refrigeration? Is your fridge, ice maker, etc. DC or AC

I d probably consider using 4 golf cart batteries which will give you 440 AH but it depends on how you use the boat. Do you spend a lot of time on the hook? Overnights? And yes charger size is important , as well as type and capabilities. For instance you don't want it to cook your fully charged start batteries as it needs to recharge a deeply depleted house bank.

There is a lot more to this than adding amp hours
 
There are two of us that live aboard a 45' Chris Craft. We both work and are away most of the day.

All appliances are A/C

The charger is a Xantrex truecharge 40.

We do not spend over nights on the hook. At least not right now.

I'm not too worried about the bilge pumps or generator on the house bank as I would probably be running the generator to keep the appliances cool and for air conditioning. I am talking about daytime anchoring.

I realize I will not be running all these devises all the time, but I wanted to do it right the first time. I was thinking three 31's in parallel.
 
I don't have the edit icon.

Thanks,

Billy K.
 
30 amps of lighting? You may want to upgrade/replace many of the bulbs to LEDs it would drop that number immensely!
As for batteries I have heard good things about the golf cart batteries for a house bank. In my boat the starting batteries are my house batteries I have two banks port and starboard I can choice/switch which bank I use. Because these are also my starting batteries I had one 8D per side I found anchoring out for long days without running my genny was draining the crap out of these batteries I doubled one of the banks to two 8Ds now I always use this bank and I have never run out of power. I have greatly cut down on my generator run time as well. I believe as long as you have the room and the weight is not an issue then more is better when it comes to battery power!
 
I changed all the lighting circuits that were a/c to d/c and LED. It is a generous amperage estimation, but I would rather err up then down.
I am rethinking the generator and am going to leave it where it is.
I don't know anything about golf cart batteries, so I will start looking into it.
Pascal brought up over charging the batteries. Will a Xantrex truecharge 40 do that. If necessary I could get another charger for the house bank.

Thanks,

Billy K.
 
I have the Xantrex 60 and no it is an intelligent charger so it will turn off when the batteries are charged. I forgot to mention I have a third bank as well with a 27 type battery just for the Generator if for some reason I were to drain both my house banks I could still start my generator and run the charger to recharge all my batteries. I'm very happy with this setup!

I have a hard time believing you led lights could draw 30 amps this said I think you have a lot of safe options.
 
quote:
Originally posted by BillyK

I realize I will not be running all these devises all the time, but I wanted to do it right the first time. I was thinking three 31's in parallel.

Click to expand...


If you've got room for three 31s and maybe just a tad more, you'd get better service from four 6V golf cart batteries. The 31s would give you about 300 Ah, but the GCs would give you about 440 Ah AND they'd be true deep cycle batteries (i.e., designed for it).

Note that you really only have about half those Ah for actual use, so as to not draw the batteries down to lower than 50% state of charge.

If 300 Ah (so 150 actual) is sufficient for now, consider that you might want more in the future... and the 440 (220) option up front would set you up better for then versus now.

-Chris
 
quote:
Originally posted by gcolton

I do not know that I would put bilge pumps on the house bank. I do not know this, but my intuition tells me that bank has more chance of running down than the operating bank.

George

Click to expand...


I checked into separating the bilge pumps back into the engine bank and am going to do it. Thanks for the suggestion.

Billy K.
 
a single 8D battery should do you overnight to run the refrig and general lighting in the evening. best real world load calc; an amp meter at night when you are running from the battery. check with the lights/misc loads on and then just the refrig and anchor light. it shouldn't be too hard to derate the ref load for frequency.

if you haven't checked already you may want to be sure you have a three leg battery isolator in place so your alternators can see all of the batteries and isolate the charge/loads.
 
quote:
Originally posted by vic33004

a single 8D battery should do you overnight to run the refrig and general lighting in the evening. best real world load calc; an amp meter at night when you are running from the battery. check with the lights/misc loads on and then just the refrig and anchor light. it shouldn't be too hard to derate the ref load for frequency.

if you haven't checked already you may want to be sure you have a three leg battery isolator in place so your alternators can see all of the batteries and isolate the charge/loads.

Click to expand...


Thanks for the tips. I think I'm going to go with the golf cart batteries.
I have twin screw and they are already separated one engine to each battery. I thought running the generator would be enough to charge the house batteries.

Billy K.
 
I'm considering the switch from an 8D to four Golf Cart batteries and wondering if they will be charged properly by the same charger that charges the 8D?
 
quote:
Originally posted by PJS

I'm considering the switch from an 8D to four Golf Cart batteries and wondering if they will be charged properly by the same charger that charges the 8D?

Click to expand...


I think the only place to get an accurate answer, is the mfg. of the charger with your model # and the specific battery type(s) you would like to use. in theory, there is no reason why you could not make the transition.
 
I'm going to put another option on the table - 12 volt AGM batteries. While golf car batteries (in pairs wired in series) make a great house bank and probably provide the most cost effective solution, they do require monthly checking of the electrolyte levels and topping off with distilled water and they do emit hydrogen gas as they charge. Any overflow or spillage is highly corrosive.

AGM (and I'm thinking Sears DieHard Platinum Marine batteries here) are essentially maintenance free. This can be a significant advantage if the batteries are in a place where routine maintenance is difficult. They can be paralleled as needed, no need to install them in pairs as with golf car batteries. They are also available at any Sears auto store which simplifies purchase and/or replacement.
 
I must second rawidmans suggestion. I have been using similar house batteries ( 2 interstate DCM100L 100 AH AGM deep cycle) for years with very good luck.
Ron
 
Thanks guys,

Now I have something else to consider, because I really don't plan to be away from a dock for more then an afternoon. Maybe an overnight, but the genny will be running a lot for the fridge, a/c, tv etc. I could squeeze in four batteries but two will fit much cleaner. I'm a complete novice when it comes to figuring the dc load and battery needs. I guess I will figure it out as I go.

Thanks

Billy K.
 
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