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Old 09-01-2014, 06:30 AM   #21
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...and a metric Cresent wrench.
Good one, took me a second to catch it.
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Old 09-01-2014, 08:07 AM   #22
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Six 6V golf cart batteries (e.g., T-105s) in series/parallel would give you approx. 675 Ah (2x225), ...

-Chris


Edit/typo correction: Six 6V golf cart batteries (e.g., T-105s) in series/parallel would give you approx. 675 Ah (3x225), ...

-Chris
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Old 09-01-2014, 08:13 AM   #23
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You guys forgot being sent (on a Navy ship) to the Bosun locker for 200feet of shoreline, or the electrician/electronics tech striker sent out to look for 115v Fallopian tubes...
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Old 09-01-2014, 10:19 AM   #24
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I know that you guys are having fun. But has anyone noticed that the OP has not responded after 21 replies, some asking questions about how he uses his boat?

I think we drove him away.

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Old 09-01-2014, 10:26 AM   #25
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I sorry OP...please come back...
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Old 09-01-2014, 10:30 AM   #26
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Edit/typo correction: Six 6V golf cart batteries (e.g., T-105s) in series/parallel would give you approx. 675 Ah (3x225), ...

-Chris
And you can use only half of that before recharging.
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Old 09-01-2014, 10:35 AM   #27
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Yep, and I try to leave a 65% charge instead of half.
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Old 09-01-2014, 11:58 AM   #28
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The original poster is at the very beginning stages of putting this all together. He is talking about specific batteries (an 8d) not its capacity in amp hours. He talks about configurations of banks, but again not capacity. Configuration is how we figure out how to make it fit into a particular space, not whether it can supply a particular capacity. It's okay, we all start somewhere, but we have to give the original,poster an idea as to whether it is even feasible.

In short, it's possible, but not easily feasible without a very significant investment in charging, battery capacity, wiring and load planning. The red flags in this scenario center primarily around large energy consumers. Large energy consumers are first any load that generates heat. Specifically in this case the water heater. A water heater can consume roughly 75 amp hours from cold and another 50 to reheat from warm. For three or four showers in the morning plus morning dishes it's possible we're talking over 150 amp hours alone. A coffee maker is a surprisingly large load and can consume 20 amp hours. A fridge/freezer easily takes 150 amp hours each day. So right there with some very rough math we get a daily load of 320 amp hours. How much battery capacity do we have? Two 8d batteries are in the neighbor hood of 450 amp hours, but we can only use about 50% of that when really needed or about 225 amp hours. For lead acid batteries that we want to last, we actually should not even go to 50%, so let's call a normal daily load closer to 200. Already, we have seen we have 120 amp hours in load more than we have capacity to supply, but we have not even considered everything:
-what other loads do we need to supply? Will anyone try running a hair dryer? Curling iron?
-What kind of compressor?
-what about cooking, do you use propane?
-what is our charging capacity? We need to put back over 300 amp hours this day and that could be over 6-12 hours with a standard 60 amp alternator or battery charger.

The point is that each of us will have to do some very specific math. Those of us using battery power for large loads, tend to track and husband each load and amp hour expected to be used. You will need a worksheet and a plan for both consuming and charging. Nigel calders book is a great place to start.

This can work. I have a 1200 amp hour bank, sometimes cook with electric and top up the temp of the water heater once in the morning, and can often get by with either running the boat or a generator for two hours each day to get most of the load replaced. By the third night, I either need about six hours of engine running or generator to charge back to full capacity.

It can be done, but it's not cheap or simple. Having a generator for most people is the best option and using the inverter at night when you don't want to make noise.
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Old 09-01-2014, 12:28 PM   #29
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Thanks ghost, that was so well explained even I got what you where saying. Not everyone comes to the table with the requisite lingo and it's refreshing when someone understands the subject well enough to be able to break it down.
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Old 09-01-2014, 12:50 PM   #30
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Agreed!! Great explanation of the underlying fundamentals, Ghost.
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Old 09-01-2014, 01:59 PM   #31
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On a flight line in the navy we would sent the new guy to the officer of the day for the keys to the jet.
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Old 10-14-2014, 06:44 PM   #32
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Living off an inverter at anchor with no generator will drastically shorten the battery life.
. Best advice is get the generator running.
Hi, It seems you know some stuff about batteries and inverters. I'm also a newbie, but have a different, but related question.

I have no generator, but a 2000w inverter. My Norcold refrigerator currently runs only on 12v dc power. It's something on my list to figure out. I've only had the boat for a few weeks.

My concern is this is going to be hard on my batteries even though I'm usually plugged into shore power. It seems that a constant drain on the batteries to fun the fridge and consequently inverter/charger constantly topping up the batteries seems bad to me. Am I right?
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Old 10-14-2014, 07:04 PM   #33
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Hi, It seems you know some stuff about batteries and inverters. I'm also a newbie, but have a different, but related question.

I have no generator, but a 2000w inverter. My Norcold refrigerator currently runs only on 12v dc power. It's something on my list to figure out. I've only had the boat for a few weeks.

My concern is this is going to be hard on my batteries even though I'm usually plugged into shore power. It seems that a constant drain on the batteries to fun the fridge and consequently inverter/charger constantly topping up the batteries seems bad to me. Am I right?
No problem for an inverter/charger. Once the bank is charged, it will switch over to "float" charge which maintains the bank charged and supplies enough current to carry normal house loads as needed such as your refer.
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Old 10-14-2014, 07:10 PM   #34
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You are right...you should not let your batteries drop below 60% of their rated capacity. With no generator and I assume no solar you are tied to the dock or spoiling your food. Inverters have their place, and a very limited place in most cases. The accepted penalty is 10% for invertred power. You have been hit with that before it gets to the appliance.

I have 10 golf cart batteries and I have to keep an eye on things. I have a 1.5 kW inverter. The only thing it is used for is TV, cable sat box. I could go on, but go get Nigel Calders book, do your math and pick a path.

When you know what you have, what you want to do, have a plan to get there then run it by us....new eyes never hurt a thing.
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Old 10-14-2014, 07:28 PM   #35
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Hi, It seems you know some stuff about batteries and inverters.
I have no generator, but a 2000w inverter. My Norcold refrigerator currently runs only on 12v dc power.

My concern is this is going to be hard on my batteries even though I'm usually plugged into shore power. It seems that a constant drain on the batteries to fun the fridge and consequently inverter/charger constantly topping up the batteries seems bad to me. Am I right?
Not really. . . as long as you are plugged into shore power, you aren't taxing your batteries. The battery charger is supplying whatever DC power your boats devices require. As long as no one disconnects your shore power you are golden. What shortens the life of your batteries are significant discharge cycles followed by a recharge cycle, no recharge cycle or poor maintenance. Most people will tell you to stay well above a 50% discharge level. Otherwise your battery life will be greatly reduced. Is your Norcold not AC/DC? It should run on your shorepower when at the dock.

Since you have no generator you have no choice. If you anchor out or otherwise have no shore power, then you begin a discharge cycle, until you restart your engines and begin a charging cycle. How far you discharge your batteries and how many cycles you put your battery system through, will have a lot to do with how often you replace your batteries. With no generator you're looking at probably 4 or 5 years if you're using more expensive deep cycle batteries and are careful and limit your discharge cycles.

Mine are off the shelf 4D lead acid batteries (bus batteries) which handles the engine starting and short term DC power needs such as my cabin lights and refrigeration, until the generator is started after anchoring. So any battery discharge is very small and immediately replenished. My four batteries have an average life of 8 - 10 years and cost about $200 each.

So either way, you pay for batteries or you pay for diesel, just pick your poison. . .
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Old 10-14-2014, 07:33 PM   #36
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Inverter/battery advice for a newbie

I'm not sure if you have room or not but I'd try to fit a genny in.
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Old 10-15-2014, 06:34 AM   #37
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>as long as you are plugged into shore power, you aren't taxing your batteries.<

True , but the dumb chargers may go to a high charge rate every time IF the voltage when the fridge switches on drops enough..

Doing this constantly does not harm the batt set , but it requires the battery water be checked far more often.

Operating batts with the plates showing does shorten their life.
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Old 10-15-2014, 08:14 AM   #38
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>as long as you are plugged into shore power, you aren't taxing your batteries.<

True , but the dumb chargers may go to a high charge rate every time IF the voltage when the fridge switches on drops enough..

Doing this constantly does not harm the batt set , but it requires the battery water be checked far more often.

Operating batts with the plates showing does shorten their life.
=========================================
nailed it again FF

If you continue to operate without an alternative charging system it might be wise to go with AGM batteries insofar they are more forgiving and be sure o have a good, smart charger . Aside from no maintance, higher voltage float they also take a charge fast. Ya might look into the small, quite Honda gasoline generators.
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Old 10-17-2014, 11:11 AM   #39
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tegdesign

This is the manual for your Norcold. You are correct, this is probably your boats original fridge as it's model dates back to Sept 1985.

The schematic gives you an idea of how they convert and invert the AC/DC power to compressor voltage. Unfortunately, there are no indicated component values on the schematic. I'm sure a Norcold technician could trouble shoot this for you, if you're unable to correct the problem.

The rattling you hear may be loose sheet metal, but in my experience that can also be a sign of an impending compressor failure in the older slug style compressor. They get noisy when they fail. Norcold switched to a Danfoss compressor on the new model two door fridges, much quieter and more reliable. I would start putting money aside for a replacement, just in case!
Good luck
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Attached Files
File Type: pdf Norcold DE828 Manual.pdf (1.17 MB, 25 views)
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Old 10-17-2014, 11:59 AM   #40
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My understanding is at least from a 1984 Norcold frig you are actually internally inverting 12VDC to 23VAC. There is a relay that is no longer available to handle the conversion but a replacement can be found. It all depends on if you have an "A" or "B" type power supply. Either way the older models run off of 23VAC when using either voltage. Using AC it's a step down circuit when using 12VDC you use a inverting supply. Typically the relay's failure mode is a set of contacts welded together or get real noisy. I hope this helps and doesn't confuse.
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