Batteries Life for a V318 while anchored a weekend?

Wawaron · **Joined:** Thu Jun 02, 2011 6:36 am **Posts:** 5

I wonder what should I expect when I am anchored and on batteries with my v318. While anchored I usually have the 2 fridges running at minimum level and a few toilet flush, the fresh water pump, the TV and DVD on stand by, the detectors of course, the radio/amplifier

I have the original house battery plus I have added 3 deep cyle. I had them tested last week and they were all very good.

Question;
should I be able to last a weekend without charging with the Gen?
When I am charging on shore before my trip, what voltage should I see on my batteries? I see 13.2.
What is a voltage too low? So I fire up my generator?
How often should I start my gen, in a 24 hours period to last a week...
Many questions wonder where is the answers?
Wawaron, thanks for feedback!

Wawaron

cougarcruiser · **Posted:** Tue Jul 05, 2011 11:00 am

4 house batteries should give you some staying power! No reason that you couldn't launch on a Friday afternoon and make it through Sunday. However, if you are in and out of the fridges alot, using the radio/amp, and watching movies or tv... You may have to fire up the generator to recharge.

Remember, you will also take alot longer to charge your batteries unless you upgraded those to support so many house batteries.

jrcinnh · **Joined:** Fri Sep 14, 2007 9:13 am **Posts:** 313

First be careful when measuring battery voltages, the built in meters are pretty sloppy and batteries often read higher than normal until they sit for a while or have a load.

According to Wikipedia:

Terminal voltage
The open circuit voltage, is measured when the engine is off and no loads are connected. It can be approximately related to the charge of the battery by:

Open Circuit Voltage (12 V) Open Circuit Voltage (6 V) Approximate charge Relative acid density
12.65 V 6.32 V 100% 1.265 g/cm3
12.45 V 6.22 V 75% 1.225 g/cm3
12.24 V 6.12 V 50% 1.190 g/cm3
12.06 V 6.03 V 25% 1.155 g/cm3
11.89 V 6.00 V 0% 1.120 g/cm3

Open circuit voltage is also affected by temperature, and the specific gravity of the electrolyte at full charge.

The following is common for a six-cell automotive lead-acid battery at room temperature:

Quiescent (open-circuit) voltage at full charge: 12.6 V
Fully discharged: 11.8 V
Charge with 13.2–14.4 V
Gassing voltage: 14.4 V
Continuous-preservation charge with max. 13.2 V
After full charge the terminal voltage will drop quickly to 13.2 V and then slowly to 12.6 V
Open circuit voltage is measured 12 hours after charging to allow surface charge to dissipate and enable a more accurate reading.
All voltages are at 20 °C, and must be adjusted -0.022V/°C for temperature changes (negative temperature coefficient - lower voltage at higher temperature).

ric · **Posted:** Tue Jul 05, 2011 1:18 pm

Break out the calculator and spec sheets!!

Figure you don't want your deep cycle batteries getting below 30%.

Example:
Typical marine start/deep cycle battery = 75amp/hr

That gives you around 45amp/hr of power. Figure the typical car radio draws 1amp, so you have 45 hours of power.

So just add up your battery amps, that will give you available power... and start looking at the spec sheets of everything you're running and that will give you a good estimate of run time.

In the IT world we use something called a "Killawat". You plug everything into that, and it tells you your amp/watt draw to size battery backups. I'm sure they make something like that for 12v

jnizi · **Posted:** Tue Jul 05, 2011 3:25 pm

Have been considering adding a house battery as well. Is there a concern as to the capacity of the alternator? I can see needing more capacity from the AC battery charger but is there a concern with the alternator not having enough to charge the batteries while the engine is running? Will the battery isolator compensate for the additional draw? I think the standard alternator on the FW is 85 amps.

ric · **Posted:** Tue Jul 05, 2011 4:15 pm

It's not hard math to figure, let's be safe and not draw below 50% battery to make them last a long time.

Let's say you have a small LCD TV: 50w x 8hrs of use = 36 amp hours
Coffee maker: 1000w x .25hr use = 23 amp hours
Blender: 300w x 10 minutes = 3amp hours
microwave 900w x 30 minutes = 42 amp hours
LED or efficient lighting 100w x 8hrs = 74 amp hours
Mini Fridge 150w x 8hrs (it cycles) 110 amp hours
Radio 100w x 16hrs = 150 amp

That makes for a decent weekend with not much more power draw. Roughly you'll need 450 amp hour of power, so to not go below 50% battery draw, you'll need give or take 1000 amp hour worth of battery. That will cost you a good $3000-$5000 for a battery setup that will last about 5 years.

Better? Pick you up a Honda EU2000i to charge a smaller onboard battery bank during the day. They are tiny and make 50db of noise. You could set it next to you and talk to someone without even raising your voice. My father owns sailboats and those guys swear by these things. if you have the radio on during the day while you're playing in the water you won't even hear it.

Yamaha also sells one Yamaha EF2000iS. Also around 50db. Either model will run 8hrs on 1gal of gas.

I'm not sure of your current setup, but if you're just charging batteries you might get away with a 1000w model. A 12v 20 amp marine charger = around 300w draw and figure some overhead... a 1000w inverter gen will power that nicely

ric · **Posted:** Tue Jul 05, 2011 6:41 pm

Now this is just all in theory and don't go writing checks for this stuff without consulting an electrical engineer based on your actual load and current boat setup, but... shouldn't your boat already have a charger/converter already installed in the boat to run the 12v lighting/appliances and charge the batteries when plugged into shore power? Probably has an inverter also to run 120v equipment too.

Find out the power draw on that charger/converter unit that plugs into shore and just get a EU1000i or EU2000i based on what it needs to run. Your factory battery setup should already last a good hour or 2 under full load if not longer, it would be crazy to spend thousands on batteries and adding literally a ton of weight to your boat when you can just get the job done with a $1000 "silent" generator

http://www.youtube.com/watch?v=SZHUGvO60Bc

wkearney99 · **Posted:** Tue Jul 05, 2011 7:47 pm

He already has a generator, so the advice about using a portable one isn't necessary. Nor are they all that safe, but that's a whole other argument.

Few boats come with a built-in inverter to power the AC devices. That's what a generator is for.

I found it necessary to add a pair of 6v golf-cart style deep cycle batteries to our 348 setup. That has given us enough capacity to get through long weekends without issue. I went with the 6v in series because they were relatively inexpensive. If/when I have to replace them I'll go with a pair of 12v AGMs in parallel. That'll provide even more capacity.

We do use the generator for running the appliances when anchored, and for AC when it's really hot. But most of the time we get by just fine on the 3 batteries.

Do not let the voltage drop below 11v. Fire up the generator for an hour or so to see how much the batteries recover. It harms the lifetime of the batteries to run them until dead.

When charging it's typical to see 13 to 14v, that's normal.

Paul I. · **Posted:** Tue Jul 05, 2011 9:42 pm

I agree with Bill, I an so sad to say!! (ha ha) I too have 3 batteries and what I have found that AGM are the best as deep cycles batteries. What I have done as a test, is to push the each time we are away from the slip. By running the fridge, and other thing longer and the start the engine the next morning. Everyone's D.C. load is going to be different so you may want to do some testing you self.

SW Florida Dave · **Posted:** Tue Jul 05, 2011 9:53 pm

I will say I like the idea of adding more batteries, but on a 318 how the heck did get them in there. My house battery is beginning to go and I don't think it will fit out the small opening around the exhaust riser. Also I am not sure I have the stones to lift it and push it through there. Any words as to how you accomplished the feat?

wkearney99 · **Posted:** Tue Jul 05, 2011 10:27 pm

I had enough room to get mine in there but it's reeeeeally an effort to lift/push/shove them into place. The single most IMPORTANT thing to be careful about is to avoid short-circuiting the battery terminals. You do NOT want to have them arc. I've seen pictures of horrific injuries to people's hands when they got zapped. So be sure to keep any terminal covers firmly in place when installing the batteries. When I did mine I went as far as to firmly tape down some cardboard over the terminal covers. I really wanted to make sure to avoid accidentally shorting them out.

Wawaron · **Joined:** Thu Jun 02, 2011 6:36 am **Posts:** 5

Thanks you all for excellent feedback.
Yes the opening is narrow but there is enough space through the back to get them in. I have to admit that it was done by Craig marina in the thousand Island.
I realize when I am reading all comments that probably what I am getting is fairly normal. Last long weekend, I have run my gen about 2 hour a day and was good for the weekend. Even though I wish I would have not done so at all, I have to be realistic. When I have a look at what is "actually" running it does make sense. Example of that is that I have 2 fridges running but also the fresh water pump once in while plush toilet vacuum, a bit of radio with the amp. But also in the back ground the co2 detector (2) and two vampire that I am not even using ( TV and DVD on stand by). And I wonder what else that I am not aware?
So my solution based on what you guys are says will be the following:
I will turn off the TV (small switch on top of TV), will need to figure how to turn off the DVD I see no switch, I will use ice pack for the fridge in the back (but I do not know to turn it off, there is not switch for it...), and I do have a Honda 2000 so this might be a solution for long stay on a same location.
My only puzzle is that when on shore and charging, I nevr see my voltage going a bove 13.2 volt, and see some saying as high as 14.
Mario

Mario

jrcinnh · **Joined:** Fri Sep 14, 2007 9:13 am **Posts:** 313

13.2 is the minimum for charging and 14.4 is the maximum. Above that they will bubble away your battery water too fast. I would check with a real volt meter on the battery terminals while on shore power and a the charger on. Check the charger for switches, so have slections for different battery types like flooded, AGM and Gel.

If you have a built in generator, why even consider a Honda? Just fire up the generator once a day, to charge the batteries. Do it at dinner time, that way the microwave and cook top are available and you can cool the cabin with AC while you cook. Once you fire up the generator, leave it running for awhile and put a load on it. I hear they don't like light intermitent use. They need to get up to operating temp.

www.iFourWinns.com

Batteries Life for a V318 while anchored a weekend?

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