Deep-Cycle Batteries

waterfun4me · Mar 15, 2013

Hello,
I am wanting to know what is the best thing to use for overnight boating trips? I was wanting to stay away from using a generator. And was thinking about a second battery. A deep cycle battery.
I am wanting to use it to hook up a power inverter. And just run my laptop to watch movies at night. And a coffee maker in the morning. And maybe a 12 volt heater, if needed.
I would only need it for maybe a weekend. Would getting a battery over a generator be a good idea? What do you guys use?

UncleWillie · Mar 15, 2013

Re: Deep-Cycle Batteries

A group 27 Deep cycle Battery might deliver 100 Ah on a good day.
100 Ah x 12v = 1200Wh. About the same as a pound (pint) of gasoline.

100watt Laptop (12 Hours)
300 Watt inverter (4 Hours)
1200 Watt coffee maker (1 Hour)
1200 Watt Heater (1 Hour)

2 hour on the laptop and 20 minutes to make coffee will leave 30 minute for the heater. (If you're lucky and the battery is new.)
Watch your movie for 2 hours at night but don't run the heater until after you make the coffee in the morning.

A 2000 watt generator will use about one gallon of gas in 8 hours.

smokeonthewater · Mar 15, 2013

Re: Deep-Cycle Batteries

yep to run the things you mention (including the heater at night) for a weekend you will likely need 10-15 deep cycle batts

You are either in the water cooled marine genset ($3000) territory OR ditch the heater and change movies to movie.

I use a genset for heat, a/c, and cooking and I save the laptop(mostly) and movies for times when I'm not out boating

waterfun4me · Mar 15, 2013

Re: Deep-Cycle Batteries

I am thinking a small generator. I was thinking about the room it would take, and how much it would weigh. But found one with low db. and it weighs less then a battery. I just like to watch maybe a couple movies at night, while winding down in bed.

smokeonthewater · Mar 15, 2013

Re: Deep-Cycle Batteries

waterfun4me said:
I am thinking a small generator. I was thinking about the room it would take, and how much it would weigh. But found one with low db. and it weighs less then a battery. I just like to watch maybe a couple movies at night, while winding down in bed.

Air cooled Generators on a boat are a bad idea at best... the exhaust is lethal

A marine generator goes in the engine room and mixes the exhaust with cooling water and then overboard at near water level.. because it is substantially cooled it does not have near the tendency to rise and enter the boat as hot exhaust from a genny on the swim platform

Even worse places for the air cooled genny are the deck, the bow, or the engine room.... VERY good ways to never recover from winding down

You might look into a portable dvd player.... they use WAY less power than laptops do.

MH Hawker · Mar 16, 2013

Re: Deep-Cycle Batteries

You can use a propane coffee pot and heater and a self powered DVD player and a propane grill in the morning for breakfast. Think camping stuff. I sleep on the hook a few times a year.

smokeonthewater · Mar 16, 2013

Re: Deep-Cycle Batteries

propane heater sounds SCARY but propane grill and coffee on the grill I'd consider as good options

MH Hawker · Mar 16, 2013

Re: Deep-Cycle Batteries

I don't have any details on the propane heaters but some are made for boat use.

bruceb58 · Mar 16, 2013

Re: Deep-Cycle Batteries

Never use a battery for doing any kind of heating be it for heating food or heating the air. Just way too much power needed.

blackhawk180 · Mar 17, 2013

Re: Deep-Cycle Batteries

bruceb58 said:
Never use a battery for doing any kind of heating be it for heating food or heating the air. Just way too much power needed.

+1
I use a little JetBoil for coffee and a Mr. Heater for heat though any flame source on a gas powered boat needs precautions. On my drift boat, I have no problem bringing a little BBQ and after dinner, actually add wood for a real campfire. Get some strange looks from other fishermen as they float by but hey, it's an aluminum boat powered by oars and surrounded by water + a fire is very enjoyable.

Descanso7272 · Mar 20, 2013

Re: Deep-Cycle Batteries

No ome has mentioned running 2 6v batt. In series they if buy good ones have 225-250 amp hours each 2 in seeies gives u 12v and 500 amp hours will run your movies cofee pot pretty much what u want except heater. For a weekend i run 4 of them in my motorhome and can go 4/5 days without running gen set. Using lights and everything else in the motorhome

bruceb58 · Mar 20, 2013

Re: Deep-Cycle Batteries

Descanso7272 said:
No ome has mentioned running 2 6v batt. In series they if buy good ones have 225-250 amp hours each 2 in seeies gives u 12v and 500 amp hours will run your movies cofee pot pretty much what u want except heater. For a weekend i run 4 of them in my motorhome and can go 4/5 days without running gen set. Using lights and everything else in the motorhome

With 2 6V 250 Ah batteries in series to form 12V, your Ah is still 250 Ah. The capacity doesn't double since you are drawing the same current from each battery.

jhebert · Mar 20, 2013

Re: Deep-Cycle Batteries

I do not recommend using a storage battery to power an electrical heater to heat water. If you want boiling water in the morning to make coffee, purchase a JET BOIL Zip Heater:

Shop | Jetboil - Zip Cooking System

I have been using a JET BOIL Zip system to make coffee on the boat when we are overnighting away from the dock for several years. This stove heats water for coffee in just a few minutes. One small cylinder of fuel will make a lot of coffee. The system is designed to stow inside the main heating pot, so it is very compact.

To operate a laptop computer you should get a power adaptor for the laptop that runs from 12-VDC instead of a power adaptor that runs from 120-VAC. It is not very efficient to turn 12-Volt DC into 120-VAC so the adaptor can turn it back to DC again. Find a DC-to-DC power adaptor for your particular brand of laptop. It will typically be much more efficient at providing power than buying a DC-to-120-VAC invertor. I have had very good experience with DC-to-DC power convertors made by LIND ELECTRONICS.

http://www.lindelectronics.com/

Todd4 · Mar 20, 2013

Re: Deep-Cycle Batteries

Good advice above. The electric heat (space heater or coffee) will kill a battery fast.

gm280 · Mar 21, 2013

Re: Deep-Cycle Batteries

Like so many have already stated above, any time you convert any voltage to another for whatever reason you loose efficiency. There is no such thing as a 100% conversion ability with anything, be it gasoline to Horse Power, electricity from one level to another, or any conversion from one form to another. If there was, we would not have any energy problems in America or the entire world ever. So converting 12.6 DC volts (battery voltage) to 120 AC (standard wall outlet power) and connecting your Laptop power converter into that to change it back to whatever your Laptop requires, is so wasteful and needless. There are so many other easier ways to accomplish those things in a more efficient way. Coffee making is the easiest. A simple dual fuel Coleman stove could easily accomplish that. And you already stated you found a small generator that was much lighter than a battery and would solve everything else. Like stated, think camping equipment...don’t try to reinvent the wheel...

Silvertip · Mar 21, 2013

Re: Deep-Cycle Batteries

Some time ago I showed a picture of what it took to power a 75 watt light bulb from an inverter hooked to a 12 volt battery. One must consider in that example, current draw from the battery was 6.5 amps to power a 120 volt 75 watt bulb. The current draw for the bulb at 120 volts is .62 amps or. That;s a conversion factor of 10:1. Now consider that any 120 volt AC heating appliance draws many hundreds to 1000 or more watts, that battery would be sucked flat very quickly (whether you had two six volt in series or one big 12 volt). Power conversion is not a free lunch.

UncleWillie · Mar 21, 2013

Re: Deep-Cycle Batteries

If the 12 volt battery was only supplying 6.5 Amps (78watts) to power a 75 Watt lamp at 120volt after inversion, I would be impressed. (96% efficient!)

1000 watts at 12 volts is 83 amps.
A typical auto battery is going to be fading in 30 minutes or less. :blue:

The voltage ratio was 10:1. The power ratio was quite a bit better.
The maximum power transfer into impedance matched supplies and loads is 2:1.
Efficiencies between 50% and 99% is the price of the Conversion Meal.

MH Hawker · Mar 21, 2013

Re: Deep-Cycle Batteries

Well last year I slept a few nights on the hook, my pontoon is set up with enough room to put up a 8 x 8 x 72 in tent on the front deck and I use a Colman propane coffee maker to keep the wife happy and a grill to cook on, and yes I use one of the MR Heaters just to knock the chill off, but it is off when sleeping. Those are designed for tent use and have the built in sensors but wont do so well if the boat is rocking. But that's OK Its very still where I tie up and yes I know its not a boat approved use but again its just to warm it up in the mornings. The admiral likes to get up early and have a cup and fish while I sleep in, Sort of funny actualy she will light the heater, then mumble some thing about it being cold, then go and start her coffee then come back in and mumble some more then she turns it off and she goes away for a hour or two, then I smell the bacon frying

and it time to start a great day on the lake.

bruceb58 · Mar 21, 2013

Re: Deep-Cycle Batteries

Bubba1235 said:
Have you ever known that to happen to anyone anywhere? I'd say you have as much chance of dying from the exhaust fumes of a small genset as you do of dying while sitting in heavy traffic.

You have got to be kidding!! :facepalm::facepalm::facepalm::facepalm::facepalm:
Posting info like this is completely irresponsible.

Boats have enclosed unventilated areas where CO can build up. At Lake Powell a few years ago, some kids that were swimming under a pontoon houseboat died because a generator was running.

There have even been deaths just from neighboring boats in raft ups!

http://www.boatus.org/onlinecourse/course_re-write/carbonmonoxide.html
http://www.doubleangel.org/documents/NatlCaseListingBoat-RelatedCOPoisoningsMay2007April2008.pdf

bruceb58 · Mar 21, 2013

Re: Deep-Cycle Batteries

DC to DC convertors are also very inefficient because they are using the exact same process as the 110V inverter/adapter combo is doing. They are also only around 80% efficiency depending on what you are paying for it.

Having said that, using a laptop is not a huge drain on your battery. I would be way more careful with lighting. My MacBook Air uses between 11W and 20W during use. Not a huge concern for me. If your laptop is actually consuming 100W, that's an old laptop.

Deep-Cycle Batteries

Recruit

Captain

Fleet Admiral

Recruit

Fleet Admiral

Vice Admiral

Fleet Admiral

Vice Admiral

Supreme Mariner

Petty Officer 1st Class

Recruit

Supreme Mariner

Ensign

Petty Officer 2nd Class

Supreme Mariner

Supreme Mariner

Captain

Vice Admiral

Supreme Mariner

Supreme Mariner