Venting question from rookie - small system in cabin

GXB2000 · July 2017

Hi everyone,

We are working on installing a very small system for a summer cabin. It will consist of a single deep cell marine battery and a few small solar panels. We will use it with an inverter to power 3 8watt LED bulbs for a few hours each night + charging cell phones.

The current plan is for the battery to go into a small closet area with no door that is open to the cabin (cabin is about 800 square feet).

I've been reading a bit about venting and want to see if this is something we need to do.

Part of the reason we are going to solar is because we don't like the idea of coleman lanterns in the cabin (safety + a pain), but now realizing there might be some issues with solar as well.

Any information, suggestions, ideas are appreciated.

(i don't have full system specs at hand as I'm not leading the project).

BB. · July 2017

OK... Your loads are small, which make the system less expen$ive, and potentially le$$ things to go wrong (shorts, fires, theft, etc.).

First, the 12 volt Marine battery is not (usually) a very good "deep cycle" battery. But it is relatively cheap and not bad to start to learn about your operating your system. If your battery lasts 1-2 years--you are doing good.

Using 6 volt @ 200 AH "golf car" batteries is usually a good start (cheap, rugged batteries)--But even this "minimum" system is, probably, about 2x the 12 volt @ 110 AH (?) battery you have. Golf Cart batteries will typically last 3-5 years (lead acid batteries will last longer if in a cold environment).

I always like to start with loads, then design the battery bank to support those loads. Then design the solar array (plus genset backup, if needed) to keep the battery bank happy.

Since you typed about safety--Yes, you really need to uses fuses or circuit breakers to protect your wiring. Fuses/breakers are there to protect your wiring from overheating (overloads, short circuits) and not to "protect" the devices (i.e., a fuse/breaker will not keep your radio/lights/computer supply from failing).

I have to go right now, but if you can tell us a bit more about the installation. Roughly, where it will be located (nearest major city) so we can figure out how much sun you will get. How much and when the cabin will be used (summer weekends, any winter usage, a couple weeks full time a year, or what)?

Also, do you need just 12 VDC or will you want a small AC inverter to power laptop/cell phone chargers, run power any distance (12 volt systems can only send "usable" energy a few 10's of feet cost effectively. A 120 VAC system can send power 100's of feet very easily---I.e., outdoor lighting, etc.).

See you in a bit.

-Bill

GXB2000 · July 2017

Thanks Bill - getting the specs as we speak.

We are using a marine battery because we already have it.

Yes, we will be using an inverter to power the 3 8 watt LED lights.

We use the system only about 8 weeks per year, and it is located in southern Quebec. We will take the battery in for the winter and will charge it every month or two as needed.

We have used the system before on a temporary basis and everything works, battery charges etc. This will be the first time we are "making it official" and installing things on a more permanent basis.

Thanks!

Solray · July 2017

Actually lead acid batteries don't like being too cold. Freezing them damages them. They like being about 70° F
For cell phone charging just put a couple cigarette lighter sockets hooked to the battery and plug in a USB adapter there, or get a 12v USB and just hook that into the battery. Either will work.
I wouldn't want to mess with an inverter for your needs.

For winter, just keep the battery connected to a maintainer, rather than hassle with remembering to charge it up all the time.

For a lead acid battery you will want it in a box and vent it outdoors with some pvc. You don't want hydrogen gas inside with you.

Have you considered some small battery powered stick up led lights? They will probably do all you need to do and you can charge the phones in the car.
There are even small solar ones you can stick outside.
https://www.amazon.com/gp/aw/d/B016O9EZA6/ref=mp_s_a_1_1?ie=UTF8&qid=1500493225&sr=8-1&pi=AC_SX236_SY340_FMwebp_QL65&keywords=led+stick+up+light&dpPl=1&dpID=41EnkH6WFOL&ref=plSrch

GXB2000 · July 2017

Thanks Solray.

We already charge our phones directly to a 12V as you outline above.

The 2 mantle Coleman lanterns we use throw a lot of light - nothing in the battery powered LED space that we've tried comes close. The 8 watt AC LED's (65W equivalent) throw a similar amount of light to the Colemans.

Re: putting the battery in a box outdoors - I take it you are saying even a very small setup like ours poses a risk of gassing?

littleharbor2 · July 2017

For your small loads you should consider a small AGM battery. You don't have to deal with venting problems. They will vent if charged with too high of voltage. The solution, charge them at the proper voltage, simple. They have charging info on the battery case. Typically 14.4 volts in bulk/absorb. Now you don't have to worry about having the battery indoors.

BTW a fully charged battery will withstand some pretty extreme low temps without damage or threat of freezing. a fully charged Flooded lead acid battery can withstand temps down to -80 degrees F.
http://usbattery.com/winter-storage-maintenance-tips-flooded-lead-acid-batteries/

Solray · July 2017

I never wanted a lot of bright light in a cabin personally, but you might be doing some surgery in there for all I know. I have an LED battery powered pole light for an outdoor umbrella that is extremely bright (24 or so leds, 12000 lux) so there are a lot of options in the battery powered arena that will give the same or similar illumination as your 8 watt lamp.

Image: https://images-na.ssl-images-amazon.com/images/I/61QIsW2YmJL._SL1000_.jpg

Solray · July 2017

GXB2000 said:

Thanks Solray.

We already charge our phones directly to a 12V as you outline above.

The 2 mantle Coleman lanterns we use throw a lot of light - nothing in the battery powered LED space that we've tried comes close. The 8 watt AC LED's (65W equivalent) throw a similar amount of light to the Colemans.

Re: putting the battery in a box outdoors - I take it you are saying even a very small setup like ours poses a risk of gassing?

You can have the box indoors and vent it outdoors through a wall, you can use an RV wall vent made for venting an oven or furnace, it will have a screen inside that prevents critters from entering.

Estragon · July 2017

> @GXB2000 said:
> Thanks Solray.
>
> We already charge our phones directly to a 12V as you outline above.
>
> The 2 mantle Coleman lanterns we use throw a lot of light - nothing in the battery powered LED space that we've tried comes close. The 8 watt AC LED's (65W equivalent) throw a similar amount of light to the Colemans.
>
> Re: putting the battery in a box outdoors - I take it you are saying even a very small setup like ours poses a risk of gassing?

You might find the LED lights are 12vdc fed by 120vac wall wart. I've found some (most?) work fine with the range of voltages involved in running direct off batteries (~11-16v).

I personally wouldn't get too worked up about the battery in the closet thing. On my boat I have a 12v starting battery and 2x6v golf cart deep deep cycle in a box not much bigger than the batteries, under the transom steps in the main cabin with no outside venting. Ideally I'd use AGMs, to avoid the gassing issue, and also to eliminate the possibility of leakage when heeling or rough weather, but it's worked fine in the 8 years I've had the boat, and it's quite commonly done. I'd be a lot more concerned if I had my 12 L16s from my cabin system sitting 3 feet from the stove in the boat.

One thing to watch for is when the battery gets older it may need to have distilled water added more frequently.

Marc Kurth · July 2017

Solray said:

I never wanted a lot of bright light in a cabin personally, but you might be doing some surgery in there for all I know. I have an LED battery powered pole light for an outdoor umbrella that is extremely bright (24 or so leds, 12000 lux) so there are a lot of options in the battery powered arena that will give the same or similar illumination as your 8 watt lamp.

@Solray, You use amazingly similar vernacular and writing style, while displaying the same online persona as another person posting under another name here.

Point blank questions:
Are you posting here under multiple names?
How do you decide which name to use?

Marc

Vic · July 2017

Marc, this has been my thinking exactly ... had almost asked a moderator ... Thanks! Vic

GXB2000 · July 2017

uh oh, look what I started!

Anyway...we use the full light for cooking and cleaning. Everything else gets the low light level.

Our setup is very basic - I think we have 3 15W panels somebody bought at harbor freight 8 years ago.

Anyone else have an opinion on the need to vent?

(great forum btw).

Marc Kurth · July 2017

@GBX2000 Sorry, I did not mean to derail your thread and I apologize.

Marc

Horsefly · July 2017

@GXB2000 - I am certainly not an expert, as my system uses AGM batteries without an enclosure. However, for the last 15 years or so we had a little tiny 12V panel on our deck at the cabin, charging a marine FLA "deep cycle" battery that we used only for charging cell phones when someone was at the cabin. The wooden box that the battery has been in all that time is right in the living room / kitchen / great room of the cabin, and has never been vented. Sounds like a fairly similar set up as yours. As far as I can tell we are all still alive.

Steve

P.S. You're right, this is a great forum. It's where I learned a ton before we installed our system. It has had a great atmosphere, prior to the arrival of a couple of people (maybe one?).

mike95490 · July 2017

My suggestions:
Use either a very efficient inverter (Morningstar suresine 300 comes to mind, but it's pricey) or go with straight DC lighting.
For DC lighting, look at www.superbrightleds.com or /www.wiredco.com/LED_Lighting_Low_Voltage_s/1874.htm
Both sites have GOOD LEDs that are bright and engineered to have a decent lifetime, Also many strip lights will give great ambient lighting too. LED's are all about beam pattern, and the largest problem is not brightness, but dispersing that light evenly. Second is heat.

GXB2000 · July 2017

Thanks everyone, this is great!

Solray · July 2017

You are quite welcome, friend.

mike95490 · July 2017

venting battery fumes. Two things here, first is H & O gasses from the recharge process, second is the smell from the sulfuric acid that can really stink up a house when charging a battery hard. for a couple batteries, Hydrogen buildup is not very likely, but you may still have fumes..

Venting question from rookie - small system in cabin

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