Top Navigation  
 
U.S. Flag waving
Office Hours Momday - Friday  8 am - 5 pm Pacific 1-800-835-2418
 
Facebook   YouTube   Twitter
 
 
Backwoods Home Magazine, self-reliance, homesteading, off-grid

Features
 Home Page
 Current Issue
 Article Index
 Author Index
 Previous Issues
 Print Display Ads
 Print Classifieds
 Newsletter
 Letters
 Humor
 Free Stuff
 Recipes
 Home Energy

General Store
 Ordering Info
 Subscriptions
 Kindle Subscriptions
 ePublications
 Anthologies
 Books
 Back Issues
 Help Yourself
 All Specials
 Classified Ad

Advertise
 Web Site Ads
 Magazine Ads

BHM Blogs
 Ask Jackie Clay
 Massad Ayoob
 Claire Wolfe
 James Kash
 Where We Live
 Behind The Scenes
 Dave on Twitter
Retired Blogs
 Oliver Del Signore
 David Lee
 Energy Questions
 Bramblestitches

Quick Links
 Home Energy Info
 Jackie Clay
 Ask Jackie Online
 Dave Duffy
 Massad Ayoob
 John Silveira
 Claire Wolfe

Forum / Chat
 Forum/Chat Info
 Enter Forum
 Lost Password

More Features
 Contact Us/
 Change of Address
 Write For BHM
 Meet The Staff
 Meet The Authors
 Disclaimer and
 Privacy Policy


Retired Features
 Country Moments
 Links
 Feedback
 Radio Show


Link to BHM

Get Powered Up! Certified Energy Manager Jeff Yago answers your alternative energy questions

Wondering about a great new energy-saving device
you found on the Internet? Then CLICK HERE!

Sorry. Jeff no longer answers questions online.
This will remain as a searchable
resource for all BHM website visitors.



Archive for the ‘Battery room’ Category

 

Questions about small solar installation

Wednesday, April 29th, 2009

Hello Jeff,

Thanks for all the great information you provide BHM readers. I’m planning to install a small PV system using the instructions in your article in issue #116. This will be a very small system and used primarily for back-up during a black out. I have a Uni-Solar US-32 panel and Sunsaver 10 amp controller. I’m installing the panel on a carport roof, (I live in Massachusetts), running the wires to connect to one or two 12-volt deep-cycle marine batteries in my attached garage. I’ll be using the 2-pole fused disconnect and correct wire size for the panel and ground wires you recommend.

I have three questions.

1. What can I use as a bracket to mount the panel to the roof? I’ve seen small RV racks for sale and wondered if there is an alternative mounting bracket that can be purchased at a hardware store.

2. The wiring diagram in your article shows the load wires going to two 12 volt lights, hooked-up in parallel. I plan on wiring one light for the garage and continuing the wires about 30 feet to be run to the inside of the house. Those wires will be hooked up to a wall plate with a 12-volt cigarette plug receptacle mounted on the wall. I want to use the plug for a 12-volt TV or any other 12-volt appliance/charger that works using the auto style plug. What do you think of this arrangement and do you have any suggestions or recommendations.

3. Do I need to vent the batteries outside if they are in an un-insulated garage? I plan on putting the batteries in an insulated box for the winter and wondered if I can drill a hole into the top of the box and let the batteries vent into the garage.

Thanks for the help.

Ernie Smith

Ernie,

I can give you some general answers, but since we would not know everything about a specific installation, we cannot be too specific.

Although most solar dealers offer an “approved” angle “foot” to attach any solar module to a roof, I have taken 1-1/2 X 1-1/2 aluminum angle and installed the leg standing up to the side of the solar module and the flat leg bolted into the roof framing. Keep in mind that if you do not use the pre-drilled mounting holes on the back of the module you will void the warranty, so you might try a combination of two short lengths of angle back to back to make a “Z” shape. This will give you a way to utilize the bolt holes on the back of the module.

As long as your loads are 12 volt DC and wired in parallel, they do not all need to be at the same location. However, I would increase the wire size to the more distant load as there is 10 times the voltage drop at 12 volts DC that there is at 120 volts AC.

Finally, a few RV or golf cart batteries out in a garage will not give off enough gas to cause a problem due to the large space, but don’t locate them next to a gas fired hot water heater. Hydrogen gas is only explosive when highly concentrated like in a small sealed up closet or battery box. If you do place the batteries in an insulated box, you will need a vent at the top. For larger battery systems we use a 1-1/2″ PVC pipe vented outside, with screening to prevent insects from entering. The pipe needs to slope uphill since gas rises, but you will need something to keep out the rain.

Good luck,

Jeff Yago

 

Solar battery room

Sunday, December 28th, 2008

Jeff,

I have been reading your articles on solar power and have decided to build a small battery room in the basement, as opposed to the battery box. However I am not certain about something and would like your advice. I will put the batteries on a treated plywood on upright 2×4’s floor in this 4′ x 7′ floor area room x 8′ ceiling height.

I am planning to run a vent from the wood furnace into the room to keep it at optimal temperature for battery performance. However I am not certain about how much venting to the outside is needed and won’t the vent to the outside also cause all the heat in the room to be lost?

Is there a one way valve of some kind that will allow fumes out but no cold air in? The furnace vent will provide fresh air as I am not going to have a cold air return from this room back to the furnace because of the battery fumes getting into the house air. Currently there are 8 batteries but there may be more batteries added in the future.

Your insight and advice in this matter will be greatly appreciated and hopefully will help other readers as well.

Sincerely,

John Mc Andrews

John:

We do not get into detail design advice for a specific application on this web site for obvious reasons, but I will pass along the following general guidelines for building a battery room. Under no condition would I duct supply air into a battery room from a furnace, wood stove, air conditioner, or anything else that moves air. Any room, no matter how well it is sealed, is not air tight, and if you duct or blow air into any room it will find its way out, and not always out the path you intended.

I have seen a sealed battery room with a small exterior pipe to vent battery gases to the outside actually “suck” air back into the room located in the basement due to wind pressure acting on the home’s exterior wall surfaces, and this backward air flow forced hydrogen gas back into the basement. You want to always EXHAUST air at the highest point in a battery room and let the makeup air come from a louver located near the floor, under the door crack, or anywhere else it can find a path, but the room should be under a negative pressure (air being forced OUT of the room to the outside) in reference with the rest of the house and basement so any hydrogen gas will be exhausted to the outside and not forced back into other rooms or up through the ceiling to the floors above.

We usually use a battery-powered in-line exhaust fan installed inside a 3″ PVC pipe. These are made for battery gases and the brushless fan they use will not spark and cause a gas explosion. I would expect almost any basement under a house to not get too cold or too hot and would not expect any heating will be required. However, if you want to heat a battery room the only safe method that I am aware of is a very expensive explosion-proof electric radiant heater, or baseboard radiation around the walls that is heated by a hot water heating boiler or domestic hot water tank.

We always build a battery shelf made from pressure treated 2 x 4’s on edge with 1/2 x 4 spacers between each to allow for good draining and air flow. We place these on 8″ concrete blocks spaced every 3 or 4 feet to provide good air flow and to keep the battery bottoms from touching the much colder concrete slab floor. A floor drain is also helpful as it can get a little wet when you wash down the batteries with water and baking soda. Finally, we always add a good ABC type fire extinguisher, a vapor-proof glass “jelly jar” type light fixture, and a locking door having a warning sign.

Good Luck and don’t light a match when you are in your battery room if you can’t see!

Jeff Yago

 
 


 
 

 
 
 
 
 
Copyright © 1998 - Present by Backwoods Home Magazine. All Rights Reserved.