Battery Power

[freddy]

Ok, here's my idea for an off-grid, semi-modern log cabin. For everything that generally uses electricity, substitute rechargeable batteries. Then I would build a solar panel battery charger for recharging the batteries, with backup recharging provided by a small generator or perhaps just the automobile. The kitchen appliances would run off propane, and the space and water heating provided by wood/passive solar. Plumbing...?

This set-up would eliminate all the photovoltaic infrastructure downstream from the panels, as well as the electrical wiring system. IOW, substitute small batteries for big batteries.

Thoughts?

freddy

[ponyboy]

Maybe if you had one battery that fit everything it wouldn't be to bad, but having to manage recharging 15 different types of battery's would be a pain. :shock:

[rreidnauer]

Yea, that sounds like it would be extremely high maintenance, and if you're OK with that, then by all means. I think I'd grow bored of the "daily chores" pretty quick.

I been thinking on just how I want to go about setting up my electrical system. Originally, I was going to convert as much stuff to 24 volts as possible, use 24v lights, and what I couldn't, place small inverters. As time progressed, and I saw the difficulties of routing low voltages throughout a building, along with the cost of low voltage devices and heavy wiring, I decided on a new plan.

I'm going to build a power station. My two tracking solar arrays will be in close proximity, as well as the planned wind turbine. All RE energy will be pumped into the powerhouse, run through controllers, to charge a large forklift battery or two. Then, that will power an inverter(s), sending 120 VAC to the home to be used conventionally. I loose some 10~15% of the energy through the inverter, but I figure that's a small price to pay compared to low voltage line losses, and use of small individual inverters.

[Mark OBrien]

Rod, I always knew you were smart! That seems like and excellent plan. I used inverters for years while over -the-road trucking to power a fridge, microwave and a TV. They last for a long time in that usage and are easy to replace. Your planned setup sounds like just the ticket with the forklift batteries. Yes, they are big, heavy and expensive but you only have to move them once and they last for years with proper maintenance. I'm sure you already know this but for those that don't, you need the heaviest gauge wiring possible between the batteries and the inverter. That is an expense you cannot compromise on.

[jeffro]

Go to the welding supply store. Good quality wire, large size selection, and reasonable prices by the foot.

Jeff

[dcbrewmeister]

Why can't you just use regular house wiring? I have been talking to several people in Alaska you are completely off-grid and they used regular house wiring... regular wall switches... light fixtures have 12v bulbs instead of the stuff most people buy... regular outlets - labeled if they are wired for 120v from the inverter.

[freddy]

Brew, I'm not sure who you are addressing your question to, but supposing it's me.... The key phrase is "semi-modern". This house will be a guest house or a short-term apartment house. My idea is to avoid the wiring altogether. I remember rough wiring a log house with my father when I was a teen, and there's a lot to it. So I'm trying to avoid the time and expense of the electrical infrastructure while still realizing some benefits of electricity. I want to achieve somewhere between minimum electrical needs and unnecessary electrical luxury.

For lighting, I imagine a few strategically placed LED or compact flourescent lamps, each with it's own rechargeable battery pack. For the entertainment center, perhaps a dedicated solar panel or pedal power generator http://www.los-gatos.ca.us/davidbu/pedgen.html#FAQ with a dedicated deep-cell battery.

Please keep in mind this is just preliminary brainstorming...creativity is key, and anything goes.

freddy

[dcbrewmeister]

freddy - I think trying to power one or two lights per battery would be counter-productive compared to a central setup. Deep cycle batteries "made" for RE recharging are better equiped to be used from full charge to full discharge and back again when compared to any other other battery. I think the cost of a 3-6 cell system ran from a central location would be less than placing batteries all over the house or running wiring to them (with the current price of copper).

A simple 3-6 battery setup would run a cabin/camp for 3-5 days without the sun being out. If you are running stove, refridge, hot-water, and heat from propane you've knocked out your power "robbers" in the house.

Be careful running the entertainment setup on a inverter - most manufacturers void your warranty if/when they find out. Along with the fact that some won't even work on one because of "startup", most inverters fail to pick up the signal to turn them on, and an inverter is just like having a 60w light on 24/7 unless it will go into "seek" mode. Doesn't sound like much - until you remember your power is coming from batteries. You can save a ton of reserve power by unpluging all of them when not in use as they are "ghost" power robbers.

I'm moving to Alaska and building a small house - I am planning on solar and wind combination for my power as the land is nowhere near power lines. No expert here - I'm stealing my ideas from a guy who has been off grid for 8 years now. All his power comes from 6 165w panels and 2 1000w wind generators and 6 200w/hour batteries.

[freddy]

Brew,

Three other considerations are crucial to my plan. First, the small house (say 24 x 24 with 1/2 loft = 864 sq ft) will be designed for maximum daylighting, reducing the hours that any light will be used. Second, the house will have an open floor plan, with only 2 enclosed rooms, the bedroom and the bath. I think the number of interior lights can be kept to 8-10. Third, LED lights will reduce the number of recharges to a point where battery cost and maintenance is minimal.

I'm not well educated in LED, but I've been reading that dispersion is improving, to a point where they might give adequate whole room lighting. If they can't, or the cost is prohibitive, well, I guess that might be a deal breaker.

The other problem I anticipate is that these light fixtures may not exist. I'm picturing battery-powered camping lanterns, but with more muscle and perhaps more style.

To summarize, my plan has the following features:

1. Minimize the deep cell efficiency advantage.
2. Eliminate virtually all electrical costs (wiring, outlets, switches, breakers, etc)
3. Avoid deep cell battery cost and storage.

Thanks for the critique,

freddy

[rreidnauer]

Why can't you just use regular house wiring? I have been talking to several people in Alaska you are completely off-grid and they used regular house wiring... regular wall switches... light fixtures have 12v bulbs instead of the stuff most people buy... regular outlets - labeled if they are wired for 120v from the inverter.

Well, you could do that, but I don't recommend it. (hmmm, that sounds familure :roll: ) Here's the problem. The lower the voltage, the more pronounced the line losses become. Wire of similar size has the same resistance. Because 12 volt power is one tenth that of household voltage, the same resistance of the wire causes losses tenfold when similar amperages are drawn. This is due to the increased amperage by operating at lower voltage, for a similar wattage device. (example: I have an 84 watt AC/DC TV in the camper. It draws 0.7A at 120v, but 7A at 12v) So, with 14 gauge romex, you'd have to keep your amperages very low (under 2 amps) to be able to run any distance without massive line losses. Two amps, a mere 24 watts, isn't much power to work with. See the comparison charts for 120v, 24v, and 12v line distances at different amperages and wire gauges here ----> http://www.windsun.com/Hardware/Wire_Table.htm So, your only options are to increase wire size (expensive) or localized batteries like Freddy mentioned (which can be a pain keeping them all charged) I guess you could have the localized batteries at each point of use, and use house wiring to slow charge the batteries, but it starts to get complicated as you'll have to get into some electronics to control and isolate individual batteries and charge rates.

Also, you said regular 120v light switches for 12v lighting. BEWARE! - This is a great way to burn down a house!!! DC has a nasty habit of not wanting to disconnect when a switch is opened. If the amps are sufficient, the gap of the opening contacts will carry an arc across them. At least, the contacts will be damaged, and the switch will stop functioning in a short amount of time. At worst, it could start a fire. Most household switches will be specifically marked for AC use only. Then you mention using some 12v appliances and lighting AND 120v outlets, so now you're talking about running more wiring. (probably 25 ~ 35% more throughout the home)

The other thing that made me dismiss a low voltage home is the cost of appliances and lighting. For one example, have you priced 12v CFLs? Yikes! :shock: Heck, Lowes just recently gave me eight 120v 13 watt CFLs through a rebate program.

Use great care in whichever situation you decide.

[dcbrewmeister]

About a 3rd of the way down are the lights you are looking for http://www.backwoodssolar.com/catalog/led.htm but they use standard bulb sockets.

I'm un-sure exactly how you plan on eliminating wiring... you still have to go to and from a light, switch or what ever source you have for charging. wheather or not the battery is right above the light, or in another part of the house, wires will have to be used in order to charge the battery.

I think I can word this the way I mean it - the idea behind a RE source is to get power where you need it, as cheap as you can. the idea of "Free Power" is truly a myth. the equipment needed to do it doea not come cheap.

If you used the 6LED bulb, you could use one battery, run it all night, and most likely still have power in reserve.

I'm also not sure how you plan on eliminating the infrastructure for the solar panels... Yes, solar panels put out DC in various voltages, so how do you plan on controling the voltage? And what do you plan on doing with the "extra" power when your batteries are charged and the sun still has 5-6 hrs til it goes down? It has to go somewhere and somewhere other than your charging system. Your batteries won't last if you continually overcharge them. And if you plan on using car/truck batteries that are not sealed units, how are you going the vent the smell from an overcharged battery? Let's not even mention the fact that it's toxic.

Don't forget - solar panels will "draw" power when the sun goes down. Causing your system to discharge if you don't have a way to stop it.

Eliminate the infrastructure - I don't think so. Unless you plan on doing all this manually (more switches and wires) then you have to ask yourself "How am I going to handle this when I go out of town for a few days?"

Now I'm curious - how many batteies are you planning on using, and instead of one central locaton - how many locations are you planning on? I'm curious because 8-10 lights is nothing, and the system to recharge it can be had very cheap. You don't want to get away from switches, actually quite the opposite - you want more - one for every light. You have to think more along the lines of "task" lighting and get away from the idea of "general" lighting.

[dcbrewmeister]

rreidnauer - The only people I know of who "go cheap" on house wiring are cookie cutter builders.

You are also buying you switches and outlets at the wrong place. IF you are building a house that does not have 220v (mine won't) you can use 240v rated outlets and switches - different plug, so it eliminates the needs to "label" anything, check with code before you do this. My place I'm planning on in AK is outside any area where I need code to inspect anything. Read this disclaimer - I do plan on building within code standards because I may sell it someday, and any lender will require you to meet their code.

You also build a RE house differently. The endless supply of outlets providing power will be gone. And most lighting is individually ran and switched. Turning on a switch and having 4-5 lights come on at once is not a way to wire a house that runs on batteries...

I've got most of the details on what I plan on using... it will run fine on romex. It's going to cost ~$9,000 for the solar setup, the wind generator, the batteries (should run my place for 5 days without generation of any kind) charging control, inverter (to run the washing machine and dryer) and other "nick-nacks" for the control center.

Many people are running houses in Alaska (off-grid) using solar, wind, and/or hydro power sources on romex without burning down the house. You just can't wire it the conventional way.

By-the-way, 600v romex is part of the UL standard 83 code for building in the US, Canada and Mexico... If you are buying anything other I'm curious who's carrying it. It's also spec by the National Building Code, not sure what you have been using.

[jeffro]

I was referring to this:


I'm sure you already know this but for those that don't, you need the heaviest gauge wiring possible between the batteries and the inverter. That is an expense you cannot compromise on.

with the welding supply store comment in case that got things headed in the wrong direction here. For short runs of large wire, you can't beat the place.

Jeff

[dcbrewmeister]

I was referring to this:


I'm sure you already know this but for those that don't, you need the heaviest gauge wiring possible between the batteries and the inverter. That is an expense you cannot compromise on.

with the welding supply store comment in case that got things headed in the wrong direction here. For short runs of large wire, you can't beat the place.

Jeff

Well, you don't run your house with a bank of inverters, they are one of the most wasteful elements in a battery powered home and are not real efficient. You try to get away from running them if you can, but there are things you just can't avoid it on. Like satalite TV systems and modems for internet are just a couple examples. If you're going to run an inverter for lighting, you're doing it wrong.

The inverters I'm lookings at (well actually just 1 inverter) use 4/0 gauge cable. But that's the only "special" gauge wire I need, and it's less than 3' away from it's source.

[dcbrewmeister]

rreidnauer - The house I am planning is a Yurt style construction, except it will be a cordwood construction. The utility room will also be where my whole control setup will be, at most it will stick out from the wall about 16" so I won't loose much space, it will just cover almost the entire wall. The washer and dryer (propane dryer) will be in this room, the kitchen will be on the other side of the wall, with a propane refridge. The longest cable run will be just over 30' and the heavest power draw I will have on one run is just under 3 amps.

I still don't see the problem with standard house wiring. It's called planning. You have to get away from the way houses are currently built or it will never work for you. DC lighting, DC ceiling fan, DC well pump, DC presure pump, propane stove, fridge and dryer, an extremely efficent washing machine that only uses 165watt hours per load, instant hot water heater and wood heat (I have acres of trees) no A/C as it won't be needed.

If you take an existing house and convert it to solar you will have BIG problems. First an foremost is cost, you won't save a dime for at least 10 years becasue of the $20k - $30k it will cost you to do it. Second problem is the home was never set up to run DC, EVER! I'll be able to take my house and convert it to the power grid very cheaply - if they ever run power lines that far. But why would I want to?

[ChainsawGrandpa]

Ahhh...I know what you want Freddy...just what I'm planning for
the storage building.

It WILL be used for storage, then after we have our garage built, it
WILL be used as a sewing WORKSHOP for home use. (a sewing
room, sewing building, quilt studio, guest building, etc. require a
permit, more money, etc.). So, this is specifically being built as
a STORAGE BUILDING and then converted to a WORKSHOP.
Just sematics but the wrong term (as we have learned in class)
can be costly.
Had mine planned out several times when I was re-routed by an
electrician, and then again by an electrical engineer. So far the
plan looks like this:

4 Trojan L16 (or similar) batteries.
1 1800w Trace inverter
12 gauge wiring.
120v/20 amp outlets are used for 12v outlets.
Very few 120v outlets are employed.
All lighting is switched, and dedicated to a small work space.
New this Spring are the 80% effecient LED lights. Since the
work spaces are small, and the demand for lumens are low,
the LEDs will be used exclusively.
The heat is only on when the building is occupied. radiant
floor wood heat is used and the pump is powered by the heat.
We should (yeah, we'll see :wink: ) average 37 watts/hour at
12 volts. The EE suggested the most effecient and cost effective
way to charge the battereies was by (ohh, get ready for this...)
bicycle power. Many years ago I used to race bicycles and I was
pretty good too. Still, I don't think I'm going to recharge my
batteries with a stationary bike. I may just use a Honda EU1000.
At 37watts/hour, and four batteries it will need to be run for a
short time every few weeks.
The cost is "low" for what I have in mind, but "low" is a relative
term. The electrical may be 25% of the total cost for the
building. Ouch!
-Rick