I found your website after doing a search on some possible options for power in my small cabin. I am visually impaired, so please forgive me if the information I am looking for could be found somewhere in the text on your site. My screenreader doesn’t always work like it should on some web pages.
The cabin is very small, 12′ x 12′, but it’s perfect for my needs. I am a musician and it gets me away from the phone and computer when I need to compose. I currently have one 25 watt D.C. light bulb in a ceramic socket mounted in the center of the cabin on a ceiling joist. This is wired to a deep cycle battery with about 12′ of wire. I keep a backup battery in the cabin also. There is a standard A.C. outlet mounted in the wall and wired to the battery in case I wanted to use a regular lamp with a D.C. bulb. I had a friend do this for me last Spring, so this system is fairly new.
As I mentioned above, I lost about 95% of my vision, so the brighter, the better. The 25 watt bulb puts out plenty of light and I got about 20 hours out of the first battery before I had to switch it out. I brought it home and put it on a battery charger with a deep cycle setting. The other battery was newer, and lasted about 10-15 hours longer. When it started getting weak, I switched back to the original battery. This time the battery only lasted about 3 hours.
Here are my questions:
1. Do you think there is something wrong with my battery charger?
2. Is there a different system you would recommend?
I know there are many variables and what I have now is probably not the most efficient. I just want something affordable, simple, and safe.
I would appreciate any advice or info you could give me.
Thank You,
Jeff Madewell
Jeff:
Since you did not provide any information about your battery, its hard for me to tell you what’s wrong. For example, batteries are rated in amp-hours, based on a specific time period. The same battery will have different ratings since the slower you discharge, the more power it can provide. You did say you were using a deep cycle battery, so I will assume its a 12 volt RV/marine battery since these are the most common you can buy locally, weigh 55 to 63 pounds, and will have a 20 hour rating of 105 to 120 amp-hours. I will assume your batteries are in this range, and you should not discharge the batteries more than 50% on a regular basis, although I will use 60% discharge in your case since this would not be an everyday situation.
Using and average battery capacity of 110 amp-hr, with a maximum discharge of 60%, provides 66 amp-hours of useful energy per charge cycle. A single 25 watt bulb at 12 volts requires slightly over 2 amps (25 / 12), so this battery will power this load for 33 hours maximum. However, there are other losses we should consider like wire losses, battery capacity reduction due to temperature, etc., so my best guess is you should get an average of 25 hours of light before battery voltage starts to drop below the level that will keep the lamp illuminated.
Here are my suggestions:
1. Make sure you are using a really good battery charger. Check the battery voltage after it has rested a few hours after being charged. It should measure around 14 volts. Any reading you get as soon as the charger is finished charging will not be a true reading. I would want a charger that has a built in 3 step charging cycle, with bulk, absorption, and float. This charger will charge must faster using the bulk setting, then switch to the lower charge rate as the battery starts to charge up, then it will switch to a low float charge to keep the battery at full level until you are ready to use it.
2. If I was carrying batteries back and forth like this, I would replace with a sealed AGM or GEL battery so there is no danger of gases or corrosive acid spilling out.
3. You did not say what 25 watt light you are using. If this is an incandescent 12 volt light I would throw it away now. A 15 watt compact fluorescent lamp will equal a 60 watt incandescent lamp, and a 25 watt compact fluorescent light will equal a 75 watt incandescent lamp or more. Obviously, your standard compact fluorescent lamps from the local builder supply are for 120 volts AC wiring, but the RV and Boating world now sell these in 12 volt DC models.
4. If you really want to solve you problem, buy a new LED lamp. These are easy to find in 12 Volt DC models and they will require only a tiny amount of battery power to operate. Yes, one bulb may cost $75, but it will never burn out, and it will run for days on your battery.
5. If you do switch to the better type battery and LED light, your system will require so little power that it would be very easy to add a single solar module and solar charge controller to keep them operating and you could stop hauling a battery back and forth. I have many past articles in this magazine that tell how to do this, so you might want to check out the back issues on line.
Good luck,
Jeff Yago
Jeff,
Thank you so much for taking the time to give me some advice. I guess I was pretty sketchy on my system’s description. Can you recommend any online vendors where I could purchase the 12 volt D.C. florescent bulbs or the 12 volt D.C. led lamps?
I have a large shop I spend most of my time in, 40 x 60 x 16, heated with a Taylor water heater with radiant heat in the bathroom, office/machine room and selected places in the concrete floor out in the shop.
I recently acquired a new 15 ton heating/cooling unit – it’s the building air handler end of a chiller system. It has two coils, one copper one for heating and another aluminum one for cooling.
What I would like to do is use ground water, drill a deep well, high water table where I stay, to get down to 55-58 degree water and use a coil made from pex or some other inexpensive piping to build a close loop system to cool my shop. I need to know how big the coil needs to be and made out of what?
I’m in eastern NC and it has high humidity. When the temp gets over 80 and sometimes up to 100 degrees here it’s hot inside. I have Foil/Foam/Foil insulation on all the walls and roof, it never gets hotter inside than what the temp is outside, unlike the horse barn across the driveway.
I was thinking of using the first well to do most of the cooling and then have a second well, pump heated water from the first into the second to keep cool water going into the first cooling well, this would have the ground as the heat sink.
How do you calculate for the size and type of piping needed to get the cooling I need? I’m hoping this would be cheaper than just installing a conventional A/C system.
Hello, whoever you are since you did not sign your email:
I know it is tempting to do what you are planning because you have this air handling unit that includes coils that can be used to do this, but this air handling unit is the lowest cost part of the system. For any geo-thermal heat pump or ground-coupled system, the highest cost is drilling the wells and installing the loops. As you already mentioned, your big concern is dehumidification which requires cooler water than just straight cooling as you must lower the air temperature below the dew point to do remove any moisture with the coils.
Each area of the country has different types of soil conditions and different water table depths, so this is why there is not a simple magic number of wells per BTU, but here are a few suggestions. Normally, you need 400 cfm of air flow per ton of cooling. I would expect you will need 2 or 3 wells for your size shop.
Have been reading your articles for years. Especially liked the one about reducing loads that just eat you to death.
I have been pointing out to people for years that their phone chargers use electricity whether the phone is connected or not. They are incredulous. So for years I have been shopping for a power bar, (multiple outlets), that has a separate switch for each outlet. Seems to me like the perfect set up for families with multiple phones, tooth brushes, etc that all need charging. It doesn’t exist, so I intend to make one, one of these days.
At any rate, I have a couple questions to ask.
1) Could styrofoam packing peanuts be scattered in an attic to make insulation? I hate working with fibreglass. Seems like we get them all the time, and out they go in the trash. And what about the wheat paste version?
2) Awhile back, a fellow came to our house to steam clean a couple carpets. His cleaner machine was 240 VAC powered. Instead of waiting for me to open the garage to plug into the Arc welder outlet, he had a simple solution. He had twin extension cords to plug in around the house until he found two that were on the separate sides of the sine wave, and went to work.
So I was wondering, if I took a couple automobile-type inverters and hooked them up to my truck, could I get 220/240 by hooking both neutrals together in an adaptor? Or do the waves have to be coordinated? I was just hoping I could use my arc welder anywhere I could drive.
Thanks
Glenn Willis
Glenn:
Good questions!
1. You are not the first who wanted to insulate with these “peanuts”. The problem is these are not all the same materials and many are polystyrene, which is extremely flammable and will give off very toxic gasses when it burns. Others are made from bio-degradable materials which can break down when damp or with time. Since you are planning to do this over time, this means you will be collecting many different packing materials even if they are all peanuts. Due to the danger of getting the highly flammable materials, I would not recommend this. If you want to check this out, take a few samples outside and light with a match and you will see, but do not breathe the gasses given off so stay upwind!
2. The power from the grid into your house has each “phase” of the 240 VAC power in phase, regardless of which outlets you use, as long as one is wired to each phase. However, when you have 2 different inverters, there is no way for one to know what the other is doing, so taking the output from each separately will have the differences between the phases changing all over the place. Not only will you not hold 240 VAC, but you could actually damage your connected load because the resulting voltage will be changing over 60 times per second. However, many high end inverters now include a communications cable that allows each inverter to time its output with the correct timing and phasing in reference to the other inverter so you can get a true 240 VAC output.
I doubt if your lower cost automobile inverters will have this timing capability.
Not wanting something for nothing, I just became a subscriber to backwoods home. I found the website most helpful and your answers also. More I read, the more confusing it gets. So much info is out there.
Eventually I want to put whole house on either solar or wind power or both (gridtied). I will discuss that when I get to that point in my remodeling. But that appears to be one or two years away.
But for now, just to start small.
I would like to power my LCD tv (200 watt), vcr /dvd combo (30 watt), the surround sound amp (135 watt), two laptops (max 120 watt combined), internet radio antenna (14watt), and wireless router (10 watt) from a small solar panel and a battery backup. They add up to about 540 – 550 watts
Both laptops have built in batteries for shut down purposes, and one is on a battery backup for longer grid interrupts, along with the internet radio antenna and router. But will probably use the UPS battery as the backup for the router and internet radio antenna and leave it hooked to the grid as is for now and remove the laptop from it.
When we are home or not everything runs constantly. Tv, vcr, amp are off, but have the keep warm circuit. I would like to put a manual (for now) switch in the system, so I could manually switch these items back to grid if needed. I know I could save energy by turning everything off when not in use with a power strip, but for now that’s not my point in this matter.
I live in Rocky Mountains at about 41 /42 degree latitude.
Could you give me an idea of the size solar panel, batteries, and inverter I would need to support running these items?
Does a charge controller just interrupt the power the panel produces to the batteries so a “dump” is not needed as would be needed in a wind generator?
Would I still need the GFC between the panel and controller, and the circuit breakers between the controller and batteries?
I know sounds like a lot of work and expense for a little gain. But every little bit helps down the line. And I could move these components later on out to the work shop, when I get it built.
Nobody is home all day, and split shift at nights.
Thanks
Choo
Choo:
We get many questions like this and the answer is – you can do this but the cost will be out of sight. It’s just not a good return to buy a solar power system dedicated to a few specific electrical appliances when still on the grid, as the solar system’s output would be totally wasted for any time periods when solar was available but these loads were not operating. Since you lose about 15% in efficiency when charging a battery, and another 10% when converting it back to 120 VAC, its not economical to charge a battery to power a load later in the day.
If you want to reduce your electric usage, install a small grid-tie solar system that feeds back into your house electric panel where it can off-set part or all of the electric loads that are operating at the same time.
If you want a battery backup system, add a battery bank to the grid tie system. Once the battery is charged, all of the solar power is sold back to the grid and the battery stays full until the next power outage. This way you will not have these charge/discharge losses during normal utility power.
We have a solor system and although we have not been there in the last week. My husband went to the camp yesterday and the battery bank does not appear to be charging, We have some contraption set inside so when you have the genertor is going it will tell you the current chage state.
We think maybe the battery bank for the system may have froze. None broke, but how can you that? Can you use a heater of some sort?
I hope you can help. We live in upstate New York.
Kathy
Kathy,
Yes a liquid electrolyte lead acid battery can freeze if left uncharged. Remember, when totally discharged, the mixture in the battery is a weak acid and mostly water which will freeze. For example, if the battery is 60% discharged, it will freeze at minus 16 degrees. If it is discharged even more, it will freeze closer to zero.
Do NOT try to re-charge a battery if it is frozen, it must be fully liquid from top to bottom before charging. You don’t say what kind of batteries you have, but the two most popular solar batteries are the #T-105 size 6-volt golf cart batteries, and the 6-volt traction or floor scrubber batteries called “L-16″. Most likely you have one or the other, and the smaller golf cart battery will typically last about 3 to 4 years in a solar application, and the larger traction battery will last 6 to 7 years in a solar application.
If your solar array or solar charger is under-sized for the size batteries you have, or if your electric loads are too large for the battery bank you have, then your batteries will constantly be totally discharged which will cut this expected life in half.
If your batteries are frozen, disconnect all wires to the batteries before placing a heater in the room to thaw them out.
I have two solar panels 80 watt each on my boat wired in series to make 24 volts 160 watt. I have two sets of two batteries also wired in series 24 volt. Start and house batteries. I also have a Morning star 24 volt 10 amp controller.
When I leave the boat I would like to charge both sets of batteries. When using the boat I would like to charge the house batteries only as they will be running a fridge etc and the start batteries will be charged via engine Alternator unless it fails at sea. So I will need a switch for off, battery 1, battery 2, or both.
Is there anyone that can help me with a circuit diagram required for this project?
Regards,
Simon Brock
Simon:
As noted on the web site, we cannot provide specific wiring diagrams and other detailed design assistance since we do not have all of the information about your specific application, and this is a free site so time is very limited for each reply. However, I can give you some basic guidelines. You have to be careful because if one battery gets really discharged, and the other is fully charged and you close a switch between them, there can be a huge in-rush of current from one to the other that could easily melt any smaller wires between them. There are 2 ways to charge these batteries separately without tying them together and have a potential melt down.
You can buy a battery isolator at the RV store which has a connection for a charger or alternator input, and two separate outputs to connect the 2 batteries. This device has diodes that will allow charging current to flow from the single solar charger or alternator out to 2 separate batteries, but will not allow one battery to flow back to the other. Although intended to connect one alternator to 2 batteries, you can use the solar charge controller as the charging source. Make sure the isolator has a common negative and one in and 2 outs. Just let both batteries stay connected to the solar charger. If one battery starts to get charged separately from the engine, when it raises the voltage of that one battery, the higher voltage will stop the flow in from the solar charger so all of the solar charging will divert to the battery not being charged by the engine because its voltage will be lower. You would not need any switches to do this, but your connection should be on the battery posts so the existing 1-2-both engine switch will not isolate the charger from the batteries.
The alternative is to use two identical solar charge controllers with one to each battery, and both connected to the same solar modules. The battery with the lowest voltage will receive most of the charge until they are close, then the charge controllers will be charging equally and sharing the same solar modules.
Be sure to install a DC rated fuse in each charger output connection to each battery.
