Tag Archives: batteries

Solar battery maintenance

It’s the middle of the summer and what better time to talk about off-grid solar power. The days are long and the sun is bright. Lots of power to harvest for sure. However, you are never running anything directly off the solar panels. All of that incoming power is stored in your batteries. The power you use always comes from the batteries. If it is bright and sunny, you can use a lot of power before your batteries will start to drop.

Typical batteries used for off-grid systems are of the flooded lead-acid variety and these do require maintenance. How often they need it is dependent on usage; we use our system everyday. If you have a summer cottage and are only there for few weeks during the year, you can do maintenance less often.

The main form of maintenance involves adding distilled water to the batteries’ cells. We’ll talk about that in a minute. The first maintenance I want to talk about, which is less common, is keeping things clean.

As you can see from this first picture, the terminals where the cables are connected have large amounts of blue corrosion. This needs to be cleaned as corrosion increases the resistance in the circuit and this is bad when you are trying to maintain a certain level of voltage to your system. In this case, I hadn’t cleaned the terminals since we had initially installed it, which is almost three years.

There are anti-corrosion compounds you can get, and I did get some for this job, but I should have obtained some shortly after doing the initial install. That ended up being on of those things that got pushed way down on the to-do list apparently.

In any event, armed with my battery terminal cleaning spray, steel wool, a rag and a screw driver, I scraped and scrubbed, polished and rubbed until the copper was once again visible on the terminal cables.

I should mention that is highly recommended that you shut off all main breakers in your system before attempting this. Additionally, you need to be very aware of what you are doing. Closing the circuit across the terminals on the same battery probably won’t do you much harm (it’s only 6 volts), but it will kill your battery really fast. If you still have all of your batteries connected together and managed to short-circuit them (in my case, that’s 8 batteries at 6 volts each, adding up to 48 volts) that not only will probably cause a fire, but it is enough to give you a really serious health risking jolt. Be careful.

Take your time, don’t be rushed and pay attention to what you are doing. Simple enough. After you’re all done, it should look something like this.

Now we’re going to talk about the regular maintenance, the one I do once a month: topping up the cells with distilled water. For this job, we’re going to need a few things to make our job easier.

First, of course, is the distilled water.

This is a 4L (slightly more than 1 US gallon) jug. This time of year, in the middle of summer, I can go through almost a full jug with one refill. During the winter, that same jug will last 3 fillings. The batteries are much more active during the summer and they don’t like the cold.

Incidentally, I should mention the sound the batteries make. This isn’t something one thinks about a whole lot when thinking about batteries and solar power. If your batteries are doing well (and it’s not below freezing) you will hear lots of pops and fizzles, kinda like a cross between a low simmer on the stove and the sounds a healthy horse’s gut makes. If you don’t know what that sounds like, I’m sure youtube can help you.

Moving on in our tool list we have an empty, well cleaned yogurt container.

Next up is one of these fancy thinga-ma-jigs. It’s actually a hydrometer and it measures the density, or specific gravity, of liquids. In this case, this one is intended for testing flooded lead-acid batteries. You can also get hydrometers that test how much alcohol is in your wine and beer, for all those wanting to start their own home brewing.

Last, but not least, a working noggin lamp. Some people just call them head lamps. To each their own.

The head lamp is essential because you’re going to have both of your hands busy and you’re going to need some light to look into the cells of the batteries.

The process is really quite straight-forward. I fill the yogurt container with distilled water. I use the hydrometer to suck up a bulb’s worth of water and gently squirt it into each of the cells until they are full. Nothing too complicated, but I’ll give you some justifications for using this method.

First of all, having the distilled water in the yogurt container and not in the jug just makes it easier to fill the hydrometer. Leaving the water in the jug and trying to suck the water out of it directly just becomes more of a pain the more empty the jug becomes.

You could use a funnel and just pour the water into each cell, but then you’re going to have to stop a lot, pulling the funnel out each time to see if it’s full. You don’t want to overfill it. Using the hydrometer allows you to have great control over how fast you are filling the cell and, with the use of the noggin lamp, shows you how much is in the cell at any given moment.

Here is a close-up picture of one of the battery cells open.

From that picture, you can’t really tell how full it is. The bubbles help a bit, but I tell you now, it’s not much easier when you’re actually doing it. So, how do you know when it’s full? Good question.

If you look at the opening of the cell, it has around 2cm (3/4″) of plastic forming a cylinder down to the liquid, with a vertical cut in it. You can see that in the picture above.

The way I have been filling my batteries, I do it until the water just kisses the bottom of the plastic. This way I can easily see when I’m done and I don’t need to sit there trying to judge if it’s actually 3mm (1/8″) from the top, which is next to impossible.

I did take pictures of a full cell, but they all turned out blurry, unfortunately. I included one anyway, as you can still see how the water is just touching the bottom of the cell’s opening.

You also may be wondering about that hydrometer. It’s main purpose isn’t to fill the cells; it’s for testing the health of your batteries. If you suck up regular water with the hydrometer, the little arrow indicator will be at the bottom.

Ironically, pointing at the “water” setting. If, on the other hand, you suck up the liquid from the battery’s cell, it might look something like this:

My charge controller said the batteries were at about 96% when I took this reading so that matches. I will mention that this type of hydrometer isn’t the most trustworthy as all it is, is a float inside the plastic housing; not super accurate for sure. However, what you really want to check is consistency across cells in the same battery and across the batteries as well. If you test all of the cells and you find one that is way off compared to the others, then something is up with that battery. It’s usually best to test your batteries when the charge controller says they are at 100% so you know they should all be full. Also, don’t do your cell testing after you just added more water to them, as the readings will be off. Do your testing first, then start adding more water.

That’s the end of our lesson for today, boys and girls. You can now all be happy battery maintenance experts.

Solar & Wind Electricity

It’s time to talk about using electricity in an Earthship. From the title you can probably surmise that this is about using solar and wind to generate electricity, and you would be correct.

I should add here that renewable energy sources, in general, are what is desired. If you live on the coast and can harness tidal power, that is equivalent to what I’m going to talk about here. Similarly, micro hydro and geothermal would also fall under this category. Solar and wind just happen to be the two most common renewable energy sources.

The vast majority of people these days are familiar with solar panels and wind turbines, at least to a point where they understand that they can be used to generate electricity. There are a number of details to be aware of.

First and foremost, as mentioned before in other posts, an Earthship is designed to be independent. That means not connected to an electrical grid. This independence arose from the basic principle of wanting to create a building that could be built anywhere in the world, regardless of available infrastructure. The advantage to this is that if the grid goes down, you aren’t affected. Conversely, if you have issues with your electricity, you aren’t affecting anyone else. Considering how many times a year we have weather that knocks out the power grid, this can be a big advantage.

Once you start down the path of generating your own power, you need to take on a certain amount of responsibility for that. After all, when something goes wrong you are the one who will have to deal with it. There are some companies that will sell you all of the equipment and hook it all up for you. If something goes wrong you can call them, but you should be aware of what you are buying and what you are getting yourself into. It just makes sense if you want to get the most out of generating your own power.

Solar power is pretty ubiquitous these days. If you are interested in solar, some basic things you should research are: the average number of sun hours per year in your area (called insolation), what your power requirements are, what kind of sun-based view you have available to you and what type of system you are looking for.

When generating your own power, you have basically three options in terms of how to set it up: completely disconnected from the existing electrical grid, grid- tied and a hybrid of the two. Off-grid is pretty self explanatory: you are not connected to the existing electrical grid at all. In the case of being grid-tied, this means that all of the power you are generating is being fed directly back into the grid; you aren’t using any of it yourself. The electrical company pays you for the power you generate and this shows up as rebates or credits on your existing utility bill. The advantage to this is you don’t ever have to worry about using too much power. The downside is, if the grid goes down, so do you. It could be a beautifully sunny day, but if the grid is down, you have no power and you aren’t getting paid for all that power the solar panels are generating because the grid is offline.

A hybrid system is where you have battery backup and if the grid goes down, you still have whatever power you have stored in your batteries to use. It seems like the best of both worlds, but this is also the most expensive way to do it as you need more hardware to handle it all. You also need to have a grid line close by to tap into.

Solar panels come in lots of sizes and power ratings. You should probably aim for getting enough panels to generate a little more than double the power that you plan to use on a daily basis. This will help to compensate for cloudy days.

Wind turbines are a whole different ball game. I don’t have any personal experience with my own turbine, but I have done a fair amount of research and talked with those who have tried it. My biggest piece of advice to anyone wanting to try out wind power is to live on the property where you are planning to install it for at least three years (probably five is better) before getting a system. This will give you some idea as to what the wind is like over many seasons. As always, there are exceptions, such as if you live in a coastal region or the prairies where it is windy all the time then you probably don’t have much to worry about. But in areas like where we live (forested hills) wind is hard to come by a lot of the time. Most of the people I have talked to in the area, including some who have turbines, say it’s not really worth it in our area.

Some other things to consider with wind turbines is that they are motors in motion and as a result of that, they will wear out and break. Solar panels have no moving parts so they don’t have that problem. Also, there will be times when there isn’t enough wind to turn the blades as well as times during storms when there is too much wind and it may destroy your turbine. Remember this if you are in tornado alley.

The vast majority of wind turbines are the horizontal axis kind. Those are the ones with the blades all facing into the wind, like in the picture below.

These are generally speaking the most efficient, because their blades are facing directly into the wind. They also get the most wear and when really strong winds come up, most susceptible to damage.

The main other type is the vertical axis wind turbine. Here is a picture of one they have at Earthship Biotecture in Taos, NM.

These ones are less efficient in terms of the amount of wind the blades capture, as only one side of the axis catches the wind and the other pushes against it. There are lots of online articles about them and I’m sure the technology has changed over time, but this type of turbine are favored by Mike Reynolds. According to him, they take less wind to start turning, don’t spin as fast in strong wind because of that push back effect and last longer without needing repairs. If this is true, then if you amortize the average power generation over time between a vertical and horizontal axis turbine, taking into account down time for repairs, you might come out ahead with the vertical axis turbine simply due to the fact that it doesn’t break as often.

Of course, no discussion of off-grid living would be complete without talking about batteries. Your basic battery used for power storage for an off-grid home is the lead-acid battery. These are the same type used in golf carts and marine settings (boats). These are the cheapest, but by no means are they bad. They do require maintenance, however. You need to keep them topped up with distilled water as the electrical reactions use up the liquid over time. I do our battery maintenance once a month.

You can get sealed batteries and they have gel batteries as well. You may have heard about the company Tesla coming out with a battery solution of their own using Lithium-Ion batteries (the same type in your phone). I have looked into this somewhat as it seemed like a nifty thing, but it turned out to be not as nice as I would have hoped. First, it is not just a battery, as it includes a built-in charge controller, inverter and computer to control the whole thing. This isn’t very convenient if you already have an inverter and charge controller. The system is meant more for a backup/hybrid grid-tied setup. Also, it requires a connection to the internet to function (so they can give you over-the-air updates and monitor your usage). Ummm, no thank you.

There are other options out there as lots of companies are working on battery technology. In the end, it usually boils down to what you are looking for, what is available and what you can afford.

These are all the types of things you get into when you start thinking about going off-grid. For some people it is very interesting and they jump right in. However, there are many others who don’t want to be bothered with it all and just want power when they flip on the switch. Personally, I like knowing how much power we’re making and using and we manage our usage to match what we make.

We have been running our solar off-grid system now for over two years and we love it. We do have a generator as a backup for those long stretches of cloudy days during winter. We wouldn’t need it as much if we added more panels to our system. That will happen eventually when we get our Earthship up and running.

I do apologize for this article taking so long. I have worked on it several times, but it was degrading into long descriptions of Volts, Amps and Watts and I was trying to keep it a little simpler. If you do have any questions about this, feel free to leave a comment.

Voyages on this Earth

Earth
Our common frontier
These are the voyages of the Earthship Walden
Our five year mission
To explore strange building concepts
To seek out new life in dead architecture
To boldly build what Mike Reynolds has built before

Captain’s Log, Earth date: Two zero one six point one one point zero five. With the cold weather increasing, we constantly worry about attack. We have many projects to help us with this, but progress seems to have slowed down.

Kat-Hura: “Captain long range forecasts indicate White Klingons are closing in.”
Captain: “White Klingons? I hope we’re prepared for that. Captain to Engineering.”
Scotty: “Scott here Cap’n.”
Captain: “Scotty, how is that new shield coming.”
Scotty: “Already installed, Captain.”

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Captain: “Will that hold off the White Klingons, Scotty?”
Scotty: “Aye, Cap’n. We tested it last year and she worked a beauty.”
Captain: “How about the energy storage compartment? Did we get that closed up?”
Scotty: “Prrrrr, prrrrr…. GET OFF THE BLOODY COMMUNICAT… @#($&^#*#!!!…”
Captain: “Scotty? Everything okay down there?”
Scotty: “Aye, the dang cat walked across the console again.”
Captain: “Well, try to keep the hair balls down there to a minimum.”
Scotty: “Aye…”
Captain: “About the energy storage compartment…?”
Scotty: “Oh that sir! That’s also finished.”
Captain: “The energy modules are secured?”
Scotty: “Aye, snug in their own little box.”

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Captain: “Did we managed to seal it off.”
Scotty: “Aye, did that too. Even put on an access hatch so we can get in easily for doin’ maintenance.”

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Captain: “Good work, Scotty. That should work quite nicely.”
Scotty: “Thank ya, Cap’n.”
Captain: “Captain out.”

Captain: “Well, it seems we’re quite well prepared for those White Klingons. Nothing to worry about, Kat-Hura.”
Kat-Hura: “Yes, Captain.”
Captain: “Now, if only we could get to putting the bulkhead panels back on the walls in my sleeping quarters.”
Kat-Hura: “That work is still underway, but some progress has been made, Captain.”
Captain: “Really?”
Kat-Hura: “Yes, Captain.” (Brings up the view of the Captain’s quarters on the main screen) “As you can see, we have started with the section around the new porthole that was added.”

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Captain: “Well, that’s looking much better.”
Kat-Hura: “That’s not all, Captain. We have even put on several coats of paint.”

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Captain: “Wow, you guys have been busy.”
Kat-Hura: “Also, some of the detailing around the porthole has been completed as well.”

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Captain: “I’m liking the pine, it adds a nice touch.”
Kat-Hura: “Agreed, Captain. It will go well with the deep green colour.”
Captain: “Any other surprises, Kathura.”
Kat-Hura: “Just one, Sir.”
Captain: “Well, spit it out.”
Kat-Hura: “We also insulated and put a finished panel over the step up to your sleep quarters, Sir.”

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Captain: “Hey, that’s looking snazzy.”
Kat-Hura: “We also stained it for you sir, so it will match some of the other decor.”

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Captain: “Well, I’ll be worn out dylithium crystal. Things are progressing quite nicely around this shuttle craft. Is there any word from Earthfleet about getting started on the Earthship?”
Kat-Hura: “Unfortunately, Sir, they want us to have some engineers look over and approve the plans.”
Captain: “Dang them and their bureaucracy. Hopefully we can deal with that this winter so we can stay on schedule to begin next spring.”
Kat-Hura: “Yes, Captain. That would be ideal.”
Captain: “I guess we’ll just have to deal with it and keep on going.”
Kat-Hura: “So it seems, Captain. So it seems.”

We’re lovin’ the sun

A few posts back, I showed you this picture…

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… as a hint of things to come.

Well, things have come.

While Kat has been working hard on tearing out the interior of the trailer, I have been working on getting the solar array up and going. We bought the system back in the Autumn of 2014 and we are just now getting to hooking it up.

With the help of our good friend Andres, who happens to be an electrician, we went over all of the components one day in mid August, and then we went out and bought a whole bunch of little fiddly bits that he needed to get the job done correctly.

One of those fiddly bits was a grounding plate.

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This is a big plate of solid metal that you bury in the ground and run a large gage wire (#6) from it to your electrical box. This provides proper grounding to all of your electrical system. This is especially important if you get hit with lightning. ZAP!!

Here is the picture of the hole I dug for it and the trench for the wire. The plate needs to be at least 60cm (24″) underground.

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In addition to the electrical stuff, I also had to buy some stuff to make a rack for the solar panels. I chose to use these things.

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I’m sure they have an official name, but I don’t know what it is. They’re L shaped pieces of heavy gage metal with holes all along them. The holes make it convenient to connect them together.

I cut some pieces and bolted them together. Then I painted them with rust-proof paint so they will last longer in the weather. Then I started to haul them up and attach them to the roof over the trailer.

Here is the very start.

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I chose a spot on the roof along a screw-line so I knew there was something to connect to. I also reinforced the wood strapping underneath the roof, with a much larger piece of wood, and then drilled holes through it so I could bolt the metal rack supports I had built through it.

It seemed to work just fine, though I had a heck of a time climbing up and down the ladder, going back and forth from under the roof to on top of it. Oh, and I had to remove a hornet’s nest the size of a volleyball to be able to do the work under the roof. Nothing a little late night spraying couldn’t fix.

Here is the shot of the two bottom supports in place with a cross piece at the bottom.

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Lo and behold, here we have the first panel mounted on the rails.

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I ran more of the same metal rails down the back of the roof, which is what I connected the main supports to. I can unbolt them and change the angle if so desired. However, after getting all three panels up there, it felt a bit wobbly, so I added some extra supports. It’s nice and sturdy now, but the number of bolts I need to loosen to change the angle that the panels are set at has increased drastically.

Oh well, I’d rather have it stable and a bit more work to change than have it fall over in a big wind or heavy snow storm. Here is a picture of the final result with all three of 250W PV panels installed.

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Here is another look from a different angle.

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With the rack completed, we now needed to build a platform for the batteries to sit on. These aren’t regular car batteries. They are massive, deep-cycle, marine style batteries and we have eight of them. Each one weighs in around 55kg (120lbs). Needless to say, they aren’t the easiest things to move around.

For the platform, I took three cinder blocks and spent some time leveling them as perfectly as I could. The batteries have liquid in them so you want them to be as level as they can be.

Once I had that part completed, I took a nice new wooden pallet we got free from one of the building centers in town, and I cut a section off it to the size that I needed for the batteries. A piece of 3/4″ (1.9cm) plywood was screwed down on top of the pallet and then I put extra pieces around the edge. The final result looked kinda like this, but less blurry.

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With that all done, we could cart over the batteries. Here is the picture of all of the batteries in place on the wrack, with their connections to each other.

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The solar panels are mounted and the batteries are connected. Its time to start putting all of the connections together, so we need to crack open that big control box you saw in the first picture.

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Electrical work, like a lot of things, seems very complicated at a casual glance. In addition to the complicatedness, you have the issue where if you mess up you can electrocute yourself or burn your house down. These are not good things.

Luckily, I had Andres there to do all of the connecting. Each individual part is fairly straight forward, but once you start putting a lot of simple things together, it gets a lot to keep track of.

We eventually got everything connected. That was late yesterday, and the sun had already gone behind the trees, so we weren’t going to get much solar power that day. Today, however, it was a beautiful sunny day and around 10am I snapped this picture of the display on the charge controller.

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In case you don’t read “electric”, that basically says we have 79.5 V(olts) coming in from the solar panels and the batteries are currently sitting at 51.8V. I’ll talk a bit more technically about it at the bottom, so read on if you want the technical stuff.

The system we bought is pretty fancy; far more than what we need for just the trailer. We bought it for the house, though we will be adding a few more solar panels to it when we get to building the Earthship. It will be overkill for the trailer, but that means we shouldn’t have to worry about having power, once the batteries are fully charged.

Our inverter came with a nice little monitoring device. It came with 15m of cable too, so we disconnected it from the control center and ran the wire into the trailer so we can keep an eye on things without having to go outside. Here is a picture of what it was doing this evening.

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At the time that picture was taken, it was about 18:00 and I had turned on the generator. You see, with the batteries having been unused for two years, we want to make sure they are fully charged before we start using them. This is why we are still running the generator in the evening, to help top of the batteries.

Charging batteries is an interesting topic all on its own. We have 8 batteries, each one being 6V. A good analogy for a battery is a car tire filled with air. A tire stores a certain quantity of air at a certain pressure. Volts can be thought of as electrical pressure. Electrical quantities are measured in amperes, or just A(mps) for short.

Let’s say your tire is getting low and you want to put more air in it. If your tire is at 25psi (172kPa) and you want to get it up to 30psi (207kPa) you must be pushing air into the tire at a pressure greater than 30psi. If you don’t, you will never fill your tire. This works the same for batteries, except I can connect batteries together to make larger batteries. You can’t really do that with tires :P.

In our case, our eight batteries are connected in series to create one big 48V battery (8 * 6V = 48V). So if we want to be able to charge those batteries properly, we need to be pushing more than 48V into them. On top of that, you don’t ever want your batteries to drop down to only 48V, that would be too low. For this system, getting them up around 57 is where they will be fully charged, roughly speaking.

Luckily, each of our solar panels puts out 30V at max capacity. The panels are also wired in series so, they can push over 90V into the system. There is a magic box called a Charge Controller that takes that incoming voltage from the panels and regulates it to properly charge the batteries. Ours is pretty fancy and it does a lot more than just that, but I can’t say I know even half of it yet. Having the solar system now so we can learn about it and get used to it will make things easier when we get to using it in the Earthship.

You may be wondering where Watts come into all of this, as electrical devices usually have a maximum Watts rating on them. Well, Watts are just Volts * Amps, or pressure * volume if you’re following the analogy. Watts is a measure of energy. Electrical companies charge you by the kWh, which is kiloWatt-hour. A kiloWatt is just 1000 Watts. An hour, obviously, is a measure of time. This gives a unit of power, which is energy used for a duration of time. If I have a light bulb on that uses 60W and I leave it on for 1 hour, that’s 0.060kWh of power used.

The math can get heavy as you go further, but you can start to get an idea of what it would take to determine:

  • How much energy your batteries can store
  • How much energy your solar panels can put back into your batteries, on a good day of sunshine
  • How much energy you can expect to use per day, based on the electrical appliances you use

Once you start working that out, you can figure out just how large a system you will need to run the stuff that you want. However, solar equipment isn’t cheep and your best course of action is to reduce your usage. If you can do that, and buy only the solar gear that you need, it will easily pay for itself within a short amount of time. As the costs of being connected to the electrical grid continue to rise, being disconnected from it makes a lot of sense.

Oh, just so you know, we put 3.3kWh worth of power into our batteries today from the sun. We look forward to days like this.

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