# Taking a Garden RR Off Grid



## Tom Farin (Apr 3, 2008)

I'll bet I'm not the only forum participant concerned about global warming and/or our dependence on foreign oil. As much as I'd like to convert my whole home to solar Photovolactic power, without more incentives than those available in Wisconsin, it currently doesn't work economically. Not on a system that would cost me at least $75,000. Besides, my major chunks of spare cash are putting two kids through college. 

But I'd like to experiment a bit, preparing for the day when solar PV is a bit more cost effective. I ran across this article on getting your toe wet and gaining experience by taking a bedroom off grid. 

http://www.off-grid.net/2008/03/27/take-one-room-off-grid/ 

I thought, "If you can do that with a bedroom, why not a garden railroad?" By the way, this approach could work for any of you that would like to run a GR in a location not close to grid power. 

Why did I post this here? It's the battery power forum isn't it? /DesktopModules/NTForums/themes/mls/emoticons/laugh.gif Solar panels are being used to generate power which is stored in batteries. Power is being drawn from the batteries to power stuff. Sound at least a little similar to some of the other posts in this forum? Now if I could get Tony Walsham enthused about developing a radio control system to manage an entire solar powered railroad ... /DesktopModules/NTForums/themes/mls/emoticons/laugh.gif 

Yes, the scale of the battery power in this project is somewhat greater than the scale of most battery power posts to this forum. But I consider this to right on topic for this forum. And you are the august group of participants in MLS most likely to be able to help me out. 

My North Pacific Coast garden railroad almost came alive at the end of last summer. The track was laid. The golden spike ceremony was set. I just ran into a few last minute problems getting power to the layout. So a bunch of friends attended and complimented me on the static trains I had on display. I won't get into the power snafu here as it might subject me to ridicule from this group. But I've been obsessing about power all winter. Now that the 100" of snow we received in Madison, WI this winter has mostly melted, I'm about ready to get going. 

The NPC was built to be a radio controlled, battery powered layout - the old fashioned way - packing rechargable batteries in tenders and battery cars. I also planned to light my structures with solar power outdoor light components. That won't change. You might say, "Farin, you're already off the grid with battery power and solar." That is an incorrect statement for a number of reasons. 
(1) The batteries need to be charged. I'll bet most of you do it with grid power. 
(2) I have a very nice string of old fashioned metal low voltage lanterns that will be used to illuminate the walkway running through the middle of the layout. Input to the transformer powering these lights is 120V AC. 
(3) There will be a water feature requiring a lift pump to bring water from the catch pond at the bottom of a stream back to the top. 
(4) I ran 20A 120V lines and placed outlets all around the layout for occasional and possibly unplanned continuous use. 
So what I'm talking about is taking all of the above off the Alliant Energy power grid and substituting a small off-grid setup conceptually along the lines of that pointed to by the bedroom link earlier in this post. 

I've researched the components and have refreshed my mind on electrical math. Five books on solar PV power are on their way from Amazon. So I think I can deal with the general issues - what components to use and how much capacity I will need. I plan significant overcapacity in all but the solar panels and battery banks so I can upgrade later. 

Here's where I can use some help. 
(1) Have any of you ever tried this stunt? If so, I'd appreciate learning from your successes. And from your failures. 
(2) It seems ludicrous to generate 12V DC with PV panels, charge a 12V battery, invert the battery output power to 120V AC, then plug in transformers to convert back to DC to charge the batteries my engines will pack. Any thoughts on a shortcut? 
(3) The same could be said for the pump that will move the water except the AC back to DC step would be skipped. 
(4) The same could be said for the low voltage lanterns. DC to AC to DC. 
(5) What are the gotchas I'm missing? 

I'd also welcome comments from anyone intrigued by the idea that would like to network on implementation. 

By the way, I realize this is not the most cost effective way to power a garden railroad. But then, is there anything about a garden railroad that is cost effective? /DesktopModules/NTForums/themes/mls/emoticons/crying.gif 

It's a hobby, and an opportunity to learn something new while making a very token contribution to solving some of the problems we all face. 

Tom


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## Guest (Apr 3, 2008)

Tom, 
I have a heart for Off-Grid Power, but I'm really only interested in less dependence on anyone (fed/state/local gov, foreign oil, etc...) and If the choices I make help the environment, so be it... 
I mentioned in another posting that I'd like a small PV unit to power my MAHA Batter Charger so I could be a "Green RR", for no other reason, than the heck of it. Thought it was a cool idea! 
Like you I'd love to have the funds to invest in a full-blown system to power my home or heat the water at my Salon...but it's just not there right now. So what do I do?....I'm taking another route for now, which reminds me I need to log off the train fourm and read some more on Home Brew Diesel for my truck...again for less dependence! 
I have seen Solar lift pumps for garden ponds-google should help there! you could always replcae the bulbs in your old lights to LED's and power from solar (or even retrofit some solar bulbs into them) 
Interesting stuff for sure! Good Luck 
cale


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## Del Tapparo (Jan 4, 2008)

Posted By Tom Farin on 04/03/2008 1:13 PM


(2) It seems ludicrous to generate 12V DC with PV panels, charge a 12V battery, invert the battery output power to 120V AC, then plug in transformers to convert back to DC to charge the batteries my engines will pack. Any thoughts on a shortcut? 

Tom




Tom - It's actually difficult to find an AC input battery charger. Look at the R/C car and Airplane hobby shops. Most of their chargers take a 12 volt input, usually their car battery when out in the field.


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## Guest (Apr 3, 2008)

Great Idea Del....nvr considered it! Pick up a PV from Northern Tool...and done! 

Thanks, oh and Welcome into the world of LS Trains Tom!


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## jimtyp (Jan 2, 2008)

For a charging batteries for a loco could you use one of those solar garden lighting systems?


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## Dave Ottney (Jan 2, 2008)

The RC flying club I belong to has a solar panel charging a deep cycle battery at each field. The battery is connected to panel that allows us to connect chargers for flight packs. This works very well and gives us the ability to recharge packs without using our vehicle batteries. I can't see why this type of setup couldn't be used for model RR'ing. 
Dave


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## Tom Lapointe (Jan 2, 2008)

For a charging batteries for a loco could you use one of those solar garden lighting systems?

Most inexpensive solar panels provide only a few milliamps (1 milliamp - 1/1000 amp) of output, vs. the AMPS most LS locos require. 
In short, to run a loco maybe an hour or so a week, you MIGHT have to have it on your "solar charger" ALL WEEK./DesktopModules/NTForums/themes/mls/emoticons/crazy.gif 
This is also assuming LOTS of sunshine  (no rainy or cloudy days/DesktopModules/NTForums/themes/mls/emoticons/unsure.gif ). I also would try it ONLY with either Nicad or NiMH batteries, NOT LiPo batteries because of their intolerance for improper charging./DesktopModules/NTForums/themes/mls/emoticons/sick.gif 


/DesktopModules/NTForums/themes/mls/emoticons/blush.gifTom


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## Tom Farin (Apr 3, 2008)

First of all, thanks for the responses. 

Cale, 
Thanks for the tip on solar lift pumps. After spending some time with Google last night, I found many are too small for the lift I need. On the other end of the spectrum are solar well pumps for watering livestock and the like - $1,000 on up. But there is a much wider range of DC pumps than solar DC pumps. I need to spend more time figuring exactly how much GPH I'm going to need. I should be able to find a solar pump or a DC pump powered by my solar setup that meets my needs. 

Also, I calculated the power needs of my string of low voltage lights. Let's see, 18 Watts times 13 lights is 234 Watts. Assuming 4 1/2 hours of lighting per evening and 4 1/2 hours of sun per day (wisconsin average) it would require 250 watts of PV panel at about $5 per watt - Yikes - $1,250 worth of PV panels just to run the lights (not counting batteries and other stuff). As you point out, I could replace the 18 watt bulbs with parts from solar lights for about $7 a light --- $91 plus some labor - not a difficult decision to make. In addition I pick up a photo sensor at each light that knows when to turn it on and off. 

Del & Dave, 

Never even thought about the radio control battery operated car market. I know a whole lot more now than I did 24 hours ago. You are right. Take two 7.2 volt packs, wire them in series and you have 14.4 volts of battery power. 7.2 volts is a real common RC battery pack voltage available in a variety of NiMh battery form factors for different engine sizes and power needs. And you are right, there are plenty of DC chargers that take 12 volts as an input voltage and charge 7.2 volt packs. In addition if more voltage is needed, there are 8.4 volt and 9.6 volt packs. 

Jim, 

The reason why you want to go with a purpose built charger is to stop charging when the batteries are fully charged, trickle charge to maintain, and cycle batteries that are performing in a less than optimal way. I had been thinking about one of the Maha chargers and discovered last night that the MH-C204F can accept both 120V AC and 12 V DC. But the problem that creates is charging individual 1.2 volt AAA or AA batteries which once charged are pressed in place in a holder rather than soldered together in a 7.2 volt pack. I like the RC approach better as it offers a much wider range of battery form factors, voltages, and 
mAH capacity ratings and would allow me to charge the batteries while still in the engines. 

Tom, 

You are right about the inexpensive solar chargers. But I'm planning on putting a bit more coin into my setup. A BP 3125 solar panel puts out 125 Watts for $580. 125 Watts at 12 volts is just over 10 amps. In 4.5 hours it would put over 500 Watts into a storage battery. At 12 volts, that's roughly 40 AH of potential re-charge per day. I'm thinking about starting with two 6 volt deep cycle batteries wired in series, totalling 12 volts. I'm still working on what I need for Amp Hour ratings on the batteries (based on load calculations). But let's assume 120 AH with a maximum discharge of 50% or 60 AH of usable stored juice. In normal days, a battery 50% discharged could be brought back to full charge in 1 1/2 days using the BP panel. I don't plan to run trains that often. 

I'll use stored power in the deep cycle batteries to charge the NiMh packs in the engines. This setup should provide more than enough power for that application. What is holding up my design is working through the lighting and pump issues discussed earlier in this post. Thanks to Cale, with the issue of the lights out of the picture, it's really down to the current draw from the pump. 

Again guys, thank you for your thoughts and help. Any additional thoughts on the pump issue, my math or any gotchas I've missed will be appreciated. 

My $65 1000W DC-AC inverter just showed up from UPS. Now that you guys have helped me figure out how to do most of what I want to do with DC, I may just have to throw it in the trunk.  

Tom


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## jimtyp (Jan 2, 2008)

Tom, I think this is very interesting, I would like to see what you end up with.


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## Dave F (Jan 2, 2008)

Phew.. I thought you were lost to the Live Steam crowd there for a minute...


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## ConrailRay (Jan 2, 2008)

Tom, 
Pretty interesting project. 
I think you should convert part of your pond/stream to a working hydro-dam to replace some of the power " border=0> 

Our local club is going to build a small layout for a local arboretum and was considering charging a battery from solar power and came across this site: 
http://www.hightechscience.org/solar_express.htm 

-Ray


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## lownote (Jan 3, 2008)

This is such a great idea! So I have a couple questions--are you planning to use a solar panel for each charger, or one big solar panel that feeds a bigv battery, which then feeds individual chargers? Whatever you do, please keep us informed. I'm really interested 

ConrailRay, that's a cool link--thanks 

Beats me why we don't have an equivalent to the Manhattan project to work on alternative energy


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## Tom Farin (Apr 3, 2008)

Dave, 

I do have an investment in some live steam engines. While you might argue they are off the grid, they are not consistent with using renewable energy (unless you converted to a wood smoke box to raise steam). Most run on butane, a petrolium product. So no, this will be primarily a sparker railroad. 

Ray, 

Hydro-dam? Interesting idea. Are you aware of anyone that has ever done this in scale? No, please don't tell me if you know of one. I certainly don't need another project right now./DesktopModules/NTForums/themes/mls/emoticons/hehe.gif 

Thanks to the link to the solar powered garden RR. 

Lownote, 

That's an interesting question. If you look back through this thread, my intention was to power lighting, pump and chargers with a single PV system. But thanks to Cale, I'm going to power my 13 path lights with 13 solar units. The verdict is still out on the pump as I can either go with a solar pump or a DC pump tied to my solar setup. 

As for battery charging, it makes a lot more sense to me to use a single solar setup regardless of the number of chargers I want to hook up. My railroad will actually terminate in my basement (see following photo) and the charger setup will be down there. I plan to put a solar panel on my roof above the place where trains enter the basement and run the solar CD output lines to the basement where the rest of the equipment will be located. 

Everyone, 

There are two main kinds of PV systems. The first is grid-tied. The PV solar system is tied to power company power. When a grid-tied solar setup is producing more power than is being consumed by electrical devices tied to the system, excess electricity is sold to the power company. When the use of power exceeds the supply of power from the solar PV system, it is supplemented by power from the grid. 

The advantages of a grid tied system are: (1) it doesn't require batteries, (2) all of the power being produced by the solar system is used (locally or by the grid), and (3) the solar system doesn't have to be sized to deal with peak power usage as peak needs can be met with grid power. 

The disadvantages of a grid tied system are (1) grid-tied systems do you no good if power needs are nowhere an electrical line,(2) you need to get permission from the power company to hook your system to theirs, and (3) you need to invert the DC power produced by the system to AC to supply it to the grid. 

Tying your PV solar system to the grid will probably require professional installation and certainly makes no sense if all you want to do is power a yard light like I'll discuss in the next post. 

The advantages of a non-grid-tied system are (1) you can do it yourself as long as you conform to electrical codes, (2) you can have power in locations where running an electrical line could be cost prohibitative (like a Garden RR on your recreational property where you have no grid power), (3) Where the needs are small enough that it doesn't make sense to tie to the grid, (4) Where for moral, personal, or political reasons you want to be totally independent of the grid. 

The major disadvantages of a non-grid tied system are (1) you will need to invest in storage batteries as your need for energy often occurrs at different times of day than when the sun is producing power, and (2) you may find yourself in a situation where you will need to overdesign system capacity to deal with peak load needs. 

Having said all this, my experimental PV system aimed at powering my garden RR will be a non-grid tied system. In my next post, I'll cover my first step, the least expensive non-grid tied railroad application I can think of. 

Tom


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## Tom Farin (Apr 3, 2008)

Oops, 

Forgot to include the photo. 










The NPC garden railroad will enter my basement staging area through the culvert/window opening in the photo. The charging station, and the equipment for the non-grid tied solar system will be located in this area. The solar panel itself will be on the south-facing roof above the culvert. 

Tom


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## Tom Farin (Apr 3, 2008)

Here's an example of one of the simplest and cheapest off-grid solar systems available. 



It is a stainless steel solar powered yard light available from Harbor Freight for around $5. I stuck two of these in beds last summer. Every night (almost without fail) the two lights turned on at dusk and supplied power well into the evening. We had a sunny day yesterday. They were still shining as the sun came up this morning. 

The self contined power center of the unit is a disk about 5" in diameter and about 1" thick. Visible in the top of the unit are the light sensor (small dot in the bottom left of the top), and the Photovolactic unit (square in the center of the top). 



Unscrew the four screws in the bottom of the unit and open it up and you will see this. 



The large disk in the left of the photo is the top half of the power unit. The smaller disk to the right is the lower half of the power unit. The left disk contains the printed circuit board that is the brains of this device. The PC board takes incoming sun-generated power from the PV unit, converts it to the 1.2 volts needed by the rechargable battery in the right side, storing the sun's energy in the battery. It also contains a charge controller that cuts off charging to the battery when it is fully charged. This portion of the circuitry operates best when the sun is out, not quite as well in cloudy conditions, storing the electricity in the battery. 

When evening comes, assuming the switch on the right disk is turned on and the light sensor detects a low light condition, the brain will begin pulling current from the 1.2 volt battery rectifying the voltage to that needed by the LED and turn on the light. The LED will continue to produce light until either the battery's voltage falls below the minimum allowed by the brain, or the light sensor indicates that it is daylight. 

The LED would not normally be visible in this photo. But you can see it laying just to the left of the center in the left hand disk. Its two silver leads originally protruded through the two holes dead center in the right disk. The two leads were attached to the green and blue wires laying loose in the right disk. To remove the LED, I merely shipped these wires and pulled the silver leads through the holes by tugging on the LED located on the non-visible side of the right disk. 

Why did I destroy the electrical continuity of this neat little unit? Because I wanted to adapt it top an alternative use. Read more in the next post. 

Tom


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## Tom Farin (Apr 3, 2008)

You don't need to know anything in the last post to use a solar powered yard light. Turn on the switch, stick it in the ground where it will receive light and use it to illuminate pathways around your railroad. But this cheap $5 self-contained off-grid PV system can be adapted to a variety of other uses. 

But before doing so it is useful to understand that LEDs are not light bulbs. LED stands for Light Emitting Diode. The diode is the electrical equivalent of the plumbing check valve. A diode allows current to move through the device in one direction, but not the other. A Light Emitting Diode produces light when the current moves through the diode in one direction, and is completely dark when current attempts to move in the wrong direction. So it makes a difference how a LED is wired into a circuit. 

The two leads coming out of a LED are the LED's cathode and anode. Generally the cathode is marked in some way. With the Harbor Freight LED there is a flat spot on the diode's bottom next to the cathode. The cathode was connected to the green wire before the leads were cut. You don't need to know the difference between a cathode and anode. You just need to know that when you reconnect the spliced wires, the green wire needs to be reconnected to the cathode and the blue wire to the anode. 

The most common reasons for separating the LED from its incoming wiring is that we want to increase the distance between the power unit and its LED or change its orientation. 

One other thing about LEDs. They produce more light per unit of power than any other lighting device priced at less than a king's ransome. And they last nearly forever. 

Powering Your Garden RR Structures Off Grid 

Say you spent 20 hours putting together your steam engine house. To be prototypical, you want it to light up at night. You could run wires from the grid and light a grain of wheat bulb in the engine house. But what a bother. First of all you would need to run wiring. Then you would need a switch to turn the lights on and off. Then if you want to take it inside out of inclement weather, you would need to disconnect it from the grid. If it's raining and you're in a hurry, you'll probably forget, yanking wires out of the ground. As Winnie would say, "Oh Bother." 

Of course, you could power that nasty power consuming incandescent grain of wheat light with a locally contained battery. You could use a light sensor to turn the lights on and off. But then you'd need to change batteries as those power hungry grain of wheat bulbs run them down. We build railroads to run trains, not to perform maintenance. Have you wondered why most traffic signals have been converted to LED lighting? 

On the other hand, we could splice about a foot or so of wire between the the LED leads and the blue and green wires in our Harbor Freight power unit, mount the LED inside your structure, and place the control unit in a sunny location, maybe on the back side of the structure's roof. But there would be this big power thing mounted to the back side of the roof of your otherwise-pristine engine house. But with a bit more creativity you might be able to remove the light sensor and PV unit from the power unit, splice some additional length into the electrical lines feeding those devices and mount the electronics under the roof and just the PV and sensor on the roof. 

Doing so would substantilly cut maintenance and allow you to move the whole thing inside in inclement weather. 

Best yet, you could brag to your friends that your engine house has a "complete self-contained, off-grid Photovoltaic system". Then you could launch into an explanation of how an off-grid PV system works. You know, the PV unit, the electronic brain, the battery storage, and the controls over your LED light. Those bragging rights would come at the princely cost of $5 and a few hours of your time. And in a tiny little way, you'd be reducing our dependence on non-renewable energy sources and making use of our vastest renewable source, the sun. 

Cool. /DesktopModules/NTForums/themes/mls/emoticons/hehe.gif 

Tom


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## Tom Farin (Apr 3, 2008)

I bought 13 of these Malibu low voltage lights at pre-winter close out at Home Depot around 6 years ago. They are all metal powder coated lights. My recollection is they listed for around $40 apiece and I paid around $20. they are as close to a railroad lantern as anything I had seen. Their boxes have been decorating my shed until this spring. 










In a few weeks, the 13 light string will illuminate the walkway running through my garden railroad headed down to my pond. They represent a great little case study in the issues of using solar power in a Garden RR. I'm going to look at three alternative approaches to powering these lights. 

GRID POWER 

The approach I had planned to take is to pick up 100' of gauge 12 low voltage cable ($50), string the lights down the cable and power the lights with a 300 watt Malibu transformer ($100) plugged into 120V AC courtesy of the grid. Assuming my cost in the lights themselves is sunk, my total up front cost is $150 plus my labor.  

But that's not the end of the costs. 13 lights with 18 watt bulbs consumes 234 watts of power. Assuming they are lit 4 hours per night, they will consume 1 kilowatt hour of grid electricity per day or 365 kilowatt hours per year. At a cost of 10 cents per kilowatt hour, my electrical cost is $36.50 per year. 

Assuming I also replace six 18 watt bulbs per year, my maintenance costs (exclusive of my time) will be another $16.50 per year. 

SUBSTITUTE SOLAR POWER 

Assume that I power the same lights using the same low voltage power cable with solar power. I will save the cost of the transformer ($100) and the annual cost of the electricity ($36.50). 

But a self-installed complete off-grid PV system is estimated to cost about $7 a watt. In Wisconsin, daily full sun solar radiation averages 4.5 hours per day. Given that I gather power 4.5 hours per day and light the lights 4 hours per night, the solar generating capacity of the PV system would need to be roughly 234 watts. At $7 per watt, the system would cost $1,638. Net of the savings from eliminating the Malibu transformer, I'd be out about $1,500 up front. Based on the $36.50 annual electrical savings, my payback on my $1,500 net investment would be OVER 40 YEARS. 

You could validly argue that my payback calculation fails to consider the increasing cost of electricity over time. I could validly counter that it also fails to consider the time value of $1,500 spent now against future savings in energy costs. But our arguments would be moot. At age 62, I'm never going to see a return on my $1,500 investment. 

The above example illustrates why most people feel solar power is not a cost effective solution. But this next example will prove that assumption wrong. 

REDUCE POWER CONSUMPTION THEN SUBSTITUTE SOLAR POWER 

Pick up any book on installing a PV system and you'll find the first recommendation in the book is to focus on reducing power consumption BEFORE sizing a PV system. That's because steps taken to reduce power consumption often have very short payback periods. A good example is replacing incandescent light bulbs with compact fluoresent bulbs. The case is so compelling that some states have enacted statutes REQUIRING the replacement of incandescent bulbs with CF bulbs. 

But beyond that, a movement to PV solar power forces you to change the way you think about power consumption. You are moving from a situation where power feels like it is unlimited as long as you are willing to pay a nominal cost (10 cents a kilowatt hour where I live) for your additional power consumption. You are moving to a situation where additional power is extremely expensive ($1,500 for 236 watts of solar PV power). 

I found a good example by accident in following the TOC/GR/Bachmann controversy. By the way, in spite of the fact I've crossed swords with TOC once or twice in the past, I'd defend to the death his right to free speech. But that's not my point. 

I stumbled across an article TOC wrote at the GR Web site explaining a potential modification to the Bachmann K-27. It involved removing the LED from the headlight and substituting a grain of wheat bulb. That recommendation comes from a world where asthetics are important and additional energy has been really cheap. The esthetics of a more prototypical color warmth produced by the grain of wheat trumps the minor additional energy cost in TOCs mind. I understand TOCs viewpoint as I've lived there all of my life. 

But were TOC to find it necessary to pay for the additional energy capacity needed to PV solar power the electrically inefficient incandescent grain of wheat bulb as compared to the very energy effecient LED, he might be forced to make a different decision. This very small example represents the change in priorities we all may be forced to make as we deal with global warming and our dependence on non-renewable energy sources. 

The TOC grain of wheat/electrical cost concept directly applies to my string of yard lights. The problem with powering the yard lights with PV solar isn't the cost of PV solar power. The problem is the highly electrically inefficient 18 volt incandescent bulbs. 

What if I were to substitute a white LED for the 18 volt incandescent bulb in each of my 13 yard lights? What if I was to power each LED with the self-contained off-grid solar PV unit provided as part of the $5 Harbor Freight Yard lights? How would that change the economics of my decision? 

I would save the cost of the Malibu Power pack and the 100' of low voltage cable ($150). I would save the annual cost of grid power ($36.50). I would save the annual cost of replacing the 18 volt bulbs ($16.50) -- the LEDs are unlikely to burn out in my lifetime. 

And it would cost me $65 for 13 Harbor Freight lights. I come out $85 ahead up front and save about $50 per year. 

"But what about your labor, Farin?" I'm betting that my up front labor investment won't be significantly greater in converting my 13 lights to solar than the initial time needed to string the cable, attach the lights, debug the system and set the timer on the grid based system. Annual time savings could be significant as I won't be squatting on old legs to change bulbs and won't have to deal with interruptions in my electrical line cause by critters and shovels. 
It's time to get the soldering iron and solder out. Step one will be to solder the LED to the two terminals shown in this photo. 










Once I've done my first conversion, I'll post some conversion photos. 

Tom


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## Dan Pierce (Jan 2, 2008)

Why just think solar, think windmill for generating electric power. 

Also, windmill for pumping that water. It only flows when the wind blows.


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## TonyWalsham (Jan 2, 2008)

Tom, 
I am reading your thoughts with great interest. 
Have you considered that the incandescent bulbs actually radiate light very well from the side, whereas LED's generally are very directional and don't radiate light from the side very well at all. 
You may have to construct a special pcb insiide the lantern holding multiple LED's pointing sideways to radiate light through the frosted lens.


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## Guest (Apr 7, 2008)

to add to what Tony said...well not really, but another thought...I use the 12v GOW bulbs in my engines, very little draw...and a nice light?


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## Tom Farin (Apr 3, 2008)

Dan, 

Assuming your question wasn't tongue-in-cheek, are you talking about a scale windmill (1:20.3, 1:29, 1:32) or full size? I doubt that a scale model windmill would generate enough power to pump the water I need to pump uphill. I doubt whether the City of Madison is going to allow me to install a full size windmill to power my garden railroad. Then there's the whole issue or either battery storage or not being able to pump water when the wind isn't blowing. For now, hydroelectric and windmills are on my back burner. 

Tony, 

Thank you for your comments. You certainly raise a valid issue relating the the relative light dispursion of GOW vs. LED. In my yard light application, my primary need is to illuminate the pathway through the bottom of the light rather than through the sides. So the LED will probably work in an acceptable manner in this application. I'd have to put up with the lack of significant glow through the sides of the light unliss I dispurse the light in some manner. 
Lack of dispursion would be a much greater issue in lighting a structure. Some kind of diffgusion method would be needed in that application. 

Cale, 

I plead guilty of trying to stretch an example a little too far. What you are saying to me is that the draw from the GOW is relatively small in relation to the draw from the engine, sound board and other accessories. Fair enough. 

But that raises a much larger issue in powering a garden railroad with solar. One of the criteria we may be forced to elevate in evaluating engines and their accessories in the future is the overall current draw of the eengine. In a today's world where the supply of power seems to be infiniite and the marginal cost of power is very low, they are not huge factors. Not as long as we are willing to put up with shorter run times on battery powered locos and purchase higher capacity transformers for track powered engines. 

But in the future when the marginal cost of additional power is much higher than today ($7 a watt in a solar PV application), we may need to reevaluate our priorities. I wonder how the solar powered railroad linked to earlier, dealt with the issue of power usage in their model railroad. 

Solar Railroad 

In their site they talk a lot about the system they use to supply the power. But I don't see any discussion as to the choices they made to limit power usage before designing the system. Maybe they had enough funding that they didn't need to address the power usage issue. As you and I already stated, most of us are not in that position. 

I appreciate the comments and feedback guys. 

Tom


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## Tom Farin (Apr 3, 2008)

*Components of an Off-Grid PV System* 

The simple off-grid PV system discussed a few posts back (Harbor Freight Solar Powered Yard Light) has the most important components of an off-grid photovoltaic system. But as an off-grid PV system gets upsized to deal with more and more power requirements, additional components may be necessary. So this is a good time to review the potential compenents of an off-grid PV system. 










*Photovoltaic Array* 

The system begins with the photovoltaic array that turns the sun's energy into direct current electricity. As our electrical needs grow, we will need to upgrade from the small (2" x 2") array in our yard light to a much larger array as we add power demanding components to our system. In a whole house system, an individual PV panel might provide 10 amps of DC at 12 volts, 120 watts of electrical power. Need more watts of power? Add more panels. Panels can be wired in series (increasing voltage) or in parallel (increasing amperage). 

*PV Array Disconnect* 

This allows the array to be disconnected from the rest of the system for maintenance. That's important with a big PV array as large DC loads can be as fatal as large AC loads. It also protects components down stream from the PV array from overload. For example, should an incoming house 240 V AC line be knocked down by a wind storm and make contact with the right spot on the array, the off grid system is suddenly an on grid system and the load might be way beyond the capacity of the wires and other down stream components. The PV Array Disconnect's main breaker would trip, protecting the components. 

*Charge Controller* 

The primary job of this component is to protect the battery bank from being overcharged. It does so by monitoring the charge levels of the batteries cutting of the current from the PV Array when the batteries are fully charged. It might provide a trickle charge to maintain the battery charge level once the battery is fully charged. It might also monitor battery voltage levels to make sure the charge doesn't get too low. It can be very hard on a battery to go through multiple cycles where the battery is full discharged then fully charged. Full discharge cycles can significantly shorten the life of the batteries (often the second most expensive component of an off-grid system. 

It is not uncommon for charge controllers to cut off output from the battery bank to power users when the batteries are 50% discharged. That is an important consideration in designing battery capacity of an off grid system. You will need batteries totalling twice the amp hour capacity you will need to power your devices if battery discharge is limited to 50% of capacity. 

*Battery Bank* 

This is the bank of batteries used to store the current generated by the solar panel until needed by devices using the power. Keep in mind a solar panel will generate electricity during daytime hours only. The generation will be greater in full sun than when the PV array is shaded or there is cloud cover. In Wisconsin, we average 4 1/2 hours of full sun per day over the course of a year. The batteries are needed to deal with power needs at times of day when power is not being generated and during stretches of overcast days. 

It is common for small off-grid systems to be 12 volt systems. That's because 12V is a common battery size and many electrical devices are designed to operate at 12 volts DC. We could store and deliver 12 volts with a single 12 volt battery, multiple 12 volt batteries wired in parallel, two six volt batteries wired in series, or some combination of the above. 

But larger off-grid systems are often 24 or 48 volt systems, created using 6 or 12 volt batteries wired in some combination of series and parallel. Why the higher voltages? Because for a given number of watts of power, the higher the voltage, (and the smaller the amperage) the smaller the wires needed to distribute electricity in the system. Because PV arrays can be wired in any combination of series and parallel, just like the batteries, you could construct a 48 volt array to charge a 48 volt battery bank. The electrical wires wouldn't need to be anywhere as large for a 48 volt system as those needed for a 12 volt system producing the same amount of current. Anyone who has tried to buy brass track lately knows that copper is the new gold. Smaller wires on long runs between PV arrays and battery banks can significantly reduce cost. 

The down side of a 48 volt system is transformers are needed to step the voltage down to 12 volts if 12 volt DC devices are to be powered. 

*System Meter* 

Larger systems often have system meters that monitor things like the state of the battery charge, and current utilization by the system. They provide much the same function as the gauges (or idiot lights) on your auto that monitor battery voltage, alternator charge rates and the like. 

*Main CD Disconnect* 

This component does much the same thing as the AC panel found on your home. There is a main breaker that protects the electrical lines going to the devices and the battery bank from current loads in circuits that are abnormal (short) or beyond the capacity of the wiring. In addiiton there may be breakers controlling current to individual DC circuits for lighting, pumps, etc. This panel may also include the transfomers need to step voltage down from the 24 or 48 volts provided by the batteries to serve 12 volt circuits powered by the system. 

*Inverter* 

If you are going to power 120 V AC devices with your off-grid solar system, you need to convert 12, 24 or 48 volts DC to 120V AC. In addition the inverter may monitor incoming power vs. outgoing demand for power and tap into a supplemental power source when demand for power exceeds supply. 

*Backup Generator* 

Some inverters are sophisticated enough to turn on a backup generator to increase the supply of power when the demands for power exceed supply as a result of a load beyond the PV system capacity or when the battery bank source is turned off by the Charge Controller because of the level of discharge of the battery bank. 

*AC Panel and Disconnect* 

Many smaller inverters allow you to plug AC devices directly into the inverter. But in larger systems there may be multiple AC circuits, each needing an appropriate capacity breaker. In addition the main breaker will allow the AC lines to be disconnected from the inverter and trip when the AC load exceeds the capacity of the inverter and DC system components. 

Not all of these components will be needed to power a model railroad. But this is a pretty good checklist to go through in deciding whether the right components are in place to meet your needs. And each of these components need to be appropriately sized based on the electrical demands of the system. What i've done in a few posts is take you from one of the simplest off-grid PV system (solar powerede landscape lights) to a sybolic diagram of a system that could be used to take an entire home or cabin or workshop off grid. 

In designing my GRR solar PV system I will cut down on the number of components to those that are actually needed for this application. But because your needs and application may be different than mine, I thought I'd start big and scale down. 

As we move to greater capacity components, total cost of the system can rise significantly. This is particularly true of the investment in the PV Arrays and battery banks. That's why it is a really good idea to first do everything you can to reduce system power use (substitute LEDs for incandescent lights) before sizing the system. 

A few posts back I dealt with reducing the power demands of my yard lights. My solution was to convert from 18v incandescent lights to LEDs then power them with individual solar units. As a result, my main off-grid PV system won't need to deal with powering yard lights. In my next few posts, I'll deal with the power needs of the pump powering my water feature and the circuits needed to charge the bateries powereing my radio controlled battery operated railroad. 

Once the power needs are defined, I'll move on to selecting and sizing the components. 

Tom


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## Tom Farin (Apr 3, 2008)

Readers, 

Stuff on my NPC Garden RR has been scattered in forums all over MLS. All my posts from 2007 are in the archived version of the previous forum. The Solar stuff has been here. Frankly, it's confusing and a bit difficult to manage, especially because I tend to hop from project to project. 

I just discovered the Builers Log (Blog) feature of the new MLS site. It allows you to create a bullders log with one or more child blogs. That's really cool because when a big project has multiple subprojects, they can be organized into child blogs. 

Comments are also separated from content in the blogs. That means you can update a post on a subject by adding material to the entry. That's idel for a little project like my solar powered pathway lighting project. 

So I'm gong to move the material into my new NPC builders log. The link to the top of the log is: 

NPC Builders Log 

The link to the child web containing these posts and any additional posts on the subject is: 

NPC Builders Log - Solar 

It will take me a few hours to get the posts out there. Look for a continuation of this story there. 

Tom


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## Tom Farin (Apr 3, 2008)

Readers, 
Stuff on my NPC Garden RR has been scattered in forums all over MLS. All my posts from 2007 are in the archived version of the previous forum. The Solar stuff has been here. Frankly, it's confusing and a bit difficult to manage, especially because I tend to hop from project to project. 

I just discovered the Builers Log (Blog) feature of the new MLS site. It allows you to create a bullders log with one or more child blogs. That's really cool because when a big project has multiple subprojects, they can be organized into child blogs. 

Comments are also separated from content in the blogs. That means you can update a post on a subject by adding material to the entry. That's idel for a little project like my solar powered pathway lighting project. 

So I'm gong to move the material into my new NPC builders log. The link to the top of the log is: 

NPC Builders Log 

The link to the child web containing these posts and any additional posts on the subject is: 

NPC Builders Log - Solar 

Another major advantage of a builders log is tat it persists. The topic doesn't roll off because no posts have been made for a while. 

Look for a continuation of this story there. 

Tom


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## Skip (Jan 2, 2008)

Check out the RV market as well for solar charging equipment. Remember, every convertor/control device in the chain consumes power. Stabilize your planning on a workable voltage that you can sustain on charge. I charge/maintain a 12v storage battery for my travel trailer by solar - 60watts (4x15watt panels or roughly 8 sq ft of PV surface). A std deep cycle takes a week to charge from flat in normal southern Ontario summer sun. When charged and in maintenance mode, will run my trailer for a weekend provided good sunny days, but if I need the furnace or the weekend is overcast, it could be dicey. The only thing the battery is driving in the trailer are the lights, water pump, and TV and radio if I have them on. The maker of the panels also has a charge regulator that will shut the panels down at night and when the battery is fully charged so as not to let the battery leak back. The secret is a parallel storage bank of batteries at 24v, but you're looking at a lot of panel area to keep that reliable in Wisconsin.


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## Skip (Jan 2, 2008)

Smaller wires on long runs between PV arrays and battery banks can significantly reduce cost.

Be careful. Ohm's Law doesn't monitor the commodities market. Long runs with smaller wires will also consume electricity and waste it as heat, and in the solar arena, every milliamp counts. You need to size the wire to reduce the effective resistance of the wire to as close to zero as can be reasonably achieved. That generally means err to oversize the wire, not undersize it. You are in the efficiency game, unfortunately, and unfortunately, high efficiency comes at a price. This is one of the most important structural weaknesses of solar power - how to achieve performance efficiency without breaking the bank. For all practical purposes, this hasn't yet been achieved. This isn't to say you can't do what you want to do, but you'll likely discover that the smart money goes into simplicity and quality rather than quantity and technical innovation. For example, most solar powered garden lights are extremely inefficient, and generally poor performers. This is a result of several things, all related mostly to economies of components, manufacture and market. I.e, a $29.95 light will give you $14.95 worth of performance in the long term. 
If you can get PV at $7 per watt, you're doing well. My 60 watt panel array cost me $14 per watt capital investment. I have no idea of the service life of the panels - they are used infrequently so I'm hoping years. The longer I get to use them the lower the power cost will be until I reach the watt/unit cost of maintenance and battery replacement. Don't know what that number is ...


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## Tom Farin (Apr 3, 2008)

Skip, 

I really appreciate the comments from someone with your experience. Your comments are very helpful. 

My comments on the lower capacity wiring requirement when running higher DC voltages is the standard justification for running higher battery voltages in an off-grid PV system. I've always over-wired on my house wiring installs. But you were right to bring to my attention the fact it is even more important in solar PV installs. Fortunately the wiring runs in my installs will be very short so the penalty of over-wiring will be nominal. 

My $7 per watt estimate is for self installed large PV systems where some economy of scale benefits are captured. I'm not surprised to hear the cost of a 60 watt system came in significantly higher. I'll bet a pure sine wave inverter to power your TV is part of that $14 per watt cost. I'm hoping to get by without any AC at all so my cost may come in under yours. 

I'm not sure I agree wih your solar garden light comment however, at least in my application. I'm only talking about $5 to $7 for the solar power unit and LED per light converted -- a total of $100 for 13 lights. That compares to $100 for a transformer and $50 dollars for wiring with the incandescent lights currently installed in my units. That doesn't include the $36 per year for electricity if I stay with incandescent. 

There may be a more cost effective way using solar to power those lights than the approach of powering each unit individually I'm taking. But at a capital expenditure of $100, there isn't all that much money to be saved.


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## placitassteam (Jan 2, 2008)

I have solar powered lights similar to what Tom is using along my driveway. I haven't really looked at their construction, but they do put out bluish light in a 360 degree pattern. I have have two fifty watt panels on my travel trailer charging two 6 volt golf cart bateries in series. This system powers everything in the trailer except the air conditioner and the microwave. It work very well and we have camped off grid for up to two weeks at a time. 
I don't think a hydro power would work to recover any power as the drop from one end of your system to the other ( head ) would only be a few feet, not giving enough pressure to be of significant value. One thing you need to be careful is not over charging the golf cart batteries. I have found that if there is not much current being used that the batteries can boil dry. In my case this is mostly due to the fact that I have a very simple charge controller which simply cycles on and off but does not control the charge amperage and the system is not drawing any power while the trailer is stored.


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## Skip (Jan 2, 2008)

My $7 per watt estimate is for self installed large PV systems where some economy of scale benefits are captured. I'm not surprised to hear the cost of a 60 watt system came in significantly higher. I'll bet a pure sine wave inverter to power your TV is part of that $14 per watt cost. I'm hoping to get by without any AC at all so my cost may come in under yours. 

The tv is ac/dc - no inverter involved, other than the solid voltage multiplier circuits in the tv to generate the necessary CRT voltages. The TV has dual input. This is an example of choosing for fitness of purpose. An inverter wastes a lot of power, much better to choose (or assemble) products or systems to operate on the supply voltages available. The trade-off, of course, is cost. In the case of the TV, it was almost 75% more expensive than an equivalent single voltage supply set. Some of my cost difference is reflected in our different economies (I'm in Canada). 
It work very well and we have camped off grid for up to two weeks at a time. 

I should qualify my "weekend" comment on the ability of the 60w panel array and the 12v battery. In summer conditions with good sunny weather, I can operate the trailer pretty much indefinitely on the battery/panel, provided I am frugal with power use. Of course, the microwave is offline, needing 110v, and I never put an air conditioner in mine - not really needed in the Ontario climate. Where demand can easily outstrip supply is in the use of the furnace in the shoulder seasons. The furnace fan is 12v, but it is a big consumer of power. I do carry a secondary battery - at times its appropriate to hook the panel to that battery, and just let it float the battery. When the trailer battery begins to drop, swap them out. That's a more efficient use of the charger, as there isn't a concomitant demand on the battery at the same time as charging is going on. Panel efficiency is directly related to energy being received by the panel as close to 90 degrees as is practical, which means sun tracking is important. An optimal system would track with the sun, but that requires power. Manual tracking is important where supply just meets demand. To avoid the need to track means a significant excess of panel area over demand. On warm summer days, I can usually get away with just laying the panels on the roof of the trailer; however, I do have a rack made up that the panels will mount to that allows me to position the panels optimally to the sun. About once an hour that needs to be adjusted. Now, there is a practical problem, especially in the summer: trees. Its typical to park the trailer in the shade if available to reduce heat load, but trees greatly diminish panel efficiency (one of the reasons why the panels are not fixed to the trailer roof). Siting the trailer becomes important if solar is to be relied on. I'm going on at length about the trailer usage only to illustrate some of the practical issues that come into play with a low volume supply solution. Site circumstances will greatly affect hardware choices, so before you get too deep into hardware you need to look at the capacity of your site to generate solar energy. Mid-northern latitudes tend to have long stretches of cloudy or partly cloudy days, and if you are near large bodies of water, even clear muggy humid days will operate the panel significantly below optimum due to infared absorption by water in the atmosphere. There are few pristine clear dry days in mid-northern latitudes, which means again, you have to "oversize" capacity, both in storage and in generation. Beware the solar author who lives in Arizona! LOL! 

A wind generator might be a good complementary add-on. Wind is frequently more reliable than solar in terms of its capacity to generate. The yachting trade has a variety of efficient well designed compact wind generators for yachts (not cheap, particularly), and if your location suits will provide power more steadily than solar. Particularly useful "after hours". Unless you have a steady stream flowing through your property, hydro is a non-starter. There is no pump lift system that will not consume more power than it generates (no perpetual motion machine...).


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## Tom Farin (Apr 3, 2008)

Skip 

"Of course, the microwave is offline, needing 110v ..." 

That was really the point of my post relating to the need for an inverter. I just had identified the wrong piece of equipment (TV) in your setup. I'm exchanging e-mails with TOC relating to how to charge batteries with DC power rather than use an inverter. Pure sine wave inverters are expensive. An AIMs 640 watt runs $250. On your 60 watt system, that would be $4 a watt right there. 

"Siting the trailer becomes important if solar is to be relied on. I'm going on at length about the trailer usage only to illustrate some of the practical issues that come into play with a low volume supply solution. Site circumstances will greatly affect hardware choices, so before you get too deep into hardware you need to look at the capacity of your site to generate solar energy. Mid-northern latitudes tend to have long stretches of cloudy or partly cloudy days, and if you are near large bodies of water, even clear muggy humid days will operate the panel significantly below optimum due to infared absorption by water in the atmosphere. There are few pristine clear dry days in mid-northern latitudes, which means again, you have to "oversize" capacity, both in storage and in generation. Beware the solar author who lives in Arizona! LOL!" 

With the scarcity of camp sites in this part of the country, I can relate to your need to find an ideal camp site for your solar setup. I'm fortunate in that the back of my house (where the RR is sited) faces due South. Roof pitch is nearly ideal. And trees are fortunatley placed where they won't interfere with a solar panel right above the place where my trains will go through a basement window into the staging (and charging area) of my basement. The charts say we can expect 4.5 hours of average full sunlight a year. That will be lower in the winter and higher in the summer. That's good as I'm not inclined to run trains if it requires clearing significant snow and dealing with cold temperature in the winter. Last winter we received 100" of snow. That's 2,000 inches in scale. 

"A wind generator might be a good complementary add-on. Wind is frequently more reliable than solar in terms of its capacity to generate. The yachting trade has a variety of efficient well designed compact wind generators for yachts (not cheap, particularly), and if your location suits will provide power more steadily than solar. Particularly useful "after hours". Unless you have a steady stream flowing through your property, hydro is a non-starter. There is no pump lift system that will not consume more power than it generates (no perpetual motion machine...). " 

Wind isn't a good option here as wind speeds are low in this part of the country. When we do get wind, it tends to be very gusty. I'd have to install a tower to get up to the wind, a move that is unlikely to be approved by the city. 

You are coming through loud and clear about the need to design excess solar capacity. I'm thinking about one or two of the 125 watt BP PV units. They come in around $5 a watt. I want to go whole house size on the PV panels, should I decide to move in the direction of a grid connected system for the home later. 

As you suggest, I'm working on the needs side first. Then I'll move onto the delivery side. 

Tom


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## placitassteam (Jan 2, 2008)

One thing I forgot to mention, use big wire from the panels to the batteries, I'm talking #8. Theoretically you can use less but you don't want to lose any of that expensive power to resistance.


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## Skip (Jan 2, 2008)

110 v on solar are powered by an array of 10 12v batteries with a 1:1 sine wave inverter if needed, rather than using a 12v:110v inverter. The latter is very inefficient. Be careful with "average" sunlit hours. What is as important is the variability. Five days of overcast followed by 6 days of sun will give you your average, but you'll be out of power by day 3 if you haven't planned properly. For cahrging things like batteries for trains, get to know the R/C car/aircraft market. There are very sophisticated chargers for a variety of battery types and capacities from both 110 and 12vdc, many with auto discharge/recharge/cycle and float capabilities. 

For a solar application, "if it were me", I would chose ni-cad batteries for the trains over the newer types. They'll hold their charge longer between charges, and generally require less power to top off. The NiMH and the LiON batteries tend to dissipate their power quickly after charging. Charge rates for nicads, depending on type will be at C10 or C3 rates typically, meaning you arrange your charge current to be 10% or 30% of the battery capacity ( x1.4 times calculated charge time (charge rate is logarithmic, hence the 1.4). 

e.g. 500 mah NiCd battery, at C10 rate is 50ma/hour x 10 hours x1.4 = 14 hours. (this is where the ubiquitous "charge for 12-14 hours" comes from). 
Its important to know the charge current into your packs - with that little bit of information, along with the rated battery capacity, you can calculate any charge time needed to charge a given pack: Capacity of pack/charge rate x 1.4 = charge time. 

The C10 rate is generally safe for any battery. C30 and other high rates may not be. If the battery gets more than warm, the rate is too high. Generally, batteries that are designed to dump lots of power in a hurry can also be charged quickly, but they also tend to be voltage leaky. Conversely, batteries that are designed to sip power out (like deep cycles) don't appreciated being bang charged, and may blow their seals.


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## nkelsey (Jan 4, 2008)

I saw a nice little wind turbine at a house yesterday that is built for Yachts to recharge their batteries, guy has it hooked to deep cycle marine batteries. Put that together with PV.


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