# Battery question...



## DM1791 (Oct 6, 2014)

Okay, quick question. I have been doing a lot of reading, searches, and researches on all kinds of systems. I have a degree in optical physics (with a focus on high power laser systems), so a lot of the principles here are somewhat familiar to me. However, I have never worked directly with photovoltaic systems, so this has helped me a great deal.

(by the way, love the wealth of info on this site) 

One question I am having a somewhat difficult time answering on my own though... and that has to do with battery selection.

After doing many searches on the forums and reading page after page of articles here and out on the web, if anything, I am more confused than when I started.

A little background: My mom came to me a few months back and said she wanted a "little solar generator" to run her six chest high freezers, a well pump, electric stove, toaster oven, etc. etc. etc. She does not have a solid grasp on amp and wattage requirements for systems, needless to say.

In doing my research, I have come across several different options for battery use in the battery banks for this system. I am planning on going with either a 24V or 48V bank with at least two arrays in parallel. I know a lot of people on here have recommended golf cart type deep cell batteries for such a system. After researching here and online, though, I think I need some direct guidance.

Is there a significant advantage for AGM (absorbed glass matt) batteries for this application? Some sites push these batteries, but I'm not sure how much of that is marketing, and how much is legitimate performance concerns.

Also, what kind of life expectancy would say a 2-array 24V system using 6V golf cart batteries expect? If I have to replace the batteries within 5 years, then it might make sense to invest more now to get a longer operating life?

And lastly, I know flooded batteries are not recommended for indoor use unless you have really good vent system in place. Is the same true for cart batteries? I am putting this system in place in my grandmother's farmhouse, so the only option if ventilation is a must would be the attic, which gets incredibly hot during summer months and may affect battery life.

For reference, I am planning on this being a grid-tie system with battery bank back-up.

Thanks for the info and the help. So far, I am still in the design phase of this, so any advice/tips would be greatly appreciated.


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## cowboyhermit (Nov 10, 2012)

The reason you will see so much conflicting advice is that people have different views and experiences based on varied situations, manufacturers, and luck. I have worked with hundreds of batteries, of many different types, over many different years and still cannot in good conscience give you a quick answer.

The life cycle of a battery is based not only on years but also charge/discharge cycles, temperature, the level and duration or discharge state, etc, etc.

I can honestly say that imo AGM are generally better batteries. They are extremely robust (I have seen several where the cases were completely broken and yet still functioned), require no maintenance, do not need venting, are resistant to freezing in a failure situation, and are generally made to a high standard of quality. Their lifespan tends to be very good as well, obviously.
However, the big downside which I am sure is obvious to you is price and while I am sure there are many people out there who will have a formula that tells you whether or not they are worth the premium I think it is much more subjective. Things that might matter if they are installed in a on-site shack in the middle of Canada are not going to apply as much in a basement.

IMO, assuming you keep the batteries maintained and in a good state of charge, and are careful (easily automated) to keep the discharge states from going too low in voltage or lasting longer than necessary, AND you can get the golf cart type batteries for as cheap as many seem to be able to, then they are probably the most economical.

I have several deepcycle/marine batteries (not in a household system) that everyone will tell you are complete junk that are over 10 years old and still kicking, just for reference. They weren't all treated perfectly but they were topped up most of that time. That is what I expect from good batteries that are treated right, more than that is a bonus and generally is with batteries that have had little load on them. 5 years is the minimum acceptable for even heavily worked batteries, I expect better.

If you do go with the flooded batteries I would avoid the attic if at all possible, there are vent/fans specifically designed for battery boxes if you need.


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## DM1791 (Oct 6, 2014)

*Awesome info...*

CBH, thanks for the info. I've read a lot of your posts over the past few days, and I appreciate you sharing your knowledge and experience.

I like the idea of the golf cart batteries, as they seem to be the most economical and relatively low maintenance. One thing that concerns me a bit is the number I would have to purchase to get the level of battery backup I need. However, needing a good number of batteries makes it even more attractive to go with the more economical (i.e. penny-pinching) system.

Storage is my biggest concern. I'm working with a 60+ year old brick farm house (she still has screw in glass fuses in the fuse box). My biggest concern is where to put the batteries, controller, inverter, etc. My first instinct was to house it all inside the utility/laundry room that also holds the 4 freezers. However, that will take up a considerable amount of room, and it puts the entire system right next to my granny's bedroom (not ideal).

The space is there, even if I have to utilize one of the spare bedrooms at the other end of the house. I just mainly wanted to keep the length of transmission wires as short as possible.

If I were to construct a power shed, I'm guessing I should insulate it to cut down on thermal fluctuations? Or is housing the power infrastructure inside not a huge safety issue?


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## TheLazyL (Jun 5, 2012)

DM1791 said:


> ...My mom came to me a few months back and said she wanted a "little solar generator" to run her six chest high freezers, a well pump, electric stove, toaster oven, etc. etc. etc. ...


May I'd suggest a auto start generator instead? Topping of the gas (unless natural or LP is available) and an annual trip by you to service the generator will evolve a whole lot less time and expense IMHO.

I'm going thru a similar experience with my 85 year old mother. It would be a shorter list of what she doesn't want on a generator then what she does what on it.

$6,000 for a auto start natural gas generator, installed. I'd guess solar would be 2 to 3 times that plus all of my trips maintaining, cleaning and continuous answering why everything is dead from lack of sunshine, lack of power management (leaving unused lights left on) and early replacement (and cost) of continuously 100% discharging the batteries. :brickwall:


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## mosquitomountainman (Jan 25, 2010)

TheLazyL said:


> May I'd suggest a auto start generator instead? Topping of the gas (unless natural or LP is available) and an annual trip by you to service the generator will evolve a whole lot less time and expense IMHO.
> 
> I'm going thru a similar experience with my 85 year old mother. It would be a shorter list of what she doesn't want on a generator.
> 
> $6,000 for a auto start natural gas generator, installed. I'd guess solar would be 2 to 3 times that plus all of my trips maintaining, cleaning and continuous answering why everything is dead after several days of no sunshine and leaving unused lights left on. :brickwall:


This would be my suggested option as well. For that much power you'll need quite a solar system but as TLL pointed out, it's more than just installing the system. The biggest problem I've seen with people on solar power systems is that they don't understand what's going on or the little "nuances" of living off the grid. Plus, solar power is not free as many would lead you to believe. While the lifespans of panels, electronics, etc. is long the lifespan of batteries is limited. Figure up the life expectancy of the batteries and the cost to replace them (at the inflated prices of the future) and you'll see what I mean. As CH mentioned, battery life is dependent upon how they're taken care of as much as any other aspect including battery type. I've seen some people who just didn't know what they were doing ruin AGM batteries in five years.

Since you/re doing grid tie anyway you are not looking for something to be used 24/7 for eternity. You're looking for a back-up system. The stuff in the freezers can be canned or dehydrated if the power goes out long term (we do it all the time by purchasing frozen meats and vegetables to can/dehydrate later). I wouldn't rely on a freezer for a long-term SHTF situation at all.

So if you're looking at a temporary power system of even a month's (or more)duration I'd look into a whole-house, permanent mount system using diesel, natural gas or LPG. All can be set up with bulk tanks to avoid constant refueling and to kick in and out automatically when the power goes out.

You may be able to get some money back by selling power to the electric company but will it be enough to offset the problems? Off-grid systems require periodic maintenance even if you aren't using them.


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## DM1791 (Oct 6, 2014)

*HAH!*

If only it were that simple.

We have two gas-operated generators that my mom is used to and knows how to operate. Her concern, though, is not so much for blackout situations as it is for a full on SHTF grid shut down.

She wants to be set for if there is some kind of hard crash that leaves us back in the "dark" ages, so to speak. And, to be honest, the more things go the way they are, the harder it is to argue against that. All of the power supplied in her area is from one Nuclear plant, and that worries her.

She is dead set on solar since there's no fuel to purchase in a worst case scenario. And, since she's dead set on solar, I want to make sure the system she gets is going to handle what she needs it to.

Good thing is that, as convinced as she is, I don't think price is going to be a stumbling block unless it gets outrageously high. Bad news is that means I have a lot of work ahead of me.

And all this at the request of a woman who once called and had me drive 3 hours round trip because she couldn't figure out how to switch her TV from VCR back to satellite. She swore up and down I'd broken it.

So, in short, I agree with you that it would be much simpler, cheaper, and probably just as effective for a short-term backup. Unfortunately, that's not what she's looking for. And my biggest fear is that she'll find someone on-line, do no research at all, and pay whatever they ask. She did that for a deck on the back of her house, and nine years later she still has a make-shift wooden staircase and no deck.

*sigh*


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## DM1791 (Oct 6, 2014)

mosquitomountainman said:


> Since you/re doing grid tie anyway you are not looking for something to be used 24/7 for eternity. You're looking for a back-up system. The stuff in the freezers can be canned or dehydrated if the power goes out long term (we do it all the time by purchasing frozen meats and vegetables to can/dehydrate later). I wouldn't rely on a freezer for a long-term SHTF situation at all.
> 
> So if you're looking at a temporary power system of even a month's (or more)duration I'd look into a whole-house, permanent mount system using diesel, natural gas or LPG. All can be set up with bulk tanks to avoid constant refueling and to kick in and out automatically when the power goes out.


 I like this concept, but every time I bring it up she asks where we'll get the gas in a full on crash. And that's just not a question I can readily answer. As far as the maintenance goes, that is probably going to fall on me. My wife and I have been discussing moving back to the farm for a few years now, and it is looking more and more like that is going to become a necessity. My mom's side of the family has an average age of 75 with a good amount of farmland to maintain. That's just not the kind of thing I can effectively manage from 3 hours away.

I do agree that she needs to cut back on the freezers, though. As it is she regularly pulls stuff out that is way past its prime and unusable (8 year old hamburger isn't good even if it has been frozen the whole time). I already told her that a system to do what she wants would take way more than she realized (25-35k range), and she never hesitated. She is dead set on having the ability to unplug from the system whenever she wants, or whenever she is forced to; whichever comes first, I suppose.

Either way, the large-scale system is at least a year out, probably more like 3-5 years out. I am still 100% in the planning and design phase of that. In the meantime, she wants a minimal system to use as a backup for her home (as opposed to Granny's old farmhouse), completely separate from the large system for my granny's. Mom has 2 freezers, though only one is really used (the other could be re-tasked as a high efficiency refrigerator, if need be), a few lights, and some simple chargers for laptops, etc. A 500-1000W system (looking at 4 275W panels) would be plenty. And it would also give me a chance to get some experience with this stuff and learn it from the ground up.

Believe me when I say I have resisted this as much as I am able to, and have fought tooth and nail on it. We've been "discussing" this for about six years now. But, bottom line is, when mom wants something done she is going to get it done one way or another. At this point, I've given up fighting the avalanche and have decided to ride it out and hope for the best.


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## TheLazyL (Jun 5, 2012)

DM1791 said:


> If only it were that simple. ...woman who once called and had me drive 3 hours round trip because she couldn't figure out how to switch her TV from VCR back to satellite. She swore up and down I'd broken it....


I know where you are coming from.

I learned from a 3rd party on a Sunday that my mom didn't have heat all weekend. It was winter and she get pneumonia at a drop of a hat. When I get there she had heat. "Oh it started working this morning all of a sudden"

My guess is she or the sister started punching buttons on the smart thermostat and took it out of the programmed mode.

Next weekend furnace stopped working again! Furnace Repairman found a pantyhose fastened to the furnace's cold air intake. Pantyhose would frost over causing the furnace to be starved for air. The morning sun would melt the pantyhose frost and the furnace would start working again.

Mom put the pantyhose on the furnace air intake to keep mice out of the basement. :scratch


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## cowboyhermit (Nov 10, 2012)

I kind of skipped over the grid-tied aspect, the advantage to this is that the batteries will essentially be sitting fully charged until needed, this should give you the maximum possible life from them. They would probably benefit from a desulfator/charger at some intervals, but it isn't necessary.

As far as having someone who doesn't know much about solar at the site, the only way imo is to have everything on LVDs. The batteries cannot be discharged past your preset level with this setup (aside from the tiny self-discharge rate) so a system will only need a check-up on a annual schedule (more is better of course). There is always a chance of low water levels but with a proper charger/charge controller that shouldn't be an issue with batteries sitting charged.

I agree with the others, the economics on designing a system like this are tough, assuming things don't go to heck, the batteries at some point down the road will be a write-off (except that they are worth decent $ as scrap). One factor to consider is that if you are going grid-tie then installing a *lot* of panels might make the most sense economically. If you have a lot of solar capacity then there are ways to reduce the size of the battery bank needed.

For instance, deep freezers can be turned off overnight with absolutely *no harm done*, they can be turned off much longer (especially if set to really cold temps) and still remain safe. Simply putting the freezers on timers could stretch your batteries a lot. Putting them on a separate circuit with a separate LVD is another option but much more involved.

Also, if you have enough capacity, cloudy days will still provide a decent amount of power. Overcast days should still be producing more than half of rated power.

So, imo, if going the grid-tied route I would try to get a solid array as the main priority and keep the battery bank sized to the minimum power use possible (factoring things that can be run when the sun shines). Having a generator as a backup is great too, I would make sure to have an efficient way of charging the bank with that as well, it can make things much more efficient (less fuel/runtime).


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## Caribou (Aug 18, 2012)

You may want to look into a high voltage battery conditioner (desulfator) to extend battery life of your wet cells.

If you decide to put the batteries in the attic, not my first or even second choice, not only will you need to worry about the heat but I would be very concerned about the weight.

I have recently run across capacitors that are being used to replace 12V batteries. Price is a factor but is counter balanced by longer life, reduced weight, reduced maintenance, and less affected by cold. If memory serves these work well to -40*. Since you battery bank would do better closer to the power source (solar panels) the attic might be a workable spot for these capacitors. I'm thinking that a shorter run on the low voltage side and the longer run on the high voltage side will produce less line loss over all. If anyone has experience with capacitors as a battery bank I would be very interested in your input.

Glass fuses? Does she have knob and tube wiring also? You may be looking at rewiring the whole house.


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## DM1791 (Oct 6, 2014)

cowboyhermit said:


> ...For instance, deep freezers can be turned off overnight with absolutely *no harm done*, they can be turned off much longer (especially if set to really cold temps) and still remain safe. Simply putting the freezers on timers could stretch your batteries a lot. Putting them on a separate circuit with a separate LVD is another option but much more involved.
> 
> Also, if you have enough capacity, cloudy days will still provide a decent amount of power. Overcast days should still be producing more than half of rated power.
> 
> So, imo, if going the grid-tied route I would try to get a solid array as the main priority and keep the battery bank sized to the minimum power use possible (factoring things that can be run when the sun shines). Having a generator as a backup is great too, I would make sure to have an efficient way of charging the bank with that as well, it can make things much more efficient (less fuel/runtime).


 That is very much along the lines I was thinking. For this system, I'm looking at setting up an array that will provide about 1.5 - 2 times the actual needed electricity. This is basically our bugout location in case things really do get bad, so the added capacity isn't just for the grid-tie but for a true worst case scenario to make sure capacity is covered. I was also thinking that with a grid tied system and a small battery bank to start with, I could possibly add other batteries and charge controllers over time as long as the system is set up with that in mind from the beginning, correct? Assuming I don't establish more batteries than I have array to cover, that is...

I've also looked at some simple timers for the freezers. I'm gathering data now on how often they actively cycle, and how much of an R-value they have. There are simple analog garden timers for outdoor lights that I've used on heaters and what not that seem to work well. Running the freezers as little as possible will definitely be a priority for power conservation.

As far as the LVD goes, do all MPPT controllers have those built in? If I am using one or two MPPTs to control the battery charge, would that be sufficient to cover the LVD switches as well, or would I need those standalone for redundancy?


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## DM1791 (Oct 6, 2014)

Caribou said:


> You may want to look into a high voltage battery conditioner (desulfator) to extend battery life of your wet cells.
> 
> If you decide to put the batteries in the attic, not my first or even second choice, not only will you need to worry about the heat but I would be very concerned about the weight.
> 
> ...


 I hadn't even considered capacitors for the "battery" bank. Interesting concept... I've dealt with some massive capacitors in my day, and there are definitely ones big enough to handle this kind of load. I'll have to do some reading on that...

As far as keeping the low voltage wiring short, this is a huge concern of mine as well. That has me really questioning the best set-up for this large-array system. I doubt I will be roof mounting the panels, to be honest. My granny's roof has about 9 different angles and pitches, so that wouldn't be the best place for them.

Thankfully, her house sits on the edge of about 125 acres of field/forest land, one of several tracts that our family has in that area (thank God for Granddaddy's foresight in buying up defunct farms back in the 50's). So the problem of where to put the array is easily solvable. However, if I ground mount the array on pillars (I would probably not opt for trackers.... too much of a risk for mechanical break-down) then the problem of line lengths for power transfer comes back into play. At that point, I would really have to build a power shed to house the batteries, mppt controllers, inverters, etc. Which, that isn't an issue, per se, just a factor I hadn't considered in my original plans and designs.


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## cowboyhermit (Nov 10, 2012)

DM1791 said:


> I was also thinking that with a grid tied system and a small battery bank to start with, I could possibly add other batteries and charge controllers over time as long as the system is set up with that in mind from the beginning, correct? It is pretty simple to add a second bank with a backup system, there are always potential problems but in a scenario like this I would consider them minimal.
> 
> I've also looked at some simple timers for the freezers. I'm gathering data now on how often they actively cycle, and how much of an R-value they have. There are simple analog garden timers for outdoor lights that I've used on heaters and what not that seem to work well. Running the freezers as little as possible will definitely be a priority for power conservation.
> 
> ...


Pretty much any good charge controller should have a sufficient LVD. If you want to do more complicated things such as have certain things shut-down sooner then a standalone can make things easier. All inverters have their own LVD as well.

As long as you are staying around 100ft, then even with 12V line losses are easily kept to a minimum by just spending a few $ on wire. How much it will cost to keep the losses down is as much a function of system size (amps) as it is of distance. Service wire is really not all that expensive really, if you go that route. If going with a higher voltage like 24 or 48 it is even less of an issue, on a 100ft run it might save you a couple hundred bucks (with a very high amperage system). More than 100ft means more $$$ obviously and can get crazy with a big system (multiple conductors most likely).


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## Caribou (Aug 18, 2012)

DM let us know what you learn about the capacitor idea. This is a new concept for me as well. The system I saw was designed for long haul tractor trailer rigs to reduce weight and operate more efficiently in cold weather. I'm unaware as to how capacitors deal with high temperatures.

My first thought was that if it would work for an vehicle then it would work for a home system. My second thought was that off the shelf parts were probably available that would allow someone to build a system for far less money. I do have safety concerns dealing with capacitors of this size.


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## DM1791 (Oct 6, 2014)

I can tell you just from my experience with semi-conductors in general that at high temperatures you risk a break down in the junction for most capacitors. But, the good news on that, is for most that I am aware of the temps have to get really high (as in danger danger Will Robinson kind of high) for that to really become an issue. I'll do some research on the efficiency curves of large cell capacitors and let you know what I find out. 

When I used to work with high voltage laser systems, a lot of the power supplies were designed with huge bucket-style capacitors. They would scale up the 240V AC to insane DC loads and then stabilize the output with the capacitors. Lucky us, we got to do maintenance on those beasts. We had to discharge them with a nasty metal shepherd's crook that was grounded to a 30ft deep grounding rod set in the center of the concrete floor.

Talk about something that will make your no-no areas tingle.... that was always an intense experience. 

I imagine the biggest danger with the capacitors would be over-charging (as opposed to draining in a battery). Over charge one of the bucket types, and it will explode. I'll make sure to check on that and on the discharge time since capacitors tend to leak voltage much more than a standard battery does.


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## DM1791 (Oct 6, 2014)

*Math check...*

I just want to make sure my math is working right....

Battery bank set up:

2 batteries per array in series: each battery has 12v 200AH rating
3 arrays paralleled for the bank

Totals: 24V and 600AH (at the 20hr rating of 10A per hour)

This math sound right?

I'm not saying I will be using a battery bank that large, but I just want to make sure my math is adding up the way it should.


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## cowboyhermit (Nov 10, 2012)

DM1791 said:


> I just want to make sure my math is working right....
> 
> Battery bank set up:
> 
> ...


I have been avoiding math related questions on here because my attention is divided :nuts: but I think I see what you are saying. At first glance, by array I thought you were referring to the solar but I think you are strictly referring to the battery layout.

Assuming I see what you are saying; 3 strings of 2 batteries each, that each are rated for 200Ah @ 12V, then you are exactly right as far as I can see.

24Vx600AH=14400Wh, divided by 6= 2400Wh. 
12Vx200AH=2400Wh


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## Tirediron (Jul 12, 2010)

I am just going to stick my 2 cents in about the in efficiency of conventional chest freezers, the condenser is in the freezer shell, right beside the insulation that is trying to keep the removed heat out, I haven't done it yet but I am pretty sure the input would drop a huge amount if the condensors were removed to open air or mounted on heat sinks. yes this would cost money, but so does building a system.


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## DM1791 (Oct 6, 2014)

cowboyhermit said:


> ... At first glance, by array I thought you were referring to the solar but I think you are strictly referring to the battery layout...


 Yeah, looking back at that now, I can see where that could be confusing. My bad.

Good to know my math isn't as rusty as I thought. It's been a few years since I had to do circuit calculations and what not.


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## LincTex (Apr 1, 2011)

Tirediron said:


> ...conventional chest freezers, the condenser is in the freezer shell, right beside the insulation that is trying to keep the removed heat out, I haven't done it yet but I am pretty sure the input would drop a huge amount if the condensors were removed to open air...


The amount of BTU per hour is so small I'll bet you wouldn't see much change - certainly not for the $$ you spend.

The insulation of a chest freezer is pretty darn thick, too. They make great refrigerators when converted.


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## Caribou (Aug 18, 2012)

When I first brought up the capacitor as a battery idea what I found was quite expensive. I have recently stumbled across this and the price is far more reasonable.

http://www.amazon.com/Gravity-1000-...=1428706062&sr=8-3&keywords=battery+capacitor

DM, have you found any information on these? I'm thinking that the advantages here might include weight, life expectancy, greater percentage of usable capacity, no damage if frozen, lower maintenance, and easier addition of capacity. If you increase capacity on a lead acid battery bank you need to add an additional bank as old batteries and new ones don't play well together. I have been looking on information on these for months but there is nothing I can find. Any information about these would be very appreciated.


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## forluvofsmoke (Jan 27, 2012)

Caribou said:


> When I first brought up the capacitor as a battery idea what I found was quite expensive. I have recently stumbled across this and the price is far more reasonable.
> 
> http://www.amazon.com/Gravity-1000-...=1428706062&sr=8-3&keywords=battery+capacitor
> 
> DM, have you found any information on these? *I'm thinking that the advantages here might include weight, life expectancy, greater percentage of usable capacity, no damage if frozen, lower maintenance, and easier addition of capacity. If you increase capacity on a lead acid battery bank you need to add an additional bank as old batteries and new ones don't play well together.* I have been looking on information on these for months but there is nothing I can find. Any information about these would be very appreciated.


Caribo, you got me thinking here on the possibilities. If you posted your thoughts on this earlier, please send me a link, as I'd be interested in what you're aiming for, and any responses you may have received. I read back on your earlier posts on this thread, but if you have inquired elsewhere, I'd like to read it. I'm not quite sure what application(s) you are intending to use capacitors for. Are you thinking of replacing batteries with super-capacitors, or, using capacitors to carry the surge-current when starting larger inductive loads, which will be used for short durations, with a smaller battery system?

Also, the link you posted on the car battery capacitor is probably just to boost the peak battery draw current, such as for high-output car audio systems.

I did some digging, and this page best explained to me how super-capacitors are designed, the difference between them and small capacitors, and how they they could be used for energy storage:

http://www.explainthatstuff.com/how-supercapacitors-work.html

Here's some more info explained in layman's tems:
http://johnhearfield.com/Physics/Capacitor_energy.htm

In a different article, I read that capacitors store electrostatic energy, which didn't make sense to me at first, however, there is no chemical reaction in a capacitor like there is in a battery, leaving static as the only energy transfer...so, I believe that what you state about them being low-maintenance would be true, as well as everything else I highlighted above. They also would have little to no change in resistance due to low or high ambient temperatures, unlike batteries, which would make them very attractive as an energy storage device.

Capacitor longevity may very likely be effected due to internal erosion of the conductors (plates) over time, based on cycling, similar to a FLA or SLA. They won't last forever, question being, how long, based on (1) and construction of actual plate material/thickness and surface area, (2) plate insulator type and it's susceptibility to erosion/burning from passage of static discharge, and (3) load and charge cycle characteristics/profile, and (4) any additional unknown factors.

What I previously thought was true of large capacitors dictated that they were only good for rapid charge/discharge cycles, and that they were best suited for carrying heavy surges in electrical circuits requiring a high current drain on start-up of inductive loads such as motors. After reading a few articles though, I'm seeing a potential for off-grid battery systems, as well. I'd need to do more research and find out just how much difference in energy storage capacity (in Whrs, or in the case capacitors, Joules) there would be between, say, a single 6-volt 225 Ahr battery and a similarly-sized capacitor set. Maybe capacitors would not be suitable as the sole energy storage device due to cost and/or size, but be better suited to assist an otherwise under-rated battery bank for those surge currents which may not be possible without a capacitor of adequate rating. Installers of high-output car audio systems commonly use capacitors (such as the one you linked above, though there are much smaller, single units available for the same purpose) for providing adequate input voltages to amplifiers during peak power surges. Another example: I've experienced AC/DC inverter shut-downs/faults due to lack of input voltage from the battery during start-up of an inductive load, yet when more batteries are added it will start the load, then continue operating after the additional batteries are disconnected from the inverter. The single battery simply could not provide enough surge current to maintain proper input voltage for the inverter. A capacitor of proper size would reduce/eliminate the low-voltage problem. So, for assisting a smaller battery bank to start-up a heavy inductive load, they would provide considerably better performance.

What I found the most interesting is that super-capacitors, because of their simplicity, could be made at home with simple materials and methods. Example: use paper-clad foil (such as that used for food-service) as the internal conductors in a capacitor...the foil could be etched (with a moderate to mild acidic solution) to increase surface area and reduce it's resistance to static energy capture/release. I may just do some experimenting in the future and see if it is a worthwhile venture. Sure, aluminum foil will likely not be a good conductor for long-term use, as it would suffer a short cycle-life, but for base-line experimental purposes it would offer some insight as to assembly technique, conductivity and capacity achieved, insulation properties of the paper-backing...just for what-if, sizing, etc.

What are your thoughts? Total energy storage with capacitors, or to assist the surge-capacity of batteries?

Oh, also, were you considering Lithium-Ion capacitors? (sounds expensive)

OK, now I'm jumping back and forth looking for some more answers while I write this reply. Question: would one need to regulate the output voltage potential from a super-capacitor to avoid voltage surges from damaging electrical equipment, and what would that form of voltage-regulation consist of? Just a surge suppressor? (surge suppression would, to some degree, defeat the ability of the capacitor to carry a heavy current load, unless it could be by-passed at the proper moment, on demand)

I'll patiently await your response while I ponder this further. Just want to make sure I'm on the same page as you are.

BTW, thanks for posing me with the opportunity to do some research on something I find to be quite interesting, as well as the possibility to be able to apply this to my own future plans... This post just kicked me into gear and got my wheels turning again. I'm thinking along the lines of a smaller battery bank, but want the punch that a few capacitors can provide for start-up current surges, while having a low-current charging input.

I've researched the basic design and fabrication of my own high-current FLA batteries a few years ago, but that requires far more available space, materials and time than I can provide to make it happen. Manufacture of Capacitors, now, that just may be a viable solution, provided they will store enough energy in a small enough package to make it a worthwhile project vs spending big $$$ on industrial or RE batteries...that's the biggest question I need to be able to answer.

Thanks again!!!

______________________________

DM1791: any thing else come up with your studies and experience lately?


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## Viking (Mar 16, 2009)

I started electronics as a hobby in my early teens, Geek?, probably. I learned early on that capacitors can give you a nasty shock, luckily, I never got shocked by the one for the oscilloscope that stored about 4,000 volts, it did however startle me when I used a screwdriver to discharge it. I didn't even come close to the other terminal and it went "Bam". A lot of the capacitors I worked with were Navy surplus oil filled with porcelain insulators protruding from metal cans. A few years ago I bought an old 1980's IBM 5525 main frame computer that was given to the school district I worked for, I think I paid $5. I took it and a very large IBM printer apart for salvage and I still have all the large Mallory capacitors, most are rated for 5 volts but I have a few rated for 15 volts, one I have in my lap right now that is 145,000 MFD , I haven't tried using any but I might for the solar battery bank to help smooth out inverter start up. The only thing that might concern me is the potential for inner capacitor electrostatic discharge, however, at those low voltages it might not be much of a factor. I was told many years ago that the capacitors used on high voltage power lines was use for lagging or leading current in conjunction with voltage, perhaps for motor start up as needed in factories or mills? As to use in a solar power system using very large capacitors, I'd have to hear from people that have used them before I would consider not just adding more batteries.


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## Viking (Mar 16, 2009)

cowboyhermit said:


> Pretty much any good charge controller should have a sufficient LVD. If you want to do more complicated things such as have certain things shut-down sooner then a standalone can make things easier. All inverters have their own LVD as well.
> 
> As long as you are staying around 100ft, then even with 12V line losses are easily kept to a minimum by just spending a few $ on wire. How much it will cost to keep the losses down is as much a function of system size (amps) as it is of distance. Service wire is really not all that expensive really, if you go that route. If going with a higher voltage like 24 or 48 it is even less of an issue, on a 100ft run it might save you a couple hundred bucks (with a very high amperage system). More than 100ft means more $$$ obviously and can get crazy with a big system (multiple conductors most likely).


This is why I'm glad I found out early, in going to solar power, about high cell count solar panels. The panels we bought for our solar standby system are 72 cells per panel, maximum load voltage is 36.2, I have eight panels and because the wire distance from the array to the storage batteries is roughly 70 feet, I have decided to connect the array series parallel for 72.4 volts so that any line loss will make very little difference. That's the beauty of using an MPPT solar controller, since the battery bank is 24 volts that leaves a wide voltage range for charging, even if the sun day is far less than perfect, like cloudy, foggy or hazy days, it's roughly a 40 volt spread to work off of.


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## devyn (Apr 13, 2015)

Alright so I'm a pretty young prepper and I was wondering do u have any ideas that I could be ready and also save money???


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## Caribou (Aug 18, 2012)

forluvofsmoke said:


> Caribo, you got me thinking here on the possibilities. If you posted your thoughts on this earlier, please send me a link, as I'd be interested in what you're aiming for, and any responses you may have received. I read back on your earlier posts on this thread, but if you have inquired elsewhere, I'd like to read it. I'm not quite sure what application(s) you are intending to use capacitors for. Are you thinking of replacing batteries with super-capacitors, or, using capacitors to carry the surge-current when starting larger inductive loads, which will be used for short durations, with a smaller battery system?
> 
> Also, the link you posted on the car battery capacitor is probably just to boost the peak battery draw current, such as for high-output car audio systems.
> 
> ...


I ran across an add some time ago for a capacitor battery that seemed to be intended to replace a lead acid battery on an 18 wheeler. They touted several benefits including weight reduction. I started thinking that if this would would work in a truck then it might also work in a solar/wind system. I lost the original link but I recently found the one I posted above. My idea was to replace the lead acid batteries. I have seen many days of -40* so having a car battery that was not susceptible to the cold would also be really sweet.

I have only brought this up here and to a couple of guys that I thought might know this stuff. You appear to know this better than anyone that I have run into so far.

I have a very basic knowledge of electronics. I can put some stuff together and make certain repairs but design is well past my skill level. I don't even know if what I am trying to accomplish is possible but if it is I could see where these batteries would fit a need. For example, a friend of mine has a remote cabin. The batteries in the solar system are at the end of their useable life. Each battery will require a separate plane trip to replace it, due to weight. These batteries might just be the ticket. I believe in "trust but verify". I have not been able to verify anything about these batteries yet. Whether that is because they are totally bogus or because it is an emerging technology I have no idea.

Thanks for your reply.


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## Caribou (Aug 18, 2012)

devyn said:


> Alright so I'm a pretty young prepper and I was wondering do u have any ideas that I could be ready and also save money???


Hi devyn, Welcome! Your question is not really a good fit in this thread but it is in many others. In fact there are many threads that discuss just this issue. If you read some back posts you will certainly find many.

Drop by the introduction section and let us know who you are and what your situation is. This will help us understand what your needs are so that we can do a better job for you.


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## smaj100 (Oct 17, 2012)

Here is a link for some super cap modules, similar to what some here have asked about. They have several sizes and types. I'm not sure on the price point vs longevity and storage capability. The 48v module on one website is $1300+/-, some of the 16v modules are in the $500 price range. While you could purchase and construct a similar 12v battery type system cheaper. I would be interested in learning how to calculate the Ah rating if that would even be possible for a capacitor based battery. If nothing else like someone mentioned using a few capacitors to help with surge loads and startup.

http://www.maxwell.com/products/ultracapacitors/modules


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## Viking (Mar 16, 2009)

Caribou brought up an interesting point, the use of capacitors for 18 wheelers. My thought about this is that it's much like having compressed air starters on 18 wheelers, which is fairly common. I will say this however, the diesel engines are probably serviced regularly so that they will start quickly or you'd likely run out of compressed air, so the same applies to capacitor systems for starting, for example, on a very cold day a diesel is going to be harder to start and I doubt that a capacitor (battery stand in) would have a very long cold cranking capability. I know that when I was in the Air Force the generators we had in Ground Support that were used for starting reciprocating aircraft engines had battery heaters under their batteries for cold weather starting, a bit strange to me because they would use the generators own battery for running the heater which always seemed a bit self defeating to me, discharge a battery to heat it so it would be more efficient in cold weather. Perhaps the fact that they were 24 volt batteries might have given them a better margin of voltage to work with, however I don't remember the Ground Support training instructors mentioning that and since it was never really cold enough where I was stationed we never really had to use those heaters.


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## LincTex (Apr 1, 2011)

devyn said:


> Alright so I'm a pretty young prepper and I was wondering do u have any ideas that I could be ready and also save money???


Scroll to the bottom of this page - you'll see 5 additional threads listed which are related to this topic.

There's a LOT of info in this forum, but it's VERY HELPFUL - - so don't be afraid to read through some of it!


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## forluvofsmoke (Jan 27, 2012)

Caribou said:


> I ran across an add some time ago for a capacitor battery that seemed to be intended to replace a lead acid battery on an 18 wheeler. They touted several benefits including weight reduction. I started thinking that if this would would work in a truck then it might also work in a solar/wind system. I lost the original link but I recently found the one I posted above. My idea was to replace the lead acid batteries. I have seen many days of -40* so having a car battery that was not susceptible to the cold would also be really sweet.
> 
> I have only brought this up here and to a couple of guys that I thought might know this stuff. You appear to know this better than anyone that I have run into so far.
> 
> ...


OK, now I understand where your heading with the idea. One thing I failed to include in my earlier post was that for long-term energy storage, from what I've read up to this point, some types of capacitors would not be well-suited due to internal losses. If it were used in a system that was under a nearly continuous use, the system's potential storage capacity may not suffer as much, but for infrequent use the self-discharge rate could cause a high loss in capacity...that is without having current input for maintenance. In the case of a renewable energy system, if you had little to no maintenance input current during several off-days and a demand for power during this time, stored energy capacity could become and issue. I'm sure there are certain types of capacitors that are less susceptible to internal losses over longer storage periods while idle...which ones that may be I have not determined...someone probably already knows this and they're not talking about it, or at least not here. Capacitors to boost battery output for surge demands can be done successfully, though.

I searched for "low-loss capacitors" and came up with a very broad list of topics including manufacturer's sites, though many pdf spec sheets were on the list of hits just on the first page...may be worthwhile to check this out further as time allows. I have this sneaking suspician that these are more along the lines of circuitry use, possibly as a very short-term power source for interrupted circuit power applications...think UPS for a circuit board requiring continuous power to maintain volatile memory chips, only for limited time periods, unlike on-board power sources in a PC or similar application. Not being a electronics engineer, I can't say for sure at this point.

There are still some aspects regarding different types of capacitors that I don't fully understand, as this particular notion for use of capacitors has not really come up for me in the past...so I'm digging for more info as my own questions come up. The only practical experiences I have was mostly related to electronic circuit repairs in low-voltage applications with smaller devices, and when I was young and dumb, getting zapped from CDI in small engines (snap, OUCH) and the old breaker-type vehicle ignition capacitors. Maybe I know more than some, but believe me, I have a lot to learn yet.

Energy production and storage, mainly in the renewable and off-grid sectors, have been topics of interest for me for longer than I can remember...I know I have suffered several computer crashes during this time, so somewhere around 15-18 years. I toss some ideas around, do some digging, hit a dead-end, look for alternatives and the process begins all over again...huh, you're probably experiencing the same thing, to some extent..."welcome to the club" or, better put, "welcome aboard" is in order, I'm guessing. In times past, I may have felt that I might have to be the only guy looking for a way to do this or that with an unconventional means, but, there probably were several thousand attempting to do something similar at any given time...so, I think it's safe to say we're not alone. Thing is, there are dozens of companies with rather large R & D teams that looked into most every angle like we are trying to do, and, have deemed certain aspects of a theory to be attractive, yet the concept as a whole likely was deemed to be not economically viable...after-all, if production/marketing cost exceeds the benefits and potential profit margin, they go back to the "drawing-board". It's all economically-driven, and controlled by majority share-holders. On the individual level, things change a bit...we're looking for a specific application...possibly a specialty deemed not economically viable by a company, yet it may have merit for someone like you or me...if only we could tap into their scrapped project files...(insert sigh here).

I do feel that the idea of a total replacement of standard battery systems with capacitors would be premature at this point, based on the self-discharge energy losses...as you say, "trust, but verify". As for the six-pack capacitors with a battery look-alike design, I can't vouch for them as being an actual energy storage system, but they could provide quite a punch to boost the output of a battery for short engine cranking cycles, or just to get the engine to begin rolling over in extremely cold conditions, then allowing the battery to handle to rest. Here lies the possible down-fall in that scenario: if the output profile of those capacitors is of extremely short duration with a high current (which I suspect is the case), then little benefit would be realized. Little info was provided for specs on those capacitor packs you linked, but if one were to search for the brand name and model it may yield more data directly through the marketing source. If what you found was inconclusive or incomplete data, it may clue you into an other search topic for the web...might have to think like Sherlock Holmes to eventually find what you need to know. I've had to do that when researching some specific brands of RE batteries, and I received the info via email through their reps...it may not have been exactly what I was looking for, but it was the most complete info they had to offer and at least gave me a better idea what to expect from their products.

Hope I didn't rain on your picnic, so to speak. After last night, and not being around internet access all day while at work today, I had some time to think about this a bit more...it just seems too easy to be a viable solution...gotta be a reason why no-one is doing it yet...doesn't work, or is too complicated with protection circuitry, and/or cost prohibitive...but that's yet to be determined, so don't give up the ship just yet. I'll keep my campfire burning 'til all hope is lost.

Who knows, we may just be looking from the wrong angle and can't see something that would be otherwise be obvious. More later, I'm sure.

BTW, if anyone has info to support the capacitor energy storage idea, or, blow it out of the water, I'd like to see it...I'm sure Caribou would as well.

Thanks!!!


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## forluvofsmoke (Jan 27, 2012)

Just had a another thought...could be a scary thing this late at night...

Search the web for electronics forum and see what a site's main and sub-forum topics contain for subject material...could be there are tons of sparky-types hangin' out chewin' on silver-solder over this kinda stuff.

OK, gotta do eye-lid inspections before work in the morning...crap, it IS morning already!!! Later!!!


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## bunkerbob (Sep 29, 2009)

*my system*

This is my system and 36-T-105 battery bank. Solar, about 4.8kv and a wind turbine, 1000 watt, 500 average. Replace batteries about every 10 years. Equalize regularly, make sure water is level at all times, I even make my own RO water for replenishment. Runs a normal household, refer, 2 freezers, well pump(2 hrs. a day, keeps 2-5,000 gal tanks full). Been off grid for 10 years with this house, previous home grid-tied with a bit smaller system. Also have a 8.5kw Kholer genset for backup, ties into system, auto start when needed.
We are mindful of power usage though, conserve(everyone should anyway) by turning off lights and using elect., washer, dryer, lawn mowing etc. during peak solar generating.

BB


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## smaj100 (Oct 17, 2012)

bunkerbob said:


> This is my system and 36-T-105 battery bank. Solar, about 4.8kv and a wind turbine, 1000 watt, 500 average. Replace batteries about every 10 years. Equalize regularly, make sure water is level at all times, I even make my own RO water for replenishment. Runs a normal household, refer, 2 freezers, well pump(2 hrs. a day, keeps 2-5,000 gal tanks full). Been off grid for 10 years with this house, previous home grid-tied with a bit smaller system. Also have a 8.5kw Kholer genset for backup, ties into system, auto start when needed.
> We are mindful of power usage though, conserve(everyone should anyway) by turning off lights and using elect., washer, dryer, lawn mowing etc. during peak solar generating.
> 
> BB


BB, what are you running for inverters? I followed the link to your website and its broken. Pages aren't loading any pics. Just curious thats a good looking system.


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## bunkerbob (Sep 29, 2009)

*inverters*

I run Trace/Xantrex SW 4024's. Each are 24vdc and put out 4000watts. They are tied together with a ribbon data cable that allows them to synchronize the AC sine wave to create 240vac. 
These were over built and should last for years to come. I also have a backup just in case, and a spare for parts.
By the way, I use Outback Flex80 charge controllers, each handles half of the panels, but could by themselves handle all. Just a good backup measure, remember "1 is none, 2 is one, 3 is two, etc.".

Thanks, BB


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## Caribou (Aug 18, 2012)

forluvofsmoke said:


> Little info was provided for specs on those capacitor packs you linked, but if one were to search for the brand name and model it may yield more data directly through the marketing source.
> 
> If what you found was inconclusive or incomplete data, it may clue you into an other search topic for the web...might have to think like Sherlock Holmes to eventually find what you need to know.
> 
> ...


I found the manufacturer's website and they had little more information than Amazon did. I have not yet contacted the manufacturer directly.

Yes Watson, there does seem to be a dearth of information available.

I don't feel like you have rained on my picnic but if I spent a ton of money to find out that it does not work it would feel like a downpour.

More people looking gives more perspectives on the problem. Even if people don't have the right answer they may have the right question.


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## cowboyhermit (Nov 10, 2012)

sherlinsmith12 said:


> I am waiting here and do you have any new thoughts that could save money???


You are posting in the wrong thread. Start a new one or search out one with that topic, but this one is about batteries and under the energy and electricity sub-forum.


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## camogirl (Apr 18, 2015)

I'm trying to build m y own battery bank. Also. But I have a gas generator, for back up to charge. As. I know gas could become scarce at some point I have built a Gasifier. I absolutely love my gasifier and am now fitting my truck for one!!! I have 23 battery's total. This I am new too, now the only problem is that I need convert my fifth wheel over to pure battery bank power. And. I have to say I am a little overwhelmed. Anyone have any. Suggestions.


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## Viking (Mar 16, 2009)

camogirl said:


> I'm trying to build m y own battery bank. Also. But I have a gas generator, for back up to charge. As. I know gas could become scarce at some point I have built a Gasifier. I absolutely love my gasifier and am now fitting my truck for one!!! I have 23 battery's total. This I am new too, now the only problem is that I need convert my fifth wheel over to pure battery bank power. And. I have to say I am a little overwhelmed. Anyone have any. Suggestions.


We run 4 six volt golf cart batteries hooked to a 2000 watt Xantrex pure sine wave inverter on our 33' motor home. The batteries are charged by four 100 watt solar panels on the roof which can be tilted with a set of straps for better sun coverage throughout the day. I have thought about adding a few more golf cart batteries and one more solar panel for longer run times, but as it is, the system does great. Thing is, when going to a solar charged battery system on a trailer or motor home, it's a good idea to consider what appliances you can do without. Air conditioning, microwave, and furnace can drain batteries fast. There are web sites for solar/battery systems that have system for figuring what you will need but you will need to know the current draw of what you want to use, when you add all things up it will tell you how many amp hours your battery bank will have to be. Going to LED lighting is really a big thing, even over fluorescent lighting, we have a number of fluorescent lamps in our motor home, they all run off of 12 volts, but they use a lot of energy so we just don't use them all that much and I will probably switch them over to LED. A lot of people here have solar/ battery systems, in use or as backups, so don't hesitate asking questions or to even PM us. One thing I have found in getting solar panels, solar controllers and inverters was, if possible, find a local supplier and pick up the equipment yourself, it's amazing how much you can save off of shipping costs. I recommend staying away from RV and trailer supply companies unless they give deep discounts, we saved about over $800 by driving about 130 miles to buy the inverter/charger for the motor home and hundreds more, later on, for the solar panels, solar controller and inverter for the solar standby system that I have been putting together.


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## Viking (Mar 16, 2009)

One thing I will repeat from a friend that works on generators, who I consider to be an expert and what he has said more than a few times is, so far there is no really good battery other than a lead/acid deep cycle for solar systems as for affordability and long term use. With proper charging and the addition of distilled water they are still hard to beat, AGM's are supposed to be great as well but need properly controlled charging from programmable solar charge controllers and inverter/chargers, AGM batteries are considerably more expensive and so there are happy mediums available such as Sam's Club and Costco, Costco is where we've gotten all of our 6 volt golf cart batteries, at about $85 a piece with core turn in, so far I have found them to be a good price for a decent quality battery. At this point I can't see using capacitors or other types of batteries, not that I wouldn't mind to have gotten a set of Rolls Surette very high amp hour batteries, it's just that they are far beyond our financial means.


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## camogirl (Apr 18, 2015)

I most definitely will stay away from RV supply co. In my experience they have high pricing. I am not keen on the idea of solar panels they are a little outside of my price range. That is the reason for the gasifier. I have a large wooded area on my property so it's a little more reasonable for me.


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## Viking (Mar 16, 2009)

camogirl said:


> I most definitely will stay away from RV supply co. In my experience they have high pricing. I am not keen on the idea of solar panels they are a little outside of my price range. That is the reason for the gasifier. I have a large wooded area on my property so it's a little more reasonable for me.


Did you make your gasifier? The reason I ask this is because years ago "Mother Earth News" magazine had plans for making one and I still have that issue. As to the use of solar panels, I can certainly understand the cost factor, as it is it will be a while before I even get the solar array frame set up and the panels wired in, that's the beauty of having an inverter/charger, I can keep the battery bank charged with grid power and have emergency power for a few days. Although we have a generator I don't want to use it unless I have to, it's noisy and uses close to a gallon of gasoline per hour. My friend that works on generators has an older generator out of an old motor home, it's a slow RPM type, 1,800 RMP, so it runs a lot quieter and at $125 for 4,000 watts it's a good deal. It might be a good candidate for gasified fuel.


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## smaj100 (Oct 17, 2012)

I have the fema basic plans along with several other sets of plans to build a gasifier. On the list of things to do some day lol. IF you want a gasifier that has had some serious scientific research put into you can check these guys out.

http://www.allpowerlabs.com/products/gasifier-kits


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## camogirl (Apr 18, 2015)

I have already built several gasifier and I love them I'm always looking for ways to improve it.


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## LincTex (Apr 1, 2011)

The FEMA for sure and (maybe?) Mother Earth News units are bad for making "tar". 

Keep lots of solvent handy to free up your intake valves after shutdown, if it's a tight engine. Loose engines can handle some tar a little easier.


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