As I get closer to getting off the power the power grid, the number one factor that has played on my mind is the cost of a decent size battery bank. I recently met up with a wind turbine enthusiest, (has 1200w turbine kits available including a tower $650, search for Phil Mann on the backshed website). This guy convinced me (and uses himself) that regular lead acid batteries are by far the best option for DIY off grid set ups.
They are more durable (will handle abuse to a degree) and can be monitored and maintained, which can't be done with any sealed type batteries, (he has a stockpile of thousands of dollars of dead sla and agm batteries in his shed)
With this in mind I have been searching far and wide for a cheap source of new batteries that would be suitable to start building my battery bank. Considering they are not a very complicated I started investigating building lead acid batteries which surprisingly is not the easiest information to find. I eventually had to outlay a huge $16.00 for from what I could find is the only book/ebook availaible on the subject (seems to me that this information is supressed to a degree) but the ebook is well worth every cent. "The Battery Builders Guide by Phillip Hurley"
I would highly recommend reading this if you are considering buying a large battery bank, building batteries from scratch is a lot of work and would require some specialty tools however very cost effective considering that lead is easily salvaged from many sources. The book even explains how to make and build lead compounds for true deep cycle lead acid batteries (a bit more complicated and uses some scarey chemical processes and equipment, but again well worth the effort.
The chapter that I found the most usefull atm is about recyling regular lead acid batteries. Apparently 1 in 5 batteries that are thrown out need nothing more than to be charged, some peaple/mechanics install new batteries as part of a rutine, regardless of the battery condition (may have many years of life remaining) or some peaple just throw away good batteries mistaking them faulty. Almost all lead acid can be restored to working condition with minimal effort, common problems are leaks to outer casing or between inner cells which can be repaired by simple plastic welding (most battery cases are polyurethane which is easy to weld) and individual corroded plates can be easily replaced from donor batteries. Only a very small percentage of batteries cannot be restored to life or used as a donor for other batteries, due to long term corrosion. I will be pulling apart the three ( what I thought were dead )batteries in my shed this weekend to see what I can do, could be the beginning of an obsession.
Phillip has several other books availble at reasonable prices, one that might interest peaple is about making various types of fuel cells, the battery builders guide is very thorough with plenty of clear pictures, diagrams, and calculation tables, I would expect his other publications to be of the same quality.
About this topic
- Posted by wildwabbit 11 months ago. There are 9 posts. The latest reply is from wildwabbit.
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I look forward to your update, as I'm also planning to live fully off grid within the next year.
My wife and I just bought 4 acres of lush green land with huge ocean views and it only cost us $60,000AUD
You just have to look to our neighbours (NZ) great exchange rate at the moment and the local councils are very supportive of environmental housing building and welcome off-grid living, unlike what I've discovered about my local council in NSW.
And no, it's not near Christchurch!! it's in the north island 1.5 hours south of Auckland.
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I failed to revive my batteries! They had been sitting in my back yard for 5-6 years and long term corrosion had rendered them beyond repair! Only the remaining lead has been salvaged. I have been trying to find places that will give me old batteries with little success, the local recyclying center is not allowed to part with them due to saftey resons and the few automotive stores i've approched all have contracts with "Century Batteries" whom make and recycle batteries in Brisbane, to take their old/returned/exchanged batteries.
I have now begun seriously considering building my own batteries.
This is what I am considering.If you look closely at some brands of deep cycle lead acid batteries, they look like a six pack, of cans. The reason for this is that instead of using numerous plates per 2.2v cell they use two (one negative and one positive plate) these two plates are coiled into a tight cylinder shape and is infact the method that the very first lead acid batteries used. The reason they do not use this style more is that it is more difficult to mass produce, however from a DIY point of view this style is much easier to construct and is a much more rubust product.
I won't go into too much detail but anyone interested is welcome to PM me here.
There really is nothing too complicated in the construction process, however i spent many nights calculating surface area/amp hour ratio's, specific gravities, electrolyte/cell volumes, amp-wieght ratios the list of calculations to take into account is a head ache but must be firmly understood to make a battery that will work for a long peiod of time. But in a nutshell the most important factor is that more surface area of lead creates more amp hours, and thicker plates will have a longer life, so at the end of the day you have to balance up size/weight vs amp/hrs vs longevity of the plates. The very best commercial cells have 5mm plate, the plates in a car battery can be as thin as 0.3mm
I intend to go for plates of around 4mm which will still make a bloody heavy cell. I am estimating a 200Ah 2.2v cell to exceed 50kg in lead alone, but this cell should have a life in excess of 20years as long as they are maintained properly.
I intend to make the cells froms PVC pipe as this is acid resistant to sulphuric acid up to 80% pure, the battery acid is only 25-30%. The very few other components i will need are inexpensive.
The only thing slowing me down at the moment is the hording enough lead to make 12 X 2.2v cells,(I am building all my componets around a 24V system at present) as the quantity of lead needed to make a cell that will last a few of years is inexpensive, but to make a cell to last the test of time becomes very expensive, purchasing lead at new prices is not an option, I am going to approach some of the local scrap metal yards this week to see what the best price is I can get for scrap lead.
Will keep posting as things develop.
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@ wildrabbit
I wish i had your skills.I have a question for you if you've got a moment. I'm tossing up between what type of batteries I should plan on getting for my off-grid project. I've been told that if I get fully sealed batteries, I'll be able to put them in the house somewhere, but they won't last as long OR get batteries that aren't sealed which will last longer (as they can be serviced), but will have to be put up on the roof as they will leak dangerous gas' into the house if put inside...
do you have any knowledge of this? as I would rather not be putting them on the roof if I can help it.
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carcus27
yes vented lead acid batteries produce both hydrogen and oxygen, a highly flamable mixture. Most banks that I have seen use an enclosure/large box to protect the batteries with a small dc computer type fan to disipate the gases and also helps keep the batteries cool. I plan on venting the gases with a fan into pvc that will run above the hieght of the roof just to be certain although I haven't seen anyone else go to that extent Generally I think if they are vented into an open area there is minimal danger, I think putting them on the roof is a bit extreme but you are 100% correct that putting them in the house is strongly not recomended even if you have it vented by a fan and ducting. All of the banks I have seen are outside (on a veranda or sheltered side of the house where the gases will disipate on thier own.To the best of my knowledge good quality deep cycle wet(vented)lead acid batteries are by far the best choice of battery. They do require maintence(watering) and in rare cases desulphering at some time in thier life, but they are more robust and more likely to last a long period of time, even if they are mildly neglected or abused.
The sealed and agm type batteries are safer in some situations like on a boat or caravan but I get the impression regardless of what manufacturers claim that these types of batteries are more for the set and forget type of mentallity we have adopted with a garantee to fail 6months after the waranty. I also think these types of batteries are all part of the cyclic consumptiion mechanisim. My turbine expert friend who has been building diy off grid systems for 30 years swears by vented lead acid, the two banks of dead agm and sealed batteries in his shed are testimony and an expensive lesson for him. He swears he will never buy anything except vented lead acid again.
The following article provides a lot of interesting information about the advantages of vented lead acid batteries.
http://www.battcon.com/PapersFinal2008/ODonnellPaper2008PROOF_6.pdf -
wildrabbit
Thanks for the info. I'm decided to go for the 'vented lead acid'... as you say, build some kind of vented containment on the outside of the house. (not the roof)
I'm also following your thread about wind turbines also.
Thanks again.
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Quick update...
Visited a few scrap metal yards and metal wholesalers and made a lot of phone calls within the lead industry this week......
The bottom line is that purchasing lead, be it scrap or new is just far too expensive to be an option.(best price for scrap lead is $1.60kg and new lead is $3.00kg ) The only way this project will be worth doing is if the lead is free or I calculated around $0.50kg would be acceptable, but unlikely to find any at that price.
With a few other projects on the go atm I think the batteries will be on the back burner until I can horde a few hundred kilo's of lead. I have about 30kgs atm.
I will however in the meantime make a test cell, just a small one maybe 10 or so amp hours to make sure my calculations and construction methods work. I will be sure to post the construction process when I finish. I think most people will be surprised how simple this is. (however the calculations that dictate the construction are a bit complex, but once understood not too scary)
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Quick update...
Visited a few scrap metal yards and metal wholesalers and made a lot of phone calls within the lead industry this week......
The bottom line is that purchasing lead, be it scrap or new is just far too expensive to be an option.(best price for scrap lead is $1.60kg and new lead is $3.00kg ) The only way this project will be worth doing is if the lead is free or I calculated around $0.50kg would be acceptable, but unlikely to find any at that price.
With a few other projects on the go atm I think the batteries will be on the back burner until I can horde a few hundred kilo's of lead. I have about 30kgs atm.
I will however in the meantime make a test cell, just a small one maybe 10 or so amp hours to make sure my calculations and construction methods work. I will be sure to post the construction process when I finish. I think most people will be surprised how simple this is. (the calculations that dictate the construction design are a bit complex, but once understood not too scary)
-
Quick update...
Visited a few scrap metal yards and metal wholesalers and made a lot of phone calls within the lead industry this week......
The bottom line is that purchasing lead, be it scrap or new is just far too expensive to be an option.(best price for scrap lead is $1.60kg and new lead is $3.00kg ) The only way this project will be worth doing is if the lead is free or I calculated around $0.50kg would be acceptable, but unlikely to find any at that price.
With a few other projects on the go atm I think the batteries will be on the back burner until I can horde a few hundred kilo's of lead. I have about 30kgs atm.
I will however in the meantime make a test cell, just a small one maybe 10 or so amp hours to make sure my calculations and construction methods work. I will be sure to post the construction process when I finish. I think most people will be surprised how simple this is. (the calculations that dictate the construction design are a bit complex, but once understood not too scary)
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