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shall
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# Posted: 2 Aug 2016 02:05pm - Edited by: shall
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first, I'm a total solar novice and trying to learn about solar and I'm thinking about putting together a battery backup for my house in the event of outages.
I haven't yet settled on the size of the battery bank, however if one were putting together a battery bank in the 400ah range, it there any reason that you would not want to build it with 35ah batteries?
In other words, does using four 100ah batteries have any efficiency advantages over using...say...twelve 35ah batteries?
From checking SLA prices on Amazon, it seems like the 35ah have by far the cheapest $$ per watt hour.
I was specifically looking at the UPG UB12350 on Amazon
thanks
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Steve_S
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# Posted: 2 Aug 2016 02:42pm
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A bit more clarity on your question would help.
1) how are you charging ? Planned or Existing.
2) feeding an Inverter for 120V or running just 12v
3) Auto ON if line power fails ? Or manually switch over ??
4) Do you want to set a Genny with Transfer Switch in place ?
On batteries... FLA still remains the cheapest for now but as technologies improve that is changing quickly.
Will your batteries be subject to extreme weather ? Heat / Cold - freezing ?
In house/Cabin or external to living spaces ?
Do you want to build a system that can be expanded later if needed either by solar panels, batteries or more ? Future considerations today can cost a bit more today BUT save you heaps later.
The more info you can provide will result in a better answer or suggestions as to how best to proceed. You know that old saying, "Help Us Help You".
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shall
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# Posted: 2 Aug 2016 03:15pm
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hooboy, I hope I can answer these and not look too ignorant (which I am  )
-I was planning on having the solar panels & charge controller to charge them in the event of a blackout, however I may keep them charged using grid power and a batter charger.
-It would have an inverter.
-No auto on. It would just be a self contained unit, perhaps on a small rolling cart
-I would keep it indoors in conditioned space
-as far as expansion, I'm not sure. It seems like you can only expand a backup system so much, right? I'd want it to be "semi portable", meaning that I'd want to be able to move it within the house, but I don't necessarily need it to be portable enough to take on the road. That's why I was thinking of having something like a cart with shelves that would contain the batteries, charge controller & inverter and be able to roll it to my back patio and hook up to the panels for charging.
I'm open to suggestions. My solar experience is limited to a little 12watt foldable solar pouch off Ebay that charges a 12000mah powerpack for charging ipads, cell phones and a USB LED bulb.
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Steve_S
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# Posted: 2 Aug 2016 03:33pm
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There are options. Have you considered something along the lines of this Yeti-1250 as an all in one, ready to go kit but at 1600 USD it's steep but expandable. * Cheaper on E-Bay & Amazon * The advantage is that it is tried, tested & working while being Turn Key without the futzing about.
Speaking of EBay... they have quite a lot Portable Solar Power Generators
The Portable Generators such as this are appearing fast & furious to fill market demands so one must be cautious and likely stick to an established company with a track record.
Something like this can be self-built without huge difficulty but being portable does limit size / capacity.
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shall
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# Posted: 2 Aug 2016 03:37pm
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actually, I should amend that.
I probably would want to expand it later because since this is new to me, I'd want to start somewhat smallish in case I screwed up and killed a battery or something.
maybe start out with a single 100w panel and a battery bank of around 100ah. Expand to perhaps 400ah of storage.
Being in south Texas, I'm not sure of the solar array size for a 400ah bank. Would 200 watts be sufficient?
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Steve_S
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# Posted: 2 Aug 2016 03:54pm
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Boy... this one is quick.... LOL... almost like IRC. < yep, me = old, where's my FidoMail ? >
South Texas lots of sun and that stuff we won't mention... (think storms). TBH, the portable solutions can be pricey but worth it IF it's a Part Time use place but not terribly great if FT. If your Full Time then it would be cheaper to use standard solar parts.
It all depends on your budget but if your FT and want a reasonable, small standalone system as a backup, then (some will wag fingers) you may want to consider a Marine or RV solar system. Marine Systems have the advantage of being designed for rough / rugged environments, isolated systems with the capacity for using 'shore power' (which translates often as dirty power). Ironically the RV'ers & Marine folks figured a lot of this out ahead of the home solar crowds.
Go Power USA has kits for boats & RV and there are may listed on EBay & Amazon and for good prices. Check out http://gpelectric.com/applications/rv-marine-power to see some options.
BTW: I bought my combo 3Kw Inverter/Charger from a Marine Supplier at 1/2 the price than a Home Supplier and it has more features as a bonus.
WholeSale Solar in Cali has some good deals and worth looking at http://www.wholesalesolar.com/rv-marine
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shall
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# Posted: 2 Aug 2016 04:42pm
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thanks for the info and links, Steve_S
I have thought about the manufactured solar generators and undoubtedly, there's much value in something that has been tried and proven prior to being mass produced.
It just seems that for the money, you get so little bang for your buck.
Also TBH, I was kinda hankering for a new project and something new to learn about and I've lately been drawn to learning about solar.
What will probably be my wisest first move would be to put together a small tool box sized unit that would help me learn hands on before moving on to something a bit larger. A small portable system could come in handy in numerous ways for me.
Also, to an earlier question, if a person could get a really good deal on 35ah SLA batteries, would it be kooky to build a 350 or 420ah battery bank using just 35ah batteries?
Is there any kind of performance fall off by using many small batteries vs using a few larger batteries?
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MtnDon
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# Posted: 2 Aug 2016 04:44pm - Edited by: MtnDon
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Quoting: shall first, I'm a total solar novice and trying to learn about solar and I'm thinking about putting together a battery backup for my house in the event of outages.
For a backup system to permit the ongoing use of essentials like food refrigeration, operation of a well pump if applicable, or operation of a heating system, it is my opinion there are better solutions than solar and battery energy storage.
Also, IMO, a backup system that is not automatically activated is only a partial solution. Do you ever leave home for more than a day? Power failures can and do occur when you are absent; at least that has been our experience.
It is hard to beat an auto start generator system, fueled by natural gas or propane (with large ground tank).
IF you also want to get into replacing purchased grid power with your own solar that is another thing altogether. However for backup, emergency only power, I would stay away from batteries and solar.
That's the way I see it.
Oh, to the original question... the best battery banks have the fewest number of batteries, the fewest number of cells, and if possible no batteries in parallel connection. So, IMO, those 35 aH batteries would be the worst possible choice.
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creeky
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# Posted: 2 Aug 2016 09:18pm
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shall. you ask a very (very) interesting question.
First. It depends on the chemistry of the battery.
Yes. (note above) If you're building your battery out of dinosaur droppings you will want to be careful of the number of parallel connections. after all. ye olde tech is less adaptable than ... well. other things that have gone extinct.
but if yer building out of lithium. or today's tech. parallel connections are fine.
gm/nissan/tesla use hundreds of parallel connections. hundreds. just in case anyone missed it.
btw. i've always loved gms buick line of cars. the best car. pah. but the best car in situation X. ya. okay. I could tell stories of driving past construction barriers in the the mountains or, but.
and that goes for batteries. there's a best in this situation. and most cost efficient. and most reliable for temp variable yx.
lead wins none of those.
sla is junk. don't waste your money. get a lithium pack. kinda like buying a steak over tofu. yup. your porterhouse costs more. but it delivers.
still. your choice. buy a tofu battery for a couple of years of pathetic performance. or get a lithium battery and a few decades of red meat performance.
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shall
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# Posted: 2 Aug 2016 11:41pm
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I look on Amazon for these things. It looks like for a small starter "power pack" project, a 35ah SLA would cost $65.
For a battery with comparable usable storage, how much would that cost? Can the lithiums be totally drained vs 50%?
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creeky
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# Posted: 3 Aug 2016 10:51am
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Dod. Depth of discharge.
There are many variables here. Temperature etc. The advantage to lithium is that it can sustain deeper dod with an extended lifespan.
SLA at 50% dod has a real world lifespan of 600 discharges. While lithium at 80% has a lifespan of 5000. *mfct data varies.
I dod my lithium at 60% and did my fla at 20%. This is(was) to get max lifespan out of them. I got 1600 discharges out of my fla pack. I hope to get 3000 out of the lithium (30 and counting).
For the money your spending a throw away battery makes for a reasonable testing expenditure. building a larger battery bank out of those though. Not the best idea. good luck.
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NorthRick
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# Posted: 3 Aug 2016 12:09pm
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You should back up and decide what you want maintain power to during an outage. If the whole house, then what MtnDon said, you're better off with a generator. A battery bank big enough to power the whole house is expensive and for just backup service, not the best bang for the buck. Not even close.
If you still want to go down the battery road, you need to determine your loads first - how much and how long. Then the appropriate battery capacity can be determined. And then you will realize why a generator is less expensive.
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shall
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# Posted: 3 Aug 2016 01:46pm
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NorthRick, to be perfectly honest, I have a generator and a generator would likely fit my needs, but I'm just wanting to fart around on a zombie apocalypse project.
When my wife gets mad about my Amazon purchases, I'm just gonna blame the threads on this forum for getting me interested in this stuff. LOL
All kidding aside, I do some fairly regular reading on the grid and its vulnerabilities and I think the threats are realistic enough to make having a power backup that's not dependent on fuel a prudent move.
I'm in the "feeling out", "watching youtubes" learning stage. As mentioned earlier, it would probably be a good idea for me to start on a smaller portable project for something that would power some LED lights, a fan or two and for charging small electronics.
After I was comfortable, I'd like to tackle the project of building a larger battery backup.
For that, I know that I'll need to get the Kill a Watt and determine exactly what I'll want to power and go from there. For now, I've only been guestimating around 400ah for the larger project, but that will be settled when I get my ducks more in a row.
creeky, if I'm reading you right, if one was planning on a DOD of 80% on lithium and 40% on SLA, then for equivalent usable capacity, you can buy a lithium that's about 1/2 the capacity of an SLA?
35ah SLA @ 40% DOD = 168 usable watts
35ah lithium @ 80% DOD = 336 usable watts
Is that correct, or do I have this all wrong?
For the same usable capacity, what are lithiums compared to SLA? Twice as expensive? 50% more?
Just wondering about up front cost difference. I fully realize that you also have to factor in lifetime cost since the lithium batteries have a much longer lifespan
thanks
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NorthRick
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# Posted: 3 Aug 2016 04:14pm
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Quoting: shall NorthRick, to be perfectly honest, I have a generator and a generator would likely fit my needs, but I'm just wanting to fart around on a zombie apocalypse project.
Fair enough. I totally understand wanting to play around with things to learn more. I powered my greenhouse ventilation fans with a small solar setup instead of running power out from the house just because it was more fun to do.
Careful with creeky and his lithium suggestions. Not saying don't get lithium, but it is still relatively new for solar applications. Read creeky's posts on his recent lithium purchase. It's a fascinating but very involved project. Lithium is the up and coming thing, but it's not really plug-and-play just yet.
For getting your feet wet and learning things I'd start with your run-of-the-mill RV or golf cart flooded lead acid batteries. If you screw things up, your lesson isn't so expensive. For light use, maintaining the batteries isn't very involved at all.
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creeky
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# Posted: 3 Aug 2016 05:41pm
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North Rick. Lithium is not new for solar. Its just being used mostly for large industrial back up systems. What do you want to build? A 100 million dollar project or 10,000 10k projects? So the big guys are getting the batteries.
It is plug and play. Balqon has plug and play units now. Tesla is selling in Europe and Australia now.
Lithium has been in use for the RV and boating crowd. Many installs since 2010.
Just wanted to clarify that.
Also the batteries are available on ebay regularly. So keep an eye out there.
My brilliant (cough cough) diy lithium build is so amazingly rare in part because those batteries are going to corporate storage (in Canada, according to a solar guy who wants to interview me for his new book). So for a diy guy to get one is a statistical anomaly.
Then you kind of have to be part of that diy builder segment of the market. A rare bird too.
shall. you're right on with having fun with solar. pretty much all of us got started that way. I learned to hide my purchases from my wife fairly early on. grin.
"what. this old thing. why it's just a cheap thing I found at a garage sale." he said, kicking the amazon box under the workbench. heh heh heh.
and your calcs are right for battery size. you've got it. by jove. of course the key advantages of lithium. no dangerous off gassing. 3x lifespan. 10 to 30% more efficient on charge/discharge. plus. come on. the cool factor.
also lithium is easier to mix and match. the lead acid you buy today can't be added to the lead acid pack you buy tomorrow. while with lithium there is the opportunity to mix different age batteries.
but as NorthRick points out. A lead acid battery is a cheap way to play. i just wouldn't build any 400 amp hour battery system out of them. waste of money.
and that's 6 years of actual off grid solar experience talking. lead is dead.
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rachelsdad
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# Posted: 4 Aug 2016 02:55pm
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Creeky,
I've been listening to you extoll the virtues of the LiPo and i can't seem to find any that are on US soil or have the capacity for my relatively modest 2kw need.
I'm about to pull the trigger on 4 225 ah dinosaur turds....can you point me in the right direction
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KelVarnsen
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# Posted: 4 Aug 2016 03:44pm - Edited by: KelVarnsen
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Creeky, you got me Googling about plug n play lithium. I'm just in the early planning stages for a solar install for my unpowered 360 sq. foot cabin so I'm interested. I just came across this: Orison Kiskstarter, Orison Website. Apparently the tower will go for about $1500 USD. Not sure about availability, here is a post regarding their progress. I'm not sure what would be necessary to hook it up to panels for charging. Anyhow, I thought you might be interested.
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creeky
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# Posted: 4 Aug 2016 05:06pm
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Here are some ideas. My preference is for lifepo4
http://www.ebay.com/itm/LIFEPO4-12V-100AH-LITHIUM-PHOSPHATE-DEEP-CYCLE-BATTERY-FOR-SO LAR-WIND-SLA-Repl-/112081071636?hash=item1a188d6e14:g:6JoAAOSwtnpXoVky
Rachelsdad. You would probably need 200 amp hrs. But this is the idea.
Here's another one.
http://www.ebay.com/itm/CALB-100Ah-3-2V-LiFePO4-Lithium-Ion-Cell/191921336674?_trksid =p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D3538 9%26meid%3D6b76d542752c4067b86ad4738fd98cb0%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D 182204098650
Calb are very good quality batteries as well. And these appear to be in the US already.
KelVarnsen. That project is neat. I'm not sure what the target market is? Folks with a lot of power outages I guess.
I will post a brief tutorial on using lithium lifepo4 for a battery back up system.
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