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LastOutlaw
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# Posted: 18 Aug 2014 13:51 - Edited by: LastOutlaw
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I have a new to me cabin way off grid and have been working on it since this past winter when I purchased it.
I'm trying to get it powered up and am slowly working into a battery bank to run things off of.
Here is where I am at.
I own an older Onan emerald plus gen from an RV. It is huge. Eats gas like there is no tomorrow.
I'm in the process of looking for something smaller such as the honda eu2000i.
I bought six 100 amp hour batteries and have them wired parellel.
I will add solar panels probably this winter but am trying to run off batts and genset right now.
From what I have seen here I would need to charge at 60 amps to charge this 600 amp hour bank in a reasonable time frame.
I have a 30 amp solar charge controller for use after I add panels but cant figure out what I should use to charge the bank from the generator.
Any info would be greatly appreciated.
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MtnDon
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# Posted: 18 Aug 2014 16:11
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Quoting: LastOutlaw what I should use to charge the bank from the generator.
something like one of these Iota Engineering chargers The DLS55 (@C/10) or the DLS75 (@C/8) C/8 will give a better "mixing action" of the electrolyte and as long as you watch the battery temperature can be safe.
12 volt batteries, all in parallel??
FWIW, IMO, if you are connecting six batteries in parallel you are asking for battery problems. That many parallel batteries very often develop unevenness in discharging and recharging. That ends up with one or more batteries being discharged too deeply, more discharged than some others. Then when recharging the set, either the deeply discharged batteries don't get properly recharged or the batteries that were not discharged so deeply get over charged. Either way the end result is a shortened performance life of the battery bank.. Better would be 6 volt batteries; 2 in series to make 12 volts. Then put two or three of those series pairs in parallel. Still not ideal but better.
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LastOutlaw
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# Posted: 18 Aug 2014 16:21
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Thanks MtnDon. The chargers look good. I'll look into them.
I got these batteries through work so I was limited on what choices I had.
So I'm set with the six 12 volt deep cycles i have.
So would I be better off setting these up as 2 separate banks of 3 batteries each? If so wouldn't I need 2 charge controllers, 2 power inverters and 2 chargers as well then?
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MtnDon
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# Posted: 18 Aug 2014 17:05 - Edited by: MtnDon
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Quoting: LastOutlaw So would I be better off setting these up as 2 separate banks of 3 batteries each? If so wouldn't I need 2 charge controllers, 2 power inverters and 2 chargers as well then?
IMO, that would cost more that any savings realized on the batteries would be negated. Although the duplication of hardware does bring a certain redundancy to the system.
If I already had the batteries and could not return / exchange them, I'd probably see what happens with the six in parallel. I'd also buy a good temperature compensated hydrometer if those batteries are of the normal flooded variety. Watch and record the specific gravity readings over time and as necessary remove a battery or two to recharge on their own, not as a part of the bank. That way you'd try to even out any differences that develop. More work, but maybe good in the long run.
Getting some solar going would be a number one priority IMO, as that can save a lot of fuel and generator noise and smell. It is also going to keep the batteries better charged than most folks can do with relying solely on a generator.
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LastOutlaw
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# Posted: 18 Aug 2014 18:02
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Thanks again Don.... Im planning on adding in 4 or 6 - 100watt panels this winter. Im a bit concerned about theft though as Im not there but a couple weekends a month. I'm considering setting them up as a temp setup so I can lock the panels away when I'm not there.
Maybe one lone panel on the roof to keep the batteries up.
Another concern is distance from the cabin to the solar array. I'm guessing 100 yards to the sunny spot. Is that too long of a run from panels to batteries? If not what wire should I use for the panel to battery run?
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MtnDon
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# Posted: 18 Aug 2014 18:51
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Quoting: LastOutlaw Another concern is distance from the cabin to the solar array. I'm guessing 100 yards to the sunny spot
We have a run of about 325 feet between our PV array and the CC / batteries / cabin. Distance like that does raise some potential problem points, but they are solvable.
The main issue is voltage drop over a long wire. The solution is usually a combination of using larger diameter wires and connecting the PV panels in series to raise the voltage. Series is preferred over parallel as series connections do not raise the amperage like PV panels in parallel would do. Higher amps = the need for larger wires.
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Series connected PV panels can make the selection of a charge controller more limited. There are a couple issues.
The elevated voltage is too high for many charge controllers. There must be an allowance made for cold weather which causes voltages to rise. (Example: the theoretical max voltage of our three in series panels is 108 volts, but I have seen recorded voltages as high as 141 volts.)
When connecting the PV panels in series it is necessary to use an MPPT charge controller, not a cheaper PWM or other less efficient design, otherwise much of the power available from the PV array will be wasted.
Have you got any other DC equipment at this point? I ask because a better system can be built using 24 volt battery bank instead of 12 volts. 2 x 12 in series = 24 volts; then three parallel strings. Something to think about. I mention this as charge controller efficiency goes up as the battery bank volts go up. For example a Midnite Solar Kid charge controller can handle about 420 watts worth of panels when used with a 12 volt battery but double that when used with a 24 volt system.
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If the batteries are to be left in place over a winter it is necessary to have some charging ability on site. Otherwise the charge slowly drops due to self discharge. If the charge gets low enough the batteries can freeze as well as develop other problems when sitting in partial charge for a lengthy period.
One PV panel left on the roof should be ample to maintain the charge. It would not need to be as large as the others if we assume the battery bank would be brought to a full charge before the main array was stored. We used to use a 45 watt array to float 4 golf cart batteries over the winter. Worked very well.
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Quoting: LastOutlaw what wire should I use for the panel to battery run?
That depends on the setup; the actual distance, the PV maximum power voltage and amps and how the panels are connected.
I used #2 on ours which is actually overkill. I was looking to possibly increasing the number of panels in the future and needing to have the increased amperage capacity and low voltage drop. I could have used #4 the way things have worked out with still using the original 624 watts worth of panels. If you can give a link to the PV panels you are thinking of I can give you some thoughts if you'd like.
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LastOutlaw
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# Posted: 18 Aug 2014 19:23
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Right now I have six 12 volt deep cycle flooded plate batteries and one 12v - 2000/4000 watt inverter and one 30 amp/250 watt max Renogy pwm charge controller. I had planned on using the charge controller with a 25 or 30 watt panel to keep the charge levels up when I'm gone.
Was considering 4 to 6 of these.
[url=http://www.amazon.com/RENOGY%C2%AE-Watts-Polycrystalline-Solar-Listed/dp/B00DCCOSV0/ref=sr_1_5?ie=UTF8&qid=1408404110&sr=8-5&keywords=100+watt+solar+panels]
http://www.amazon.com/RENOGY%C2%AE-Watts-Polycrystalline-Solar-Listed/dp/B00DCCOSV0/r ef=sr_1_5?ie=UTF8&qid=1408404110&sr=8-5&keywords=100+watt+solar+panels[/url]
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MtnDon
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# Posted: 18 Aug 2014 20:18 - Edited by: MtnDon
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Some "what if's"....
Assuming; distance = 300 feet and desired voltage drop maximum is 3%...
IF there were 4 of those panels in parallel the recommended wire size is 350 AWG. Way too large to be practical / affordable. (0.681" just under 7/10 inch diameter)
IF the 4 panels were in series the recommended wire size would be 6 AWG (0.184" just under 3/16 inch diameter) Much more affordable, but requires a CC that can handle the maximum voltage which is the Voc x a safety factor. (normally 1.25 x 1.25)
OR looking at it another way, IF the 4 panels were in parallel and #4 AWG wire was used (still somewhat affordable) the voltage drop could reach as high as 23%. That would drop the maximum 17.8 volts to 13.6 which is basically float voltage. No real charging would take place no matter how brightly the sun was shining.
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The MN Kid could handle 4 of those panels on a 12 VDC battery system. MN has a sizing tool you can use. Enter the panel parameters and adjust the temperature for your local maximum and minimums. Five of those panels could be used but the system would shut down in some cold weather conditions. Five panels in series is at the upper limit recommended by MN. Six panels might be a better choice depending on where you are located & what sun hours you have.
As you can see the distance of 300 feet is a challenge. There are solutions but none in the bargain basement.
With a 12 VDC battery bank and the 300 foot wire run more than 4 panels would need a larger capacity CC or two of the Kids wired up for parallel use. (Two sets of 3 to 4 panels in series, each on their own CC.) A 24 VDC system could have a single MN Kid serving up to 8 of those PV panels. The Kid is about $300 delivered.
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Ruggles
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# Posted: 18 Aug 2014 21:43
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I have run 4 to 12 batteries at a time. You can charge them and discharge them all evenly if you use some type of tie bars (I like copper bars myself). Tie each battery to the two bars with the same length cables, charge and discharge from the battery tie, not from any of the battery terminals. I don't remember who told me that but it works. Might be from The DC Side of Life. Your batteries all charge and discharge at the same rate, assuming the same type and age. Probably not the true definition of "parallel" but achieves the same purpose. Cheers.......
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MtnDon
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# Posted: 18 Aug 2014 22:04 - Edited by: MtnDon
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Copper buss bars can help, but a lot of what will happen still depends on how good or bad your luck is.
The problem can stem from the batteries themselves. Even batteries from the same production run can have slight differences in internal resistance. No matter how large or conductive the cables or bars are nothing we can do can change whatever internal differences there may be. That is where the crap shoot starts; inside the batteries. Some folks have had good fortune with parallel strings up to three deep. I know of others who have had bad mismatches with only two parallel strings. No way to tell ahead of time.
FWIW, we use copper buss bars as a common parallel connection point. As well we have solid copper bars that connects each battery in each series string. We're just over 5 years into service and everything looks good; except for the lightning damaged electronic components.  Battery bank photo below (the buss bars have been subsequently covered with foam sleeves)
Ideally none of us would run any parallel strings. I took a chance and was lucky. Although not abusing the batteries with deep discharges may also have contributed. Like many folks the costs of using more specialized batteries such as 2 volt Rolls/Surette cells, was a big part of the decision. However, personally I would not go deeper than three parallel. In the future, whenever we need new batteries I'll either go with a double parallel string of golf carts or a single string of L-16's.
I did not sweat the cable lengths being unequal. My thought was the 2/0 cables were oversized for the power demands and that made the cable resistance differences less than what could be encountered between individual batteries internally. That's similar to the reasoning behind using high capacity buss bars in place of individual cabling; very low resistance, plus the ability to remove one string from service w/o disturbing any connections for the other series strings. A plus was the bars were cheaper than a bunch of large cables and lug ends. And neater.
Five years later the hydrometer readings are consistent and the capacity still more than adequate. Call me happy.
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Ruggles
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# Posted: 18 Aug 2014 23:10
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Roger the Happy. I use batteries that are taken out of the UPS at my aerospace company. We have a contract that requires upgrades at given intervals. The old batteries go to the recycler for $12.50 each so I give the guys $125.00 for ten batteries whenever I need some for another project and they happen to be replacing a string. Limits my choices but also my cash outlay hahahaha. My oldest ones from this are now going on 6 years at the cabin. Happy is good............
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LastOutlaw
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# Posted: 19 Aug 2014 16:27
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Thanks for the info....lots here.
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creeky
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# Posted: 22 Aug 2014 12:14
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As well as Iota there are other good 4 stage chargers. Powermax comes to mind. You need 4 stages for float, bulk, absorb and the occasional equalize. If you have solar, let the solar do your equalize ... imho
And if you're thinking 4-6 100 watt panels at $140. why don't you buy 300 watt panels for $270?
So instead of 840 dollars for 600 watts you could pay 540. and have better quality panels. and need far fewer connectors etc.
Now use the $300 savings to get reliable equipment.
the basics of todays solar continue to be
pure sine inverter ... 200-300 (no killing your expensive rechargeable batteries for your tools, cell phone, etc. this will save you hundreds in the long run)
mppt controller ... 200 - 500 (use higher voltages and run cheaper wire, better electronics. you'll have to buy one eventually)
high voltage panels ... around .75 cents a watt now (need I say more)
And lead acid batteries are so last year. You are foolin' yerself if you think a lead acid battery pack is nearly as cheap as LFP (lithium iron phosphate) over its lifespan. My battery pack (lead acid) runs 3 kw max dod for long life... max 8 years but really 6. If I do the same 3 kw dod on a 9 kw LFP battery I get 20 years. Do the math. 2k for my battery pack at 6-8 years. 3.3k for an lfp battery pack at 20 years.
one costs 6k over 20 years the other costs 3.3. Unless you're building a really small system I would forget lead acid batteries.
I know. Some folks like getting those little hydrometers out and measuring the cell balances and topping up with water and pretending it's a mystical art while they dance around the rocks they've laid out along the earths ley lines. Me. I like to plug it in and forget about it. And, of course, I am cheap. I like a bargain.
Now if I could get cheap batteries at 1/20th of the cost the rest of us have to pay. coughrugglescough.
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bobrok
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# Posted: 22 Aug 2014 15:50
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Quoting: Ruggles Roger the Happy. I use batteries that are taken out of the UPS at my aerospace company. We have a contract that requires upgrades at given intervals. The old batteries go to the recycler for $12.50 each so I give the guys $125.00 for ten batteries whenever I need some for another project and they happen to be replacing a string. Limits my choices but also my cash outlay hahahaha. My oldest ones from this are now going on 6 years at the cabin. Happy is good............
Mine came from a cell phone tower when the cabin was built.
That was in 1998/1999.
They are still in service. Admittedly they aren't performing at optimum, but they get us by for 3 days at a time with our minimal demand.
Talk about HAPPY 
I don't even want to think about cost to replace my system when the time comes.
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LastOutlaw
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# Posted: 26 Aug 2014 10:50
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so, where can i get 300 watt panels for that price?
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LastOutlaw
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# Posted: 26 Aug 2014 11:11
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can someone look at these and tell me good and bads? They said these are available at $150.00 per panel. Seems too cheap to me.
http://www.alibaba.com/product-detail/China-best-PV-supplier-12v-solar_1400779828.htm l?s=p
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creeky
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# Posted: 26 Aug 2014 12:45
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those seem okay. you can look up any good solar provider. the usual google solar panel 300 watt plus the name of your state or province. should get you going. imho higher voltage panels will be more useful over their lifetime. personally I would look for a 48v class panel ... but there are many variables.
and I love the dropping price on solar. What. 7 years ago panels were selling for $6/watt. Now it's .60 cents a watt. I'm jiggy with that. With your 600 amps of batteries I'd probably get a good mppt controller at 60 amps and 1kw of panels. Why not. It's about 1000 bucks. You'll save that on gas in a couple of years tops. Or when you buy your fridge and can go mainstream electric vs "solar" electric or propane. Just the savings on the fridge will pay for your panels and controller.
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LastOutlaw
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# Posted: 26 Aug 2014 14:08
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thanks Creeky. I'm somewhat already invested in 12 volts so I need to run with it. This system is in a hot area so we are trying to make AC run. I may add another 6 batteries in 6 months or so after these are paid off. I ran the window unit last weekend off the bats as a test and it didnt run as long as I thought it would. i didnt charge the new bats before i took them to the cabin so i think they didnt have a full charge to begin with.
I used a killawatt on it to see the draw. The startup draw was 10 amps and leveled off to almost 8 amps once running. i only got about 6 hours out of them and drew the bats down much more than i should have.
I'll be back up there this coming weekend so I'll check them again. I just bought a used Honda eu2000i to recharge with so that will also be tested this weekend.
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MtnDon
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# Posted: 26 Aug 2014 14:30
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IMO, it is a losing battle to try and run a standard air conditioner off batteries via the inverter, especially 12 volt batteries. That goes double for any brand of window A/C or any brand of the portable A/C, because those have lousy SEER ratings.
IMO, if you really need A/C you should either;
(1) buy a mini split system. They have SEER rating up to 27 these days vs. about a SEER of 10 for a typical window unit. And then you should have a 24 volt battery system.
(2) run the A/C you have directly off the generator.
Also note that best power use off batteries will be with a pure sine wave inverter. That is because the compressor motor runs hotter and much less efficiently on square wave / modified sine wave than they do on pure sine wave. They will also generally have a shortened life span and be noisier although that may be hard to tell with the racket a typical window shaker makes.
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If you live near companies that sell solar systems, even those that target grid tie installations, I would ask them if you can buy PV panels from them. Not many of the grid tie oriented companies care to be bothered by small sales. However, there is at least one outfit near where I live that will sell anyone a single panel at a cheaper price than paying shipping costs. They will have the cheaper per watt higher voltage panels that are perfect for use with an off grid MPPT charge controller.
Personally, I would give serious thought to moving to 24 VDC. I know several cabin owners who started with 12 VDC and eventually were forced to switch to 24 VDC because of their power hungry equipment; A/C, electric fridge, etc.
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creeky
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# Posted: 26 Aug 2014 16:31
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last. If you've read my posts you know I also have a big 12v battery bank. no worries there.
however, an mppt solar controller means your batteries/inverter can be 12v. but your panels can be whatever. 12.24.48.96.
that's why mppt is basically the standard now. if you had a truck would you use a 20 year old 4-banger ranger to tow your new 250hp bass boat. H*** no. okay. maybe a couple of times, been there ... but I did have the 6 ... times have changed.
yah. you've got a controller already. but if you go... ooops. and throw it away (so it was 30 bucks, or sell it, or keep it as a back up) and get a new better one. you will do what every person who's built a solar system has done. admitted you made a minor error. it's like doing math. ooops. calculated that wrong. turn pencil over. erase erase erase. fix.
so. no worries.
***
Re: 12v vs 24 vs 48.
Note: at this very moment in time:
I'm running a 13 SEER 5000 btu air conditioner. It's chilly in my great room but 29 (84 F) and really humid outside.
I also washed dishes this morning in an all electric dishwasher.
I am running an electric fridge.
I'm streaming music over the internet (evil ways, santana).
I'm writing to you on my laptop.
My morning shower used electricity for the pump.
Yet my 1200 amp hr 12v battery bank is fully charged and is on float. it's summer ... lots o'sunny hours.
So I'd agree with MtnDon that while a system with 24 or 48v battery/inverter has advantages. Your 12v battery / inverter system is workable.
And this is thing about all of us. We each recommend what we've built. So I'm running 48v solar panels. 3 sets right now at 48v/12amps each. Adding up to 1500 watts. If you ran 12v that would be 60 amps. each.
Amps are the expensive part. You need bigger wire. That's the second reason I'd recommend you do high voltage. And I also recommend a 48v battery pack. Esp. if it's lead acid. If you added two more batteries you'd have 200 amp hrs at 48v btw. But here's the thing. Stuff is changing. So if you have something that's good quality. Shrug your shoulders and see what happens.
kind of the long way of saying you don't need 12v panels for your 12v battery pack. lol.
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LastOutlaw
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# Posted: 26 Aug 2014 17:02 - Edited by: LastOutlaw
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so, i can stay with my 12 volt bank, dump my $40 charge controller, keep my 2000/4000 watt 12 volt inverter and run 24 volt panels? Keep my 12 volt/55amp iota charger?
At this point all i need to dump is the charge controller?
btw...it was 104 degrees F here today.
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creeky
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# Posted: 26 Aug 2014 18:54
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you are correct.
get a good mppt controller. it will do what needs to be done. and you will get more power out of morning and afternoon sun.
and in due respect to 24 and 48v panels. ps. I still recommend 48v panels ... those 12v panels are .60 a watt. 12v panels once upon a yesterday were more expensive. last month, as you climbed up the voltage ladder you got a better price.
that's the whole magical thing about off grid solar. or on grid solar. the whole world is going horse whip buggy combustion engine electric motor microwave quantum effect. so things are changing fast. right now the best advice I can give is to go with what is available at a reasonable cost with safe installation right now.
ps-someone just went to my website and "took me to the pub" bless you.
bearing in mind that your solar system will produce energy for you for several decades to come. parse the $ equation carefully.
yesterday i had a friend who has seen my solar build ask me why I didn't buy a lithium iron phosphate (lfp) battery pack 5 years ago. I told her, it was only available two months ago. seriously. 9 months ago no one would have recommended a lfp pack without a heapin' handful of reservations. And one year ago it was basically "vapour ware". so.
.60 cent a watt 12v panels. I've never heard of that before. let us know if you can actually buy them. and how they do.
who was it that first said, yee hah!
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LastOutlaw
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# Posted: 28 Aug 2014 00:28
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How about 2 of these?
https://www.renogy-store.com/300W-Poly-p/rng-300p.htm
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LastOutlaw
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# Posted: 29 Aug 2014 10:35
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or is this better?
https://www.renogy-store.com/250W-Mono-p/rng-250d-bk.htm
unless someone else knows a better panel at a better price.
Also looking for good prices on 100 ft of wire
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creeky
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# Posted: 29 Aug 2014 13:50
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those are better, in my opinion anyway. note how by going with the big panel you've gone from 1.50/w (100w panel) to .80 cents (300w panel). I do accept beer in thanks. lol.
i've seen the site you mention. certainly pricing seems to be improving.
Their "brand" mppt controller you see under a lot of other names. it's a lighting controller I think. be interesting to see how it works. if you go that route keep us posted.
for wire nothin' wrong with the big box. or if you have an electrical installer/wholesaler in town see if they have any end of job bits. I have scored amazing deals on end of roll. (300 feet underground 10 g ... plus lots of other useful bits for 100 bucks, boolhay!).
Does this mean you're running 100 ft of DC from panels to controller/batteries? Check a voltage drop calculator. at 24v you're looking at #4g. but at 48v you'd be running #10g. A lot cheaper.
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LastOutlaw
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# Posted: 1 Sep 2014 21:54
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Creeky, I was at the cabin this weekend and built an outhouse about 60 feet from the cabin, close to the area where i would want to locate panels. While building it I decided to add rainwater collection with a short piece of leftover gutter so I could add a gravity feed sink . I built a 4 foot tall shelf to hold two 55 gallon drums onto the back of the outhouse.
I began to wonder if I can hide my battery bank under the barrel shelf in an enclosure and convert to 110volts there (close to the pv array) then send it into the cabin 60 feet away through regular household wiring. Would this be feasible? less voltage drop? Less power loss?
And believe me the first chance I get I'll buy both you and MtnDon and anyone else who wants to join us a few beers
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Indyenergy
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# Posted: 3 Sep 2014 16:49
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Check the UL listing and the warranty.
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LastOutlaw
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# Posted: 3 Sep 2014 16:52
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??? check ul listing and warranty on what?
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MtnDon
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# Posted: 3 Sep 2014 18:00 - Edited by: MtnDon
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Quoting: LastOutlaw I began to wonder if I can hide my battery bank under the barrel shelf in an enclosure and convert to 110volts there (close to the pv array) then send it into the cabin 60 feet away through regular household wiring. Would this be feasible? less voltage drop? Less power loss?
Depends. Often there is nothing to be gained by that. reason: the amps from the PV to CC will be generally low. IF your AC power needs include large amperage draw things like a microwave then you may have sufficient AC drop to make it no better than the usual way of running DC power from the PV to the CC at the cabin.
The enclosure for the inverter and CC would have to be watertight and yet ventilated. Both the CC and inverter can give off a lot of heat. That might be a trick to pull off. They should be sealed from the batteries as well. Personally I don't like the thought of putting electrical stuff under water tanks.
Not to mention you would lose the ability to have 12 VDC items, such as RV style water pumps.
If you can think through what the maximum AC loads (AC amps or watts) that could be on at the same time and report back we can do a comparison. We'd also need to see the data on the PV array (voltage and amps) to compare over that 60 foot distance.
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MtnDon
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# Posted: 3 Sep 2014 18:21
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Quoting: LastOutlaw ??? check ul listing and warranty on what?
UL or ETL approvals should be on any components used in any electrical system. Some bargain basement PV panels may not have UL / ETL stickers. Electronics (cheapy CC and inverters) that come direct from China may not have approvals either. And cheapy direct imports from China may as well not have a warranty even if they claim they do.
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