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Small Cabin Forum / Off-Grid Living / Off-Grid Elec/How Small Can I Go
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gcrank1
Member
# Posted: 26 Nov 2020 22:36
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Winter is coming on quickly here in south central Wisconsin; the cold anyway and the snow will sometime and we will be unable to get in. So I just pulled most of the cabin batteries to bring home for over winter maintenance rather than leaving a mis-match of batteries all ganged together on the 2sx2p 408W 12v panels. The last two, fairly well matched big honkin ups batteries are staying this year! At almost 68 I dont need to be damaging myself moving stuff that is too big.
The whole of the solar system is on/in my 8x12 ice shanty now repurposed to a tool/parts/supplies/powerhouse some 25yd from the cabin. I swap out a grp 27 battery in the cabin when I use up a max of about 30%.
The cabin elec is modest. I had 12vdc, then a mix with some 110vac off inverter, now all inverted 110. With this I can power all up on a power strip inside if the inv/gen is plugged in or off the battery/inv (300w psw). All 5 bulbs are 110 LED 9-13w, plenty of lights and all only on when showing off what Ive got, usually 1 running, sometimes 2. The ceiling fan or a box fan are the only two heavier loads, not often used but for summer. The microwave and toaster only are run with the gen, and tools; short run times for those.
So earlier in the fall I stopped paralleling 2 12v mismatched batteries in the cabin and began swapping one x one as needed and it worked out well. In fact, this past weekend a 3 day/2 night affair for us, ran one battery the whole time leaving a 70% soc. We ran what we wanted when we wanted, charged a phone and i-pad a couple times too (though I am convinced that is better done on a 12v tap in the car cig-lighter my wife 'wants 'em close).
With the big batteries at home now Im going to be trying out a pair of old Jump Start Packs, the old school kind with a sealed lead acid 17ish ah battery, jump clamps on short leads and cig-lighter sockets (one even has a USB port!). We will go up with both charged, hook one inside to the 300w inverter and I think have enough power to have good lights for an overnighter. If not it is easy to grab #2 pack. I wouldnt have to even take the inv/gen as we can cook on the propane stove.
We carry enough water in for our anticipated stay and have a propane wall heater to kick the chill off while the woodstove gets up and running.
This is our first winter at this cabin and we have more mod-cons than our old 1983-84 build where kero lamps ruled the night. Im loving the LED's!
Pretty sure Ive got this seamlessly workable, at least for me, my wife is still confused by it all so she tolerates me working it all out......another reason why the solar is not on/by the cabin, she Hates It. But she likes the elec power, go figure. She would just as soon run grid in (which we can), Im not ready for that quite yet lol.

Brettny
Member
# Posted: 27 Nov 2020 06:05
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Your dragging jump packs back and forth for lights? You alreaty have a generator there so why not have a 120v to 12v charger?

I also pulled my batteries home for the year but next year I have alreaty decided that I'm leaving then up there and the solar hooked up.

On a side note I seam to get more output on my pannels after the leaves went down compared to late summer. Even on a cloudy day I'm pulling about the same as a sunny day.

In about 1 month almost all battery powered Christmas lights go on sale. They make for good night lights.

spoofer
Member
# Posted: 27 Nov 2020 07:16
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I'm with you Brittany. Batteries are staying at camp this year. I will prob drive up to the Tug and disconnect around New Years. Gcrank1 I only have a 100 watt panel connected to 2 six v batteries. I power a small tv and radio and 4 seven watt 12v leds. Works fine for almost all days.

paulz
Member
# Posted: 27 Nov 2020 09:22
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Quoting: gcrank1
my wife is still confused by it all so she tolerates me working it all out......another reason why the solar is not on/by the cabin, she Hates It. But she likes the elec power, go figure.


Lol, same here. "You working on that solar thing again?", as she's burning lights and watching TV. My arms are two inches longer from carrying grp 24 and 27 batteries back and forth to the cabin. But for the last couple of years I have had batteries mounted in the truck and just run a cord to the cabin, also charge them in the truck back at the grid. Working on changing that with solar now.

My 2 tractors and dump truck have no charging systems so still I hustle batteries in and out of those quite a bit. Like to get my hands on a lithium motorcycle battery, I have seen them start cars and weigh a fraction of a g24 lead battery. That might work for you too.
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gcrank1
Member
# Posted: 27 Nov 2020 10:31 - Edited by: gcrank1
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Brett, I have the quiet little Champion 2000(peak) inv/gen; such a dandy too, but it also 'went home'. We dont like running a gen any more than necessary so for just lights that is not happenin. And we have what has been a decent smart (auto) charger that I keep hooked up for whenever the gen does run; it too has gone home to maintain all the batteries I must take care of.
My two big UPS type batteries on the solar are in the shanty. Ive considered having an inverter there and running a 110 ext cord to the cabin, still might as Im playing with all this.
As to the jump packs, they are kinda like an earlier, cheaper, simpler version of these new-gen 'solar generators'; ie, a Power Pack you plug things into and when needed hook a solar panel to (or grid-plug) to recharge. Ive been doing that for a decade. I know the batteries in both of mine are old and tired, and can be replaced but they still work as a portable low draw power supply even if they wont start a car. In fact, that is how I got my second one, somebody threw it away because it wouldnt start their car. Neat piece, it has the cables&clamps (rarely used) and two cig-lighter ports as well as a USB port. I can plug my 10a or 15a portable panels right in at one cig-lighter port and still use the other.
Mostly I want to see and note the run time of mine using whatever I want use in the cabin. It will give me a baseline of equipment capability.
And I really dont need to even do that, we have candles, kero lamps, LED battery camp lanterns and flashlights and, my fave, the 3 pack of LED Edison looking solar 'light bulbs'. I have hooks and hanging chains around the cabin, just unplug a 'bulb' from the charge wire, push the on button and hang it where needed, Waayyy Good.
At this point leading into winter I need 'good enough for our use', not optimum. Buying new matching batteries now would be a waste of whatever warrantee they have; and I am loathe to buy $1k+ of batteries anyway..... Im also not sold on the idea of AGM or LFP over 6v GC for my use.
Part of this 'how small can I go' is to settle on what total ah bank we require for our use and still stay in the optimum soc of whatever batteries are used.

gcrank1
Member
# Posted: 27 Nov 2020 19:10
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I couldnt stay away....and it was a nice day here so we drove up to the 'North 9'. Got the propane wall furnace running right away and started the wood stove, then brought in the jump pack. All the lights run fine off the 160w msw inverter as well as the 300w psw as expected, I just dont know how long. It is a quick, easy hook up and easy transport, and the packs will recharge off solar, car plug or home grid.
Then the real deal. I hooked up a cheap 400w msw inverter at the shanty batteries and ran a long run of two basic outdoor 16ga. extension cord to the cabin. Works like a champ. So I am leaving cord 1 (C1) in place from the shanty, keeping the inverter in the shanty so it doesnt walk away, and have the far end tied in a tree as my 'pedestal'. We can get there and all I need do is hook up the inverter, switch on and plug the cabin cord (C2) into the ped, light comes on. I can set the inv/gen right there too and just swap the plug when needed.
Think I will refine this set up next year like a simple RV ped. I have all winter to think on it.
One thing I havent seen and wish I have is a low voltage cut-out; ie, set the voltage for a low that still has a battery recovery rate to the desired soc. When in use a battery volt read will drop lower than the 12.2v I think I want to use as a 'recovered at rest' low to stay in the 70-80ish % soc. A typical inverter seems to have a low voltage cut-out well below what is healthy for the batteries. I have to wonder why that is.....

gcrank1
Member
# Posted: 1 Dec 2020 18:53
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Just today picked up a used 12v x 12ah kids 'ride-on' toy vehicle battery at our local recycle center (formally known as the dump). It has become my habit to take my dig-meter along and read the batteries brought in. Anything deep cycle that reads 12.5ish and up while cold and resting gets my attention. This one read 12.8+, wow! Ive never messed about with these batteries. On jumpers it runs my cordless 18vdc drill fine, although slow, as expected. It also has a built in 30a breaker under the plastic cover and fits nicely into a small plastic ammo box with room to spare for some wires and cig-socket/usb port, etc.
This can be a handy power pack, smaller & lighter than my jump packs, and enough to run my little lights in 12vdc or inv/120vac and/or charge up 'devices'.
Ive been thinking of setting up a small front door 'yard' light in led at the cabin and havent liked the idea of running wiring. I can wire this up close to the door on a little shelf with a short wire run to a switch and light.

gcrank1
Member
# Posted: 3 Dec 2020 23:23
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I took that 'ride-on' battery up yesterday, as expected it runs my modest loads off the 300w psw inverter just fine. Someday I will run a given known load and see how much time I get out of it before about 70% soc, then I can calc its true capacity at this point.
The other trial was hooking up the 'gator clip cig-lighter socket, plugging in the usb and then the cheap little usb corded fan I got with a maybe 9 x 9" solar panel. It runs way better off the battery powered usb. Sat the bat and fan over by our old Avalon fireplace insert being used as a stand alone wood stove pretty much centered on the back 16' wall. It is a fairly leisurely mostly convection stove.....this little fan really kicked the warm air around to all the corners!

Brettny
Member
# Posted: 4 Dec 2020 06:03
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Gc that's a free prob well used battery..draw that thing down to 50* and treat it like it was free. With a free scavenged battery I wouldnt care much about how I treat it. I have 3 deep cycle batteries like this that I beat the heck out of and they keep on ticking.

I too am in the 6v GC2 battery camp. I had 4 at our shabin all year and never needed any maintenance. I was running a 4.5cuft freezer/fridge on weekends with 470w of solar that only ever got 3hrs of sun max. We also have interior lights and 100ft of exterior commercial style string lights. So running the fridge and lights for a weekend of cloudy days they got down to 75-80*. Even at 75* next year I'm going to add 2 more gc2 batteries.

Any weekend place can benefit from a large battery bank over more pannels. More battery capacity means you can run 2-3 days with no sun then when your gone and not useing power they have 4-5 days to charge.

gcrank1
Member
# Posted: 4 Dec 2020 13:35 - Edited by: gcrank1
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I currently have 2s x 2p 102w panels into Blue Sky 50 mppt and agree, the 2 big, but old and tired, 12v ups batteries typically charge up in our absence good enough for a couple of days modest use. I know I would get more ah's out of a new pair of GC2's, maybe in the spring. Might even be enough to run my small Heier 'fridge then though I have a clone of the Yeti cooler that works just fine. Takes a good long time to bring a fridge down to temp if not left running.
I have another pair of those panels I can go another 2s in the array but Im thinking of doing those as a parallel set with their own pwm cc as a bit of a 'moveable' array; ie, carry it out well into the meadow with good sun as a remote charge site.
Going into this now I would have certainly gone with 24v even for a small scale system. Anybody starting out would be smart to seriously consider that. Anything bigger than med size should be 48v, imo.
Hear ya on the free part but Im loathe to abuse even free stuff; when I was a kid we were poor but I didnt know it. The skills I learned have served me well.

FishHog
Member
# Posted: 4 Dec 2020 15:17
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Quoting: gcrank1
Going into this now I would have certainly gone with 24v even for a small scale system. Anybody starting out would be smart to seriously consider that. Anything bigger than med size should be 48v, imo.


I keep reading people saying this but I have yet to figure out why. I have a 12v system, everything runs off 12v except the odd 110v item in which case I run my inverter. Lots of 12v accessories out there, and very limited 24 and 48v ones.

So what is your perceived advantage?

jhp
Member
# Posted: 4 Dec 2020 15:27
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The sizing mostly has to do with how big you expect your system to grow and how difficult it will be to expand past a certain point.

When your system is a few lights, radio, LED TV, etc 12 volt is the way to go because everything is cheap and easy to find. When you are looking at large loads of thousands of watts consumed at an given time the literal infrastructure costs (wire sizes, fuses, etc) grows pretty fast.

Here's a simple article on it explains better than I can.

https://earthshipbiotecture.com/what-is-the-advantage-of-a-24v-system-over-a-12v-syst em/

gcrank1
Member
# Posted: 4 Dec 2020 16:11 - Edited by: gcrank1
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When your loads, and inverter sizing, crowd to the 1000w high end the wire sizes and fusing/cb'ers become huge, and expensive for safety. I am shocked (pun intended) reading about folks using 1500w and higher inverters with substandard wires and fuses/cb'ers. Just look up how large a gauge wire and what size fuse/cb'er is required for even 3' (bat-bank to inv) at the 1000w; but it needs to really be oversized for the peak load.
There seems to be a common misconception that if your desired load is x all you have to do is hook up an inverter of that (often over)size to whatever size battery bank (often way inadequate) with whatever size cables are left over and Bob's yer uncle. Then the bat-bank is sucked down fast, the inverter quickly goes into low voltage alarm and shuts down. More batteries required, heavier wires and bigger circuit protection.
An inexpensive buck converter, from say 24v to 12v will let you run all the 12vdc toys while having a distinct advantage of being able to run basically 1/2 the size wire gauge and/or longer wire runs for the amps load.
That said, if your system is wired and fused safely and it works for your purposes (like in my title line), that is Great! Ive worked up mine in various ways from close up and 12v to the array farther out requiring 24v to be able to use my largest wire of 6ga. stranded and it still wasnt close to an optimum array position so it couldn't deliver to the bat's in the cabin to be inverted there or used as is (12vdc). My next best solution is the array, bat's and inverter in the 'power house' close together and run inverted 110 to the cabin. Any small scale 12vdc I use there is off a small portable 'power pack' easily swapped out when low for the 'full' one. It is really nice being able to use regular 110vsc fixtures, wiring, etc. and the little bit of 'overhead' in solar capacity to run the inverter (sized correctly for the load; not a 1000w for 140w of load) I already have.

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