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Huvrman
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# Posted: 25 Jan 2021 08:15am
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So, I’ve been researching power solutions for a 14 x 36 foot cabin with no interior walls. Intent is to run off 2000 watt generator with battery backup. Looking at power for 2 led lights recessed into the ceiling front and back, and 6 USB/standard outlets along the walls and above kitchen counter. Don’t plan on powering anything off the outlets except charging phones, powering iPads, and maybe a portable air conditioner(when Gen power is needed). Will use battery power when charged and able, and gen power when batteries die or bigger items need to be powered (tools, portable ac, etc.) The desire is to easily switch between battery and generator, which will be housed in an attached compartment on the back of my cabin. He’s the basic plan-tell me how it is too good to be true. I plan on running one light and a switch off one circuit/breaker. There will be another circuit/breaker dedicated for 4 outlets along 2 sides of the cabin. A third circuit/will be for the remaining 2 outlets, light switch, and light. All three will go into a breaker box. Power source into the breaker box will be a heavy duty 30a extension cord I can move between the generator and inverter (which is connected to the battery) as needed. Pretty much just using the breaker box as a glorified junction box for 3 circuits. Will leave the male end and excess cord coiled up in the box when I leave, bringing the generator and battery with me.
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Brettny
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# Posted: 25 Jan 2021 08:46am
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Yes it can be that simple. Small breaker boxes are prety cheap, under $30. I suggest making the generator box at the end of a 100ft extension cord. Generator noise gets annoying real quick and you wouldnt believe how quiet a generator gets at the end of a 100ft cord and behind a wall/fence.
If all your charging devices use USB I would charge them off a portable battery pack. They also make usb powered lights. This would make generator use very minimal.
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Steve_S
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# Posted: 25 Jan 2021 10:00am
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https://www.mobile-solarpower.com/
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gcrank1
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# Posted: 25 Jan 2021 11:22am - Edited by: gcrank1
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That sounds like a fancier version of what I have now. I got it functional late last fall with intensions of refining it this next season. This does work.
Some thoughts:
LED lights are SO energy efficient that you can have lots. Fwiw, I started with 12v MR16 LED bulbs and sockets and some 120 wiring too. 2 wiring systems, why bother. Now Im just inverting to 120vac at the bat-bank some 90' from the cabin by ext. cord. I use 9-13W LED edison base bulbs in inexpensive std fixtures c/w pull chain switches. No extra switch wiring to run!.
Yes, keep the gen away from the structure which will become a sound box/amplifier for and noise and vibration. An insulated gen box with a lockable drop down door facing away from the cabin will absorb and direct noise away from you. But dont annoy the neighbors. Some straw bales stacked around/over a gen would make an easy set up.
The gen already has a duplex outlet, 2x15Amp circuit breakers so you can make a test system easy, put an rv power inlet on the cabin wall to plug the ext cord into from gen. The other end inside could go to a CB box, or (like me) to a switchable power strip that you plug the heavy load stuff into; ie, my 750w microwave, toaster, smart battery charger, etc., this used only when the gen is running. The charger pumps up the inside battery whenever the gen runs. Note-only one high load appliance is used at a time. My little 1600/2000w peak inv/gen hardly baulks on the low rpm ECO setting when I power up the microwave, then it spools up and runs fine. My old hog 5000btu window AC takes a little coaxing initially on high rpm to keep from tripping the gen CB.
I can also plug the LED lights circuit into the power strip to run off the gen but usually it is just plugged into the 300w 120vac psw inverter at the battery. The draw is so slight, rarely are more than 2 bulbs on at a time (maybe 1/2amp? The inverter also has its own CB and a built in USB port.
I unlock, walk in and switch on the inverter. One bulb is left on as my 'tell tale' so it comes on automatically; I have real light, right now and 4 more on demand (16x24 one rm cabin).
Bat-bank/inverter to gen? I suppose some would want a switch box, I do it manually, unplug the one and plug in the other. I dont run the gen often but I need it for tools, etc anyway so I did the microwave and toaster thing for my wife who makes casseroles to bring and warm up for meals; the mw makes it easy for her. Then it was why not use a smart charger there for when ever the gen runs, any amps in the bat is good amps.
Guess what Im getting at is consider making yours as 'off the bat/inverter' with the gen as the big power/back up, not the other way around. You really dont want to be running the gen more than you have to.
And do make the input to the cabin from the gen easy with with an 'rv inlet plug' (think they are avail. on Amazon). You probably could get by with a 15amp (that is all the gen puts out anyway, right?) but a 20a would be better. I cant ever see me having a use for a 30amp, ymmv.
Put together a simplified system first to give it a go, if you are like me at all you will come to some conclusions in use and mod it up anyway. After the trials/testing of concept stages you will know lots better how you want to proceed.
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Brettny
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# Posted: 25 Jan 2021 12:47pm
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Gc is right about why bother with 2 types of wireing. I chose not to use 12v stuff. Everything goes through an inverter, we even use a 120v mini fridge on an inverter.
Our system is 4 golf cart batteries, 1200w inverter, 40a MPPT solar charge controller, 470w solar, 30a battery charger and a 1kw sportsman inverter generator. The only thing I have run on the generator is the battery charger. If the power gets low I start the generator and it charges the battery bank. That's all that generator does. 0.5gal of fuel lasts 8-13hrs. Generally I run the generator about 2hrs each morning when the leaf are on the trees. Less or not all all when there not.
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ICC
Member
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# Posted: 25 Jan 2021 12:52pm - Edited by: ICC
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.....
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Huvrman
Member
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# Posted: 25 Jan 2021 08:46pm
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Not using 2 types of wiring. Running 110 VAC wiring that plugs directly into a generator or battery sourced inverter depending upon my needs and battery charge status.
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gcrank1
Member
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# Posted: 25 Jan 2021 10:59pm
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Fwiw, if you dont draw a battery down far you dont have to put a lot (takes time) back in.
The inverter will have some losses (ie, 'overhead') above and beyond the draw of what you are powering up. The bigger the inverter, the bigger the overhead.
You need to size the inverter fairly close to the usage (dont use a 1000w inverter for 3 amps of LED lights and a USB port recharger).
I have been running 'Marine type deep cycle' batteries for decades. They are relatively cheap, not 'real' deep cycle but sorta and just OK. For a small scale use like you describe one 12v x 100ah would work. But there are better, At A Price!
Dont believe the stuff about you can regularly take a lead acid battery down 50%. Well, yeah, ya can....but it wont last. Better to figure 25-30%. That means you can take that 100ah battery I mentioned down by 25-30ah out of it leaving 70-75ah still in there. Figure out how much you want to power actually draws + the overhead of the inverter x the hours you want it all to run.
If you pull out 25ah you need to charge back in about 30ah. If your charger (dont bother using the 12v taps on a generator, you need a real 'smart charger' plugged into the 120 duplex on it). If your charger will output (it varies) 15amps it will take over 2 hours run time to put that 30amps draw down back in (it isnt linear, it tapers off as the battery charges up). That is why I said use less amps will charge up faster.
Now if you have a LFP battery it is a real game changer. A 100ah LFP will give you at least 80ah of usage and some 2000 or more cycles, Way More cycles than any lead acid battery. But they are pricey. A less expensive LFP would be a 40ah size that would give you the same 30ah usage I mentioned off the 100ah lead acid, have Way More cycles and be Way More cost effective. If that would match your usage need for a few days at the cabin you could just take it home to recharge until the next time. And they are Way Lighter to haul around than lead acid batteries, safer too, no acid.
The ones I was looking at the other day at the Amish store (Rhino brand, I think) have an option of a panel included c/w a cig-lighter socket, a usb port and built in voltmeter and the prices were decent, tho still not cheap. Im seriously thinking on getting one of their 100ah, maybe two so I can swap em out rather than the big 200ah.
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gcrank1
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# Posted: 26 Jan 2021 05:01pm
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Or you can charge all your usb and cig-lighter socket stuff off your car/truck. For most of that stuff the draw is so low that you dont have to start the car.
You can get some of the inexpensive LED lights that come with their own little solar panel and look like an 'Edison' bulb. I bought a 3 pack last fall off Amazon for about $30. They all charge via cable then you can disconnect each and hang it wherever you want on the included hook. These things are great! Btw, you can also charge them on a usb port. Too Easy!
Then you only need to run the gen for really big stuff.
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Huvrman
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# Posted: 26 Jan 2021 11:56pm
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All great ideas. Plan on my porch light being solar with notion detection. Will look into the solar bulbs you described soon.. And looking at a 100 ah lithium battery. All a learning process. Fun but compounded by fact my place is 6 hrs away so can't make quick trips to work out the kinks. Picked up a honda 2.2 k gunny today, so the ball is rolling.
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toyota_mdt_tech
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# Posted: 27 Jan 2021 07:56am
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And keep lighting and outlet circuits separate. In other words, breaker(s) for lighting, other breakers for outlets.
Homes have been done this way for years now. Idea is, if you plug something in and overload it, you still have lights to reset etc.
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gcrank1
Member
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# Posted: 27 Jan 2021 10:39am - Edited by: gcrank1
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Very nice choice on the genny, it will serve you well. Set up to run off it then ease in on making 12vdc bat power inverted 120vac plug into the 'system' so you only have to run the gen for 'big stuff'.
For your modest needs a pricey 100ah LFP may be overkill, but if you dont mind the expense it sure would get you set for upsizing in the future. At essentially the same size (the one Rhino I looked at and hefted) its about the same size as a common Grp 27 'marine' battery but only 27#! I think that is less than half of the lead acid battery. Even at my age 68 I could easliy haul that back & forth. It is priced at about $600.
Their 40ah (call it 32ish ah usable @ 80%) is $240ish msrp,
the 50ah (40ish ah usable) is $320ish msrp.
Given that newbies to the world of off-grid bat-based elec power systems often kill their 1st bat-bank you may want to start with a basic Grp24 or Grp 27 'marine' Deep Cycle (not 'marine Starting) battery, often priced $100/$125ish but if you are prudent you could get the LFP 40 or 50 and have a far better, longer living/way more cycles, lighter battery at only a reasonable amount of money more.
I wish I had known all this when I started 
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Steve_S
Member
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# Posted: 27 Jan 2021 11:09am
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Tossing Rocks in the Pond:
12V LFP (Lifepo4) requires 4 cells
Voltage is 10.0V (0%SOC) to 14.6V (100% SOC)
One fuse per battery assembly, ($35 +/-)
One 4S 120A capable BMS ($113.00 – $149.00)
Fuse Link: https://www.amazon.com/Bay-Marine-Single-Terminal-Included/dp/B07LC5VBPD
BMS Link: https://overkillsolar.com/product/bms-120a-4s-lifepo4/
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3.2V 120Ah LiFePO4
4 cells delivered to USA Duty/Taxes Paid : US$335.00
https://www.alibaba.com/product-detail/3-2V-120Ah-Li-ion-Lithium_62585331091.html?
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EVE 3.2V 105AH Genuine Grade A
4 cells delivered to USA Duty/Taxes Paid :US$471.20
https://www.alibaba.com/product-detail/EVE-3-2V-105AH-Genuine-Grade_1600191337923.htm l?
------
4Pcs 3.2V 90Ah Lifepo4
4 cells delivered to USA Duty/Taxes Paid :US$392.00
https://www.alibaba.com/product-detail/4Pcs-3-2V-90Ah-Lifepo4-Rechargeable_6258134170 0.html?
-=-=-=-=-=-=-=-=-=-
LFP is kept properly and operated at 90% capacity can & will last 10+ years. Maintenance-free, Safe (no fires/explosions etc and No offgassing hydrogen.
Good YT Video from GWL that shows some interesting & potentially scary things which often get mis-communicated.
https://www.youtube.com/watch?v=Qzt9RZ0FQyM
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Brettny
Member
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# Posted: 27 Jan 2021 12:20pm
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Why 100ah if your just plan on charging phones and tablets and running a few lights?
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NorthRick
Member
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# Posted: 27 Jan 2021 03:54pm
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Quoting: Huvrman The desire is to easily switch between battery and generator, which will be housed in an attached compartment on the back of my cabin. ...Power source into the breaker box will be a heavy duty 30a extension cord I can move between the generator and inverter (which is connected to the battery) as needed.
I installed an automatic transfer switch (ATS). The power cables coming from your inverter and from your generator go into it. The output from the switch goes to the breaker box.
When the generator is off, power from the inverter passes to the breaker box. When you fire up the generator, the ATS senses the power and switches over to the generator. Shut the generator down and the ATS switches back to the inverter. You won't have to keep moving a plug back and forth.
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Huvrman
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# Posted: 27 Jan 2021 05:23pm
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I like the idea of a transfer switch. But figured since I would have to walk out back to the genny shed anyway, (where the battery and inverter will be also) to start or stop the genny, I would just transfer the plug between the two at that time. And since whenever the genny is running the battery will be charging, the process to switch will also include disconnecting the battery from the charger, connecting the inverter to the battery, and plugging the cabin cord into the inverter. Eventually I’ll get a solar charger, and that will simply the transfer of power tremendously.
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gcrank1
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# Posted: 27 Jan 2021 05:33pm
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You dont have to disconnect the charger or the inverter from the battery, leave them hooked up.
They each have on/off switches and the charger isnt working when then gen is off anyway.
All you do is move the main feed cabin plug from the gen socket to the inverter socket and switch the inverter on.
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gwindhurst
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# Posted: 27 Jan 2021 05:42pm
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I too was thinking about using two wiring systems but not anymore. My only hang-up is with the 12v water pump (not yet installed). I guess I could just use an AC/DC converter for that though. Thoughts?
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gcrank1
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# Posted: 27 Jan 2021 06:24pm
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Yep, for the limited run time imo it does not need a dedicated line. In mine I havent finalized the wiring so I just move a 12v battery into place, hook up and run.
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Brettny
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# Posted: 28 Jan 2021 06:16am
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They make those small 12v pumps in a 120v version.
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rayyy
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# Posted: 28 Jan 2021 01:33pm
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Here is what I did ,I wired up a 120 volt dc series of outlets powered up by a Honda eu2200i generator and a separate 12 volt dc series of cigarette lighter outlets powered up by a 3 battery bank with a 3 bank battery charger plugged into the generator.All my lights were 12 volt and my water pump was 12 volt.
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rayyy
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# Posted: 28 Jan 2021 01:36pm
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12 volt dc and 120 volt ac.
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rayyy
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# Posted: 28 Jan 2021 01:44pm
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The batteries always provided lighting and running water 24/7.I ran the generator whenever I wanted 120 volt to run my t.v.router or satellite dish.vacuum cleaner, toaster,microwave,crockpot,ect,ect.All the while the generator was running,it was charging my batteries up!
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rayyy
Member
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# Posted: 28 Jan 2021 01:49pm
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I tried using a 12vdc to 120vac inverter but it didn't work for very long till the batteries wore down and needed charging again.
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gcrank1
Member
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# Posted: 28 Jan 2021 04:17pm
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What gauge wire did you use on those 12vdc taps to minimize line loss?
Inv to 120vac: yep, trying to run heavy load stuff off a big capacity inverter will suck the juice out of a bat-bank for sure and certain.
Using a small psw inverter to run LED lights (LOW draw, my 60w equiv./4.5w draw, only use about .4 amp each), a few usb ports and maybe a cig-lighter socket for low draw stuff (like my small fan) also can run off of basic, cheap household extension cords, not heavy 12 ga. contractor cords or Romex.
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Brettny
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# Posted: 29 Jan 2021 05:38am
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I wouldnt bother with a pure sine wave inverter for things like lights or even a fan. I only got one because we are running a fridge off it and I wanted low standby draw.
Theres a DC wire gauge chart available online. You need to know your volts/amps, the run length and it will give you the wire size.
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Nobadays
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# Posted: 29 Jan 2021 08:18am
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Quoting: gwindhurst My only hang-up is with the 12v water pump (not yet installed). I guess I could just use an AC/DC converter for that though. Thoughts?
I've been using an ac/dc converter for 2 years now to power our water pump... works great and the stand by power draw is insignificant, can't seem to find the numbers right now but I believe it was in the mV range.
There are 120vac Shurflo/and other brand pumps but my understanding is they are not as good as the 12v versions, failing more often... a search on here will bring up some threads where this was discussed.
Some use a 12v transformer from a laptop charger, I chose a regular ac/dc converter I got off Amazon... THIS ONE I bought 2 so I would have a spare but 2 years in and this thing still works great.
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gcrank1
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# Posted: 29 Jan 2021 10:56am - Edited by: gcrank1
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Fwiw, I have several msw inverters 180w, 400w and 750w. On all of them my fans run slow and growl; that also means the motors are running hot. That is inefficient use of my limited power.
Some power tool chargers dont like msw.
My lights dont seem to care but, iirc, Ive read that led lights may be internally objecting to the msw too but we wont know until they die off prematurely?
So, for 'small stuff' I bought a 300w psw inv off Amazon, fairly priced, has an integral usb port and so far everything within its power capacity had run beautifully. Why buy a msw when for only a few dollars more you can get psw and avoid the potential problems inherent in msw? Btw, Im a firm believer in match the inverter fairly close to the load; ie, dont run a 1500w inv for 3 amps draw of a few led lights and a usb smart phone charger.
Im anxious to get the new bat-bank (hoping it can be a min. 100ah LFP) which should run my 1000w psw inv. that used to be on the 500ah lead acid bank. As that bank died off it no longer had enough beans to run that inv + load. I would have the choice of which psw inv to use based on load, the 300 or the 1K watt, a good spread of options I think.
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gwindhurst
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# Posted: 29 Jan 2021 12:49pm
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Quoting: Brettny They make those small 12v pumps in a 120v version.
Thanks Brett
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gwindhurst
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# Posted: 29 Jan 2021 12:51pm
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Quoting: Nobadays I chose a regular ac/dc converter I got off Amazon... THIS ONE I bought 2 so I would have a spare but 2 years in and this thing still works great.
I like it! TY NBD’s
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