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Possibly being forced to go off grid sooner than planned in Iowa
#1
Hello! I am new to the forums and new to 18650 batteries in general. I have only used them(knowingly) on one device(a vaporizer) and otherwise have very limited experience with them. I've seen DIY powerwalls before but until I started researching off-grid storage I hadn't taken them seriously enough.

So my current situation is that our little family of 3 has been homeless for the last 2 years and living in a friend's basement in a temporary setup that ended up being less temporary than we hoped. Fortunately though, we found a property owner in a nearby county that was willing to sell on contract. Unfortunately, the electrical infrastructure on the lot was completely in ruins. The original mobile home had been removed and the half-acre yard has a 2-stall garage there(which was wired in a disturbingly amateurish manner).

Our sun-track over the garage is actually quite great, but we're not going to be able to do solar this year. We have most of our money tied up in our tiny home(all 172 sq feet of it), the property, and all the electrical for both. So we currently have two options: figure out a way to get on the grid(more about that in a second), or run a diesel genset.

I was mistakenly lead to believe that I could do the electrical work on this place myself. I told the county, the power company, and the state main office what I was doing and nobody seemed to think it was a problem. Unfortunately, the specific inspector for my area says that I basically can't do the work myself because I don't yet live there and don't yet have the Homestead Exemption. So I either beg a licensed electrician to stamp their approval on the extensive work I've done (panels, meter base, conduit, grounding rods, outlets, etc), or I go off grid because the state inspections aren't mandatory for off-grid and my county literally has no inspectors or rules regarding it other than windmill tower restrictions.

I found a diesel genset that is abnormally cheap and has very low hours on it, and its 7500W(really more like 7200W outputting 240V), and seems to be in very good shape. I'm going to go look at it, but I am a bit scared to plop down even the very reasonable less-than-500 they want for it until I'm more sure what we're doing.

So where things get complicated is that I don't want to run the generator all the time. I have an ME2012 inverter/charger from Magnum Energy, and although its only a 2KW modified sine inverter, the charger functions on it are quite extensive. I think its really geared toward lead-acid batteries though, and as such I am not sure if it would even work with any other storage mediums. Where things get even more complicated is that we have an on-demand water heater that is 18KW(on three 30amp breakers), but would run maybe 20 minutes a day(so 6kW/h a day). Unfortunately, installing a propane water heater in its place isn't possible so for now its basically electric or just none. Between computers, TVs, lights and other things, we might use as much as 1-2kw(assuming maximum usage across the full day, that's anywhere from 24-48 kW/h). During warm weather we also have a 5000BTU window AC unit that is installed as a central air system(not sure what that draws).  During cold weather we have been heating it with one 1875W space heater that runs maybe half the time(so 1.875 kW/h multiplied by 12 = 22.5kW/h). Our place is very well insulated and is going to be a lot more so when we're finished.

As if all that weren't bad enough, we also have the garage to wire. We have a large number of kitties so they need lights and fans and probably air conditioning sometimes. I really have a few big things that spike to high draw levels but don't run constantly. I was really hoping to come up with some sort of power storage system that can take care of the high draw spikes and then get charged by the diesel genset(probably running some sort of waste oils) as needed.

Lead-acid systems are quite expensive and I am in many ways not at all impressed by their longevity or charging speed. I was curious how hard it would be to produce a bank of lithium batteries to produce the very large startup currents I need on some things and reduce generator run time. If it even runs 12 hours a day, that's at least 0.5 gallons of fuel per hour and so about 6 gallons a day total(currently that would be about 16 dollars a day and as much as 500 dollars a month in fuel(if I buy road legal fuel. So reducing the genset to as few running hours per day as possible is vital.

I would appreciate any thoughts that you all might have on what sort of storage to build, what things to remove from my system. I am sure there are things I am forgetting, but that covers the core of it. Thanks in advance!
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#2
If you have limited means, and have the possibility of being connected to the grid - do it.

PV, wind and storage will require a considerable investment (time and money) and provide a very very long return on your investment.
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#3
(07-15-2019, 06:49 PM)Sean Wrote: If you have limited means, and have the possibility of being connected to the grid - do it.

PV, wind and storage will require a considerable investment (time and money) and provide a very very long return on your investment.

Thank you but its not entirely clear if I can or can't actually get on the grid. I may also be forced to do some sort of limited use of the genset until we're able to file the Homestead Exemption.

Just out of curiosity, how much do people commonly have to spend per kW/h of storage with 18650 cells?

Can you at least humor me please? People always underestimate what we're capable of accomplishing.
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#4
I use large format ex EV cells, the time required to build a functional system using them is minimal in comparison to tiny format cells such as 18650s, whereas the cost is reasonable high - I have no idea as to an exact /kWh cost - a rough estimate of what my larger home system has cost would be in excess of 20k UK for in excess of 200kWh of storage - that's not including the cost of the means by which the system is charged - I doubt many will be able to provide a truly accurate cost.

Projects of this nature, when using unknowns, such as how much you'll need to pay for the cells is akin to the restoration of an old vehicle, you'll only know the total cost when the project is complete.
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#5
For your water heater, I'd suggest to install another tank outside (like an IBC tote or water pressure tank), paint it black. Then have a small 12V DC pump that'll push the water between your tank in the house and the one outside. Have a small solar panel rated for 12V RV so the pump will run during the hot day.

Also connected to the outside tank is solar water heater panel. That water can easily reach temps close to boiling. Don't use PVC pipe to make the runs, you want to use copper. You might be able to use PEX, but I haven't tested that one yet. PVC, or CPVC more accurately, will actually flex, bend, expand in the heat and will drastically weaken the joints.

The panel can be made from an old sliding glass window (it's tempered, that's why to use this type of glass) and the sides can be made from 1x6 or aluminum. The back should be at least 3/8" wood paneling (osb, plywood, panel, etc) with some sort of metal sheeting inside that the copper tube is securely fastened to (either screwed down or soldered, which soldered would be better thermal conductivity wise).
This is the route I'll be going when I add on my solar water heater.

The pump has to be a decoupled pump/motor, though. So the pump head is not bolted directly to the housing of the motor. This is because of the heat the pump head will be subject to while the water heats up. The pump head is also on the cooler side of the loop, though, so it is pulling from the bottom of the tank, pushing into the panel.
If you can't find a DC powered one, but have a cheap inverter, then a good decoupled pump/motor combo would be one used for fish ponds or chemicals.
Here's a pump I got recently. Waiting on delivery to really give it a test:
Electric Industrial Centrifugal Clear Clean Water Pump For Pond Farm Aquarium for $30 shipped.
It's a low volume pump, which is needed for this type of application.
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#6
(07-15-2019, 08:09 PM)Amish_Fighter_Pilot Wrote:
(07-15-2019, 06:49 PM)Sean Wrote: If you have limited means, and have the possibility of being connected to the grid - do it.

PV, wind and storage will require a considerable investment (time and money) and provide a very very long return on your investment.

Thank you but its not entirely clear if I can or can't actually get on the grid. I may also be forced to do some sort of limited use of the genset until we're able to file the Homestead Exemption.

Just out of curiosity, how much do people commonly have to spend per kW/h of storage with 18650 cells?

Can you at least humor me please? People always underestimate what we're capable of accomplishing.

I pay about 15 to 20 cents per kWh for grid power…  Battery can cost about $100-200 per kWh depending on where you get the cells, sometimes more.  I am using large format EV cells from a low mileage electric car.  Personally I don't like salvage 18650 laptop cells, medical packs on the other hand are great, but it's a lot of labor vs EV cells.
 
That does not take into account the cost of power in/out, battery life, and other infrastructure.  Your cost per kWh increase considerably depending on the rest of the system and the estimated life cycle of the battery. 
 
The only reason I am even doing this is for fun… it is far cheaper for me to just pay for grid power.
 
My finished system is estimated to be about 10k for 33 kWh which IMO is pretty cheap for the types of batteries I am using.  Its not above the ROI, but it educational, emergency, and power independence perks.  If I didn’t find this fun, I wouldn’t even bother because where I life power is reliable and affordable.
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#7
(07-15-2019, 09:22 PM)Korishan Wrote: For your water heater..........

That's definitely along the lines of what I'm considering. Even if we do get grid power here, I would still like to supplement our water heater with a preheat stage of sorts.

My friend Gerry's dad built a solar water preheater when I was in 5th grade. He basically built boxes that had greatly reduced air pressure(not quite a vacuum, but very low pressure). They had polycarbonate panels over the sunward side and tubing of some kind inside(maybe copper painted black????). I am not sure exactly how it plumbed in to the main house system, but eventually it reached the water heater.

Crimp Daddy
I pay about 15 to 20 cents per kWh for grid power…  Battery can cost about $100-200 per kWh depending on where you get the cells, sometimes more.  I am using large format EV cells.........
......and power independence perks.  If I didn’t find this fun, I wouldn’t even bother because where I life power is reliable and affordable.

---------------

In my case its a mix of things. I love projects like these and I absolutely despise our electric company. Every dollar I can deny them puts a smile on my face. They've done bad things to us and I am not a fan.

Nobody around here that I have ever seen uses EVs outside of a few off-road types like golf carts. Certainly on the roads I have never seen any sort of EV thus far. I suspect actually getting cells out of them would require I have them shipped in from elsewhere.

Could you please explain to me what you mean by "medical packs"? I have a friend who does medical computer equipment and probably has access to all sorts of worn out laptop battery packs and likely other sources as well. I truly do not mind tedious and repetitive work like that. I used to make chainmail, and I can tell you that putting 10,000 or more links in a vest is not for everyone; but I truly enjoyed it.
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#8
(07-16-2019, 02:26 AM)Amish_Fighter_Pilot Wrote: ....

Could you please explain to me what you mean by "medical packs"? I have a friend who does medical computer equipment and probably has access to all sorts of worn out laptop battery packs and likely other sources as well. I truly do not mind tedious and repetitive work like that. I used to make chainmail, and I can tell you that putting 10,000 or more links in a vest is not for everyone; but I truly enjoyed it.

In medical applications, batteries are replaced as routine maintenance, at manufactures specified intervals, regardless of their condition. Some of these batteries have hardly been cycled, and aside of degradation from staying fully charged often still yield 80% of their original capacity. Also they are often very high quality cells, as batteries used in medical equipment have to be very reliable.
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#9
Yes, and I would limit charging to 4,0V/cell for maximum cycle life, and up to 4,2V only when you really need it.
We'll try to help you as much as possible, so ask any questions you want.
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#10
If you can connect to the grid, so it, but also consider the self-powering option even if you do it.

Legislation differs from country to country. Sometimes you only have to ask for you to be connected to power as in having an pole with the grid wires and meter on it and what's after that it's entirely your business. But in some cases, an approval it's needed if you want to connect a whole infrastructure that is already made to the grid. I think the approval should be fine if you did a good job and respected the general electrical engineering recommendations when doing it. If you present it well to an engineer I''m sure it will sign for it if it's fine.

If you need storage batteries for power spikes / temporary high demand I think a good solution is to use lead acid batteries of high capacity (or gel ones) like the ones made for trucks. Each can give you 200Ah to work with. You can use something like that to supplement your usage when needed and they will charge back up when power usage is low. They are indeed expensive but many could be harvested from a junkyard if you have access to one...and can be in pretty good shape still.

The Li-ion alternative needs some work, it is also a good choice, but you will have to find quality cells and get used to building things with them.

So the choice is actually up to what types of batteries you can get at the lowest possible cost and still good enough to be used for your purpose.
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