How much power do you need?

[Silent Bob]

Good list of what wattage your going to need

 

[DrHenley]

Thanks, I've been wondering whether I could run the whole house on my 6,000 watt continuous/12,000 watt peak inverter.

Now the only question is how much do the central A/C compressor and dryer use? I think that those are the only two things I would not be able to run. Probably have to use a few small window units, and hang the clothes to dry.

 

[Silent Bob]

Thanks, I've been wondering whether I could run the whole house on my 6,000 watt continuous/12,000 watt peak inverter.

Now the only question is how much do the central A/C compressor and dryer use? I think that those are the only two things I would not be able to run. Probably have to use a few small window units, and hang the clothes to dry.

I was using the same document to try and answer the same questions...lol. Our home A.C. is a monster and well think it would be a no-go...my solar power doesn't generate enough to support it either. I have been looking at a natural gas generator that is sold at a farm tractor implement distributor, but they are running near $25K and with the drought here, we're in limbo of not investing, if the lakes run dry, then we have an empty home. Hope it doesn't get that bad, but our leaders are not leaders/nor progressive enough to think out of the box.

 

[DrHenley]

Some of the building supply stores like Home Depot and Lowes will install a natural gas generator. I was looking into it a while back and if I planned on staying in our current home, I would have installed one. The prices were surprisingly reasonable. (I don't remember details, but I don't think they were 25K)

I have a 3500 watt portable propane generator that can be used as auxiliary power to the inverter, and to recharge the batteries. I wish I knew how much propane the generator burns with no load, and how much DC power the inverter uses with no load. I would imagine the inverter is a lot more economical at zero load than the generator, but I don't really know for sure.

 

[Silent Bob]

Some of the building supply stores like Home Depot and Lowes will install a natural gas generator. I was looking into it a while back and if I planned on staying in our current home, I would have installed one. The prices were surprisingly reasonable. (I don't remember details, but I don't think they were 25K)

I have a 3500 watt portable propane generator that can be used as auxiliary power to the inverter, and to recharge the batteries. I wish I knew how much propane the generator burns with no load, and how much DC power the inverter uses with no load. I would imagine the inverter is a lot more economical at zero load than the generator, but I don't really know for sure.

Your right on the residential ones costing around 4-8K ones that run off LP, but I was looking at one of those 100KW Commercial grades for possible installation at a proposed BOL site. I know a bit more power than we would need, but was thinking way outside the box too. Sorta get carried away, when looking, lol..

Lol, like I said in another thread, if you gave me a billion to prep...I'd have it spent.

 

[Graynomad]

I would imagine the inverter is a lot more economical at zero load than the generator, but I don't really know for sure.

All good inverters will go into a standby mode when there's no load, as such they use very little power at all, so I would say the inverter should win hands down.

Another thing to think of is that the charging of lead acid batteries get very inefficient at the upper end as their ability to accept current reduces but you are still running a whole generator. Battery technologies like LiFePo4 are much better as they will suck 100% of the available current until they are full, then stop. This means you can run a gennie for a much shorter time at a higher rate. Also LiFePo4 are not damaged if you don't fully charge them for whatever reason, lead acid likes to be fully charged all the time and constant use at any level less than a full charge does them harm, deep cycle or not.

One problem though with Lithium batteries is that you need hi-tech to control the charging.

And of course no matter what fuel your gennie uses it will be in very short supply if TSHTF.

 

[DrHenley]

The genny is for short term power outages here at home. Long term for the BOL, I will have some other source of power, I haven't decided what yet. Possibly hydro since the BOL has a free flowing artesian well, but I'm looking at solar and wind too.

Right now I have two 125 Ah AGM batteries for the inverter. (the inverter requires two batteries with separate inputs) AGM batteries have their strengths and weaknesses, but it's what I have at the moment. I'd love to have a couple of LiFePO4 200 Ah batteries...but they are around 3 grand for the pair.
http://www.batteryspace.com/lifepo4...60wh-10c-rate---un38-3-passed-3-2vx4-dgr.aspx

 

[Silent Bob]

The genny is for short term power outages here at home. Long term for the BOL, I will have some other source of power, I haven't decided what yet. Possibly hydro since the BOL has a free flowing artesian well, but I'm looking at solar and wind too.

Right now I have two 125 AH AGM batteries for the inverter. (the inverter requires two batteries with separate inputs) AGM batteries have their strengths and weaknesses, but it's what I have at the moment.

My buddy (like my brother to me) and I have a good plan to make electricity. Our big problem is security. We run any larger wind turbine up and its like placing a "flag on the hill" and say come take it. We've played with camouflage, tried doing the old WWII Z pattern, still no effect, if your within line of sight, your going to see it. Solar panels are the same way, they stick out like a thumb pointing toward habitation, if anyone has the ability to use a remote drone or aerial observation after the ShTF, if not then we are pretty good there.

As for a batteries, we've got enough to start off with, but I'd like to be able to place a few in reserve, just as back up, etc.

Right on the AGM batteries...good and bad, but we work with what we have. I've tried to find out from the manufacture of Goal Zero, how long their YETI power system is rated. Typical of them, they like to say they are good for life. I know otherwise that no company should put that our there. They are trying to sell product that is yet proven. However, the one 1250 that I do use for tail gating is pretty good at holding a charge, I always make sure like a lithium to decharge it to zero before hooking it up to commercial electricity to recharge. The solar part is a bit slow, but I typically hook up about 8 x 30 Panels to pick up the pace...not as efficient as my solar panels on the house and what I have in storage, but they do a pretty good job.

 

[Graynomad]

Mini hydro would be great if you have a permanent water flow, I have a mate with one and although it doesn't output a lot of power it's constant, day and night 24/7 so it really adds up. Also, unlike solar and wind, it would be easy to conceal.

I've been using AGMs for years, what's their weakness?

Assuming a 12v system you can get 200Ah for about $800, buy 4 of these

http://www.evworks.com.au/index.php?product=BAT-LFP200AHA

and make up the pack yourself, all you need to do is physically clamp them to stop bulging under charge.

As I mentioned though LiFePo4 requires you to be very precise with charging and you have to monitor each cell while doing so. This cannot be done with a simple charger and apart from a Kickstarter project (https://www.kickstarter.com/projects/electrodacus/open-source-programmable-solar-bms-development-boa, he's in Alaska) I know of no commercial (and reasonably priced) chargers. People I know who use these batteries DIY a system from existing components. It's not very expensive, just some mucking around.

Also with LiFePo4 you have to balance the cells before you connect them up.

I've never heard of an inverter that needed two battery inputs, that's bizarre and can't see a reason for that. I would get a different inverter

I'd like to be able to place a few in reserve, just as back up, etc.

Any ideas as to how long they would last? I've seen one manufacturer that claims 20 years if left on float, another way is to store them dry whereby you fully charge then drain the electrolyte. At my age if I can get 20 years I'd be happy

they like to say they are good for life

Lifetime guarantee, meaning the lifetime of the batteries They cannot make such a claim.

decharge it to zero before hooking it up to commercial electricity to recharge.

What type of battery, that trick was only for NiCad AFAIK, it will kill a lead acid battery.

 

[DrHenley]

I've been using AGMs for years, what's their weakness?

I've never heard of an inverter that needed two battery inputs, that's bizarre and can't see a reason for that. I would get a different inverter

From what I understand the AGMs do not last as long as conventional Lead Acid batteries that are properly maintained. Of course if you deep cycle the conventional Lead Acid batteries, they dont' have much of a life span.

And there is the weight. Each 125 Ah AGM battery weighs 75 pounds.

The dual inputs may be due to cable limitations. The heaviest battery cables I could find are not rated high enough to handle the current at a full 12,000 watt output of the inverter. Two of them together are.

 

[Graynomad]

Ah yes I see, 12kw is a huge inverter so I can see it would be hard to get wire thick enough unless you have a higher voltage battery bank, normally you use bus bars for really high current. That's a 1000A at 12v but I can't believe you have a 12v battery bank...do you?

AGMs are known as "lazy man's batteries" because you don't need to maintain them (that's one reason I have them ), but you're right, a well-maintained LA battery will outlast an AGM.

 

[DrHenley]

I would probably use a bank of conventional LA batteries if it weren't for the fact that they are not safe for indoor use. I can bring the AGMs indoors safely.

My "battery bank" is simply two 125 Ah AGM batteries hooked directly to the inverter on separate inputs.

It's not meant for an all-in-one single solution, but rather a means of supplying high current for short periods indoors.