Group Think! Duration of SHTF! - Page 5

Group Think! Duration of SHTF!

This is a discussion on Group Think! Duration of SHTF! within the Off Topic & Humor Discussion forums, part of the The Back Porch category; Another problem when powering anything that has an electric motor in it is the start-up surge. A motor may only draw say, 3 amps when ...

View Poll Results: What is the Duration of the SHTF Scenario You Plan For?

Voters
88. You may not vote on this poll
  • Less Than a Week

    14 15.91%
  • One to Three Weeks

    39 44.32%
  • A Month or Two

    14 15.91%
  • More than Two Months

    14 15.91%
  • Whoops! I Forgot to Plan!

    7 7.95%
Page 5 of 5 FirstFirst 12345
Results 61 to 69 of 69

Thread: Group Think! Duration of SHTF!

  1. #61
    Senior Member Array madmike's Avatar
    Join Date
    Dec 2005
    Location
    Spring Hill, FL
    Posts
    750
    Another problem when powering anything that has an electric motor in it is the start-up surge.

    A motor may only draw say, 3 amps when running, but when it first turns on, it can take 2 to 4 times that much current to get it going.

    In the case of a refrigerator, if it uses 500 watts while running, every time it cycles "on," that will surge up to 2,000 watts.

    A 1 hp well pump that draws only 1,900 watts when pumping might draw 5,700 watts to start the pump.

    If both of those come "on" at the same time, the combined draw would be 7,600 watts. Add a few small items that continually draw a small amount each, such as lights and/or a radio, this would trip the breaker on a 6 Kw generator, especially since most of those are designed to run at much less than that, but are often sold based on their "surge capacity."

    In fact, that would likely be too much for what is often sold as a 7.5 Kw model.

    I've seen serious battery back-up systems before. That's why I won't consider one. In order to work well, they are made up of multiple battery banks, using deep discharge batteries. Very expensive and must be maintained. The large batteries have to be kept charged and still require replacement every few years.

    I am looking to reduce the size I need. Although I wasn't going to at first, I'm now going to included a good transfer switch that will not only isolate the emergency power from the outside supply, it will let me set up whatever "emergency power circuits" I need, and switch them on and off, as needed.

    This way, I can keep high-draw items from coming on at the same time, overloading the generator. I can keep the well from cycling as it normally does from time to time and only run as needed.

    If I want or need to run an "amp-eater," I can shut other circuits down during that time. A form of self-imposed "power-sharing."


    mm
    Political Correctness has now "evolved" into Political Cowardice.


  2. #62
    Senior Member Array elkhunter's Avatar
    Join Date
    Jan 2006
    Location
    Colorado
    Posts
    562
    Quote Originally Posted by Tangle
    I hate to be the one that keeps saying something doesn't look right here, but something doesn't look right here. First, a 12V car battery is not designed to be used in a deep discharge application such as a long term power conversion and supply. A few deep discharges will kill the battery. (I should mention that I worked for five years in a huge electric vehicle test program) A deep cycle battery is built to handle the deep discharges, but OTOH, doesn't make as good of a cranking battery.

    Second, to convert 12 volts to 120 volts is a 10:1 conversion. The power supplied by the battery will always be more than the AC power it supplies. For example, a table shows that a freezer draws about 700 Watts. Hence, the battery has to supply more than 700 Watts because the convertor is less than 100% efficient. But, even assuming 100% efficiency, in order to supply 700 W, the battery would have to supply a a bit over 58 amps! 12 V x 58 amps = 696 Watts. The cables connecting the battery would have to be the size of welding cables. The battery might last an hour minutes at this rate.

    There are no ways to get around the fact that input power must always be greater than output power and so one can basically divide 12 volts into the power required out to determine how much current will have to be supplied by the battery. A group 24 size deep cycle battery is probably a bit larger than a car/truck cranking battery, and is rated for about 1.7 hours at 25 amps. At 58 amps it's gonna last about 40 min. Of course if the device it's powering only runs 20 minutes at a time or so, it's gonna last a while longer.

    Power inverters (12VDC to 120VAC) are available from a lot of places and the technology is very mature. I'm an electronics/electrical engineer and I build lots of electronic stuff including an all MOSFET power controller that can handle 800 amps in-rush current from a 24 volt battery pack. I doubt even with my sources/resources that I could build an inverter for what I could buy one for.
    I don't want to argue with you on this, I only know what I saw and was a part of. I ran the sound system for this band for quite a while as the battery backup was powering the system. When I fist saw what he was intending, I thought I would humor him and we would be back on house power in a little while. I was surprised.

    This friend was developing this power supply for the purpose of powering bands who wanted to perform remote without the smoke & noise of generators. I understand your questions, I think I need to check with my friend and get his numbers.

    One thing I can say as I recall a conversation I had with him about 6 months ago, I asked how the development was coming and his reply was something in the lines of it not going to be efficient enough to be marketable, but could serve as a battery backup for occasional use.

    Also, I think the battery he was using is an Optima Marine battery. So I think I miss spoke about it being a car battery.
    Sorry.
    I have one in my Jeep. I've had it for 6 years and transferred it to my new Jeep recently. That Optima battery just won't quit.

    I may be misinterpreting my friend's intended application after seeing what it did for the band. I’m not an electrical engineer, (I don’t even play one on TV) but I know that there was a lot of electricity flowing to power that band. I helped wire it all up, the entire system was being powered by the battery.

    Anyhow, your questions/comments are going to drive me back to check this out further and I will get back to you with some specifics.

    All the same, this subject facinates me and I want to get it straight.
    It’s so much easier now days, to "Love and honor" my wife, when she is armed, and shoots a better group than I do. (Till death do us part, eh?)

    “The way you get shot by a concealed weapons permit holder is, you point a gun at him,” the Sheriff said.

  3. #63
    Senior Member Array madmike's Avatar
    Join Date
    Dec 2005
    Location
    Spring Hill, FL
    Posts
    750
    Haven't seen anything yet that looks like an argument to me. Just passing different thoughts on the same subject.

    One thing that makes the two situations very different is that most electronic devices don't have much of a "starting surge," when compared to household appliances that contain electric motors. And those motors are a major difference.

    If you search the Web, you'll find a number of alternative power sites. Some do have a lot of info on actual, working battery-based systems. I think you'll find that these are very expensive and require a high initial investment, compared to a generator system. And keeping those batteries charged can represent a challenge. A system of any size that is meant to last any length of time will have to have some way of being re-charged.

    These systems are in use and do work. I've just never seen or heard of one that would be more practical than a generator, for my needs.

    mm
    Political Correctness has now "evolved" into Political Cowardice.

  4. #64
    Senior Moderator
    Array Tangle's Avatar
    Join Date
    Dec 2004
    Location
    Chattanooga
    Posts
    9,827
    Quote Originally Posted by elkhunter
    I don't want to argue with you on this, I only know what I saw and was a part of...
    elkhunter,
    I didn't mean to be argumentative. I wasn't trying to criticize or put down your friend or his device. If I came across that way, you have my sincere apology.

    My honest intent was to point out some things, that as a practicing electrical engineer of over 30 years, I find suspicious.

    OTOH, if you were about to send money on a system that you were going to depend on, and when the time came it wouldn't do what you expected, that wouldn't be good.

    Quote Originally Posted by elkhunter
    I ran the sound system for this band for quite a while as the battery backup was powering the system. When I fist saw what he was intending, I thought I would humor him and we would be back on house power in a little while. I was surprised.
    The power required by a band can vary immensely. The power the power source has to deliver depends on many things, but mainly on the contiunous average power they are consuming.

    We really don't know how much average power was being consumed by the band. We can't go by the power rating (watts) of all the instruments and esp. the amps, because we still wouldn't know how much power was being consumed because the actual power would depend on the volume. Plus, music tends to have high and low levels of sound which averages out much lower than a continuous output would.

    Quote Originally Posted by elkhunter
    This friend was developing this power supply for the purpose of powering bands who wanted to perform remote without the smoke & noise of generators. I understand your questions, I think I need to check with my friend and get his numbers.

    One thing I can say as I recall a conversation I had with him about 6 months ago, I asked how the development was coming and his reply was something in the lines of it not going to be efficient enough to be marketable, but could serve as a battery backup for occasional use.
    There's a clue, "...something in the lines of it not going to be efficient enough to be marketable...". Lower efficiency means the battery will be drained quicker. It also implies that there are more efficient units on the market it would be competing with. So for an emergency situation, it seems that we would want a system that is as easy on the battery as possible so it would last longer.

    Quote Originally Posted by elkhunter
    I may be misinterpreting my friend's intended application after seeing what it did for the band. I’m not an electrical engineer, (I don’t even play one on TV) but I know that there was a lot of electricity flowing to power that band. I helped wire it all up, the entire system was being powered by the battery.
    Elk, everything looks better until we know the actual numbers. The numbers here are how much average, continuous current is being drawn from the battery. When power is converted from 12vdc (battery) to 120Vac, the power supplied by the battery must be more than the power supplied to the AC load.

    Since we're talking about a conversion of 12 to 120 volts, there's a ratio of 10:1, meaning that whatever current is drawn on the 120 volt side, ten times that current must be supplied by the battery.

    Actually it has to be considerably more depending on efficiency. Eleven or 12 times would be more realistic depending on efficiency.

    Quote Originally Posted by elkhunter
    Anyhow, your questions/comments are going to drive me back to check this out further and I will get back to you with some specifics.

    All the same, this subject facinates me and I want to get it straight.
    Then this discussion will be beneficial. Honestly, I'm not trying at all to be a balloon popper, etc., but if you are considering such a system for an emergency situation, you do need to know pretty accurately what you can realistically get from the system.

    Well one more thing. What madmike pointed out is true - devices with motors do behave much differently than mostly electronic devices. Most appliance motors are both voltage and frequency sensitive. What that means in a nutshell, is that if the voltage gets too low, and it doesn't take a lot, or the frequency changes, it can cause the motor to overheat and eventually fail. Better invertors both regulate the voltage and frequency to compensate for decreasing battery voltage over the discharge cycle of the battery.

  5. #65
    Senior Member Array elkhunter's Avatar
    Join Date
    Jan 2006
    Location
    Colorado
    Posts
    562
    Thanks guys. I know I am at a serious disadvantage because I am not a trained electrical engineer. I think we are talking about the capacity & performance of the battery, and the efficiency of the inverter as compared to the demand, right?

    I just had a lengthy discussion with my friend who IS an electrical engineer. He did confirm for me that it is the specific design of the Optima battery that makes this possible. The Optima battery is a new technology using lead/acid (LA) paste in a spiral cell, not gel, not liquid. This does not have the effect of deep discharging that a liquid LA battery has in dropping particulates in the bottom of the cells, it is the build up of those particulates that causes the internal “short circuit” that kills the battery after several discharges. The Optima does not have that problem. By the way, the Optima battery he used IS an automotive truck battery. Can be purchased from Optima for about $225.00 +/-. That is the one I have in my Jeep, a “yellow top”. (A gift from another friend who was at one time, an Optima sales exec. I’ll bet it didn’t cost him $225.00.)
    Check it out:
    http://www.optimabatteries.com/publi...ig/splash.html

    The unit used was a proof of concept package that, 5 years later still sits in his garage and did, without being recharged over that time, power his refrigerator for several hours one day in a recent power outage. These Optima batteries have an incredible shelf life, not needing recharge from time to time.

    Now, on to the ultimate design of this power supply. His plan is for making this portable unit expandable by adding batteries as required. A typical unit consisting of up to three of these truck batteries @$225.00 with an inverter of his choice costing about $1,000.00 bolted on top would cost around $1,700-$2,000 to make and be mounted to a hand truck with a total weight of about 150#. He predicts, the inverter would operate at 80-90% efficiency, and could power a house in normal use, (appliances including washing machines) for a day, maybe two if conserved. This is based on the house drawing average 50 amps tops at any given moment. He is intending on providing about 3,300 watts of power. (I would personally reduce all unnecessary loads in an emergency situation.) You can run these numbers through your electrical engineer’s slide rule I suppose, but this is what he gave me over the length of the conversation.
    He has heard of someone in Italy that is said to have developed an inverter that is supposed to have 97% efficiency. He can’t verify this though, but if we can get our hands on one of those, …..$!?)

    Again, I’m not an electrical engineer, but I think I am talking about not powering any motors here. Refrigeration pumps are the question. I’m not sure if they are motors in the classical sense with spinning core, or are they wobble type pumps more like a piston moving back and forth without circular motion. That would make a difference. (I’m thinking of some fuel pumps that only have an internal part that moves back and forth. They are powered electrically.) I now want to get some data on the frequency & duration of the operation of my freezer to determine what kind of actual power demand it has. Hmmmm.

    We talked further of long term power supply being possible with up to three solar cells providing power, and recharge for the batteries. This could provide a way to get a house “off the grid” if that is a requirement. Now all this is far more expensive than a generator, as you were talking of at first, but would remove the noise that would draw a crowd in a SHTF situation.
    My thinking eventually is for powering an underground shelter for long-term use, no frills, just survival.
    You can’t, until fuel cells become economical, beat the price of converting gasoline to electricity at this time, but once you get over the initial investment, this solar/battery power will outlast the generator if you can’t refuel within a month. (Long term power outage means gas stations can’t pump gas and it spoils in the tanks unless you have stocked up on stabilized gasoline.)

    My idea is that a fridge, or freezer would cycle and not be a continuous draw lasting, as he predicts, for a day or two depending on the efficiency and size of the appliance. In my original post, I was thinking of just keeping existing foods preserved until they could be cooked or consumed before they spoil. A couple of days would be plenty of time to do that. (I suppose we would be eating well for the first several days of SHTF.)

    The problem with this “invention” came when he couldn’t find a market to pay the cost of this technology. It was developed just after the Y2K scare but the scare has passed so generators are the temporary power source of choice. He is an ideas kind of guy; maybe I can help find a market for this and we can get this going again.

    So, if I have understood your comments/questions correctly, it is the capacity of the batteries and the efficiency of the inverter, and the power demand that makes the equation work, or fail. Did I make any sense? Did I answer your questions?
    It’s so much easier now days, to "Love and honor" my wife, when she is armed, and shoots a better group than I do. (Till death do us part, eh?)

    “The way you get shot by a concealed weapons permit holder is, you point a gun at him,” the Sheriff said.

  6. #66
    Senior Moderator
    Array Tangle's Avatar
    Join Date
    Dec 2004
    Location
    Chattanooga
    Posts
    9,827
    Very thorough reply!

    There are several brands of batteries that can serve as both cranking and deep cycle batteries, Optima is one of them. Still it is truly a matter of battery capacity, i.e. how much current the battery can supply for how long before the battery is considered discharged.

    Certainly the $225 Optima battery is far superior to the $59 batteries most of us have in our cars. Most batteries in cars are "cranking" batteries will be damaged by deep discharges. Other batteries, often referred to as marine (water, not soldiers) batteries, can both crank a car and handle deep discharges. The two things that really got my attention in your original post was "regular car battery" and not efficient.

    One of the things we learned about electric vehicles was that the higher the voltage, the more efficient the entire system became. Of course, the opposite is true too, the more current required, the less efficient the system became. So our 20 HP motors were powered by 144 volt battery packs.

    I'm looking for a power source to cover weeks, and I'm not sure batteries are the way to go. You've pointed out that the battery/inverter system may power a "house" for a day or two. Even on limited loads, the batteries are going to need a recharge every now and then. Recharging the batteries from solar panels is a mature technology and is used pretty widely in the south west. But solar power is the most expensive power source there is and will cost far more than the batteries. Plus the solar panel has to be able to recharge the batteries during daylight hours and depends on bright sun for enough hours each day to replace the charge used by the batteries each day. If you had a week of partly cloudy or overcast skies….

    It looks to me like an LP driven generator would provide power over a much longer time period and cost less than a battery/inverter/solar system. A 3300 W LP generator would cost about $600 and a 250 gallon tank of LP would cost about $500. It would cost about $325 to fill the tank. So for an initial cost of about $1400, you could have a long term electrical supply, not dependent on whether the sun shines or not. The LP has no shelf life, doesn’t degrade and is easy to store and replenish. You can even get “tri-fuel” generators that work on LP, natural gas, and gasoline.

  7. #67
    Senior Member Array elkhunter's Avatar
    Join Date
    Jan 2006
    Location
    Colorado
    Posts
    562
    Well this has turned interesting.
    Once again I find that my memory (or lack of in this case) continues to get me into trouble if gone unchecked. Thanks for the questions. You have served me by forcing me to re-align my facts. I do need to do that from time to time.
    In my recent research (for this thread) I think I have re-opened the possibility for a business relationship with my friend and his emergency power ideas.

    It never occurred to me that LP gas powered generators would be an option. That looks like the economical solution I would want to consider. As I was talking with my friend about the solar panel system we had to figure out a way to “harden” the panels against hurricane damage or vandalism. The costs just keep rising ya know.

    All this conversation is serving me to fill the remaining gap in the design I’ve had in my head for several years now, for a shelter intended for long term use in the event of a serious disaster.

    A long time ago, I worked in the construction industry, specifically in the construction of storm & sanitary sewer systems. I then changed careers to work as an aircraft mechanic. I now (although unemployed) am a Technical Writer with a Business degree. So, I’m thinking about marrying up some of my experience to produce an underground concrete pipe based shelter with some aircraft interior for comfort and practicality. All I need to put it all together is some power to run some basic needs like lights, maybe some air recirculation, sanitation, you know, the basics for a few months.
    (What I really need is a market for this idea. Unfortunately that might not come unless we really do experience a national disaster. I do not wish for THAT to happen.)

    I saw a blast shelter built by another friend once. This one was constructed using a 10’ X 100’ underground fuel storage tank. He had this buried in his back yard with an access tunnel and blast doors from his basement. He had a bicycle powered generator, and hand powered air pump with a 5 gallon bucket latrine. Sparse, but survivable for all but a direct hit.

    Examining his shelter gave me the idea for my concrete based shelter with an interior. I’d put a well and hand pump (if not too deep) in the shelter for water supply. Any number of offshoot pipes can be laid and connected for food and other storage. The limitation might be real-estate and drainage. You don’t want water to pool in your sealed basement ya know. I’ve had plenty of experience helping people deal with wet basements over the years, drain pipes below and sufficient watershed on the surface should cover most problems depending on local geography.
    Anyhow, I’m starting to think that if I can find a market for this, I could build these shelters and make a small living.

    Wadyathink?
    It’s so much easier now days, to "Love and honor" my wife, when she is armed, and shoots a better group than I do. (Till death do us part, eh?)

    “The way you get shot by a concealed weapons permit holder is, you point a gun at him,” the Sheriff said.

  8. #68
    Senior Moderator
    Array Tangle's Avatar
    Join Date
    Dec 2004
    Location
    Chattanooga
    Posts
    9,827
    Well, a fellow student in one of my Gunsite classes was making a living (killing) turning missle silos into "unique" dwellings, so...

    There woud sure be some problems to solve, like what do you do with the 5 gal. bucket when it's full? But if you resolve the problems, you'd have a unique product. After the coming hurricane season, you may have more jobs than you can do.

    Just my thought, I'd be very reluctant to "self-power" (bicycle) anything essential. If you got sick, got tired, didn't have time that system would fail. Plus, you'd use more air.

    Renewable power seems to me is the real issue. Solar panels are iffy, because of things you mentioned, like survival in a storm.

    Actually, what I have in mind for long term power is a 500 - 1000 gallon LP tank and maybe two gens. - if I can ever figure out what the fuel consumption really is. My thinking is reduncy and back-up. It would be advantageous to have two smaller units as opposed to one larger unit. Circuit loads could be divided evenly between the two. But if a single larger unit fails, all is lost until it can be re-started. But with two smaller gens, if one fails, you could switch more critical circuits to the other unit and at least limp on.

    I'm not optimistic about the solar/battery power, but it would be good to have a small system that could charge starter batteries, etc.

  9. #69
    Senior Member Array elkhunter's Avatar
    Join Date
    Jan 2006
    Location
    Colorado
    Posts
    562
    Yah, I saw that on a news segment a few years ago, luxury silos.

    I suppose, in a perfect system and unlimited $$ I’d set up a system with the battery backup so if there is a generator failure, there would be time to fix (if you can) before total blackout. I’ll bet there is data out there on the conversion of LP to electricity somewhere. I gotta look into this now.
    Here it is from a google search:
    http://www.kohlerpowersystems.com/on...te_gas_lp.html

    I also keep thinking about some of those luxurious Gulfstream interiors I worked on & in. I can’t remember the exact dimensions but they are similar to a 10 or 12 foot diameter inside. It should sell to some of those Gulfstream owners with $$ to burn.
    It’s so much easier now days, to "Love and honor" my wife, when she is armed, and shoots a better group than I do. (Till death do us part, eh?)

    “The way you get shot by a concealed weapons permit holder is, you point a gun at him,” the Sheriff said.

Page 5 of 5 FirstFirst 12345

Sponsored Links

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Similar Threads

  1. SHTF ???
    By 929bigo in forum General Firearm Discussion
    Replies: 26
    Last Post: February 19th, 2009, 02:26 AM
  2. SHTF?
    By JD in forum Carry & Defensive Scenarios
    Replies: 58
    Last Post: May 18th, 2007, 03:26 PM
  3. Indiana permit duration
    By sixgun in forum Concealed Carry Issues & Discussions
    Replies: 3
    Last Post: March 12th, 2007, 07:19 AM
  4. What do you have in your SHTF bag?
    By vinnie in forum General Firearm Discussion
    Replies: 13
    Last Post: February 15th, 2007, 03:22 AM
  5. shtf soon ??
    By Redneck Repairs in forum Off Topic & Humor Discussion
    Replies: 40
    Last Post: March 31st, 2006, 12:25 PM

Search tags for this page

beulah colorado shtf

,

how long to run refrigerator on generator

,

shtf groups florida

,

shtf solar power

Click on a term to search for related topics.