Newbie with big ideas but little experience

ja1724ja1724 Registered Users Posts: 6
Ok, first off , forgive me if this idea is out there but here goes:

I have an electric motor (115VAC, 15A full load, 1725RPM) that I want to use to spin a modified Delco alternator capable of putting out 200A @ 12V (I think I can get these up to 300A). I would then feed this output into a power inverter, say 3000W. This would then go back to feed the motor. Then I could switch off the utility power and switch over to motor/alternator/Inverter power. The motor draws 1725 at full load. It has a 90% efficiency rating, so to me that means it really draws 1725 / .90 = 1917 Watts over time. Because the alt. is capable of putting out 2400W and the motor only draws 1917W I think this technically wouldn't be a perpetual motion machine, but I could be wrong.

The motor would have a second pulley on it to spin a PMA, WindbluePower advertises one that supposedly puts out 24V and 115A @ 1725RPM (Maybe Northern AZ has a better one). This PMA would then charge a battery bank. Finally at the end of the string would be one or more 1000 or 1500W grid tie inverters.

Ideas, questions, comments? Thanks for any input that can be provided.

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Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Newbie with big ideas but little experience

    Welcome to the forum.

    This is perpetual motion and won't work.

    Once the initial "jolt" from the utility is used up, the losses everywhere will eat up the power and bring everything to a halt.

    The alternator will not put out 2400 Watts without more than 2400 Watts going in to it.
    A 3000 Watt inverter will not put out 3000 Watts without more than 3000 Watts going in to it.
    Et cetera.
    Even if losses were zero the best that could be achieved is equilibrium; there would be no "surplus" with which to accomplish any work.

    Or, "there's no free lunch".

    Sorry about that.
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: Newbie with big ideas but little experience

    Not to mention the friction loses with the alt and the motor. Because a alternator can put it X amps, means that at a minimum it tax X plus power to create those amps.

    Icarus
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Newbie with big ideas but little experience
    ja1724 wrote: »
    Ok, first off , forgive me if this idea is out there but here goes:

    Ideas, questions, comments? Thanks for any input that can be provided.

    Yes, there are many many versions of such ideas out there. The ideas sound great at first, but in every case, once the actual construction takes place and the device is tried, reality sets in. There is no way to get something for nothing, no matter how much we may wish otherwise.
    Cariboocoot is correct, this is another version of the many thousands of perpetual motion ideas, it cannot work, and if you go ahead with construction, you will be shocked at how fast it comes to a total stop after the switch is changed over from grid to self powered. You'll find the motor will come to a stop even faster than if nothing was connected to it's shaft, and it's just allowed to spin down by cutting the power. If only it weren't so, what a wonderful world this would be.
  • ja1724ja1724 Registered Users Posts: 6
    Re: Newbie with big ideas but little experience
    Welcome to the forum.


    The alternator will not put out 2400 Watts without more than 2400 Watts going in to it.

    .

    Thanks for the welcome.

    Ok, so it seems because the motor is producing 1HP (746W) of energy going 'into' the alternator there is no way it will make the 2400W on the backend to feed the inverter. Got it.

    What if I modify it so that the motor (only connected to utility) spins just the PMA at 2500RPM to produce the advertised 25V and 125A (3125W) to charge the battery bank which then feeds, say 2, 1500W grid-tie inverters? So the motor is burning 1725W of utility power and I am sending 3000W back into the panel. Would this net me 1275W of created power? Also would this PMA be able to keep the battery bank charged when powering 2 1500W grid ties? If not what about 2 PMA's and two separate battery banks each bank powering its own grid-tie?

    Sorry to be long winded but this stuff is starting to consume me. Thanks again for the insights.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Newbie with big ideas but little experience
    ja1724 wrote: »
    Thanks for the welcome.

    Ok, so it seems because the motor is producing 1HP (746W) of energy going 'into' the alternator there is no way it will make the 2400W on the backend to feed the inverter. Got it.

    What if I modify it so that the motor (only connected to utility) spins just the PMA at 2500RPM to produce the advertised 25V and 125A (3125W) to charge the battery bank which then feeds, say 2, 1500W grid-tie inverters? So the motor is burning 1725W of utility power and I am sending 3000W back into the panel. Would this net me 1275W of created power? Also would this PMA be able to keep the battery bank charged when powering 2 1500W grid ties? If not what about 2 PMA's and two separate battery banks each bank powering its own grid-tie?

    Sorry to be long winded but this stuff is starting to consume me. Thanks again for the insights.

    Your motor will use 1725 Watts and produce 1 HP. The 3125 Watts output from the PMA is 1400 Watts more. Where does that power come from? At 746 Watts per HP, that PMA wants slightly more than 4 HP in to produce its output. The motor is only 1 HP. Put the load on, the energy demand on the motor will slow it down and increase the current draw (motors do not have fixed power consumption) to a level it was not meant to operate at. The extra current turns to heat, and the motor's thermal cut-out shuts it down.

    Further to this, if the goal is to charge batteries there is no point in taking AC power, turning it into mechanical energy, then back into AC power (via the PMA) then into DC power to charge batteries. Every step of the way some power is lost. Far less is lost by simply using a transformer to reduce the AC line Voltage to the lower level for charging the battery and rectifying it to DC then. You will still lose power. Most battery chargers have a pretty poor power factor. Not to mention that batteries themselves need more power to recharge than you can get back out of them afterward. There is never a 100% energy recovery in any type of system, much less over 100%.

    What's more, most GT inverters do not use batteries. Those that do are either the hybrid type (like Xantrex XW) or the cheap junk found on unscrupulous web sites that should never be used for anything other than doorstops.

    FYI, with PV powered solar the net efficiency from light hitting the panels to usable AC Watts is a horrible 52%.
    How detailed would you like me to be in describing the losses in a closed-lop system? They exceed 100%.
  • BB.BB. Super Moderators, Administrators Posts: 31,613 admin
    Re: Newbie with big ideas but little experience

    In the end, it is not unusual to get 50% losses with mechanical conversions...

    So, to drive a 4 HP alternator, you need an 8 HP motor to drive it, where you spent about 16 HP from the utility in raw fuel "usable" energy value.

    Add 80% efficiency for battery bank and 85% for typical inverter efficiency, the end to end losses from this sort of system:
    • 0.5 Fuel to utility * 0.5 for motor to alternator * 0.80 for battery eff * 0.85 for inverter efficiency = 0.17 ~17% fuel to end point energy generation efficiency

    So, you have lost over 4/5th of the energy available from that pile of coal or field of natural gas for just "one pass" through the power system...

    And with that 17% power left, what is the energy conversion of the next step (another 50% efficient motor?).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: Newbie with big ideas but little experience

    Remember the first law of thermodynamics,,,,

    Also look at entropy!

    Icarus
  • ja1724ja1724 Registered Users Posts: 6
    Re: Newbie with big ideas but little experience

    So now on to reality...If my house consumes 3000W per hour and I want to feed this same usage back into my panel how many solar panels would I need, 3000W worth or 4500W worth because of losses such as ~50% efficiency of solar panels etc.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Newbie with big ideas but little experience
    ja1724 wrote: »
    So now on to reality...If my house consumes 3000W per hour and I want to feed this same usage back into my panel how many solar panels would I need, 3000W worth or 4500W worth because of losses such as ~50% efficiency of solar panels etc.

    If you are trying to produce 3000 Watts from solar you do indeed need more than 3000 Watts of panel. As a rule, panels + GT inverter will produce at a rate of around 75 to 80 % of the panel rating. There are a lot of factors involved here: your location, panel temperature, wiring runs, actual inverter efficiency, et cetera.

    You can get a pretty good idea of what your production will be in advance by putting your relevant data into the PV Watts program: http://www.nrel.gov/rredc/pvwatts/

    The other thing is, of course, that those panels only put out in daylight. If you use 3kW 24 hours per day that's 72kW hours daily. To produce that amount in the short period of time you have good sunlight you'll need much more array and inverter capacity, and be able to send that excess to the grid for "virtual storage". Be advised that grid-tie installs should not be done without the co-operation of the utility. Not the least of the reasons being that if you don't have the proper meter installed you will get billed for any surplus power you produce (most meters only run up, regardless of which direction the current is actually flowing).
  • solar_davesolar_dave Solar Expert Posts: 2,381 ✭✭✭✭
    Re: Newbie with big ideas but little experience

    BTW 72kWh per day is a pretty huge number for most of the nation. I would be surprised you use that much. I know I do but I live in AZ with 3 AC units, 2 electric cars ....

    The utility may have TOU metering plans which play in nicely with Grid tie solar systems. You produce power when the utility charges the most for it saving you the maximum $$$. Then during the off peak times you can move to run selective loads (clothes dryer, dish washer, pool pump ...) at a much reduced rate.
  • ja1724ja1724 Registered Users Posts: 6
    Re: Newbie with big ideas but little experience

    You can get a pretty good idea of what your production will be in advance by putting your relevant data into the PV Watts program: http://www.nrel.gov/rredc/pvwatts/

    Cariboocoot, thanks for the link. I ran the numbers and it's pretty depressing for a PV system in Connecticut. My total power generation for a whole year with a 4KW system would only be worth ~$550. Probably why I don't see many at all around here. Guess I'm stuck takin' it in the rear from the ol' power company. Dammit.
  • ja1724ja1724 Registered Users Posts: 6
    Re: Newbie with big ideas but little experience
    solar_dave wrote: »
    BTW 72kWh per day is a pretty huge number for most of the nation. I would be surprised you use that much. I know I do but I live in AZ with 3 AC units, 2 electric cars ....

    The utility may have TOU metering plans which play in nicely with Grid tie solar systems. You produce power when the utility charges the most for it saving you the maximum $$$. Then during the off peak times you can move to run selective loads (clothes dryer, dish washer, pool pump ...) at a much reduced rate.

    Hey Solar_dave, I know it's a lot. This is why I'm looking to offset my costs. I actually took the 72KWh per day X my .107 rate and came up with a bill of $230 which is damn near what my monthly bill is. It actually gets closer to $350/month in the summer months with a central AC on. Very little wind in the northeast and not enough sun. I guess I'm screwed.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Newbie with big ideas but little experience

    Just how expensive is your grid power? It's probably not as bad as the cost of producing the same power with GT or off-grid.

    Here's the #1 money saving tip: conservation. Really. Get a Kill-A-Watt meter (about $30) and start measuring everything that plugs in to the wall. You'd be amazed at how many power-hungry "phantom loads" you might have.

    It never ceases to amaze me the people who are willing to drop $20,000 of a solar electric system who won't spend $2,000 on some new appliances that don't chew up so much energy in the first place.
  • solar_davesolar_dave Solar Expert Posts: 2,381 ✭✭✭✭
    Re: Newbie with big ideas but little experience
    ja1724 wrote: »
    Hey Solar_dave, I know it's a lot. This is why I'm looking to offset my costs. I actually took the 72KWh per day X my .107 rate and came up with a bill of $230 which is damn near what my monthly bill is. It actually gets closer to $350/month in the summer months with a central AC on. Very little wind in the northeast and not enough sun. I guess I'm screwed.

    So your rates are really good. As the coot says conservation is first. Cut you usage. Next is find out if you utility offers time of use rate plans,if so get one and shift you heavy selective loads to off peak rate. Now see how much power you use on peak, a small solar system may just offset the higher cost on peak. Now you get the max return on your investment and a much lower utility bill.

    I now pay my utility about $20 - 30 a month and my annual bills used to be $4000-$5000. I added 2 Chevy Volts and now get to drive them for virtually free. We also added a 700 sq. ft. Building that is air conditioned. BTW I did all the conservation as well, energy star fridge, new AC units, CFLs, add insulation.
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: Newbie with big ideas but little experience

    You re not "screwed" per se, but you should realize thy conservation is your cheapest ener dollar. If you are using 72 kwh/day, there are probably a lot of ways you could save electricity without spending much money (and what money you'll spend pays off quickly). Insulation, light bulb changes, windows,water heating technology, a/c improvements etc all can save a ton of KWHs if you go looking for them.

    A simple example, a 5-10 year old fridge will use twice as much energy as a new one. An electric water heter can be replaced with a gas one,, demand preferably or ideally solar heated hot water, (which is much cheaper than PV) before yin eat a nickel in PV spend the time to do any and all conservative, including hiring a good energy auditor to really show you where yan save.

    Goo luck and keep in touch,

    Tony
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Newbie with big ideas but little experience

    I regularly see cases where homeowners complain about their high electric bills, all the while practicing horrific waste of that electrical energy. Waste they consider perfectly normal. Waste they consider their right to continue. Waste that's taking a big chunk out of their pocket book, but they refuse to see what they're doing.
  • ja1724ja1724 Registered Users Posts: 6
    Re: Newbie with big ideas but little experience

    As far as conservation goes I couldn't agree more. I have already bought all new windows, put a new 50yr. shingle roof on my house, had the attic insulated up to an R-59 rating, bought a new energy efficient fridge and changed to 'nearly' all CFL's. I do have a 15 year old freezer in my garage that really should be replaced (wife and I are discussing that one now). My power company does provide a power audit for around 80 bucks. I think the service is worth it but not sure if I should trust them? I am a Systems/Network Specialist so I also have an office with some PC's routers monitors etc. My biggest cost is the central AC during the summer months.

    My utility does offer a RT (time of day rate) but it boosts the daytime rate to about 1.5x the normal cost. I'll keep everybody posted what I find. Thanks again all for the info.
  • BilljustBillBilljustBill Solar Expert Posts: 219 ✭✭✭
    Re: Newbie with big ideas but little experience

    Here's an interesting concept.....Letting a row of charged capacitors sustain the generator's field as the rest powers the electric motor and an additional load. I think there is a version for DC, too.

    http://www.youtube.com/watch?v=Fv53K9MnDuM

    Bill
    Bill
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Newbie with big ideas but little experience

    Oh please. It doesn't matter how you do it, it's all "perpetual motion".

    The usual gullible goof does it with a DC motor running a generator that powers the DC motor. Then they put a battery in between and voilà! Perpetual motion!

    Until the battery goes dead from chronic deficit charging - or the caps discharge. Whichever.

    Don't believe everything you see on Youtube.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Newbie with big ideas but little experience
    Here's an interesting concept.....Letting a row of charged capacitors sustain the generator's field as the rest powers the electric motor and an additional load. I think there is a version for DC, too.

    http://www.youtube.com/watch?v=Fv53K9MnDuM

    Bill

    Yeah, and I once saw a youtube video where the guy claimed he is able to burn water, harvest the heat, and have water as a waste product. Right.

    I once told my wife that if we put smaller wheels on the front of our car it would get better gas mileage because it would always be rolling downhill. She believed me for about half a second, then she hit me. :D

    The Second Law of Thermodynamics says that the best you can do is break even.
    The Third Law of Thermodynamics says that you can never break even.
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Newbie with big ideas but little experience
    ggunn wrote: »
    The Second Law of Thermodynamics says that the best you can do is break even.
    The Third Law of Thermodynamics says that you can never break even.

    I prefer the formulation of all three laws as:

    The First Law: You can't win.
    The Second Law: You can't even break even.
    The Third Law: You can't get out of the game.
    SMA SB 3000, old BP panels.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Newbie with big ideas but little experience
    inetdog wrote: »
    I prefer the formulation of all three laws as:

    The First Law: You can't win.
    The Second Law: You can't even break even.
    The Third Law: You can't get out of the game.
    Summation: There ain't no free lunch and you can't not eat.
  • solar_davesolar_dave Solar Expert Posts: 2,381 ✭✭✭✭
    Re: Newbie with big ideas but little experience

    It is a Dire Straits moment then. "Money for nothing and the chicks for free"?
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