Baby backup for a cold, frigid state

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purduephotog
purduephotog Registered Users Posts: 4
in Solar Beginners Corner #1
Rochester NY, lots of ice and snow. Not so many power outages but my job is increasing its demands of travel and I have wife and kids stuck here.

Consequently I'd like to put together a small battery backup capable of running the fan in my wood stove (do y'all know what a wood stove is out in AZ?) And I have no issues having my wife go down and flip switches and move a plug to get it running.

I have, - no laughing here - been able to buy some marine deep cycle batteries from an auto store. 210 rc as rated. Right now I have 3x but can pick up 2 more before my next trip.

I have a small 10amp charger that appears to follow the correct voltage and absorption times.

I do not have an inverter, and I have not wired the batteries yet.

Expected draw is no more than 600 watts. The stove can heat the whole house, but only so long as the fan in it runs. Add 1 cfl 23 watt and the family can retreat to the room until power or generator is up.

Given my somewhat meager choices, is there a good inverter to grab that might fit this bill?

Thanks kindly. I head to Germany next week and Phoenix in a few more... wish the family could come.

Jason
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: Baby backup for a cold, frigid state

    Welcome to the forum.

    Rochester! Ah, that brings back memories. Trying to get through the Can of Worms. :D
    To say nothing of its nickname: "The Cloud Capital of the World." :p

    If all you want to do is run the circulating fan on the wood stove, get an Eco Fan instead. <$100 and it needs no power source. I've got one on the stove here in town and another at the cabin. They're a lot quieter than the 120 VAC built-in fan (there's one on the town stove - it's unplugged) too.

    On the whole the solar power will cost a lot more and won't be very effective in a NY Winter (which is nothing compared to a Cariboo Winter, but you get more snow there).
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #3
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    Re: Baby backup for a cold, frigid state

    you would make this exercise a lot easier on yourself if you test that fan with a Kill-a-Watt meter or similar device, so you know exactly what the fan draws, not what it is rated at. I run a large oscillating 3 speed fan + + + on a 600W TSW inverter off one 100Ah battery with no issues. Same fan can also be run off a 400w MSW inverter...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
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    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
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    Re: Baby backup for a cold, frigid state

    Okay, tested the one on my stove.
    0.72 Amps peaked, 29 Watts running on low 54 Watts running on high.

    In case anyone is wondering why we tell people to use the meter rather than rely on the printed ratings, the numbers on the power supply say "1 Amp 115 VAC".
    As you can see it doesn't use anyplace near that.

    Still, this is a thermostatically controlled fan so it's hard to predict its on/off time. It is on whenever the stove is above a certain temperature, so that would be most of the day (figure 12 hours). On low: 348 Watt hours. On high: 648 Watt hours. For a 12 Volt system that would be 108 Amp hours minimum for high, not including inverter consumption. The good news is that it wouldn't take a big inverter to power it.

    This is assuming the OP's fan is similar. It may not be.
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  • purduephotog
    purduephotog Registered Users Posts: 4
    #5
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    Re: Baby backup for a cold, frigid state

    Yes, indeed- thermostatically controlled. Actually have a kill-a-watt plugged in, just waiting to fire up the stove and read the draw. The other fan is a squirrel cage and it blows cold air in. Will measure that one. I've learned to take the pf of motors and total current draw with a grain of salt... doubling it seems to have served me well.
    The wife will appreciate the fire, so I suppose I can burn a few logs to get a reading.

    Any preferred brand for small motors?
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  • bill and rosa
    bill and rosa Solar Expert Posts: 26 ✭
    #6
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    Re: Baby backup for a cold, frigid state

    ECO FANS that I have been looking at to set on my gas burning fire place.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
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    Re: Baby backup for a cold, frigid state
    bill and rosa wrote: »
    ECO FANS that I have been looking at to set on my gas burning fire place.

    Now there's a potential issue, depending on the design of the gas fireplace. The Eco Fans need to sit on top of the heat source so that the heat flows up through it and radiates off the fins at the top. This drives the Peltier effect creating the electricity to run the fan motor. I'm not sure it would work well if placed in front of the heat source. In other words you might have difficulty finding a position that the fan would work in. They work differently depending on where you place them on the stove too.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #8
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    Re: Baby backup for a cold, frigid state

    Just to move air, a couple of 12 vdc computer fans will run for days on a simple car battery. 3-10 watts, and will move a fair amount of air.

    The stove top Eco fans will also opmove a lot of air, especially the three bladed ones. I have a couple of cast offs that quit because they were over heated, that I modified to run on a rechargeable AA battery, runs for ~ 12 hours per battery, and moves more air than the heat powered Eco fan.

    Tony
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  • bill and rosa
    bill and rosa Solar Expert Posts: 26 ✭
    #9
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    Re: Baby backup for a cold, frigid state

    the gas fire place we are looking will work its a flat top already asked the maker of the fireplace. They even sell the fans there also. Just to clear things up.
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #10
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    Re: Baby backup for a cold, frigid state

    While the Eco Fan is a great idea, depending on the construction of your stove you may still want to use the built-in fan. Mine is double-walled, and the built-in fan blows air between the walls and out two ports near the top. Gets all of the heat from the inner box, much better than a fan sitting on top would. I would be worried that without the built-in fan in operation a double-walled stove design would overheat and warp the inner walls.
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  • purduephotog
    purduephotog Registered Users Posts: 4
    #11
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    Re: Baby backup for a cold, frigid state
    techntrek wrote: »
    While the Eco Fan is a great idea, depending on the construction of your stove you may still want to use the built-in fan. Mine is double-walled, and the built-in fan blows air between the walls and out two ports near the top. Gets all of the heat from the inner box, much better than a fan sitting on top would. I would be worried that without the built-in fan in operation a double-walled stove design would overheat and warp the inner walls.

    I apologize for the confusion- this is an insert- a Lopi Freedom Bay. Not running the fans would be a bad idea. I also am taking the opportunity to purchase a spare in case I lose the one (there are two) that move (supposed) 130 CFM. The eco fans don't move enough air, although I did look at them and built one for fun out of some peltiers I had from earlier computer efforts.

    There are a number of installed heat sinks and anodized SUN plugs to help move heat into the airpath.

    So while I have plenty of computer fans, there is no easy way to push the air into the double wall insert without ripping out / apart the base. I have... and don't really want to repeat that... (involved a call to the fire department when the sealing tape the installer used caught fire in the chimney...)
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #12
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    Re: Baby backup for a cold, frigid state
    Cariboocoot wrote: »
    This drives the Peltier effect creating the electricity to run the fan motor.

    Small quibble, but as a physicist I could not let it go:
    The Peltier effect, as originally discovered lets you directly use electrical energy to pump heat.
    The Seebeck effect, as originally discovered, lets you transfer heat to get electrical energy.
    Since both Peltier and Seebeck are long dead, they probably don't care anymore.

    To complicate matters, both the Peltier and the Seebeck effect are thermodynamically reversible, so one can reasonably argue that they are in fact exactly the same thing, the Peltier-Seebeck effect.

    But for convenience, you normally see the name Peltier for the thermoelectric heating/cooling application and the term Seebeck for the power generation application.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #13
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    Re: Baby backup for a cold, frigid state

    SHEESH! Peltier-Seebeck effect in the 'long form'. Happy now? Shall I explain the whole history of Volta, Ampere, Watt, and Ohm while we're at it?
    :p
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #14
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    Re: Baby backup for a cold, frigid state
    Cariboocoot wrote: »
    SHEESH! Peltier-Seebeck effect in the 'long form'. Happy now? Shall I explain the whole history of Volta, Ampere, Watt, and Ohm while we're at it?
    :p
    Very happy, thanks. :-)
    FWIW, the ECOfan site says that they use the Seebeck effect and I just did not want anyone to get confused. (Wikipedia does not help much. :-) )

    I will be happy to wait for the full history of electromagnetism in a different thread. :-)
    SMA SB 3000, old BP panels.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #15
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    Re: Baby backup for a cold, frigid state
    inetdog wrote: »
    I will be happy to wait for the full history of electromagnetism in a different thread. :-)

    Oh well now you're talking Faraday! Let's not leave him out. :D

    Back to the OP. With a built-in the Eco fan is likely not a choice as I explained before due to positioning problems.
    So it's time to get the K-A-W on that fan. This could be a problem if it is hard-wired in. A big problem. But as can be seen by my test on the one I've got the nameplate rating may not be reality.

    Even so powering a 60-ish Watt fan for 24 hours = 1.5 kW hours per day. Not impossible to accomplish. It's right around the basic "two golf cart batteries" requirement.
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  • purduephotog
    purduephotog Registered Users Posts: 4
    #16
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    Re: Baby backup for a cold, frigid state

    75.3 watts and a pf of 0.47. Disgusting. All in all then to run the light and minimum fan, 200 watts/hr. 3x 100 Ah batteries, if I do the math right, then ( or as they are advertised, 210 min @25A) or about 12 he's. Less, because the lights will be off when they sleep.

    Alright a small 400 watt inverter should work for now.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #17
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    Re: Baby backup for a cold, frigid state
    purduephotog wrote: »
    75.3 watts and a pf of 0.47. Disgusting. All in all then to run the light and minimum fan, 200 watts/hr. 3x 100 Ah batteries, if I do the math right, then ( or as they are advertised, 210 min @25A) or about 12 he's. Less, because the lights will be off when they sleep.

    Alright a small 400 watt inverter should work for now.

    Urgh. That is bad even for an induction motor.
    You figure 200 Watts for everything? Now about that run time ...
    In 24 hours the fan alone at 150 VA will suck down 3.6 kW hours. That's 300 Amp hours @ 12 Volts right there. That requires 600 Amp hours of battery minimum. And doesn't include power to run the inverter.

    See how easily a little thing like a fan runs into a big investment in back-up power?
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #18
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    Re: Baby backup for a cold, frigid state

    Sounding like a job for a smaller inverter-genset.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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