Need a battery suggestion (use indoors preferable)

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newsun
newsun Registered Users Posts: 6 ✭
in Solar Beginners Corner #1
Hi all,

First of all, I love these forums and have learned a lot here - thank you.

I am thinking of purchasing the following inverter to just keep a couple of small items running during our winter outages...
http://www.amazon.com/gp/product/B0007PGAG6/ref=ord_cart_shr?ie=UTF8&m=ATVPDKIKX0DER

Can someone suggest a good deep cycle battery or two? I would prefer to keep the inverter and battery(ies) indoors since I have a small closet in the perfect spot (I do not have a basement). My understanding is that gel type batteries are safe to use indoors - correct?

I can also put it outdoors if it is the only safe or reasonable option.

Any suggestions?

Thanks!
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  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    #2
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    Re: Need a battery suggestion (use indoors preferable)

    Gel or AGM are best for indoors. But even these, if over charged would outgas.

    Now as for the inverter loads. What do you need and for how long??
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  • newsun
    newsun Registered Users Posts: 6 ✭
    #3
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    Re: Need a battery suggestion (use indoors preferable)

    For the most part would be about 20-60 watts (ceiling fan and a light).

    In some situations, I'd also like to be able to get online and work from home if (when) I'm snowed in without power. This would take me up to about 150 watts (net) about 40 hours per week.

    I'm getting the larger inverter for the unexpected.

    So, if feasible, I'd like to find a battery or batteries that can provide the above for 1-2 weeks (or even more) on a full charge.

    Not sure if this is overly optimistic or not. Thanks again for any insights.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
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    Re: Need a battery suggestion (use indoors preferable)
    newsun wrote: »
    For the most part would be about 20-60 watts (ceiling fan and a light).

    In some situations, I'd also like to be able to get online and work from home if (when) I'm snowed in without power. This would take me up to about 150 watts (net) about 40 hours per week.

    I'm getting the larger inverter for the unexpected.

    So, if feasible, I'd like to find a battery or batteries that can provide the above for 1-2 weeks (or even more) on a full charge.

    Not sure if this is overly optimistic or not. Thanks again for any insights.

    Pardon me for butting in (I'll do anything to avoid work! :p ) ...

    That's a pretty tall order without some sort of recharge source. To wit:
    150 Watts * 40 hours a week = 6000 Watt hours per week * 2 weeks = 12 kW hours
    On a 12 Volt system that's roughly 1000 Amps hours, times at least two to prevent over-discharging.

    How are you fixed for sunlight during such an outage? How about a little generator? That much battery is not practical.

    If you could divide it up into 1 kW per day segments you could supply that with a couple of "golf cart" batteries providing you could recharge daily (either by 400 Watts of panel or a small generator used during daylight).
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  • newsun
    newsun Registered Users Posts: 6 ✭
    #5
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    Re: Need a battery suggestion (use indoors preferable)

    Haha - hardly butting in. The more the merrier.

    That's kind of what I thought. We don't want a generator due to the noise. So, what about just running our ceiling fan (20 watts) for, say, a week?

    Maybe bumped to 40 watts for a couple hours a night for a cfl?

    Doable with just battery?
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  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    #6
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    Re: Need a battery suggestion (use indoors preferable)

    Fan is 20 watts ?? How small is this thing?
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  • newsun
    newsun Registered Users Posts: 6 ✭
    #7
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    Re: Need a battery suggestion (use indoors preferable)

    Its huge -> http://reviews.homedepot.com/1999/100630835/altura-68-in-ceiling-fan-reviews/reviews.htm

    But we run it on low (actually 18 watts). It moves a ton of air.

    The problem we have is that we have a cathedral ceiling (~22' high). No matter how nice your woodstove is, the heat collects up top (where people aren't), unless you have a fan.

    When the power goes out in the winter, we freeze, even with our woodstove.

    I'm not a fan of cathedral ceilings for exactly this reason, but well, that's what we have.
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  • newsun
    newsun Registered Users Posts: 6 ✭
    #8
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    Re: Need a battery suggestion (use indoors preferable)

    Sorry, here's a better link: http://www.homedepot.com/h_d1/N-5yc1vZ1xh8/R-202060195/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

    Anyway, using coot's formula below, it looks like this would be...

    18 Watts * 168 hours a week = 3024 Watt hours per week * just 1 week = ~3 kW hours

    Which is...250 amp hours? Not sure about my math here.

    Any specific battery recommendations for this application?
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  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    #9
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    Re: Need a battery suggestion (use indoors preferable)

    Math is close.
    For batteries, we like to only run them to 50%. So that would be 500 AH. Now with this for emergency use only, we may overlook this 50% rule and go with 250-300 AH battery bank.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
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    Re: Need a battery suggestion (use indoors preferable)

    Don't discount generators so quickly. The new inverter type like the Honda EU1000i/2000i are extremely quiet. They are also very economical, once you recover from the capital investment! :p

    Also, have you considered one of these Ecofans for moving air from your wood stove?
    http://www.canadiantire.ca/AST/browse/3/HouseHome/1/HeatingAirConditioning/WoodPelletStoveAccessories/PRD~0642724P/Ecofan%252BOriginal.jsp?locale=en
    They work very well, but I'm not sure how they'd work against a cathedral ceiling.

    And yes, 3kW hours on a 12 Volt system is roughly 250 Amp hours - times two to preserve the batteries: 500 Amp hours.

    Note I run the whole cabin off 320. The difference? Being able to recharge the batteries every day. That's the key issue.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #11
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    Re: Need a battery suggestion (use indoors preferable)

    Ceiling paddle fans will use ~20-40-60 watts, and do move a ton of air for the money.

    Back to the original intent however.

    It is really pretty simple. If you "do the math" of calculating loads you will soon discover the limitations of battery based systems. A pair of T-105 golf cart batteries have a "ballpark" capacity of 225 ah at 12 vdc. Draw them to 50% and that leaves you ~110 to use. 110*12vdc=1.3 kwh of useable power, with out damaging the battery. So that will run your 20 watt fan for 67 hours. You can see how getting a battery big enough to be useful over a significant number of days is expensive.

    Now, a tiny honda EU 1000i will run for ~12 hours on a quart of fuel. It is so quite you absolutely cannot hear it out side the house on a 30' cord. The same generator will deliver ~800 watts continuously as long as there is fuel. It will need nearly no service, except for an annual oil change, and an exercise program of running it once a month or so. The cost is ~$700 for a new one, and good used ones can be had for less. In five years it will still be as good as new, while your batteries will be ready for the recyclers.

    The same pair of batteries will cost you ~$300 for the batteries, plus say $150 for a good three stage charger, another $300 for a 300 watt inverter for a total of ~$750. (I noticed you mentioned earlier a bigger inverter, the fact is you would already be pushing the limits of said battery with any inverter bigger than ~300 watts.

    A proper transfer switch would be required for either installation, but with an Eu 1000 you could power much of your house, including the computer or TV. Get a Eu 2000 for a couple hundred more and it would run the fridge or a freezer, or a furnace blower, all at the same noise level.

    As Marc ('coot) suggests don't discount the generator out of hand, without looking into it thoroughly.

    Good luck and keep in touch,

    Tony
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  • newsun
    newsun Registered Users Posts: 6 ✭
    #12
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    Re: Need a battery suggestion (use indoors preferable)

    Thanks everyone!

    This is great information, and I will certainly look closer into generators. My only experience with them is hearing my neighbor's at night (~400 feet away) and wondering how they can stand it. I guess there are ones that I DON'T hear...and that is an appealing idea.
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