New Small-ish Battery Backup system - Advise requested :)

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System
System Posts: 2,511 admin
in Solar Beginners Corner #1
Hi Friends,

I have been reading some of the posts on here for the last few days. Now that I have half a handle on how things work here, I am ready to make a post of my own.

I live in an area in Canada where it is not that uncommon for the power to go out. And sometimes for a couple days at a time. I have been thinking about creating some sort of Battery backup system. Nothing to big or real intense. My major concerns is the math that goes into determining what type of Power inverter/charge controller/Batteries to get. I was also toying with an idea of either a small solar panel for regular top ups of the Batteries, or somehow plug it in to my house for the top up.

The things I NEED to never loose power is my 180GL Salt Water Aquarium (water pumps x2). I have looked at the labels and they are 120V, 65W and 115V, 3W. Possibly even my Fridge. I do not plan on leaving this on for the whole power outage, but rather 30 minutes every couple hours. I would like to also plug in my internet modem and a couple small routers for WiFi access in my house. Maybe the odd small light too, noting to serous.

I was looking at Batteries at Walmart, but quickly determined that I have no idea what I am looking at. Haha. However, I was thinking that I would like to have a small system with 1 large battery (eventually expanding to 2 or 4 in a series).

I do not always have access to a generator as it is a shared unit. But I may have some time with it. If this was the case, I would like to plug it in my battery bank in an outage to recharge it (probably would cost MUCH less then just solar). But I am not sure.

Reading these threads I see a lot of people whom know what they talk about, and I am eagerly looking forward to a response.

Thanks for your time! And I cant wait to get started on this project.
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  • AntronX
    AntronX Solar Expert Posts: 462 ✭✭
    #2
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    Re: New Small-ish Battery Backup system - Advise requested :)

    How much money are you willing spend on this project? I am thinking Xantrex Prosine combined charger / inverter type of setup for you. If your pumps are diaphragm type, you will need pure sine wave inverter, I would think.
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  • System2
    System2 Posts: 6,290 admin
    #3
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    Re: New Small-ish Battery Backup system - Advise requested :)

    Thanks AntronX. I was thinking about the $400-$500 for now.

    Here is a link to the Type of pump i have:
    http://www.lagunaponds.com/lagunaeng/maxflopumps/maxflo900.php?link=141 . The other one is VERY small is at this link: http://www.aquahub.com/store/product31.html .

    I know its nothing fancy, but i was thinking about this Power Inverter: Motomaster Eliminator 600W Power Inverter

    and for a Charge controler, i was thinking about: Sunforce Charge Controller. This handles up to 100 Watts.

    If I grasp even 10% of the math involved with with, my two pumps should be able to handel this controller?

    Is this correct?
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #4
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    Re: New Small-ish Battery Backup system - Advise requested :)

    Far and away by best suggestion is to by a Honda Eu1000 inverter generator. Very quiet, will provide ~800 watts of continuos power, using ~ 1 litre of fuel every 4-8 hours depending on the load.

    For ~ $6-800 you will have reliable standby power, 24/7 and with a small amount of fuel stored, it will run your critical loads for ever, with no worry about the batteries running down. You also won't have to replace the batteries at any regular intervals. The only requirement is keeping a small amount of fresh fuel on hand.


    A EU generator, plus a number of cords and splitters is, IMHO going to be a much better long term solution, cheaper net/net and infinitely more reliable and flexible.

    Tony
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #5
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    Re: New Small-ish Battery Backup system - Advise requested :)

    Basically, you are looking at making your own UPS from solar RE equipment...

    As a start, look at:
    And, before you purchase anything--Get a Kill-a-Watt meter and measure your daily loads (kWatt*Hours) per day to support the "minimum" loads needed to keep it alive (i.e., extra pumps, tank lights, etc. you may want to drop for a couple days of power outage--at least until you fire up a genset to keep it running).

    The amount of battery you will install depends a lot on how much power you want to supply and how many hours/days you will want to run from batteries before running a genset for recharging.

    You can also look at adding solar panels now or later to help extend the time between needing to start up the genset. -- But once you know your loads (kill-a-watt meter)--then we can talk about details of battery bank and solar panel sizing.

    You can also wire the system several different ways--You can run from the inverter directly, and recharge from AC/Solar power and "fail over" to AC mains if something fails--Or you can run from AC power and if AC mains fail, switch over to the inverter...

    The first method is done when you need very clean power--There are never any glitches because you are always drawing power from the battery bank through the inverter--But this wastes quite a bit of power--About 40% is lost through the charging/battery/inverter setup.

    The second wastes almost no power--just trickle charging the battery bank (AC mains power through transfer switch to power your protected loads)--But you can get glitched power (dropouts, slow AC transfers, etc.) to backup power...

    If these are simple pumps (and possibly controllers)--1/2 second (or less) switch over is no big deal. If you have a "computer" running the setup--you could have the computer do a reboot...

    With any backup power system, there will be maintenance and costs (keeping battery clean and filled, replacing batteries every 3-8 years, etc.).

    The Walmart inexpensive "golf cart" batteries are probably a good start... Most people end up killing their first bank of batteries.

    Again, your choices.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    #6
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    Re: New Small-ish Battery Backup system - Advise requested :)
    icarus wrote: »
    Far and away by best suggestion is to by a Honda Eu1000 inverter generator. Very quiet, will provide ~800 watts of continuos power, using ~ 1 litre of fuel every 4-8 hours depending on the load.

    Tony

    About that particular generator, is the continuous rating strictly regulated? I have a roll-around air conditioner that draws 900 watts. I'd like to use it in my shop since my location typically experiences 5 months of uncomfortable heat/humidity every year.

    The unit's wattage falls right at that line where a small portable generator won't do. My shop is small, a genny wouldn't be running full all the time, but I imagine the startup of the compressor momentarily doubles the current requirements.

    I'd like to avoid jumping to the next level of generators just for creature comfort.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #7
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    Re: New Small-ish Battery Backup system - Advise requested :)

    I doubt that it would run a 900 watt standard A/C unit... The generator is rated for 1,000 watts starting and 900 watts (probably VA) continuous.

    Do yo have a Kill-a-Watt meter? You can use it to measure your air conditioner's power usage--Make sure you measure V*A too (amps and power factor while you are at it).

    I would guess that this unit has a PF that does not equal 1.0--So it will actually consume more VA (Volt Amps) because of the compressor and fan motor.

    You might be able to run it on the eu2000i (1,600 watt continuous). Yamaha has some quiet genesets that in in the 2,000 watt range that can run many 13,500 BTU A/C units.

    The other way to go would be to look at the Sanyo Mini-Splits... They are very generator, and off-grid solar, friendly (electronic front end to run the compressor--also some models have heat pump mode too):

    Sanyo mini split AC (inverter/variable speed)

    Relatively high SEER rating too--Less fuel usage as well.

    With the direction the price of fuel is heading--Doing some conservation and planning up front may help you conserve some cash in the long term.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    #8
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    Re: New Small-ish Battery Backup system - Advise requested :)

    Thank you, B. B.

    I bought a 10,000 BTU portable AC unit in the aftermath of a home robbery, so now it sits un-used. I'm wanting to use it part-time in my shop (12' x 12'). The space is well insulated, but it'd be nice to take the edge off of the humidity when I am there.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #9
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    Re: New Small-ish Battery Backup system - Advise requested :)

    You can parallel two eu 1000s together to make ~ 2kw, or 1800 watts running. I suppose you could try starting a a/c on two and then killing one. I think that one would be to much long term strain on the 1000. I would consider an Eu2000, nearly as small, nearly as quiet, and nearly as energy efficient.

    Tony

    PS. I have some semi conductor heat tape on my water line that I need to use if I have been away from home for a matter of weeks in the winter. It draws ~ 700 watts, but curiously, I can't run it on the one Eu 1000. It runs fine on two, and after it is running, I can unplug the second genny right away. There must be some surge/inrush current requirement that is not obvious. I have never Kill-a-watted it, since I use it ~ once a year, and then it is usually -40. Since I only have to run it for ~20 minutes to completly thaw the line none of this is a big deal.

    T
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #10
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    Re: New Small-ish Battery Backup system - Advise requested :)

    Electric heating elements have a very low resistance at start-up, thus a very high starting current. Within a second they are close to their final resistance and running amps and stabilize within a few seconds.

    A related side-note, portable electric heaters tend to lie about their rated watts/amps - all 1500-rated units I've tested don't even hit 1500 watts at start-up and end up around 1000 watts running.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #11
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    Re: New Small-ish Battery Backup system - Advise requested :)

    I confess I am no expert, but are the semi-conductor heating tapes:

    http://www.heatline.com/heatline.htm

    strictly speaking, resistance electric elements and do they act like them. I assume that your conclusion is essentially correct since it is anecdotally what I have observed.

    Like so many things, things are more complicated than they first appear.

    T
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  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    #12
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    Re: New Small-ish Battery Backup system - Advise requested :)

    I would also recommend the Honda EU2000i or maybe the Yamaha 2400i

    Staying off topic, I have an old electric blanket I keep in the back of the car for the kids. It will squeal the small 250w inverter in overload for about 30 seconds then quiet down. I have tested it and it pulls about 200w then slowly over 30 second it is down to about 100w (rated on the tag). I have noticed the colder the blanket it the longer it takes to get out of the overload warning. But with almost all other resistive loads I have measured it falls off rather quickly. I wonder if heat tape behaves more like an electric blanket :)
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #13
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    Re: New Small-ish Battery Backup system - Advise requested :)

    Many heat tapes are (as I understand, what is this thing called snow that covers the outside of some homes :confused:) are PTC (positive temperature coefficient) resistive devices... It allows them to draw little power when warm, and draw lots of power when cold to help melt the ice.

    It also helps prevent thermal run-a-way. (An NTC--negative temp. coeff. device would draw more current as it heats up--Typically NTC resistors can be found in the front end of some electronic power supplies to limit inrush surge--Cold, high resistance, then quickly heat up to low resistance to support full current for the power supply).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    #14
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    Re: New Small-ish Battery Backup system - Advise requested :)

    Sorry to stay off topic, but I had an opportunity to work an electrical engineer's conference back in 1998, and electric blankets were one of the products considered as long-term, low-frequency EM hazards by that group. Another item on that list - Analog electric clock. Microwave ovens were not considered hazardous because of the short-term duration of close proximity.

    They also showed a case of two NYC fire-chiefs who died from brain cancer. The 3rd chief didn't want to die from brain cancer, so he investigated the building's blueprints. He discovered an extremely close proximity between the city's main electrical service panel, and the headboard of the fire chief's bunk.

    Anyone remember those anti-static record-cleaning brushes with the radioactive strip in the handle? I saw one of those as a teenager, but have no idea what the active material was.
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