Affordable power backup - FOUND IT!!!!

[bwester]

Anyone got any cool ideas for a cheap way to have enough backup power to run a ventilation fan for a small greenhouse in case of power outage?
and.... to make it automatic

 

[NYEric]

Voltage and amperage of fan?

 

[littlefrog]

How cheap? I run my backup power from a bank of four golf cart batteries and a DR inverter... Total cost ~800, but I think I could run the whole greenhouse for several days on battery power. I don't think it has ever come on since I put it in, but if I didn't have it I'm sure the power would go out every week. You probably wouldn't need as elaborate a system, but battery backup is far cheaper than a generator, and with fewer moving parts it will last longer.

A good inverter will switch transparently from main current to battery. Probably would't even make your clock blink. They are used a lot in solar/wind power home installations, to convert the DC renewable energy to AC 'dino-grade' power.

 

[bwester]

I only need 10 amps or less.
Rob,
got any instructions?

 

[NYEric]

look on www for battery back-up power.

 

[littlefrog]

I only need 10 amps or less.
Rob,
got any instructions?

I brewed my own after reading a lot on the web... That is your best bet.

My best advice would be evaluate what you want. You want a very simple system that doesn't need a lot of bells, whistles, and blinking lights. You probably don't need a lot of amp-hours, but it is a simple calculation to figure out how many amps your fan draws and how long you would expect a trivial power outage to be. You don't need to plan for the worst case scenario (three or four days + without power). You can't afford the solution, and it isn't very likely to happen. If it does, you will have plenty of time to find an alternate solution, even if it means packing up plants and moving them into the house or under a tree for a few days.

 

[Candace]

Blake, there was a write up with instructions in an older AOS mag. with schematics( I believe) for a battery back-up. I don't know what size your greenhouse is, but if it's on the smaller scale it might be much cheaper to go with misters that come on with power outage. Several people in my local O.S. use a system where they buy a solenoid valve that when powered is "closed" . They attach this to a pvc water line and install misters. When the power goes off the solenoid valve opens and water goes to the misters and will continue to be open until power is back on and the valve closes again. These valves are typically mail order since most people actually want the opposite, for the valve to be opened when power is on. Confusing?? Much, much cheaper than spending so much money on batteries. The down side is that the plants will be very wet if the power is off for long. In the nice weather(hot) when you need it most, great. In the winter, maybe not such a good idea. I'd probably disconnect it in the cooler months. Or aim the misters at the floor.

 

[bwester]

http://www.tripplite.com/products/product.cfm?productID=178
That thing with 3 batteries in series will provide up to 2 days of emergency automatic backup power.

 

[L I Jane]

I'm not up on all these things & when reading about it I have no idea what it's all about.Hubby & I were talking about maybe a small generator to hook up to run the heater in the grnhse if power goes out again in the cold winter.I use nat gas heat but the thermostat runs on electricity so when no power--no heat.Would this inverter thing be helpful to me.How does it work in very simple terms?Could I run the overhead fan on it as well?

 

[Candace]

My thermostat has a battery in it for when the electricity goes out. I think if you're only looking for heating backup you should look into switching out your thermostat. A new battery backup thermostat would be the cheapest and easiest solution.

 

[littlefrog]

Of course if your furnace requires electricity to run (forced hot air, power venting, etc), your thermostat won't do much good... But it is a great idea for non-powered heating units, I like it.

 

[NYEric]

Jane. If there's no power how will the natural gas heater fire up! If you hook up a generator set it to power the gas furnace, [might be illegal!]

 

[L I Jane]

I have no idea.All I know is when my heater goes on normally, the fan behind it goes on & the thermocoupler heats up & I have heat blowing out.Any exhaust goes outside with a stovepipe coonection?? Hey I'm not an engineer LOL--have no idea how these things work.I wish there was someone I could ask about these things but I have a hard enough time finding someone when the thermocoupler needs changing.

 

[NYEric]

OK OK. Luckily the thread started on a cooling problem. Heat is a much harder issue to provide backup for and some systems can be deadly!

 

[Candace]

OK OK. Luckily the thread started on a cooling problem. Heat is a much harder issue to provide backup for and some systems can be deadly!

No, not at all. It's much easier to provide back-up for heating than cooling. Many gas g.h. heaters are run by the pilot light(always on and burning a little gas) and get triggered on and off by the theromstat. No electricity needed. Littlefrog is right though, some have more systems interconnected that do use electricity, like powered venting and forced air in large g.h's. Most homes have forced heating so need the electricity.

My southern burner has a small fan in it as well but it's also gas driven, not electricity. It comes on automatically when the gas is ignited. You don't need any sort of generator or outside power source if you get a thermostat that's run by battery. The battery would give it the power to "tell" the gas heater to turn on or off. I got mine at Home Depot or Lowes and it wasn't that expensive. The batteries last about a year and you get a low battery warning on the thermostat so it won't go out on you. It frees up and electic outlet and gives you the luxury of not worrying about power outage.

Think of it this way...many gas heaters are not electricity dependent and don't need electricity to run, only to "tell" them to go on or off and a battery powered device can do this. It really depends on what type of heater you have.


One heater back-up problem is that if the pilot light gets blown out somehow during the winter and there's no temperature alarm, you're screwed.

 

[bwester]

well, cooling, is my concern down here in south georgia

 

[Candace]

Sorry to have hijaked your cooling thread
Are you going to get the inverter? I'm still not sure how it works, though as I'm not too mechanical.

 

[bwester]

Sorry to have hijaked your cooling thread
Are you going to get the inverter? I'm still not sure how it works, though as I'm not too mechanical.

Its coming. its wired directly into the dedicated line for the fan. it has an auto transfer that switches to battery when it senses a power loss. Hook 3 deep cell marine batteries in series and it keeps them charged when not in use.

 

[Grandma M]

Will that unit work for only a freezer..... or a freezer and furnace.

Where I live our power is always going out and that means everything in my freezer get dumped. There are a lot of trees across from me and with a storm so often they land on the power lines. The power on all the other streets in this condo group are underground but for some reason, possibly because we are on the far side, our lines are above ground. I sure would like to find a way to protect my freezer.

I looked up the site but couldn't find a price for it.