Backyard Aquaponics
A place to discuss aquaponics

Bump...Looks like quite a few people are getting close to having their systems running. Means that the question of backup power must seem very relevant again.

Can anyone answer me these questions:

1. What size pump would one of those cheap (100-200 dollar) generators from bunnings run? Would it run a pump at all - maybe not, probably be flat out running a light globe

2. Say you ended up building a biiiigggg system, how much would it cost to buy a generator with automatic kick in when power goes out? Anybody experienced in these things.

Reason I ask is that bublers on batteries with trickle feed are one thing, but if the power is out for any decent amount of time, a generator is the only solution as I see it.

vb

I have a $99 GMC generator that powers a 500 watt drill no problems... Supposed to be able to handle 800 watts but I reckon that is optimistic.

So I guess a 250 or so watt pump would be a piece of cake for it.

As for auto kick in gen sets, I wouldn't have a clue

Monya

Veggie - how long is a piece of string.

To work out if a generator can power YOUR equipment you have to work out the power consumption, usually in Watt's

Watts = Volts * Amps

So if you have a 240 volt appliance, drawing 0.5 Amp's you get

240V * 0.5A = 120W

Now to know get a total power consumption of a system you need to add all the elements powe requirements.

You need to consider two loads, peak load, and nominal load.

Peak Load, that is if all the devices are running at once, use the 100% cycle figure to calculate this value. The generator will have to be able to supply this load, for a short duration.

Nominal Load this is the toal of all the power requirements taking into consideration the cycle time of each device.

If you run the above appliance on 100% cycle (constanly running) it will need to be allocated 120watts, but if it only runs 50% (half the time) you will only need to allow 60Watts.

So for the peak load, you add up all the power requirements of the 100% cycle time and come up with peak load, and you add up all the power requirements of each device (taking into consideration each's cycle time) and come up with a Nominal load.

The generator must be able to supply the peak load requirements or it will be over loaded at start up, an may suffer damage.

Choose a generator able to supply the peak load PLUS 25% to 50% on top of this.

Say you have a total of peak is 500Watts, then you would want a generator that can supply 650 to 750 watts.

I'm not sure how they rate the generators, I think its usually Kva, which from memory is KiloVoltAmps or KiloWatts.

So do the math and you will have your answer

Warren

VB
I have been thinking about backup systems too over the last couple of days.
A few questions you should ask yourself:

1. How long do you want your backup system to last? hours, days?
2. Do you want it to automatically start when there is a power failure, when you are not present?
3. What is the pump starting requirements? Watts and Amps.
4. Budget?

I am looking at setting up a backup system in various stages..ending with a total substainable power system in the end.

A. First setting up a battery bank with a trickle charger running off 240v..A power failure switch will automate the start...Battery bank would feed into a small inverter..Hope to have 3 days storage.

B. Buying Solar panels to charge the battery bank.

C. Look at backup generator to kick in after no sunshine..or collapse of powergrid.

Wouldnt mind to have the whole house plugged into the alternative power system is my final goal...Big costs...

Generators are good if you are present (still need to fuel the tank)..The GM ones are ok...you would have to run it once a week thou to keep it alive. You could use the generator to charge your battery bank only...

Thats some of my thoughts....I have to research some more. hmmm

LB

LB, do you say to run it once a week in the sense of the fuel going stale? I was going to agree uintil i remembered that i'm lucky if i fire up the lawn mower once every three months! The fuel still works

Hi VB, LB,
I have long ago made up my mind that my system will be run from a battery bank which will power mostly 12 volt DC items. Any item that is more easily run of 240 volts AC and is low amp draw I will run off an inverter which will kick the 12 v DC up to 240 V AC .....Things like low cost bubblers etc. No electric motors off the inverter, takes too many amps to kick a 240 volt motor over off an inverter.
As for pumps etc, 12 volt bilge or live well pumps are going to be my main thing. As I have spent all my life in the Marine Industry, I guess it comes as second nature to work this way. Yachts, and small to mid size power boats typically do things this way with great success. There is no mystery to it at all.
LB's plan to do things in stages is exactly the same as mine.
I have a mid quality battery charger now which charges my 12 volt battery bank that runs my 500 gph rule pump to circulate water and aerate the 200 ltr temp tank I now have. My big 2500 ltr tank will have a 2500 ltr per hour 12 volt pump run off the battery bank, the tank sump for the return water will have a 1200 lph x 12 volt pump run off the battery bank.
I have added 1 x solar panel already, but will need heaps more of them like 6 or 8, but there is plenty of time to add them bit by bit.
I already have a 240 volt gen set that is 2500 watts output, need some repair, so that will go in soon to be repaired, and I need 6 x 2 volt wet cell High Capacity batteries for my battery bank. (the car battery I have now is only temp and is a bit sad.)
I will be making up a list of suitable pumps for Aquaponists to purchase from www.boatshop.com.au in the next couple of weeks. Some of you may be interested in going that way. (they will cost less than can be found on eBay)
The battery bank will run the whole thing for about 6 hours if the power goes down, if the power outage looks like going beyond 4 hours then one would start to gen set to keep the batterys topped up. Before that one would turn off the pump to the grow beds to conserve power in the battery bank, leaving the batteries to run the bubblers via the inverter.
With the battery bank just running the bubblers via the inverter the batteries would possibly last 24 hours or more before there was any need to run the Gen set.
Sorry about going on so long, but to my mind it is a natural way to go.

Watch www.boatshop.com.au for more product and by September will be transfured to my new website www.aquaponics.net.au which will have Aquaponic product such as tanks, pumps, switchs, kits etc
Murray
murray@boatshop.com.au

Steve
Known some people who's gm generators fail to start after sitting for too long...just a maintenance issue not fuel..

Murray
Great stuff ..looking forward to see your new site..
So your backup system would look like the following:

LB, That drawing is great !!! exactly...... we are on the same page !!!!
Eventually I will add a wind operated generator as well, and like you, I will run my entire house from the system.
I have just obtained a 24 volt water pressure pump/system - will run 7 taps....anyway, that house thing will intergrate with the Aquaponics eventually, and in the long run I will go to 24 volts for everything - fewer amps required to do the same job, so lighter wireing can be used, electric motors tend to have a bit more grunt without as much load, and so on. Most bigger boats operate on 24 volt systems for those reasons.
But as you can imagine there are a lot of dollars between now and the ultimate aim of everything on 24 volts, solar panels don't come cheap !!!
Murray

It would be ideal to get rid of the pumps out of the system altogether..a mechanical device of some sort to lift the water into a header tank..Could use a windmill to lift the water but the wind always doesn't blows..hmmm...

LB, there is a variation of an airlift pump that has been patented that moved HUGE amounts of water just with air. will try to wade through my hundreds (seriously) of bookmarks and find a link to it.

Steve

Well when you guys work it out let us know.
I am planning to have a power out alarm and full time staff start a generator.
But my situation here is a little different here in Bali than Oz. Staff come cheap.

What is the deal with power out alarms. Can these be obtained or made cheaply?

I think EB may have more experience with electrical wholesalers.

I was going to make one all you'd need is a power lead, small relay, small piezo buzzer , and a couple of batteries, a terminal strip and a box and 30 minutes to wire it (And possibly a legal waiver for the person who tells you how to wire it )

Might pay to price one first EB?

i just went up to get some prices for deep cycle batteries as I have been told they are the go. I told him I wanted to have a battery charger hooked to a battery bank which powered my 12 volt pump that I will buy, and he said I can't do that. He reckons you can't have a charger hooked to a battery that is drawing current, it will fry the battery. Is he right? I am pretty confused....

Monya,

Deep cycle ARE the go.

Did he say it would fry the battery or the chrager? If anything it would be the charger, not the battery. But that is only if you were drawing serious amps like starting a car IMO.

Murray would be the one with the info, he's had much experience with 12/24V gear.

Steve