spoon Posted July 27, 2008 Report Share Posted July 27, 2008 would a small UpS last long or b at all usefull in he event of a power cut? Quote Link to comment Share on other sites More sharing options...
Ianab Posted July 27, 2008 Report Share Posted July 27, 2008 Generally no. They are designed to power a PC for 15 minutes or so while you save your work and shut down normally. A filter / air pump / heater may draw less power than a whole computer, but you are still only talking about an hour or 2 of run time. The tank can handle that amount of time without power. It's the 12 hour + power cuts that are a real problem, and in that situation the UPS batteries have run down hours ago. A small generator is a better option, at least it will keep running as long as you keep putting gas in it. Ian Quote Link to comment Share on other sites More sharing options...
Ira Posted July 27, 2008 Report Share Posted July 27, 2008 Generally no. They are designed to power a PC for 15 minutes or so while you save your work and shut down normally. A filter / air pump / heater may draw less power than a whole computer, but you are still only talking about an hour or 2 of run time. The tank can handle that amount of time without power. It's the 12 hour + power cuts that are a real problem, and in that situation the UPS batteries have run down hours ago. A small generator is a better option, at least it will keep running as long as you keep putting gas in it. Ian I'm expecting about 3 hours out of a car battery running 3 cannisters. Maybe hoping is the correct term. Ideally I think you'd want to do something like just have an air pump running continuously on the UPS, no heater and any cannister or other filter run for like a minute or two every 10 minutes. Just enough refresh the water in the cannister. Quote Link to comment Share on other sites More sharing options...
Ianab Posted July 27, 2008 Report Share Posted July 27, 2008 A car battery and small inverter will get you a lot more run time than a small UPS. A normal UPS only has a motorbike size battery, maybe 12V 6amp/hour A good car battery should be maybe 60amp/hour or 6amps for 10 hours, much more usefull, especially if you just run the load for short periods. Ian Quote Link to comment Share on other sites More sharing options...
Ira Posted July 27, 2008 Report Share Posted July 27, 2008 A car battery and small inverter will get you a lot more run time than a small UPS. Car battery, small inverter and a small charger and you have yourself a UPS. Quote Link to comment Share on other sites More sharing options...
Ianab Posted July 27, 2008 Report Share Posted July 27, 2008 Not quite ;-) Technically it's a standby power supply. A UPS switches over automatically, you will have to start the inverter, if you run it all the time the battery charger wont keep up and your battery will eventually go flat. If you had a big enough battery charger, that could power the inverter AND keep the battery topped up, then you would have a true online UPS, the best kind. But your plan will work and give you a usefull amount of power for a while. Ian Quote Link to comment Share on other sites More sharing options...
markoshark Posted July 27, 2008 Report Share Posted July 27, 2008 Just buy a big UPS? Cheap 1700va ones are around 300 bucks, and should run a cannister for 10 hours. Quote Link to comment Share on other sites More sharing options...
Warren Posted July 27, 2008 Report Share Posted July 27, 2008 I have a 2kVA Online Dual Conversion UPS (Sinewave Output). It's enough to power the only tank I had for 3 days. It could run a 100W pump and 300W heater (heater on 50% of the time) for this period. It did require quite a few batteries to be connected. There's 240AH of batteries @ 72VDC (12 x 120AH in a series parallel arrangement). Luckily I get this gear at a very good price from my work. Normal sell price for something like this would be well over $4k... Quote Link to comment Share on other sites More sharing options...
spoon Posted July 27, 2008 Author Report Share Posted July 27, 2008 thanks for the advice wont really be ane good for me then Quote Link to comment Share on other sites More sharing options...
Warren Posted July 27, 2008 Report Share Posted July 27, 2008 No, not unless you're prepared to spend a lot of money. If you know you'll be there when a long power-cut is going to happen then the inverter / car battery idea is likely the cheapest option for small loads up to 12 hours. Quote Link to comment Share on other sites More sharing options...
richms Posted July 28, 2008 Report Share Posted July 28, 2008 Some mid sized inverters designed for the RV and boating market have inbuilt chargers and changeover in them - effectivly making them a UPS when connected to a batterybank. Have a look on ebay for inverters, the local market seems to only have the low power cigerette lighter ones at sane prices, anything grunty is stupid money. Quote Link to comment Share on other sites More sharing options...
Blackadder Posted July 28, 2008 Report Share Posted July 28, 2008 Why not just get a generator, you can get them quite cheap and it will run as long as your supply of petrol lasts. Also you could power more than just your fish tank if you have a power cut. Quote Link to comment Share on other sites More sharing options...
richms Posted July 28, 2008 Report Share Posted July 28, 2008 Autostart generators are not cheap at all, and you would still need a UPS there to carry the load over since heaps of pumps have "issues" starting after a power failure. Quote Link to comment Share on other sites More sharing options...
Rockerpeller Posted July 28, 2008 Report Share Posted July 28, 2008 There are "DIY emergency back-up power supply" plans on the net. They use a deep cycle battery, power inverter, relay, and battery charger. And yes they do automatically switch over from AC to DC when the power gets cut-off. Hell of alot cheaper then a UPS, and you get the same pros. just remember to use a true sine wave inverter Quote Link to comment Share on other sites More sharing options...
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