# UPS with long backup duration



## Aanand (Jul 19, 2008)

Please Suggest a UPS with a long duration backup, say around 3-4 hours. My place has frequent power cuts. What is the better option?
1. Use a power generator like Honda?
2. Use in the connection sequence of  a Invertor -> UPS->Computer
3. UPS with long hours of backup which is obviously the one I want
Is there a UPS available in the market with long backup hours? Can I connect a battery with more capacity to my current numeric 600VA UPS?
Is using a home invertor to feed the computer UPS during power failure is OK? Which kind of invertor is good for this purpose. how much do the quasi sine, sine wave invertors cost for a tube, a fan and PC usage?
In conclusion, Some how I want to prolong the backup hours with less cost during power failure. What should I do?
Thanks in advance.


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## bluebox (Jul 19, 2008)

Aanand said:


> Please Suggest a UPS with a long duration backup, say around 3-4 hours. My place has frequent power cuts. What is the better option?
> 1. Use a power generator like Honda?
> 2. Use in the connection sequence of  a Inverter -> UPS->Computer
> 3. UPS with long hours of backup which is obviously the one I want
> ...



you can connect you ups to inverter
Buy a computer ups [Preferably Sine Wave] with external batteries of around 80AH or 120AH that should give you an excellent back up time
Using home Inverter to feed computer ups is ok
Basically people don't use home inverter for computer is due to its switchover time by the inverter switches over to battery computer gets rebooted [its in milliseconds]
No, you cannot connect a battery with more capacity to your numeric 600VA since it would be a built in battery.. [Maybe it may work.. but not advisable]


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## shashank4u (Jul 19, 2008)

Invertor -> UPS->Computer its the best combo i ve tried it several times..
If you have got good money to spend that there can be a lot of solutions possible.


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## pimpom (Jul 19, 2008)

You need a UPS that uses an external battery. From basic theory, removing an internal battery and connecting a higher-capacity battery should work. However, in practice, it is not advisable because
1) the low charging current of the internal-type UPS may not be enough to keep the larger battery fully charged.
2) Internal-batt UPSes are not designed for long continuous use without mains power. They could be overstressed and have a reduced life.

For several years, I've been using a 500VA external-batt UPS with a 70-Ah car battery. I have not yet tested it until the battery runs down, but I've used it for up to 45 minutes. In theory, it should last for about 1.5 hrs.

For your purpose, I suggest a 1kVA UPS. That will run your computer, a fan and a couple of tube lights with some safety margin left. If you have a generous budget, get one that uses 24V instead of 12V. You can hook up two 12V batteries of 100-150Ah in series, and that will give you a longer backup time instead of a single 12V battery.

I've known some people who use a simple square-wave inverter, but that's not advisable. The power is often "dirty" and, as bluebox said, switching time can be a problem. A more sophisticated inverter will be quite expensive.


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## Aanand (Jul 20, 2008)

Thanks Friends. Your replies are highly appreciated. 
The regular UPSs that we use like the NUMERIC 600VA don't provide pure sinewaves as output during back up. They produce quasi sinewaves. Is this kind of quasi sine waves are  Ok to use for long duration to run the computer.
From the options, I have chosen to use the Inverter->UPS->Computer method to feed my computer. The invertor provides square waves or something of that kind. 
#These square waves- do they affect the computer UPSs connected to it?
#Computer UPS produced quasi sine waves - Are they Ok to run computers for 2-3 hours?
#At the end , the SMPS provides the DC current to the computer components. So, it doesn't matter, whether you feed your computer with  sine, quasi sine, or square waves. Is that true?
Please enlighten.


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## pimpom (Jul 20, 2008)

To your third question : It is true that a computer's PSU (SMPS) produces various DC outputs and, theoretically, it should not matter whether the input is sine, square or quasi-sine. Actually it is easier to filter square waves than sine waves in the AC-to-DC conversion.

But alas, nothing is perfect. Those electronically generated waves are usually not clean simple waves. They often contain spikes and distortions, and cheap simple products sometimes produce serious spikes that cannot be completely filtered out by the PSU.

To the first and second questions : Square and quasi-sine waves are OK as long as they are reasonably clean, that is, without major spikes.


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## sude (Jul 21, 2008)

> ...My place has frequent power cuts...



dear aanand.. b4 everything..
u need proper continuation of electricity for the charging of ur external backup solution (inverter, ups etc)
..

Do remember this..

SUDE


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## sandl (Nov 2, 2008)

I'm interesting in getting a UPS that has an hour's backup at least, so I'm curious to know what did you settle for. what did you buy


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