hello
i have several UPS ranging from 600 to 1200 VA and several car batteries ,,
i am looking to use the above to build a more powerful UPS .
i was thinking about connecting the car batteries in place of the small sealed batteries inside the ups but i wanted your advise .
thank you
watch https://www.youtube.com/watch?v=jX1OQZ1B6m0 for some info "video starts at 3:45"
or if you prefer reading and pics check http://www.instructables.com/id/Make-your-computer-UPS-last-for-hours-instead-of-m/
A good advice from that page is
CAUTION:
I discovered the hard way after nearly starting a fire and destroying a UPS that you need one that is rated at at least twice the wattage you are consuming. They can't handle being run for longer than a few minutes at this rating, but the batteries die before it's a problem normally.

So I now knew I needed 500 watts, and I wanted 60 minutes of power.. that means:
P / V = I
500 watts / 120 volts = 4.16 ampere hours (at 120 volts)

UPS batteries are usually 12 volts, but some are wired with two batteries in series. Check yours out first to make sure you won't need two car batteries.

So, assuming 12 volts, that means that, after adjusting for the voltage differences, I need a battery with at least 41.6 ampere hours. (yeah, I know there's inefficiencies in the UPS, but lets keep math easy)
how can i find the wattage needed and the wattage of a ups ?i am thinking about using this ups for a server cabinet
Stygmata wrotehow can i find the wattage needed and the wattage of a ups ?i am thinking about using this ups for a server cabinet
Watts= VA*0.6

If your ups is rated 600 VA then it can power a max output of 360 watts for a couple of minutes. The inverter in the UPS (especially the generic ones) isn't made to handle max output for prolonged periods of time. Therefore in order to protect both your house and ups from a potential fire, it's recommended to use half of the output of the UPS.

For example if you want to power your PC for long periods of time and you know it needs 500 watts to operate, then you need at least a 1650 VA UPS (notice that the max power output will be almost 1000 watts, but to play it safe you're only going to use half of that output).

And please make sure to check the videos and tutorials the other guy posted, they include some important info about wire gauge and how to store the batteries.

One more thing, if I were you I would seriously consider getting a sine wave inverter instead of salvaging an old UPS. These sine wave inverters are built to last and to handle lots of power, they produce a sine wave identical to that of the AC outlet, unlike the cheap UPS's that give out square waves which could potentially damage sensitive electronics.

Additionally, I would stay away from car batteries; car batteries can't hold a voltage that long to be used for a power back up system, instead go with one of those deep cycle batteries (also known as marine batteries).

If you want to save yourself a headache, check out a store in Beirut - Msaitbe called "Sonics". It's run by an electrical engineer who specializes in building custom UPS's for households and companies. Tell him what you have in mind and he'll give you a quote including installation. It shouldn't cost you a fortune, of course it all depends on the wattage you want to run.
i am stuck in motherfucking congo jungle .. living it a la robinson crusoe ..
maybe i can find some rechargeable battery used to industrial elevator in our garage , these should be better than car batteries .
LOL, seriously in Congo? How much power does your server cabinet draw?

And those batteries you mentioned would be way better than car batteries especially if they are sealed. Car batteries emit hydrogen gas, and when Hydrogen comes in contact with a spark, your jungle will be engulfed in flames.
random-username wroteLOL, seriously in Congo? How much power does your server cabinet draw?

And those batteries you mentioned would be way better than car batteries especially if they are sealed. Car batteries emit hydrogen gas, and when Hydrogen comes in contact with a spark, your jungle will be engulfed in flames.
yes , a rumble in the jungle ..
i have one server with 2x800 watt PSU , some switches , QNAP nas , a cyberroam , a router or two
That's some serious power; the server alone needs 1600 watts. Would you mind grabbing a pen and paper and writing down the input power of all the devices you have in mind (for the router and switches check what's written on the AC adapter) so we can come up with a rough figure.
random-username wroteThat's some serious power; the server alone needs 1600 watts. Would you mind grabbing a pen and paper and writing down the input power of all the devices you have in mind (for the router and switches check what's written on the AC adapter) so we can come up with a rough figure.
i am out of office now .. this is a remote site .
the 2 PSU are for redundancy , the servers only uses one even both are connected .
i was thnking about getting a 20KVA UPS but it costs around 5000$ here