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# How to Calculate the Energy Stored in a UPS

06/08/2012 4:54 PM

I want to sell some lighting products for decoration in a shopping arcade.

I want to rent a small booth. Unfortunately there is no electricity supply to a small booth.

The capacity of my displayed LED lighting may consume 10-20W electricity. I decide to use a UPS as a power supply to turn it on all the time.

Here is the technical specification of my UPS

 Maximum power , VA 650 Operating temperature , ° С 0 - 40 Operating humidity , % 10 - 90 Input voltage level, V 220 ± 25 % Input frequency , Hz 50 Output frequency , Hz 50 ± 0,5 % Output voltage level, V 220 ± 10 % Typical switching time, ms ≤ 10 Battery operating period, min 3 - 20 Battery capacity , А • h 1 × 7 Battery voltage , V 12 Efficiency , % > 80 Dimensions, mm 95 × 160 × 325 Weight, kg 6 Color black

Anyone knows how much energy stored in such a UPS (KWh etc)?

Thanks

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Guru

Join Date: Mar 2006
Location: Washington USA
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#1

### Re: How to Calculate the Energy Stored in a UPS

06/08/2012 5:11 PM

The energy stored in your UPS is 7 Amp Hours (battery capacity). It will operate on battery for 3 minites at full load, or 20 minites at no load, (just the inverter) I expect that it will operate for a little more than 15 minites while running your lights.

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#2

### Re: How to Calculate the Energy Stored in a UPS

06/08/2012 5:14 PM

You would do better with a marine battery and DC lighting...

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#15

### Re: How to Calculate the Energy Stored in a UPS

06/09/2012 1:01 PM

You could just run it off a car nearby with a little plug in adapter and extension cord...\$24

http://www.ecrater.com/p/11564303/12v-dc-to-220v-110vac-75w?gps=1

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#17

### Re: How to Calculate the Energy Stored in a UPS

06/09/2012 1:53 PM

You could use one of these portable jump starters for the car, with the adapter...This one has 12Ah, should last all day...

http://www.autoanything.com/electrical-components/65A5290A0A0.aspx?kc=ffproduct

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#3

### Re: How to Calculate the Energy Stored in a UPS

06/08/2012 6:11 PM

Off Topic (Score 4)
Associate

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Posts: 42
#8

### Re: How to Calculate the Energy Stored in a UPS

06/09/2012 12:04 AM

There is that off topic button - use it.

Off Topic (Score 7)
Associate

Join Date: Apr 2012
Posts: 42
#9

### Re: How to Calculate the Energy Stored in a UPS

06/09/2012 12:13 AM

That's funny. Lyn can say sell candles & not be off topic much. I say it is, 1 minute later 5 off topics - even though I already off topic'd myself. Have at it - CR4 is a daycare center with a short bus rather than the free exchange of ideas and gentle humor , I guess.

Off Topic (Score 7)
Anonymous Poster #1
#11

### Re: How to Calculate the Energy Stored in a UPS

06/09/2012 8:41 AM

That's how the off topic button works. It starts you out with an off topic score of 5. You gave them to yourself as Lyn should have.

Off Topic (Score 7)
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#12

### Re: How to Calculate the Energy Stored in a UPS

06/09/2012 8:52 AM

As in life it takes five "atta boy's" to ofset one "aw crap". There are a few trolls among us, but the great majority are A-OK!

BTW the OP states that he has decided to use the UPS, and did not ask for alternate solutions.

Off Topic (Score 6)
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#4

### Re: How to Calculate the Energy Stored in a UPS

06/08/2012 6:35 PM

The LED lighting probably runs on low voltage DC, with small transformers to make it run off of house current.

For your display, you might try to wire the displays directly to a battery, bypassing the transformers. They should run a long time that way.

Explain to your customers that you are using battery power to run the lights. They may be impressed and want to do the same!

You may open up a larger market than you first imagined.

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mike k
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#5

### Re: How to Calculate the Energy Stored in a UPS

06/08/2012 7:13 PM

The DC direct method would be most efficient if you can do it that way.

The typical UPS is not designed to be deeply discharged and then recharged multiple times. The charging circuits frequently fail, or charge the battery too fast and the battery fails, or both. There's another recent thread about this on CR4 discussing adding additional batteries to the UPS to make it run the equipment longer. The overall consensus is that is a very bad idea.

You would be much better off with a large (Group 24, 27, 31, even larger?) deep cycle AGM sealed 12V battery and a small inverter that just meets your AC power demand. Don't get a huge inverter because that will waste energy on fans and ampacity you don't necessarily need.

The AGM batteries are spill proof and do not emit gasses under discharge, so the mall should not be against this battery type. It's probably safer than the sealed lead-acid battery in the UPS anyway.

This way instead of 7Ah battery, you can have 70-130Ah in a single battery that will have a much longer life span going through the multiple discharge-charge cycles you will have. If you need a longer run time than one battery would give you - more like 150-260 minutes at the load you stated, you could always parallel (not series!!!!) two or more batteries.

Sure, this is bigger and heavier than just a UPS but it will give you many more hours run time than the UPS.

One issue with your plan is that a quality charging system will take about as long to charge the batteries as they took to discharge or maybe even longer. So you may end up needing two batteries to rotate for each mall cart inverter so the used batteries can have the proper charge time.

Cheap Charger = Early Battery Death

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txmedic3338
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#6

### Re: How to Calculate the Energy Stored in a UPS

06/08/2012 10:17 PM

84 watt-hours. (= 0.084 kwh)

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#7

### Re: How to Calculate the Energy Stored in a UPS

06/08/2012 10:37 PM

Almost. The efficiency rating of greater than 80% implies to me that one should expect no more than (0.084*0.8) kwh ≈ 0.067 kwh.

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#10

### Re: How to Calculate the Energy Stored in a UPS

06/09/2012 3:43 AM

have you thought about a very small generator?

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#13

### Re: How to Calculate the Energy Stored in a UPS

06/09/2012 11:21 AM

While there may be plenty of power many UPSs are limited in time that they can operate. That said I ran 60 watt bulb for a couple days during a hurricane and had no problems. It did give out an annoying beep every minute.

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#14

### Re: How to Calculate the Energy Stored in a UPS

06/09/2012 12:15 PM

For the UPS units that I use as inverters I go into the pc board and carefully drill out the top of the beeper and remove the little piece of metal in there. That leaves the beeper in the circuit, but it is silent.

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mike k
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#16

### Re: How to Calculate the Energy Stored in a UPS

06/09/2012 1:24 PM

With 67 Watt hours of total energy available with a fully charged battery, I think you should know your load circuitry a little better than having a 15 watt ± 5 watt tolerance. This will mean that your display will work for 6 or 3 hours of continuous operation. If this arcade is open for only two or three hours then you'll have no problem displaying these lamps with this supply. However, if I was a potential customer at this arcade I would never buy a product intended to use local power grid voltage unless it was using local grid voltages. Sell something that doesn't use electricity or pay for a kiosk with electricity.

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#18

### Re: How to Calculate the Energy Stored in a UPS

06/09/2012 7:36 PM

There is no power available in the UPS. The battery will give you 84wh, of which you will be able to use less than 50%, as the UPS will not allow you to deeply discharge the battery and the efficiency will only be about 80% due to the low load. Your problem will be getting it started and charged since you have no power at the site, most UPSs will not start without mains power available. Look at some of the alternate DC direct options already proposed. Regards, Sapper

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