Most accurate way to determine wattage pulled for a UPS

[Tristerin]

Asked earlier for some help and Im not sure maybe this is the incorrect sub forum - I need a UPS that powers a laptop, and a printer for a few hours of use (laptop being used the whole time, printer used 10% of the time)

 

I ended up getting our IT people involved and they are now asking me what total wattage will I be pulling from this.  Should I put the Laptop and the Printer on a power strip and get my Maintanance people to measure the wattage pulled at the wall during use (I.E. I get my Xeon crunching calculations and press Print at the same time and do like 50 pages and check the wattage pulled during that time as average?)

 

So basically the UPS needs to handle the max wattage I want to pull, for short burst durations (20 seconds) over a few hours so I am not tethered to any cords.

 

Please and thank you! 

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All products are required by law to state how much power they draw (or can draw up to).  If you look on the power brick for both the laptop and printer it should state the input voltage (120 V I assume) as well as the current.  Just multiply those numbers to get the wattage, and then for good measure, I'd pad that by at least 10%, maybe more like 30.

[Electronics Wizardy]

Just saying, laser printers can pull a lot of power, so Id probably try to keep that off a ups.

 

Easy way is to get a kill a watt meter, or something to measure usage, or just look up specs on devices.

[Firewrath9]

you could get a kill-a-watt

https://www.amazon.com/P3-P4400-Electricity-Usage-Monitor/dp/B00009MDBU

measures the power draw, plug a power strip into that, then plug everything into the power strip.

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4 minutes ago, Electronics Wizardy said:

Just saying, laser printers can pull a lot of power, so Id probably try to keep that off a ups.

 

Easy way is to get a kill a watt meter, or something to measure usage, or just look up specs on devices.

This is a good point.  Without seeing laser I just assumed inkjet but if it is laser, I remember how they can make the lights dim.  If that's what you need to run, then I would say basically get the largest unit you can, which is gonna be around 1800 W since that's all you can pull from a standard north american outlet.

[Eigenvektor]

A UPS is typically used to give you enough time to shut down in a controlled manner in case of a power outage, it's not really meant to keep your equipment running for hours.

 

https://www.upssystems.co.uk/blog/post/how-long-do-uninterruptible-power-supplies-last

Quote

 

Can I ride out a power cut with a UPS?

A UPS is designed to safeguard sensitive equipment and afford you the time required to shut everything down properly. What it isn’t designed to do is ‘ride-out’ a power-cut; there is only a finite amount of power stored within a UPS and a power-cut could be a long-term problem. The solution to a mid to long-term disruption would be a generator.

 

 

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4 minutes ago, Eigenvektor said:

A UPS is typically used to give you enough time to shut down in a controlled manner in case of a power outage, it's not really meant to keep your equipment running for hours.

 

https://www.upssystems.co.uk/blog/post/how-long-do-uninterruptible-power-supplies-last

He says he only needs it intermittently for short bursts (20 seconds), which I think should work fine.  A generator would be problematic to use in an office building.

[Tristerin]

@Eigenvektor @Ryan_Vickers @Firewrath9 @Electronics Wizardy

 

A UPS is all I understand on this end - and budget is....well I make my company a lot of money so I don't get push back on cost.  I need to power:

 

Dell Precision 7540 w/ Xeon E-2276M @ 180w per the brick

HP LaserJet Enterprise M506 - HOWEVER, I can easily replace this, the printer only needs to print 1 page documents approx. 10 times during this 2 hour window of use.  Back of unit doesn't have wattage, sounds like I need something diff anyhow

 

I need something, like a UPS, and can easily get a different printer if needed.

 

What device (since a UPS isn't exactly what I need) should I look into?

[Tristerin]

Generator wouldn't be applicable here, looking for a battery solution

[Eigenvektor]

2 minutes ago, Ryan_Vickers said:

He says he only needs it intermittently for short bursts (20 seconds), which I think should work fine.  A generator would be problematic to use in an office building.

That's not what I got from "the max wattage I want to pull, for short burst durations (20 seconds) over a few hours".

 

My takeaway is: He expects short, 20 second bursts, of max power usage for multiple hours.

[Tristerin]

@Eigenvektor theoretically that burst would occur around 10-20 times in that 2 hour window (the Printer going into power consumption mode)

 

I can EASILY get it replaced, its just the printer I have atm, with a cheaper low power printer

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1 minute ago, Tristerin said:

@Eigenvektor @Ryan_Vickers @Firewrath9 @Electronics Wizardy

 

A UPS is all I understand on this end - and budget is....well I make my company a lot of money so I don't get push back on cost.  I need to power:

 

Dell Precision 7540 w/ Xeon E-2276M @ 180w per the brick

HP LaserJet Enterprise M506 - HOWEVER, I can easily replace this, the printer only needs to print 1 page documents approx. 10 times during this 2 hour window of use.  Back of unit doesn't have wattage, sounds like I need something diff anyhow

 

I need something, like a UPS, and can easily get a different printer if needed.

 

What device (since a UPS isn't exactly what I need) should I look into?

I looked up that printer, HP claims it can draw up to ~750 W

https://support.hp.com/ca-en/document/c04817003#AbT4

 

That plus the PC would work on a "reasonably sized" UPS, and I'm not sure what other device could do this job if a generator isn't an option.  Really it's a matter of duty cycle - will your short bursts add up to more draw than it can charge between them, or will it be able to keep up?  That depends on your usecase and the specs of the unit.

[Tristerin]

Just now, Ryan_Vickers said:

I looked up that printer, HP claims it can draw up to ~750 W

https://support.hp.com/ca-en/document/c04817003#AbT4

 

That plus the PC would work on a "reasonably sized" UPS, and I'm not sure what other device could do this job if a generator isn't an option.  Really it's a matter of duty cycle - will your short bursts add up to more draw than it can charge between them, or will it be able to keep up?  That depends on your usecase and the specs of the unit.

 

2 minutes ago, Eigenvektor said:

That's not what I got from "the max wattage I want to pull, for short burst durations (20 seconds) over a few hours".

 

My takeaway is: He expects short, 20 second bursts, of max power usage for multiple hours.

So I need a better printer solution for sure, I don't NEED this printer for this task per-say just the one I have as my current option

 

Ill check some out unless anyone here already knows some very low power, new, printer to go for?

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Just now, Tristerin said:

So I need a better printer solution for sure, I don't NEED this printer for this task per-say just the one I have as my current option

 

Ill check some out unless anyone here already knows some very low power, new, printer to go for?

In general an inkjet would be lower power consumption, but it's also an inkjet, which means expensive and frequent refills, potentially lower print speed and quality, etc.

I don't think that printer is really an issue or a deal breaker.  20, 20 second bursts is 6.67 minutes total of continuous usage.  That spread over 2 hours is easily within the range a UPS can handle.  Hell, it should be able to run the stuff for 10 or 15 minutes, even with no breaks to charge.

[Tristerin]

1 minute ago, Ryan_Vickers said:

In general an inkjet would be lower power consumption, but it's also an inkjet, which means expensive and frequent refills, potentially lower print speed and quality, etc.

I don't think that printer is really an issue or a deal breaker.  20, 20 second bursts is 6.67 minutes total of continuous usage.  That spread over 2 hours is easily within the range a UPS can handle.  Hell, it should be able to run the stuff for 10 or 15 minutes, even with no breaks to charge.

Quality is not as important (I am creating cell schedules for manufacturing, just excel dumps) - filling then however would get annoying.  Ill stick with what I have and see what IT says with this information

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Just now, Tristerin said:

Quality is not as important (I am creating cell schedules for manufacturing, just excel dumps) - filling then however would get annoying.  Ill stick with what I have and see what IT says with this information

To be clear, given that you said you only need 10 pages per "session", it's not like you'll have to refill it during that time, but it will definitely be more often over the long haul.

[Eigenvektor]

https://www.upssystems.co.uk/blog/post/how-long-do-uninterruptible-power-supplies-last

Quote

An entry-level UPS with a rating of around 600 VA might be able to power a small office computer for around ten minutes. Make the upgrade to a 1500 VA UPS, and you might see this figure jump up to an hour. Go too small, on the other hand, and the available time shrinks to just a few minutes or less.

They don't say how much power that small office computer is using, but based on that info alone, you might want something like a 1500 VA model if you intend to run for about 2 hours "off the grid"?

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Something like this should handle the power draw and run time with zero issues

https://www.cyberpowersystems.com/product/ups/pfc-sinewave/or2200pfcrt2u/

Whether that's in the budget or we need to cut it a bit closer is for you to decide.

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2 minutes ago, Eigenvektor said:

https://www.upssystems.co.uk/blog/post/how-long-do-uninterruptible-power-supplies-last

They don't say how much power that small office computer is using, but based on that info alone, you might want something like a 1500 VA model if you intend to run for about 2 hours "off the grid"?

It's not 2 continuous hours, it's small moments spread out over 2 hours.  Those moments only add to less than 10 minutes total from what I can tell, and it will be able to charge in between them all.  The power draw will spike to much more than "a small office computer" during printing, but all that taken together, you've got the right number anyway I think (~1500 VA at least).

[Tristerin]

5 minutes ago, Eigenvektor said:

https://www.upssystems.co.uk/blog/post/how-long-do-uninterruptible-power-supplies-last

They don't say how much power that small office computer is using, but based on that info alone, you might want something like a 1500 VA model if you intend to run for about 2 hours "off the grid"?

 

3 minutes ago, Ryan_Vickers said:

Something like this should handle the power draw and run time with zero issues

https://www.cyberpowersystems.com/product/ups/pfc-sinewave/or2200pfcrt2u/

Whether that's in the budget or we need to cut it a bit closer is for you to decide.

I can swing that amount no problem no questions asked - thank you all VERY much, Ill approach IT with the wattage, suggestions (I.E. they pick me a new low power printer as well) on UPS's and go from there

 

THANK YOU!

[Eigenvektor]

Just now, Ryan_Vickers said:

It's not 2 continuous hours, it's small moments spread out over 2 hours.  Those moments only add to less than 10 minutes total from what I can tell, and it will be able to charge in between them all.  The power draw will spike to much more than "a small office computer" during printing, but all that taken together, you've got the right number anyway I think (~1500 VA at least).

I must be reading what Tristerin is saying differently then

I understood that he wants to be able to live off the grid for 2 hours and he expects his equipment to draw max power in short bursts during that time.

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1 minute ago, Eigenvektor said:

I must be reading what Tristerin is saying differently then

I understood that he wants to be able to live off the grid for 2 hours and he expects his equipment to draw max power in short bursts during that time.

Oh I think the difference in how we're reading this is I'm assuming he can plug in between these bursts and you're thinking he can't.  I think I was misunderstanding what you were thinking it was - that it was hours of continuous, max wattage use.

 

The good news is though that the runtime of a UPS is highly nonlinear - with decreased load comes massively increased runtime.  As such, even without recharging in between, given the idle draw of the computer and printer when not at max load, I am reasonably confident the unit I recommended will handle either of our imagined situations.

[Eigenvektor]

1 minute ago, Ryan_Vickers said:

Oh I think the difference in how we're reading this is I'm assuming he can plug in between these bursts and you're thinking he can't.  I think I was misunderstanding what you were thinking it was - that it was hours of continuous, max wattage use.

Yes, my assumption was that the equipment is powered on but idle and will only draw max power every now and then, while the UPS itself would not be plugged in during that time. But it's quite possible I'm misinterpreting. In any case, good to know we reached the same conclusion

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Just now, Eigenvektor said:

Yes, my assumption was that the equipment is powered on but idle and will only draw max power every now and then, while the UPS itself would not be plugged in during that time. But it's quite possible I'm misinterpreting. In any case, good to know we reached the same conclusion

It's entirely possible you're right, I don't know why I didn't think of that

[Tristerin]

@Eigenvektor @Ryan_Vickers - I will be unplugged, with desire to be unplugged and mobile for at LEAST 1 hour at idle with 10-20 times at max print burst (2 pages) and CPU usage, though my CPU calculations may be a little more frequent.  I can plug in...theres plenty of places I just get pulled aside a lot so if I leave my laptop and printer sitting for a few minutes I don't want to come back to it dead lol