How much UPS do I need?

Dave2you · Post by **Dave2you** » Sat Oct 20, 2007 9:20 am

I have a RemStar Auto A-Fex., Works great until I loose Power, then I am Doomed.

I want to purchase a ups For it, but became bit Confused on how long it will run on it before it Drains the battery.

I have seen many units

some order $100 models have 320 watts and 540 watts

I also seen some models as cheap as $120 and have
675 watts.

and I seen one model that was Roughly $200 but
had 1500 watts

to confuse this, some models only claim volts, it could have 1500 voLts but only 500 watts, What?

Now I want the Surge protection and AVR to protect the machine

But the Question lies, haw many of what do I need to run for eight hours if only the Cpap is plugged into it.?

anyone know?

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CPAPopedia Keywords Contained In This Post (Click For Definition): CPAP, Power, auto

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CPAPopedia Keywords Contained In This Post (Click For Definition): CPAP, Power, auto

TerryB · Post by **TerryB** » Sat Oct 20, 2007 9:45 am

I picked up a 1500 VA UPS at Besy Buy built by APC for $129 ( I think they goofed and it should have been around $200). I have not run my Remstar with Heated Humidifier yet. Since it will and has run my home theater for 30 minutes, I expect 10 hours from it on the CPAP. I'm going to run only the machine on the UPS as I'm not sure the UPS waveform is good enough for the HH power circuitry.

TerryB

GumbyCT · Post by **GumbyCT** » Sat Oct 20, 2007 10:10 am

Dave2you wrote:Now I want the Surge protection and AVR to protect the machine

So who knows what AVR is/means?

The easy answer is - the larger (more watts) units will hold power longer.

But then it gets into how much the current draw will be; whether you are/will use a humidifier, etc. Each additional item (ie. humidifier, clock radio, etc.) will reduce exactly how long it will supply power. There is a formula to use (P=IxE) but I will leave that for the engineers in the group.

Someone posted a link the other day to a place that sold refurbished UPS units for a pretty good price. Unfortunately, I don't remember the link or where it was.

FWIW - I used an extension cord & power strip to run UPS up from the basement to my DVD recorder w/hard drive & a few other items. The hope was to extend the life of the DVD hard drive when they serve the power in spurts here.

Both my pc's are on UPS, I haven't yet done anything about the CPAP blowers.

TerryB · Post by **TerryB** » Sat Oct 20, 2007 12:15 pm

AVR "Automatic Voltage Regulation" smooths out the spikes in the spurts.

TerryB

Goofproof · Post by **Goofproof** » Sat Oct 20, 2007 12:26 pm

AVR, provides a adjusted correct voltage, if the line voltage goes too low, it raises it, if it's too high it limits it. And it also provides spike protection.

However, I don't think you will be able to afford one to get you through the night. I have a APC 1250, It will only power my computers for under 30 minutes. They are designed to give you time to shut the computer down, not finish the internet.

A deep charge battery and a charger-maintainer, is what's needed for all night and more than one days use. Jim

billbolton · Post by **billbolton** » Sat Oct 20, 2007 2:01 pm

Dave2you wrote:But the Question lies, haw many of what do I need to run for eight hours if only the Cpap is plugged into it.?

Firstly UPS's intended for supporting computer opration are not intrinsically designed for prolonged off-mains power operation. They are sprinters, providing a lot of performance for a short time, rather than marathon runners, providing less performance but sustaining it over a long time.!

Secondly, the Respironics power specification for your flow generator is "100 – 240 VAC, 50/60 Hz, 1.0 A max".

This indicates a power consuption of up to ~100W at 120V AC. The up to part will be dependent on various machine settings, but Respironics do not appear to provide any easy to locate advice on the effect of settings on power consumption.

So, assuming a worst case, for 8 hours of operation you need a capacity of at least 800 Watt, and in realistic terms probably double that to allow for the nature of computer style UPSs.

Using a computer style UPS to support overnight xPAP operation is not something I recommend, but its your $$$!

Cheers,

Bill

kennethryan · Post by **kennethryan** » Sat Oct 20, 2007 8:26 pm

Note that not all UPSs will generate a voltage that will make your CPAP happy. Some electronics is more sensitive than others to the stepped-approximation wave that a cheap UPS generates. The results vary with the design of the device - some will work fine, some will buzz, occasionally you can find a device that will be destroyed by it (and/or destroy the UPS).

[A stepped-approximation wave uses discrete jumps instead of a smooth curve. Take 9 scrabble tiles and arrange them in a row of 1 centered over a row of 3 centered over a row of 5 - that's a stepped approximation of a half-circle. Yes it looks more like a triangle. That's part of the problem.]

The more expensive UPSs and power inverters include output filters that smooth out the waveform. APC has an application note on their website about using their SmartUPS units for various applications requiring a good sinewave. Look in the manufacturer's website for your CPAP to see what they say about an inverter (that's the device that converts a battery to AC line voltage).

As another poster said, you will not find an affordable UPS to run your unit overnight. If your power is that unreliable, consider installing an automatic backup generator (the UPS will then bridge the time it takes the generator to start and switch over).

Dave2you · Post by **Dave2you** » Sat Oct 20, 2007 9:02 pm

That's too bad, I thought I was on to something.

Figures, I got a great deal on a 875 VA 535 Watt today For $59 down from $130 It has a Led on the front that compares load to Run time. when I Run Just the CPAP it says 100 minutes so all I get is an hour and a half, hopefully the power will be back on by then.

on the bright Side it does have AVR and I live in an old house with Spikes and brown outs, So maybe it will Protect it

Goofproof · Post by **Goofproof** » Sat Oct 20, 2007 10:16 pm

I've got my computers on a flaky line like that. Power goes off 4 or 5 times daily, for less than two seconds. Try to find that... With the APC, I'M good for 30 minutes, it just makes a beep for 5 or 10 sec, then the power is back on the mains, someone has used electric heater units in my cave, somewhere something is frying, but if it's not broke you can't fix it. Jim

Dave2you · Post by **Dave2you** » Sun Oct 21, 2007 6:54 pm

well Just for tricks I tried putting the Ups to the test.

it said it would give me 95 minutes of up time according to the
LCD that devides Battery by Load.

So I unplugged it, Disabled the Warning Buzzer and took a nap. two hours later it Said I still had 65 minutes of Battery time.

Hmm so I get alot more minutes than it Says.

I don't think a cpap Draws that much. I Bet I can squeeze Six hours In a pinch.

of Course I may never loose power again but nice to know I have an option.

GumbyCT · Post by **GumbyCT** » Sun Oct 21, 2007 7:12 pm

Dave2you wrote:nice to know I have an option

Yes it is.

Goofproof · Post by **Goofproof** » Sun Oct 21, 2007 8:10 pm

GumbyCT wrote:
Dave2you wrote:nice to know I have an option
Yes it is.

And if you use a quality UPS, it will make life better for the machine circuits. Jim

How much UPS do I need?

How much UPS do I need?

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