# great deal on backup power at cdn. tire



## MACSPECTRUM (Oct 31, 2002)

this unit should be able to run your laptop/router/modem for about 4-6 hours
regular price is $199

same unit from tiger direct w/ spec 
http://www.tigerdirect.ca/applications/SearchTools/item-details.asp?EdpNo=2224144

NOTE: up to 8 hours backup


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## MacDoc (Nov 3, 2001)

Why is that such a good deal?? There are many that are better about.
Tiger Direct.

ULT31502
2.	Ultra / ULT31502 / 1000 VA / 600 Watt / AVR Backup System / UPS
If you're looking for the most complete, technologically advanced power protection unit, the Ultra 1000VA is exactly what you need. 

Manufacturer: Ultra 
$99.99

HP/Compaq T1000XR 1000VA Tower UPS Refurbished (204155-001)
$99.00

APC SmartUPS 1000VA Tower UPS Refurbished (SU1000NET)
$119.00 ( best deal this )

http://www.upsforless.com/?gclid=COHq4vS16IoCFTQkGAodMCP5qg

The APC batteries are easily replaced.


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## MACSPECTRUM (Oct 31, 2002)

MacDoc said:


> Why is that such a good deal?? There are many that are better about.
> Tiger Direct.
> 
> ULT31502
> ...



david, david, david.....

and just how long will the ones you mentioned run on battery?

amp hours is the rating we are most interested in
find out how many "amp hours" the units you quoted have
and then come back and edit your post

this link should give you a very big hint

Estimated Runtime of APC units

for computer protection AND runtime
i would plug in a cdn. tire unit into the wall (for long run time) and then an APC unit for protection

the APC units in that price range are totally different animals that the cdn tire unit i mentioned

the cdn. tire unit will run a laptop 8 hours !!!!
your APC ain't even gonna come close
it;s meant for a different purpose

======================

update
i called upsforless and they confirmed that the 1000 VA that david so highly recommends will only run a laptop for about 20-30 minutes


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## Deep Blue (Sep 16, 2005)

Now, now boys. Let's not confuse deprecation and attempts at wit.


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## MacDoc (Nov 3, 2001)

Oh you should see up in private email. 

Noma 400 40 ah - non replaceable battery

APC Pro 1000 34 ah - replaceable plus much better power control.


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## MACSPECTRUM (Oct 31, 2002)

MacDoc said:


> Oh you should see up in private email.
> 
> Noma 400 40 ah - non replaceable battery
> 
> APC Pro 1000 34 ah - replaceable plus much better power control.



ap - 20 minutes backup vs. cdn tire 6-8 hours backup

they are two different devices for two different problems 

david, maybe you should call upsforless and ask them about how long that device will backup a laptop


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## CanadaRAM (Jul 24, 2005)

The runtime of a unit is affected both by the battery, and by the draw of the loads.

The Noma/Xantrex says up to 8 hours, bur they don't specify at what draw. It's like saying a glass of beer can last you 8 hours -- if you sip it very, very slowly.

The maximum continuous draw is 320W. That's less than one gamer's desktop computer. Or, approx 3 lightbulbs. Or 1/5th of a laser printer.

on the Xantrex site they claim a laptop will run 15 hours -- but only at a 25W draw. (Their numbers imply that the backup delivers 360 - 375 Watt-hours)

However, The MacBook Pro uses an 85W adaptor, not 25W... and it is not nearly 100% efficient -- however I haven't been able to track down what it's actual draw is.

"Desktop computer, 67W" -- actual draw of an Athlon XP2400+ system: 152W, + LCD monitor 20W

I think there is a degree of smoke and mirrors going on. By seriously underestimating the draw of devices they can claim very long runtimes.


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## MACSPECTRUM (Oct 31, 2002)

> on the Xantrex site they claim a laptop will run 15 hours -- but only at a 25W draw. (Their numbers imply that the backup delivers 360 - 375 Watt-hours)


that;s why i used a number of 4 - 6 hours for a laptop

my application is for backup power for fridge, water pump, laptop, modem and low -e light and radio to keep from going crazy in winter blackouts
i;ll probably go with a charger/inverter and get a battery bank of 200 or 400 amp hours

wood stove is backup heat source

i did speak to the upsforless and they said the unit david quoted would run a laptop from 20-30 minutes

i've been doing homework on a backup power source for home for a while now and it does get complicated as electricty is measured in so many ways


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## Beej (Sep 10, 2005)

Is it not worth the added dollars to go to a small backup gas or diesel generator to handle a lot more load and energy, including multi-day power outages? Is it that a lot of $$$ is still needed to protect against the time from power loss to turning on the backup and power quality? 

Just personal curiosity.


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## MACSPECTRUM (Oct 31, 2002)

Beej said:


> Is it not worth the added dollars to go to a small backup gas or diesel generator to handle a lot more load and energy, including multi-day power outages? Is it that a lot of $$$ is still needed to protect against the time from power loss to turning on the backup and power quality?
> 
> Just personal curiosity.


1. i don't want to store fuel
2. generators need regular testing and typical ones run about 7-8 hours on a full tank
3. noisy

i can build a 200 amp hour hour backup system for about $1500
or less if i hunt around for batteries
or a 400 amp hour for $2000 or less

electrical backup is
1. noiseless
2. requires no fuel
3. easy setup for auto on/off

it also has a front end that i can one day hook up solar or wind generator

i also like the fact that it re-charges automatically once power comes back on

actually automatic fuel based generator systems get expensive once yo put in the auto switching stuff to turn the generator on and off
or else it has to be manually turned on and off with a special siwtch so u don't run generator while ac power comes back on or boom


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## Beej (Sep 10, 2005)

Thanks 'Spec.

One more thing. As battery backup, do they draw a constant bit of power ("standby" lights, power depletion of batteries, etc...)? If so, is it quite small relative to how often you use them?


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## MacDoc (Nov 3, 2001)

Well we'll do a little hands on testing - we're just charging up our 900 Pro with older battery and we'll see how long it runs a laptop. 

Have a new set of batteries we've been meaning to charge up as well - so worthwhile exercise.


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## MACSPECTRUM (Oct 31, 2002)

Beej said:


> Thanks 'Spec.
> 
> One more thing. As battery backup, do they draw a constant bit of power ("standby" lights, power depletion of batteries, etc...)? If so, is it quite small relative to how often you use them?



power blackouts have been averaging about 8-10 per year averaging 24 hours

the small of amount of draw for "lights" on the units is not important and since they are plugged into ac power, not a drain on batteries

a lot depends on what you get as your inverter/charger
xantrex.ca seem to be a leader in selling the stuff and going thru cdn. tire helps keep prices down, especially if you can catch what you want during a sale


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## MACSPECTRUM (Oct 31, 2002)

MacDoc said:


> Well we'll do a little hands on testing - we're just charging up our 900 Pro with older battery and we'll see how long it runs a laptop.
> 
> Have a new set of batteries we've been meaning to charge up as well - so worthwhile exercise.


experimental data to backup theory

da vinci would be proud....

or we could just "believe" in the gospel of IB (Intelligent Backup)


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## Beej (Sep 10, 2005)

It seems to me there shouldn't be much uncertainty with the equations.

Total energy is simple, along with some range of efficiency conversion (10%-20% loss?) versus total energy demand for a given appliance. Another 10% or so for manufacturers' claims versus a given unit. 

Granted, computer power usage varies quite widely, but the given total power in a battery should not be a "he said/she said" thing.

What am I missing?


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## MacDoc (Nov 3, 2001)

There is believe me part is on purposed part is nature of load.


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## SINC (Feb 16, 2001)

MacDoc said:


> There is believe me part is on purposed part is nature of load.


Any chance you could rephrase that in something nearer understandable English?


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## CN (Sep 3, 2004)

MacDoc said:


> There is believe me part is on purposed part is nature of load.


Hmm...

I'm thinking MacDoc is referring to the fact that as you increase the load (current-wise), the internal resistance of the battery increases, and the terminal voltage of the battery decreases? Thus, different loads on the same battery gives you different efficiencies.

But I'm not sure...


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## MacDoc (Nov 3, 2001)

Part of the problem is the companies don't encourage easy comparsions.

Part of the problem is the nature of what is being powered and the ability to feed a constant set of voltage/current over time. ( think of the problem with batteries and digital cameras )

A flashlight can go dim and fade over time - electronics can't do that.

Not so critical with a laptop as the power supply buffers pretty well but other devices do not have the flexibility.

I'm not expert on batteries - it's a pretty complex field. Type of battery, controls for the UPS, temperature, age of battery and nature of load.
So the suppliers play it super safe in terms of what they promote as run time.


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## RicktheChemist (Jul 18, 2001)

.


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## MACSPECTRUM (Oct 31, 2002)

RicktheChemist said:


> I find it very diffcult to buy anything in this field. You think you're getting a good deal but in the end you could end up with something else...
> 
> I like my little backup power but I should have invested in a larger one at the time.
> 
> RtC


the backup companies don't make it easy to understand
i've been doing research since last year and deciding on my backup system for critical items in my home
it's not wasy

it really depends on the devices you are trying to power

the powersource 1800 only has 20 more amp hours (total 60) than the 400, but can take an 1800 watt load with spikes up to 3600 , so u could use it to backup a fridge for example

for a laptop for backup power for an urban centre and recalling the price you paid, u got a good deal

u could buy another one, but i think i recall u mentioning wanting to power up your tv

tv will draw quite a bit more than a laptop


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## Beej (Sep 10, 2005)

I'm accustomed to evaluating energy in watt hours or GJs :

http://www.solardirect.com/pv/batteries/batteries.htm

"To convert a battery's amp-hour capacity to watt-hours, multiply the amp-hours times the voltage. The product is watt-hours."

So, once you've calculated the total energy for the battery in a common energy unit that is independent of voltage, is there that much uncertainty (more than 20%ish)? 

I understand varying voltage needs and delivering for peak versus constant load (quality issues), but is the total energy stored that much in doubt?


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## MacDoc (Nov 3, 2001)

In theory no - in practice temperature, variability of load ( spikes etc ), aging profile of the battery and discharge profile plus the nature of the device being powered all make it a bit of shell game.

I suspect even a single change like ambient temperature would give a pretty wide variation in run time. 

These are lead acid.


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## Beej (Sep 10, 2005)

I could see that MD, and it shows up in some estimates on a brochure for one of the batteries, but 20 mins versus 6-8 hours (from early in the thread) from a 20% difference in amp hours? That sounds more like an underlying volt difference or different assumptions on laptop power usage.


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## Macfury (Feb 3, 2006)

A guy I know powered a Pismo on what I believe was that NOMA unit. I believe it ran for 7 to 8 hours. The Pismo's battery was removed at the time.


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## MacDoc (Nov 3, 2001)

I've seen no indication of 20 minutes on a laptop - heck a laptop battery is tiny in comparison and tho lithium ion still it runs 3-4 hours.

APC has a usage chart but of course it's in their interest to get you to buy more and frankly over time that's not a bad thing as the batteries fade.

Mugs game in my mind  -buy the biggest refurb with replaceable batteries seems the best bet.

Our test unit UPS batteries have bit the dust so I have to get a fresh set in which actually will be a good test.


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## MACSPECTRUM (Oct 31, 2002)

Macfury said:


> A guy I know powered a Pismo on what I believe was that NOMA unit. I believe it ran for 7 to 8 hours. The Pismo's battery was removed at the time.


well know we have empirical evidence (albeit 2nd hand) of the cdn. tire solution

now we need some hard data from macdoc


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## HowEver (Jan 11, 2005)

Nice. (My dual-batteried Pismo can run for a very long time before the backup kicks in.)



Macfury said:


> A guy I know powered a Pismo on what I believe was that NOMA unit. I believe it ran for 7 to 8 hours. The Pismo's battery was removed at the time.


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## CanadaRAM (Jul 24, 2005)

Beej said:


> I could see that MD, and it shows up in some estimates on a brochure for one of the batteries, but 20 mins versus 6-8 hours (from early in the thread) from a 20% difference in amp hours? That sounds more like an underlying volt difference or different assumptions on laptop power usage.


Yes: The assumption on the APC was a 335W draw, and the assumption on the Xantrex was presumably a 50W draw (their claim is 'up to 15 hours' on a 25W draw). There's that d#%&ed 'up to' qualification though -- which means 'any number lower than 15'


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## Beej (Sep 10, 2005)

Thanks C-RAM.


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## krs (Mar 18, 2005)

The NOMA people must be smoking dope with the runtime they claim.
That unit has a 520VA rating if you look on the TD website; 
for $59.00 you can get an APC unit with a 750VA rating and free shipping

http://accessories.dell.com/sna/productdetail.aspx?c=ca&l=en&s=dhs&cs=CADHS1&sku=A0532940


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## MACSPECTRUM (Oct 31, 2002)

krs said:


> The NOMA people must be smoking dope with the runtime they claim.
> That unit has a 520VA rating if you look on the TD website;
> for $59.00 you can get an APC unit with a 750VA rating and free shipping
> 
> http://accessories.dell.com/sna/productdetail.aspx?c=ca&l=en&s=dhs&cs=CADHS1&sku=A0532940


i think one needs to take into acct. the power usage of the unit;s own electronics whilst running on battery backup only

the extra electronics for line stabilization and surge supression must eat up power

still i await the real world results from macdoc's experiments


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## MacDoc (Nov 3, 2001)

Have to change the batteries and then do the 16 hour charge - won't be today - I hate lugging those suckers around. I'll wait for staff.

43 lbs


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## krs (Mar 18, 2005)

MACSPECTRUM said:


> i think one needs to take into acct. the power usage of the unit;s own electronics whilst running on battery backup only
> 
> the extra electronics for line stabilization and surge supression must eat up power
> 
> still i await the real world results from macdoc's experiments


The "VA" output rating already takes that into consideration. To compare units, all you need to do is compare units with the same output rating and how long they can supply power to the load at that level.
Now, the output rating is (should be) the worst case situation - you may get a unit that does somewhat better due to electronics tolerances. And of course as the battery in the unit ages, the performance becomes less.
Surge suppression by the way takes no extra power - that's just a set of two or three MOVs (Metal Oxide Varistors) or similar connected across the line and from each line to ground. They only fire if there is a surge.

I have a Belkin 550 VA running with my G4 and 19-inch LCD. The pair draw 95 to 100 Watts measured with an energy meter - the Belkin software shows that draw as a 24% loading level on the unit.
At anothe location, I have a Mac Mini, 17-inch LCD monitor and the DSL modem connected to the smallest Belkin UPS rated at 375 VA. I tested that once - it ran the Mini/monitor/modem combination for almost 30 minutes.

I use the UPS to bridge short power outages which happen every once in a while. Easier on the Mac and you don't loose anything you're working on.
If the power goes off for 15 minutes or longer - I save my work and shut the system down. Hasn't happened since I bought the UPS a few years ago, but I had plenty of short power outages where the UPS paid for themselves.

I read through the thread, but I'm not really sure what the discussion is about. There is really nothing mysterious about this power backup.


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## MACSPECTRUM (Oct 31, 2002)

> I read through the thread, but I'm not really sure what the discussion is about. There is really nothing mysterious about this power backup.


they mystery is why would upsforless.com tech. person tell me that the APC 1000VA refurb, macdoc claims is a much better value than the Noma 400 I started the thread with, tell me that their unit (APC 1000VA) would run a laptop for 20-30 min. yet we have an ehmacer that says he has data that shows the Noma 400 powered a laptop for 6+ hours

*that's the mystery*

supposedly we are talking 40 amp hours for the Noma vs. 34 amp hours for the APC

we're waiting for macdoc's emperical data but i think the cdn. tire sale will be over by then

macdoc says the APC is a bettery buy
I say the Noma is a very good buy for backup power

perhaps there is something in battery technology used by each unit
the Noma uses AGM batteries and maybe they can discharge to a lower level before needing to be re-charged

anyway, for me it will be a battery bank and an inverter/charger as I need to backup critical items in my home as in rural areas power outages are not infrequent and my data in my area shows average 24 outage

being on a well water system, i need to backup my water pump and a system to start/run a 1/2 horse power water pump (initial ~3000 watt spike) dictates a backup system that can easily power the a fridge, laptop/router/modem and a 23 watt low-e bulb and a radio are easy to handle


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## krs (Mar 18, 2005)

MACSPECTRUM said:


> they mystery is why would upsforless.com tech. person tell me that the APC 1000VA refurb, macdoc claims is a much better value than the Noma 400 I started the thread with, tell me that their unit (APC 1000VA) would run a laptop for 20-30 min. yet we have an ehmacer that says he has data that shows the Noma 400 powered a laptop for 6+ hours
> 
> *that's the mystery*


The spec for the Noma unit on TD is as follows:

_Specifications

AC output power: (max. continuous) 320 W
AC output power: (5 minutes) 400 W (650 VA)
AC output surge capacity: (peak) 640 W
AC output voltage: 120 VAC/60 Hz
Internal AC charger: 2 A
Transfer switch: 12 A max / 12 milliseconds
Internal battery: 40 Ah, sealed, lead-acid
Weight: 32 lb (14.5 kg)
Dimensions: 18.5 x 4.25 x 10.5“ (47 x 10.8 x 26.7 cm)
_

With a rating of 320 watts its runtime will be roughly half of a 1000 VA unit. The actual time of course depends on the load.

Take a MacBook Pro as an example. The maximum DC power specified is 85 VA, the AC power required is not specified (at least I didn't see it on the Apple web site), but assuming an 85% efficiency of the switching converter gives us a load of 100VA.

Now a 1000VA UPS will run a 100 VA load for about 1 hour and 40 minutes and a 450VA UPS (Noma) will run this load for about 40 minutes.
Maybe the ehMacer ran his labtop with its internal battery to come up with the 6+ hours.

It'l be 8 PM soon. I will run my set up on battery backup starting at 8 and check how long it runs before I get into the red back up range.


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## krs (Mar 18, 2005)

Well - my first test failed.
The screen turned blue and the Mac shut down after only a few minutes. After some searching, I found that the UPS software had been programmed to shut the OS down after 3 minutes of power failure.

So after I got that fixed I tried again.

The Load was 90 watts (measured)
The UPS was a Belkin 550VA unit, almost exactly one year in operation
The load level was registered by the Belkin UPS software to be 21%. That stayed constant throughout the test period while the AC power was disconnected.

Run time was 20 minutes to a 27% battery level - at the 33% level the UPS became exited and started to beep continuously and the battery level indicator turned red, so I considered that the end of the back up time.
You shouldn't really discharge these types of batteries too much.

I expected a somewhat longer back up time, closer to 30 minutes, but perhaps the battery is sarting to get a bit weak after one year.

In any case, this UPS has a bit more capacity than the Noma one at CTC - the units look somewhat similar as well, so I would expect the back up time of the Noma to be a bit less with the same load.


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## MacDoc (Nov 3, 2001)

KRS how old is your unit??
We see two years as max for useable.


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## krs (Mar 18, 2005)

Roughly one year. 
Bought it and started using it on the 28th of March 2006.
Belkin claims three years to battery replacement.

I will probably test it on a regular basis to make sure the back up is there when I need it. There are some test programs that come with the Belkin software.


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## CanadaRAM (Jul 24, 2005)

krs said:


> The spec for the Noma unit on TD is as follows:
> 
> _Specifications
> 
> ...


No, that's where you're going wrong. The rated draw has no relation to the size of the battery. Watts is not a measure of power over time, it is a measure of the maximum or recommended load (V x A).

What Xantrex is doing is limiting the rated draw in order to get longer runtime on a given battery capacity. APC is maximizing the supportable draw, to run more equipment.

If you have a bathtub full of water, you can bail it out by bucket in 30 minutes, or by teacup in 6 - 8 hours. It's still the same amount of water though.

MacSpectrum - the mystery in the supposed difference between 30 minutes and 6 - 8 hours is that the two parties are* not *comparing remotely the same thing. The APC will last 30 minutes with a draw of 335W. The Xantrex will last 6 - 8 hours with a draw of 50W. Two different bases of measurement.


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## krs (Mar 18, 2005)

CanadaRAM said:


> No, that's where you're going wrong. The rated draw has no relation to the size of the battery. Watts is not a measure of power over time, it is a measure of the maximum or recommended load (V x A).
> 
> What Xantrex is doing is limiting the rated draw in order to get longer runtime on a given battery capacity. APC is maximizing the supportable draw, to run more equipment.
> 
> ...


C-RAM......

You're obviously correct in what you posted.....at least the first part......the trouble is that the UPS manufacturers don't specify anything in Kilowatt-hours, just a VA and possibly an equivalent Watt rating.
The Belkin UPS I use is quoted as having a run time of 28 minutes on the Belkin webpage - without specifying the load, that number is really meaningless.
http://catalog.belkin.com/IWCatProductPage.process?Product_Id=171876

I assume, maybe incorrectly, that the loads (and thus the achieved runtime) are based on some industry standard - perhaps a load that is a fixed percentage of the VA rating. That way UPSs could at least be compared between different manufacturers even if only the VA rating is specified.

Where I'm questioning the accuracy of your post is the 50 watt load - where does the 50 watts come from?


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## CanadaRAM (Jul 24, 2005)

krs said:


> C-RAM......
> 
> You're obviously correct in what you posted.....at least the first part......the trouble is that the UPS manufacturers don't specify anything in Kilowatt-hours, just a VA and possibly an equivalent Watt rating.
> The Belkin UPS I use is quoted as having a run time of 28 minutes on the Belkin webpage - without specifying the load, that number is really meaningless.
> ...


It comes from the Xantrex website, where they claim 15 hours on a laptop at 25W load. At a more realistic but still hypothetical 50W load, that's 7.5 hours which is within the range of 6 - 8 hours quoted by others. The APC figures come from their website.

You are right though -- there IS no basis for fair comparison in any of the companies advertising and specs, and the figures are largely meaningless. Thinking there must be some standard is a dangerous assumption to make, because there is no industry standard for stating runtime or capacity.


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## krs (Mar 18, 2005)

CanadaRAM said:


> It comes from the Xantrex website, where they claim 15 hours on a laptop at 25W load. At a more realistic but still hypothetical 50W load, that's 7.5 hours which is within the range of 6 - 8 hours quoted by others. The APC figures come from their website.
> 
> You are right though -- there IS no basis for fair comparison in any of the companies advertising and specs, and the figures are largely meaningless. Thinking there must be some standard is a dangerous assumption to make, because there is no industry standard for stating runtime or capacity.


Gee - I love that - a laptop at 25 watts - is there such a thing?

As to the run time - I'm going to email Belkin and ask where their 28 minutes of runtime comes from for their 550VA unit - it must be based on some assumption for the load and it's definitely not 550VA.


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## MACSPECTRUM (Oct 31, 2002)

it's these various types of electricity measurement why i decided on amp hours for as my units for measurement

even amp hours are different based on 20 rating or 100 rating
this whole thing is shrouded in technical gobbleygook

i still think it might have to do with the type of battery and how discharged they can be before needing to be re-charged

the NOMA Powersource 400 and 1800 use AGM batteries and are deep cycle as would any batteries i would buy to create my battery bank
deep cycle batteries cost a lot more than "normal" car or truck batteries and come in various voltages depending on application

hopefully with macdoc's and others' data we can come to a real world consensus on all this

like i said, i;ve been researching this since last year to figure out how to best create a COST EFFECTIVE battery backup system for my home (after i decided not to go with a fuel based generator)

i figure my avg. draw during a power outage for necessary items only should be about 5 amps @ 115 volts (laptop, satellite modem, radio, low-e 16 watt light
for say 16 hours per day
phone set and line are from bell and without power default to a POTS (plain old telephone system) phone and work off the voltage in the phone line, therefore not needing power (i can live without call display for more than a few hours)

if the water pump and/or fridge kick in, this will increase by at least double, but water pumps don't run forever and neither do fridges and of course during a power outage i wouldn't flush at will or open my fridge door humming and hawing over what to get out of it

i'm looking to build a system to give me backup power for up to 48 hours
after that i would seek shelter elsewhere

that requires a inverter/charger and a battery bank = powerhub 1800
+
2 batteries to give me 200 amp hours for $1400
i can add an "expansion unit" to allow for 2 more batteries and a total of 400 amp hours for a total cost of $1900

+ some electrician costs

i can run stuff via plug in outlets using extensions cords or have electrician wire into my power box

powerhub 1800 also allows me to charge from solar/wind sources too, for future consideration


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## MACSPECTRUM (Oct 31, 2002)

or i could by 3 or 4 of these (they were on sale a while back for $249)
one for fridge, one for water pump, one for computer, and one to backup soon to be purchased hd tv to protect DLP bulb in case of power outage and minor tv watching

4 of them give me 240 amp hours of backup power, but individually spread out at 60 amp hours per unit for a total of $1800
no electrician costs, simple 60 second installation and portable if i ever sell the house

*i await macdoc's field test data with baited breath*


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## MACSPECTRUM (Oct 31, 2002)

fyi, when i did call upsforless.com they refused to discuss ANY of their units in amp hours, which seems to be a much more standard form of unit measurement for backup power systems

from our friends at google;



> What is the Amp Hour (Ah) rating?
> An amp-hour is one amp for one hour, or 10 amps for 1/10 of an hour and so forth. It is amps X hours. If you have something that pulls 20 amps, and you use it for 20 minutes, then the amp-hours used would be 20 (amps) X .333 (hours), or 6.67 AH. The accepted AH rating time period for batteries used in solar electric and backup power systems (and for nearly all deep cycle batteries) is the "20 hour rate". This means that it is discharged down to 10.5 volts over a 20 hour period while the total actual amp-hours it supplies is measured. Sometimes ratings at the 6 hour rate and 100 hour rate are also given for comparison and for different applications. The 6-hour rate is often used for industrial batteries, as that is a typical daily duty cycle. Sometimes the 100 hour rate is given just to make the battery look better than it really is, but it is also useful for figuring battery capacity for long-term backup amp-hour requirements.


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## krs (Mar 18, 2005)

I think I'll read your posts tomorrow when I get up, but here is a pretty good site about batteries etc.

http://www.windsun.com/Batteries/Battery_FAQ.htm#Using a deep cycle battery as a starting battery

Decided to read your posts right away.

For one, I would go for a multiple unit approach simply to improve reliability. With the single unit, if something fails, your out of power totally.

As to your amp-hour approach - one thing you need to consider is the efficiency of the inverter. It's basically power lost and it could be a fair amount depending on the design. Efficiencies range from about 78% to over 95%.
http://www.solar-electric.com/solar_inverters/inverters_for_solar_electric.htm

Another consideration is the output waveform of the inverter - some devices don't like anything but a reasonably clean sinewave and some motors are less efficient when running with a square wave input.

The other item to think about - at least for some of the items you want to run - is the start up current. You need to be able to handle that without tripping breakers or shutting down units. When I still had a 19-inch CRT connected to my UPS, it would trip everytime when I turned the monitor on - ran fine as long as I only put the monitor to sleep, but if I shut it off completely, the UPS would trip everytime I turned the monitor on. The start up current was somewhere around 35 amps; only for a few milliseconds so a regular 115 volt breaker never tripped but the UPS did.


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## MACSPECTRUM (Oct 31, 2002)

i would say if i ever saw the powersource 1800 units on sale for $249 each again, i would snag 4 of them and be done with it

i do see the advantage of the units being separate in case of failure
also, the rental i am in now uses an even more complicated xantrex (makes noma for CTC) inverter/charger and huge battery bank and we had a power surge and the unit went offline taking with it all circuits which were supposed to be backed up

of course the landlord wasn't around the whole day so the NON backed up circuits worked and the backed up ones didn't until he re-set the inverter/charger

the one advantage of the powerhub 1800 solution is that i can use it as a front end for future solar and/or wind power generation and battery replacement is easy

i would still put in a small UPS between an powersource 1800 and any computer equipment for full line protection and i already have one... so why not, eh?

i'm so confused...... arrrggghhhhhhh

as part of my house re-build i am installing a special "fuse" to protect the entire house from a lightning strike which can damage all of your homes electrical components, which by the way many insurance policies won't cover


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## Beej (Sep 10, 2005)

MACSPECTRUM said:


> i figure my avg. draw during a power outage for necessary items only should be about 5 amps @ 115 volts (laptop, satellite modem, radio, low-e 16 watt light
> for say 16 hours per day
> 
> i'm looking to build a system to give me backup power for up to 48 hours
> ...


'Spec, I'd recommend figuring out the watt hours, which is a measure of energy.

Most of the batteries seem to be 12v, so 200 amp hours gets 2400 watt hours.

That can run a 50w device for 48 hours. Your quick list of electronics may fit into that, but I don't know their power loads.


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## MACSPECTRUM (Oct 31, 2002)

Beej said:


> 'Spec, I'd recommend figuring out the watt hours, which is a measure of energy.
> 
> Most of the batteries seem to be 12v, so 200 amp hours gets 2400 watt hours.
> 
> That can run a 50w device for 48 hours. Your quick list of electronics may fit into that, but I don't know their power loads.


that of course is running the 50w device like a macbook (60w) for 48 hours straight, but i have a feeling that the fridge and water pump would draw pretty big loads, especially the pump upon start up

i prefer to convert each device in amps and then go from there
60w blackbook / 12 volts (battery bank) = 5 amps
using a 2 x 100 = 200 amp hour battery bank using 12 volt batteries in parallel would that give me 40 hours of use?

is my math correct?


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## The Doug (Jun 14, 2003)

MACSPECTRUM said:


> is my math correct?


Yes. Wait, no. Yes. No.


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## MACSPECTRUM (Oct 31, 2002)

The Doug said:


> Yes. Wait, no. Yes. No.


i think the result is pretty close
seems even deep cycle batteries with an inverter/charger will allow the batteries to use up to 80% of their original amp hours before shutting the system down

so a 200 amp hour battery bank really only gives you 160 usable amp hours

160 amps hours / 5 amps (at 12 volts) = 32 hours

how is that math?


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## MacDoc (Nov 3, 2001)

Depending on temperature 

oh yeah and age of battery


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## The Doug (Jun 14, 2003)

MacDoc said:


> Depending on temperature
> 
> oh yeah and age of battery


You could've just said, "Yes. Wait, no. Yes. No."


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## MACSPECTRUM (Oct 31, 2002)

AGM, or Absorbed Glass Mat Batteries

A newer type of sealed battery uses "Absorbed Glass Mats", or AGM between the plates. This is a very fine fiber Boron-Silicate glass mat. These type of batteries have all the advantages of gelled, but can take much more abuse. We sell the Concorde (and Lifeline, made by Concorde) AGM batteries. These are also called "starved electrolyte", as the mat is about 95% saturated rather than fully soaked. That also means that they will not leak acid even if broken.

AGM batteries have several advantages over both gelled and flooded, at about the same cost as gelled:

Since all the electrolyte (acid) is contained in the glass mats, they cannot spill, even if broken. This also means that since they are non-hazardous, the shipping costs are lower. In addition, since there is no liquid to freeze and expand, they are practically immune from freezing damage.

Nearly all AGM batteries are "recombinant" - what that means is that the Oxygen and Hydrogen recombine INSIDE the battery. These use gas phase transfer of oxygen to the negative plates to recombine them back into water while charging and prevent the loss of water through electrolysis. The recombining is typically 99+% efficient, so almost no water is lost.

The charging voltages are the same as for any standard battery - no need for any special adjustments or problems with incompatible chargers or charge controls. And, since the internal resistance is extremely low, there is almost no heating of the battery even under heavy charge and discharge currents. The Concorde (and most AGM) batteries have no charge or discharge current limits.

AGM's have a very low self-discharge - from 1% to 3% per month is usual. This means that they can sit in storage for much longer periods without charging than standard batteries. The Concorde batteries can be almost fully recharged (95% or better) even after 30 days of being totally discharged.

AGM's do not have any liquid to spill, and even under severe overcharge conditions hydrogen emission is far below the 4% max specified for aircraft and enclosed spaces. The plates in AGM's are tightly packed and rigidly mounted, and will withstand shock and vibration better than any standard battery.

Even with all the advantages listed above, there is still a place for the standard flooded deep cycle battery. AGM's will cost 2 to 3 times as much as flooded batteries of the same capacity. In many installations, where the batteries are set in an area where you don't have to worry about fumes or leakage, a standard or industrial deep cycle is a better economic choice. AGM batteries main advantages are no maintenance, completely sealed against fumes, Hydrogen, or leakage, non-spilling even if they are broken, and can survive most freezes. Not everyone needs these features.


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## MACSPECTRUM (Oct 31, 2002)

Temperature Effects on Batteries

Battery capacity (how many amp-hours it can hold) is reduced as temperature goes down, and increased as temperature goes up. This is why your car battery dies on a cold winter morning, even though it worked fine the previous afternoon. If your batteries spend part of the year shivering in the cold, the reduced capacity has to be taken into account when sizing the system batteries. The standard rating for batteries is at room temperature - 25 degrees C (about 77 F). At approximately -22 degrees F (-27 C), battery AH capacity drops to 50%. At freezing, capacity is reduced by 20%. Capacity is increased at higher temperatures - at 122 degrees F, battery capacity would be about 12% higher.

Battery charging voltage also changes with temperature. It will vary from about 2.74 volts per cell (16.4 volts) at -40 C to 2.3 volts per cell (13.8 volts) at 50 C. This is why you should have temperature compensation on your charger or charge control if your batteries are outside and/or subject to wide temperature variations. Some charge controls have temperature compensation built in (such as Morningstar) - this works fine if the controller is subject to the same temperatures as the batteries. However, if your batteries are outside, and the controller is inside, it does not work that well. Adding another complication is that large battery banks make up a large thermal mass.

Thermal mass means that because they have so much mass, they will change internal temperature much slower than the surrounding air temperature. A large insulated battery bank may vary as little as 10 degrees over 24 hours internally, even though the air temperature varies from 20 to 70 degrees. For this reason, external (add-on) temperature sensors should be attached to one of the POSITIVE plate terminals, and bundled up a little with some type of insulation on the terminal. The sensor will then read very close to the actual internal battery temperature.

Even though battery capacity at high temperatures is higher, battery life is shortened. Battery capacity is reduced by 50% at -22 degrees F - but battery LIFE increases by about 60%. Battery life is reduced at higher temperatures - for every 15 degrees F over 77, battery life is cut in half. This holds true for ANY type of Lead-Acid battery, whether sealed, gelled, AGM, industrial or whatever. This is actually not as bad as it seems, as the battery will tend to average out the good and bad times. Click on the small graph to see a full size chart of temperature vs capacity.

One last note on temperatures - in some places that have extremely cold or hot conditions, batteries may be sold locally that are NOT standard electrolyte (acid) strengths. The electrolyte may be stronger (for cold) or weaker (for very hot) climates. In such cases, the specific gravity and the voltages may vary from what we show.


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## MACSPECTRUM (Oct 31, 2002)

Amp-Hour Capacity

All deep cycle batteries are rated in amp-hours. An amp-hour is one amp for one hour, or 10 amps for 1/10 of an hour and so forth. It is amps x hours. If you have something that pulls 20 amps, and you use it for 20 minutes, then the amp-hours used would be 20 (amps) x .333 (hours), or 6.67 AH. The accepted AH rating time period for batteries used in solar electric and backup power systems (and for nearly all deep cycle batteries) is the "20 hour rate". This means that it is discharged down to 10.5 volts over a 20 hour period while the total actual amp-hours it supplies is measured. Sometimes ratings at the 6 hour rate and 100 hour rate are also given for comparison and for different applications. The 6-hour rate is often used for industrial batteries, as that is a typical daily duty cycle. Sometimes the 100 hour rate is given just to make the battery look better than it really is, but it is also useful for figuring battery capacity for long-term backup amp-hour requirements.

Why amp-hours are specified at a particular rate:

Because of something called the Peukert Effect. The Peukert value is directly related to the internal resistance of the battery. The higher the internal resistance, the higher the losses while charging and discharging, especially at higher currents. This means that the faster a battery is used (discharged), the LOWER the AH capacity. Conversely, if it is drained slower, the AH capacity is higher. This is important because some folks have chosen to rate their batteries at the 100 hour rate - which makes them look a lot better than they really are.


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## krs (Mar 18, 2005)

MacDoc said:


> Depending on temperature
> 
> oh yeah and age of battery


and say 90% efficiency for the inverter.

The first thing you need to do (IMHO) is actually measure the KW-hours each of the devices you want backed up to get a realistic picture of how much back up capacity you need.
CTC has this nice little meter for $25.00 that does exactly that. You just plug it in between the AC outlet and the device and let it run for a period of time. That will give you accurate numbers for things that run intermittently like your pump and your fridge.
What about heat - don't you need any electricity for that? My two-stage furnace fan gobbles up a lot of amps and it needs to run at least on low to distribute the heat.


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## CanadaRAM (Jul 24, 2005)

A problem with any BBU unit is that the batteries will need replaced every 2 - 5 years, even if you don't have power outages. When you are talking about multiple units, or proprietary batteries, or units with hard to replace batteries (as MD mentioned about 100 posts ago ) this can become a significant problem - and expensive. 

When is the usual time to find out you need a battery? About 15 minutes into the longest power outage of the year. Most if not all units give no advance indication the batteries will fail until they are stressed. Unless you do annual unplug-under-load-tests you may be unpleasantly surprised.

The units with Automatic Voltage Regulation built in tend to make the batteries last a bit longer, because the AVR circuit takes care of many short term brownouts without having to draw on the batteries (AVR draws more A to make up the missing V in under voltage situations that aren't too extreme)


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## John Clay (Jun 25, 2006)

I decided to test the endurance of my UPS (see sig).

First of all, here is what is connected to it (for a total of 14%-16% load):

Mac mini, 2x mini stack enclosures (spun down)
AirPort Express, SpeedStream 5200 DSL modem
ViewSonic VA1912 LCD
 iBook G4, with iPod and 2.5" drive connected

Total time, before reaching 15%: 33 minutes

The UPS was purchased in early August, 2006.

Info on UPS:
http://catalog.belkin.com/IWCatProductPage.process?Product_Id=171958


> •	USB and Serial communication ports for multi-computer management
> •	Included Power Management Software
> •	3-Year Product Warranty
> •	$100,000 Connected Equipment Warranty
> ...


Mine is slightly older, though the specs haven't changed (I have 2 surge outlets, compared to 6).


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## krs (Mar 18, 2005)

John Clay said:


> I decided to test the endurance of my UPS (see sig).
> 
> First of all, here is what is connected to it (for a total of 14%-16% load):
> 
> ...


I take it you couldn't measure the actual load in watts....it looks as if it's a bit higher than mine since you had both a Mini and an iBook connected - you were at roughly 15% load on a 1100VA unit; I was at 21% load with a 550VA unit.

What surprised me a bit is that you only got 33 minutes run time down to a 15% battery level and I got 20 minutes to a 27% battery level with a unit rated at half the capacity and rougly the same age battery.
It's actually hard to compare - the thing that doesn't make sense to me is the 80 minutes of run time Belkin claims. They must measure this a 10% rated load or even less. I emailed them last night about that - no answer yet.
I wonder if there is any point of me rerunning my test to get the time to the 15% battery level and see how that compares to yours.

For 'spectrum's benefit - in practice one seems to get much shorter run times than expected based on the published data.


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## MacDoc (Nov 3, 2001)

Which fits with APC being conservative.


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## MACSPECTRUM (Oct 31, 2002)

well i had a nice long chat with an engineer at xantrex today and he did say their inverter/chargers will shut down the backup systems when the batteries have been 80% used of their amp hour rating, so the "effective" amp hour rating of 100 amp hour batter is 80 amp hours

he also confirmed that for a 60w blackbook the DC amp rating is 60/12 = 5 assuming 12 volt batteries which is different than the AC amp rating of 60/120 = 0.5

for a battery backup system i need to be concerned with DC amp ratings of the devices i need to serve power to in an AC power outage

he did say that the powerhub 1800 could be hooked up to my car (in a pinch) and batteries could be re-charged in about 3 hours - another neat feature - especially in a prolonged outage

seems more and more that the powerhub 1800 is my best option for today and tomorrow 

it's Xantrex's first foray into a do it yourself (DIY) type of solution since the powerhub 1800 is a complete unit, just add batteries and go

as for an earlier question re: electricity for heating system
i used 220 volt baseboard heaters for heat and they could NOT be used for any battery backup system unless i want to build a "battery farm" in my crawl space

my wood stove is my backup heat system, and living in a forested area, i have lots of "fuel"
and for the green types, burning wood from my own property is considered carbon neutral


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## krs (Mar 18, 2005)

Out of interest I took a quick look through the Powerhub 1800 manual.

Two things that struck me - the continuous rating of the unit is 1440 watts or 12 amps (not 1800 as I had assumed based on the product designation). That's a bit less than one standard AC circuit in a house which is fused at 15 amps.

The other thing is this warning note:
_Some chargers for small rechargeable batteries can be damaged if
connected to the PowerHub. Do not use the following with the
PowerHub:
• Small battery-operated appliances like flashlights, razors, and night
lights that can be plugged directly into an AC receptacle to recharge._

I'm not quite sure what the reasoning is behind that, but wouldn't a laptop fall into this category as well? 
"A small battery-operated appliance that plugs directly into an AC receptacle to recharge"

BTW - The efficiency of this unit is specified at 88%. I think you need to factor that into your theoretical calculations.


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## MACSPECTRUM (Oct 31, 2002)

note for macdoc;

xantrex engineer did say the batteries for the Noma 400 and 1800 are replaceable altho' the replacement batteries are not stocked by Xantrex

"you can do it if you can find 'em"


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## krs (Mar 18, 2005)

Just received a reply from Belkin to my question on the 550VA unit.

_What load is the 28 minute runtime specified for the 550VA unit based on? Enclosed Files:
Belkin Response	Mar 13 2007 17:09
It is based on a 10 percent load. 30 watt load._

My rather crude tests indicate that the Belkin unit would have absolutely no problem meeting this spec.


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## MACSPECTRUM (Oct 31, 2002)

krs said:


> Just received a reply from Belkin to my question on the 550VA unit.
> 
> _What load is the 28 minute runtime specified for the 550VA unit based on? Enclosed Files:
> Belkin Response	Mar 13 2007 17:09
> ...


you forgot the apostrophe....


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## MACSPECTRUM (Oct 31, 2002)

krs said:


> Out of interest I took a quick look through the Powerhub 1800 manual.
> 
> Two things that struck me - the continuous rating of the unit is 1440 watts or 12 amps (not 1800 as I had assumed based on the product designation). That's a bit less than one standard AC circuit in a house which is fused at 15 amps.
> 
> ...


for safety of my laptop i would still use a an APC UPS that i already have for my laptop to filter power from a powerhub 1800 or any other battery backup unit like it


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## krs (Mar 18, 2005)

MACSPECTRUM said:


> for safety of my laptop i would still use a an APC UPS that i already have for my laptop to filter power from a powerhub 1800 or any other battery backup unit like it


I wonder how the APC UPS is better than the powerhub 1800 in that respect. I assume it may switch faster than the 20 msec the powerhub 1800 takes, but I assume the output of the APC is also a stepped sinewave.
Lots of assumptions I know, but these UPS suppliers aren't too forthcoming with their technical data.


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## MACSPECTRUM (Oct 31, 2002)

krs said:


> I wonder how the APC UPS is better than the powerhub 1800 in that respect. I assume it may switch faster than the 20 msec the powerhub 1800 takes, but I assume the output of the APC is also a stepped sinewave.
> Lots of assumptions I know, but these UPS suppliers aren't too forthcoming with their technical data.



the APC, and most other UPS, have line stabilizers and filters built into them, which is partly the reason they are more costly than battery backup units like the Noma

i do agree that the entire battery backup industry is quite lacking in their info. and find it extremely suspicious why UPS are measured in VA and battery backups like Noma et al are measured in amp hours


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## MACSPECTRUM (Oct 31, 2002)

> The other thing is this warning note:
> Some chargers for small rechargeable batteries can be damaged if
> connected to the PowerHub. Do not use the following with the
> PowerHub:
> ...


i called Xantrex tech. support and asked them about this

it is due to the fact that some electronic devices won't work with a modified sine wave, which is produced by the powerhub 1800 and APC UPS and most other UPS

he also, did confirm that my idea of using a APC UPS in between my laptop and the powerhub 1800 is a good idea


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## krs (Mar 18, 2005)

MACSPECTRUM said:


> the APC, and most other UPS, have line stabilizers and filters built into them


The UPS manufacturers are stretching the truth here I find.
To me, a stabilized output means that it doesn't vary when the input AC varies.

That's not true for these UPS systems. These are "off-line" UPS systems - normally the AC input voltage is connected directly to the output of the UPS and thus varies in the same way as the AC line voltage varies. It's only when the AC input voltage exceeds a certain threshold, high or low, that the UPS switches in to bring the AC output voltage back within a pre-defined range.
Switching time is typically 4 msec, short enough to be bridged by the computer power supply.

For a true stabilized output, the UPS needs to be an "on-line" UPS, but those are much more expensive.


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## MACSPECTRUM (Oct 31, 2002)

hmm, i do have a dedicated line stabilizer


so guess for me it will be; powerhub > ups > line stabilizer > blackbook & satellite modem


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## krs (Mar 18, 2005)

MACSPECTRUM said:


> i called Xantrex tech. support and asked them about this
> 
> it is due to the fact that some electronic devices won't work with a modified sine wave, which is produced by the powerhub 1800 and APC UPS and most other UPS
> 
> he also, did confirm that my idea of using a APC UPS in between my laptop and the powerhub 1800 is a good idea


I'll dig out my scope tomorrow and take a look at the output of the Belkin UPS.

As to adding a UPS between the laptop and the powerhub 1800 - what's the point of that if the UPS gives you a modified sinewave as well?

And the issues related to a modified sinewave output are described here:
http://www.wholesalesolar.com/pdf.folder/Download folder/sine_modsine.pdf

and here:
http://www.xantrex.com/support/readfaq.asp?did=268&p=1348

Problem is that the information is in direct conflict with each other in a couple of cases.

PS: Here is a nice summary of some of the issues to watch out for:
http://www.donrowe.com/inverters/inverter_faq.html


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## CanadaRAM (Jul 24, 2005)

krs said:


> The UPS manufacturers are stretching the truth here I find.
> To me, a stabilized output means that it doesn't vary when the input AC varies.
> 
> That's not true for these UPS systems. These are "off-line" UPS systems - normally the AC input voltage is connected directly to the output of the UPS and thus varies in the same way as the AC line voltage varies. It's only when the AC input voltage exceeds a certain threshold, high or low, that the UPS switches in to bring the AC output voltage back within a pre-defined range.
> ...


What about UPS's with built in voltage regulators? AC is not patched straight through -- the VR is on-line, the battery is off-line.


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## krs (Mar 18, 2005)

CanadaRAM said:


> What about UPS's with built in voltage regulators? AC is not patched straight through -- the VR is on-line, the battery is off-line.


The only 115 VAC voltage regulator I can think of that takes straight 115 VAC from the line and regulates it, is a ferro-transformer circuit and these are much more expensive than what any of these UPSs sell for.
$410 US for a 250 watt unit.
http://www.elect-spec.com/klr_$.htm#PRICES

You only get regulation from these inexpensive UPSs when the AC is generated by the inverter and the unit runs off batteries.

The output AC waveform in the battery back up mode looks something like this:
(Ignore the leading and trailing edge overshoot - that's probably due to the incorrect compensation of the probe). In the normal mode you get a beautiful almost perfect sinewave with the tops slightly flattened - this is probably due to the spike protection in the unit.










For comparison, the output AC waveform of the Belkin UPS with a 90 watt load and running normally - ie not on batteries - looks like this:


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