600VA, 300w UPS (I dont understand my findings)

[Anonymous user]

I cant seem to get to powercom forums but I really could use your help here:
I have a POWERCOM UPS WAR-600 which I decided to experiment on. It has a firstpower 12v 5aH which gives 8min on my setup. Due to alot of interruptions where am from I got annoyed and decided to mod it to compete head to head with bad a** rack-mounts. I traced the signal that trips and converts the ups into an inverter and used it to protect it from stresses associated with extended backup time (took me quite some time since I didn't have any oscilloscope). To cut the long story short I have optimized it to do 8hrs a day.

Now back to before I decided to mod this thing, I decided to gather some intelligence on it.
My setup has an E5700 @3.5ghz, 8800GT, ep31-ds3l,500GB WD Eco-green HDD, Samsung b1930.

Amongst my experimental tests I mathematically assumed that if the stock battery am running is 5aH and am getting 8min then a 17aH should get me up to {(17/5)*8}min = 27.2min but giving it a true world test I get 43min exactly (run 3 times) but takes 24hrs to charge the 17aH to full capacity instead of 6hrs for the 5aH.

Main house control panel meter readings:

[idle with the ups 125w, load with the ups 265w]
[idle without the ups 115w, load without the ups 235w]

Therefore this ups draws a idle power of 10w when delivering 115w and 30w when delivering 235w

From the looks of its specifications it has a power factor of 0.5 now how does the apparent power get anywhere close to 600VA if its burning 30w to give 235w (78.33% of its total rating) *?????????*
by the way the power bill on this setup is very low even when I runs on load all day, so what am I missing???????!

[voidstar_apc]

Like JonPro says, you might have better luck asking POWERCOM.

>
I traced the signal that trips and converts the ups into an inverter and used it to protect it from stresses associated with extended backup time (took me quite some time since I didn't have any oscilloscope). To cut the long story short I have optimized it to do 8hrs a day.
>

Bad-ass.

>
Amongst my experimental tests I mathematically assumed that if the stock battery am running is 5aH and am getting 8min then a 17aH should get me up to {(17/5)*8}min = 27.2min but giving it a true world test I get 43min exactly (run 3 times) but takes 24hrs to charge the 17aH to full capacity instead of 6hrs for the 5aH.
>

Yes, runtime is non-linear. For a given size battery, drawing more current yields less energy. So with a larger battery, you're drawing less current per cell so you can take more energy out.

See the [runtime graph for the APC Back-UPS 650|http://www.apc.com/products/resource/include/techspec_index.cfm?base_sku=BE650G]

>
idle with the ups 125w, load with the ups 265w
idle without the ups 115w, load without the ups 235w
>

That seems suspect... if true, then at idle the UPS is 92% efficient and under load, 89%. I expect a UPS to be more efficient under load because the greater load amortizes the fixed current required by the UPS.

See the [efficiency graph for the APC SmartUPS 750|http://www.apc.com/products/resource/include/techspec_index.cfm?base_sku=SMT750]. This UPS is >94% efficient at your idle power level, and goes up to 97% at your loaded power level. At today's cost of electricity, high efficiency helps save money.

>
From the looks of its specifications it has a power factor of 0.5 now how does the apparent power get anywhere close to 600VA if its burning 30w to give 235w (78.33% of its total rating) ?????????
>

As long as you're under both the watt and VA rating of a UPS, then you're good. PF is only needed to calculated VA rating based on Watt rating or vice-versa.

[BillP]

As you already know, you have reached the APC Discussion Forum. Unfortunately, I myself couldn't speak about PowerCom products since I do not have any idea how was it designed or manufactured.

I do hope that you could get in touch with them and address your concern.

[Anonymous user · Accepted solution]

(http://www.apc.com/products/resource/include/techspec_index.cfm?base_sku=BE650G) very interesting, I see my setup would get slightly longer backup time by 4min compared to this since the 43min am talking about here is when my pc is idling (surfing & working on documents), although the unit on that link has a 200w useful power output above mine

The ups efficiency that you have drawn still remains a puzzle to me knowing that its power factor of my ups is 0.5. Funny thing is the power bill hasn't turned into a monster yet so maybe it is really that efficient but what I don't understand now is the power factor in relation to its efficiency. Allegedly I calculated with an APC Back-UPS CS 650VA with a power factor of 0.6 I would get 8 min more out of the same battery 12v 17aH battery, which would translate to roughly slightly more than a dollar a month in savings.

What really caught my attention is that the starting battery experiment test, which had a rating of 70aH/20Hr wasn't to far from the 12v 17aH backup time.
They were 55min for the starting battery and 43min for the gel battery, making the gel battery a more worthy investment also saves alot of space in comparison.
Another thing that caught my attention is that at the end of the 43rd minute running in backup time, the 6AWG massive cables running from the battery to the ups was strikingly warm to touch. There is alot I have learn't by just testing, even what happens to the unit when you connect its output to its input, I have never seen a device get so confused as this one did, that was like 2yrs ago.

Still haven't figured out how to increase the amount of useful power you can draw from my unit, but that will mean redesigning the entire ups, but am content with my unit as of now. I will try bigger fish later when necessary but funny thing is that as various consumer units get powerful their power demands also dramatically reduce. Maybe one day my ups will be enough to power the whole house for 5hrs with everything running on full load... haha!