Smart-UPS 700VA line voltage problem or not?

[Anonymous user]

I just replaced new battery to my 3.5 years old Smart-UPS 700VA (SU700INET) and I noticed possible problem when I monitored it with the PowerChute Business Edition 8.0.1 - Single Node Agent (SFPCBE801) to see that everything is OK after replacement. Firmware version is 50.14.I and manufacturing date is december 2004.

All other values but line voltage (input power) during power cut shown by the PCBE looks fine. Strange thing is that when I simulate power cut by pulling the plug the PCBE reports line voltage around 22 VAC. However UPS keep providing power to the loads and everything else looks normal.

I'm using this UPS with my HT equipment so it is not monitored. I really cannot remember what values unit did show in the PCBE when I first got it.

I noticed that reported line voltage during power cut goes down with battery voltage, so there is some connection between the two (this is monitored from System Status. Data log seems to show little bit different).

Examples
Battery Voltage 27,6 VDC
Line Voltage 24,7 VAC

Battery Voltage 27,1 VDC
Line Voltage 23,4 VAC

Battery Voltage 25,7 VDC
Line voltage 22,1 VAC

Battery Voltage 25,2 VDC
Line Voltage 20,8 VAC

Check attachments for more information.

I was advised by the APC support to "braindead" my unit but for some reason pressing 0-button for five seconds (or more) after it was turned off and all cables pulled off does not have any effect. I never tried that before so I cannot tell if it has ever functioned but unit does automatically "braindead" in about 10 minutes after it has been turned off and power plug pulled off. This did not have any effect in reported line voltage.

Is my UPS malfunctioning or not?

[BillP]

it should definitely read 0 volts. sometimes after a while the units dont braindead for some reason and you have to wait for it. i am not sure why but I have seen it.

[BillP]

i dont really think braindeading is going to help in this situation even though it wouldnt hurt anything. that basically just discharges the unit completely and resets the communication bus.

does this unit have a detachable input cable that you can remove completely during this test? i think its picking up some voltage from some place which is strange. regardless, i dont think its a problem with the UPS that you need to be concerned about, especially since its still outputting the correct voltage while on battery.

[Anonymous user]

This is what I thought too about braindeading and testing it verified this. However I don't understand why braindeading by pressing 0-button did not work but I had to wait about 10 minutes for it to automatically do that.

This unit does have detachable cable and I tested removing it both ways (from the unit itself and just from the mains) but same results. I find it interesting that line voltage displayed during plug pulled does go hand in hand with battery voltage. It would be nice to know if this is supposed to show it like that or not.

[Anonymous user]

When I first noticed line voltage showing other than 0 V during power out my first reaction was that there is something wrong with the unit. Now after testing it more relation between battery and line voltage just seems too consistent to me. Could it be normal feature for this model or perhaps firmware version? Unit is definitely measuring something and because there is no voltage in input power cord (I measured power cord and it was 0 V) it must be sensing it elsewhere.


Do you or anyone else here have a SU700INET or equalent different voltage variant? Could you please check what reading System Status screen shows when you simulate power cut by pulling the plug? When you do that you need to refresh System Status screen by using the left side menu and open it again and again.

Any idea what part is broken when unit does not braindead by pressing the 0-button? I never knew that by pressing 0-button you should be able to braindead unit, so I don't know if that ever worked. I do remember that this unit has always worked so that when you turn it off and pull the plug it will click after about 10 minutes and I presume it is then in braindead state.

[Anonymous user]

Great! Please let me know what readings you get with 120V model. Also could you test if you can braindead it by pressing 0-button for five seconds (or if it does not do anything with 0-button, see does it braindead automatically after 10 minutes)?

[BillP · Accepted solution]

okay so i am working on this right now.

I am using an SU700NET as mentioned. The UPS is online, 37% load, and battery voltage is 27.5vDC.

I pulled the plug on the UPS, battery voltage went to 24.4vDC and the line voltage is reading 7.8v.

i tried unplugging it AND cutting the breaker (so leaving the plug connected but cutting the power) and still got the same exact readings.

i'd have to say it appears to be some phantom voltage but i dont see it causing a problem.

[Anonymous user]

Many thanks. Line voltage reading you got is lower than mine but that could be results from different voltage unit (120V vs 230V) among other possible reasons. I guess we can close the book on that and call it a feature.

Did you try if you could braindead your unit by pressing the 0-button?

[Anonymous user]

One new question.

Does any of the shutdown settings configured in the PCBE have any effect when UPS is used standalone (without communication to computer)?
I would like my UPS to provide power to the loads as long as there is juice in the battery, so I was wondering if any of those settings have any affect on this.
See attachment for my settings.

I just noticed that my question is in wrong forum (BackUPS forum). Moderators please move this to Network & Server UPS (SmartUPS) forum.

[BillP]

yeah if you set the values once, it changes the values stored in the UPS and saves them. so you change them with software and then disconnect the cable/software.

i dont think the firmware has anything to do with the braindead issue. all Smart UPS no matter what model or age should do this and i honestly cant explain why they dont.

[BillP]

i did not test the braindead thing. i can say for a fact we have a unit that doesnt do it like yours, but majority do it. i am not sure what the problem is caused by. you are true in saying that after 8-10 minutes, the unit will braindead on its own. you could also disconnect the batteries for a minute to speed up that process i believe.

to answer your other question:

no, by default with no software communication, the UPS will run until it hits its low battery signaling time, which is 2 minutes. so the UPS would run until it has 2 minutes left to run, start signaling a low battery via the front panel (and it if it had software, tell everything to shutdown), then it will turn off completely and wait for AC power to return.

[Anonymous user]

**i can say for a fact we have a unit that doesnt do it like yours, but majority do it. i am not sure what the problem is caused by.**

Could it simply be that APC changed the way how braindead function works in different firmware versions?


**no, by default with no software communication, the UPS will run until it hits its low battery signaling time, which is 2 minutes. so the UPS would run until it has 2 minutes left to run, start signaling a low battery via the front panel (and it if it had software, tell everything to shutdown), then it will turn off completely and wait for AC power to return.**

Thanks. So only adjustable low battery signal time in PCBE (looks that you can also adjust this by hardware switch on the back of the unit) does work even without connection.
I presume that UPS turn on battery capacity and UPS turn on delay also work without connection?

[Anonymous user]

**i dont think the firmware has anything to do with the braindead issue. all Smart UPS no matter what model or age should do this and i honestly cant explain why they dont.**

This is peculiar. If this problem occurs in different Smart UPS models, I imagine APC should have done research to find out what is causing it. Are all Smart UPSes able to braindead automatically after about 10 minutes or does this only occur in the units where 0-button braindead no longer works?

Have you witnessed yourself same unit first being able to braindead by 0-button and later on not (to make sure units are not like that in the begin with)?

[BillP]

all smart ups are able to braindead after 8-10 minutes.

i havent noticed any with the (o) button working and then randomly start working. it is not something that happens frequently and it could mean that the capacitors have already discharged in the particular UPS as well.

[Anonymous user]

**i havent noticed any with the (o) button working and then randomly start working.**

I did not quite get what you mean here. Did you mean "i havent noticed any with the (o) button working and then randomly STOP working."? If so then I think there must be some minor difference between the two kind of units. If it is not software version then there must be some difference in hardware but I think APC should be aware of that and could tell which units does what but they don't.

[BillP]

sorry, you are right. i meant "stop."

by design, all of the Smart UPS units should braindead by holding the off (o) switch with the UPS unplugged from AC power OR by leaving them off for 8-10 minutes.

the fact that yours doesnt work by the front switch means: the capacitors in the unit have already been discharged (which is what a braindeading does), or there is something wrong with the front switch not performing the function. it seems like the first option isnt it because i believe you said if you let it sit for 8-10 minutes and it does breaindead. when this happens, you hear a click as well as see the front LEDs flash. there is no firmware/software difference in different units that can cause this after investigation.

[Anonymous user]

But isn't braindead quite similar (except relay cuts battery power in braindead) thing as disconnecting the battery?

Let's play with the capasitor theory. I don't get how some units discharge capasitors just like that and some don't. Is there so big variation in capasitor quality (can't hold charge)?

[BillP]

i just have the 120v version available, SU700NET. I can test it on that unit later today. i am not sure if there is a specific part that would be damaged inside the UPS that would cause it not to braindead but we have some here that do the exact same thing. i dont think it'd be a problem with the on/off button, more so one of the internal components if anything.