surt3000xli runtime and perhaps a load issue

[BillP]

This question was originally posted by matt on APC forums on 3/10/2009

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Hi,

model: surt3000xli (bought, a little over 7 months ago)
location: india
power input: 220~240 volts
load: 11% (1 computer system + 1, 20 inch lcd display)
load current: 1.34
apparent load power: 10.0
battery pack: rbc44

Around five months back I was able to get 4 hours of physical backup time before complete discharge. As time went by it slowly started to drop, until I could hardy get 60 to 90 minutes of physical backup time. The ups has been discharged only twice during the last 7 months.
An on site service tech corrected the battery constant value, which didn't help the physical backup time, even though in the consol it showed 300+ runtime. He also noticed the number of battery packs were 2 instead of 1, as I only have an internal battery pack and no external battery packs connected. But, by changing the number of packs to 1, my physical backup time dropped to less than 1 hour. Thus I changed it back to 2.
Later the techs, changed my battery pack 1 tray at a time (1 pair - 2 physical trays). And it seems for now the physical backup time is more or less alright. But, the runtime shown in the consol is still 390 minutes and dropping the number of battery packs to 1 will give me only 140 minutes. And thus I don't want to change the number of battery packs incase it would reduce the physical runtime as well.

I was told to run a manual runtime calibration to help reset the runtime. But, for that I need to have at least 30% non-critical load as indicated in 'Answer ID 1497', which is not possible. As I don't have any other device that would connect to the back of the ups, i.e connect to a C13 or C19 receptacle. So would I be able to do a manual runtime calibration on less than 30% load? Maybe even less than 10% load? I have read online how people have used light bulbs in order to get a 30% non-critical load, but how they did that I have no idea.

And my computer system has a 1000w psu. I'm not running anything huge on my system, and I do have a power saving motherboard. But, does a 11% load sound right or should it be more? As 11% is roughly 231W.

If it helps, a copy of the consol at the time of writing this:

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American Power Conversion (c) Copyright 2006 All Rights Reserved
Firmware revision: 17, compiled May 10, 2006. 15:02
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Model : Smart-UPS RT 3000 XL Manufactured : 03/31/08
Name : UPS_IDEN Serial Number : XXXXXXXXXXXX
Last battery replacement: 02/04/09 # of battery packs : 002
Battery charge : 100.0% Load : 011.0%
Runtime : 0420 minutes
Input frequency : 49.70 Hz Output frequency : 49.68 Hz
Input voltage : 236.1 VAC Output voltage : 230.4 VAC

-------- Control And Configuration Console -------------------------------------

Any advice or help would be much appreciated.

Thank you all,

Tom

[BillP]

This reply was originally posted by Anonymous on APC forums on 3/11/2009

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Hi matd,

If you have only the internal battery in the UPS then you will want to set the number of battery packs to 1. By having it set to 2 you are not really increasing the runtime of the UPS but tricking the interface to thinking it should have more. Also, by having it set to 2 you are tricking the battery charger into thinking it needs to charge 2 sets of batteries, this could cause reduced battery life in the long run.

Did you ever actually run the UPS on battery for 4 hours with a constant 11% load?

When the UPS has transferred to battery for about 30 seconds the runtime will recalculate and should show more accurately for the load being drawn. Before running any more test I would make sure you have ti set to 1 battery then do a pull plug test (disconnect the unit from utility power), let it run for at least the 30 seconds and then go back in and see what the runtime is reading. With 11% load your runtime should be between 1-2 hours (the smaller the load is the harder it is to calculate runtime). So 90 minutes should be around right for this UPS.

For the runtime calibration you will definitely need to make sure you have it set to the correct number of batteries or the test will be completely wrong. You will also want to make sure you have around a 30% load. The test will cause the UPS to go on battery and it will see how long the batteries last before dropping to a preset voltage on the batteries. It uses this time, the number of batteries and the load % to calculate how much runtime the batteries should be giving you. If you need to add load you might want to try using a PDU to get different types of outlets on the back to connect equipment to. Also, a runtime calibration is usually only needed about 1 time a year starting after you have had the UPS fir about 1 year to see what the difference of runtime is after it has gone through a year of discharge/recharge cycles.

I can't say enough that what ever you decide to do just make sure you have the number of batteries correct.

Let me know if you do a runtime calibration and what the results are.

[BillP]

This reply was originally posted by matt on APC forums on 3/11/2009

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Hi PowerMan,

So how do you explain what happened, when I reduced the number of battery packs my physical run time also was reduced by almost 50%. To be honest I never touched any of these figures to begin with, it has been by default set to 2 battery packs. But, cause I was told to reduce it, I tried it out to see what'll happen. Maybe it does reduce battery life I don't know, perhaps someone from APC could also confirm this. Do you know of any knowledge base articles that would give me more info. I have nothing against reducing the battery pack to 1, provided I still get 4 hours backup time, which was what I used to get. 🙂

Well, I didn't add any new load while it was on battery for those 4 hours, and surely the load wouldn't have dropped to less than 11% either. I have only seen it go up by 1% maybe even 2% at times, but never less than 11%.

It does recalculate alright, but with strange figures, like a jump of 20 or 30 minutes at a time. And when it's one 1 batter pack it jumps by 10 to 15 minutes at a time. But mind you these figures were before the battery got changed. I'm not sure how 30 seconds of power loss will recalculate the runtime and show it more accurately, cause here in India we do have power outages off and on. Like today I had 2 power outages of 30 minutes each... So if what you say is correct it would have fixed itself over time. If 1 or 2 hours or even 90 minutes is about right how come I got 4 hours before? And this is something no one can answer or explain. If I was trying to trick the ups some how by increasing the number of battery packs, surely it won't work beyond it's capabilities. In other words 90 minutes physical runtime won't give me 4 hours.

Well, I don't mind correcting the number of battery packs to the run the manual time calibration, provided it would give me the correct value. I already know I need 30% load to run the manual run time calibration, but can it be done with less than 30% load or even less than 10% load? PDUs with different connectors other than C13 and/or C19 are not sold in India by APC, as indicated on their website.

To be honest I don't know what to do. I now just go by the leds on the front display to tell me how much backup I got left, since the numbers are no help.

Thanks for your time,

Tom

[BillP]

This reply was originally posted by Anonymous on APC forums on 3/11/2009

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Hi matd,

When you say physical runtime do you mean the time you are seeing through the software or are you actually running the unit on battery and seeing how long it last until it shuts down? That model with the load you have on it and no extra battery packs should only be getting about 1-2 hours or runtime.

When you adjust the the number of batteries in the software the UPS does not know if that is the correct number or not so it will calculate the runtime based off what was entered. So if you are seeing 4 hours with 2 batteries and you adjust the batteries back to 1 then the runtime would go down by half to 2 hours and that would be correct. You can verify this by forcing the unit onto battery and after about 2 minutes check to see what the unit is reporting ofr its remaining runtime.

If you do need 4 hours of runtime I would suggest getting getting an external battery pack, part number SURT192XLBP.

Thank you.

[BillP · Accepted solution]

This reply was originally posted by matt on APC forums on 3/11/2009

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Hi PowerMan,

Sorry I should've explained myself better, when I say physical runtime, I mean running the unit on battery and seeing how long it lasts before the last led (at the bottom) starts to flash.

Well, it must know something, like I have said already above my physical runtime was cut by almost 50%, when I reduced the battery pack number to 1. And when I say it was cut by almost 50% I mean the last led was flashing and the low level battery alarm set at 5 minutes was sounding too. Maybe it would've run longer I don't know, nor would I risk using critical load to find that out.

Thanks for that, but why get an external battery pack, when my ups is able to give 4 hours? 🙂

Thanks for your time,

Tom