SU1400 fans running continuously

[Anonymous user]

We have quite a few SU1400's around. Most are on their third (or more) battery. A few found their way into office environments as we switched to newer APC RM UPS's and larger APC UPS's in server rooms and network closets where HVAC and equipment fans drown out any fan noise the UPS's make. A while ago I noticed the fans on some of the SU1400 fans were always running but not on all our SU1400's.

That seemed weird so I did searches on the Internet and on this forum. I saw other people reporting the same problem, but the only precise explanation I saw was the possibility the problem was a bad temperature sensor.

I put a new replacement battery (an genuine APC brand RBC7) in a SU1400 last week and noticed it's fan was running as well. So that's three I've noticed doing the same thing (now that I'm aware of this I'll have to check other SU's in other areas) and that's what made me curious. Is it possible these three all have bad temperature sensors?

Because these tend to power things like switches there is no where to run the PowerChute software, but I tried the serial port on one with the factory 940-1524C Smart Signal cable) and it returned a status of 33AC (is it true that 8C means "normal"?). What does 33AC mean? This particular battery was purchased and installed in 2/2007 so it's not real old and it has led an easy life (only a couple significant outages, a light load: 2 LEDs) and either machine room or office temperatures and humidity. If I recall correctly, that battery was installed when the old one failed the SU self-test. I think this battery was a genuine APC replacement. And I think the fan has been running since that battery was replaced. All three UPS's seem to work fine other than the fan issue. All three pass a manually initiated self-test.

Any suggestions/explanations? Thanks in advance.

Message was edited by: El_Kabong: Fixed a type and added the word "precise" to the second paragraph.

[Erasmus_apc]

The fans on an SU unit will run for the following reasons:

1. The UPS is on battery.
2. The UPS is charging the battery.
3. The UPS has a load greater than 75%.
4. The internal temperature of the UPS has reached greater than 140 degrees F (60 degrees C).

El_Kabong wrote:
I tried the serial port on one with the factory 940-1524C Smart Signal cable) and it returned a status of 33AC (is >it true that 8C means "normal"?). What does 33AC mean?

What did you input to the UPS to get this response? The unit does not report anything via hyperterminal without an input.

[Anonymous user]

Thanks (I saw that info earlier in search results). As I mentioned above the SU1400 I'm currently looking at is in an office environment, lightly loaded and passes the manual battery test so the only thing on that list I can't confirm is whether the battery is charging.

8C is supposedly the normal response for shift y zero which appears to be the SU's battery capacity estimate perhaps?

Message was edited by: El_Kabong: s/light/lightly/

[Techie_apc]

The Power Chute Business Edition software can allow you to view the UPS's internal temperature. This will help us to determine if the temperature is the root cause of the fan operation. It also allows you to view the UPS battery capacity and runtime. Please verify if the UPS runtime which is shown on the software is correct.

Please do not input any commands at terminal screen if you do not know why the Shift...command is used for. Entering a wrong value may damage the UPS.

[Anonymous user]

I have 2 SU1400s that exhibit the same behavior. Unit #1 wound up destroying its battery by overcharging (battery ruptured). I set that unit aside and haven't used it since last fall. Now unit #2 is beginning to show the same behavior.

Unit #2's battery is exactly 15 months old today so it's not new but it's not excessively old. According to the logs, there have been 11 power transfers since this battery was installed (most were 2-3 second blips; one was 21 minutes which I'd estimate brought the battery down to 60% charge). Add to this the automatic self tests that occur every 14 days. So all-told, this battery hasn't seen a lot of use.

I'm running APCUPSD as the power daemon. It reports currently:

BCHARGE : 100.0 Percent
ITEMP : 27.9 C Internal
BATTV : 27.9 Volts

So the temperature and battery charge and voltage appear to be okay? Yet the UPS' charging circuit appears to be wedged "on". The battery is very warm.

This is the same behavior that I saw with the other SU1400. Its battery got so hot that it was audibly sizzling when I disconnected it from the UPS.

Any ideas?

edit: I should have mentioned that current load is 19.2%

Message was edited by: jrmayfield

[Techie_apc]

hmm...If you have another working Identical UPS, swap the batteries between the working unit and the unit in question. Then, check if the UPS in question runs the fan always with the other good known batteries installed.

[Anonymous user]

Thanks, Techie. I borrowed a battery pack from an SU1500 to test. With the borrowed pack, the fan turns off after a few seconds just like it should. Turns out the old 15-month-old batteries were swollen to the point of leaking around the top (thank goodness for baking soda). I hadn't noticed this when I posted last night. So I guess it was a dead battery.

I'm curious though about what happened. The firmware was reporting battery voltage of 27.9V and 100% charge yet the charger was apparently still active. This suggests that either the firmware uses some other criteria for controlling the charger or the charger became "stuck" and killed the battery. Hopefully the former. Can you shed any light on this?

(Seems like the UPS should have some sort of failsafe that prevents the charger from overcharging a dead battery to the point of bursting. Perhaps by monitoring battery temperature...last night's battery was quite warm even though the it hadn't reached the point of audibly sizzling/hissing like the Unit #1's battery last fall).

Also, I'm curious about the reported battery voltage. The firmware was showing 27.9V for the bad battery. Is 27.9V too high? A scan through this forum turns up a message from August 2008 that says anything above 27.7V means the charging circuit is broken. Is this true? I'd hate to buy a replacement battery pack only to find out that the charging circuit has a fault.

Jimmie

[Techie_apc · Accepted solution]

As far as I know, APC Smart UPS 1400 Battery floating voltage is 27.4 Vdc(Approximately). Thus, the voltage 27.9 Vdc is no harm to the batteries. However, if the unit tries to charge the bad battery, the battery will become warm and possibly vent or swell. Did you replace the batteries with genuine APC Replacement Battery Cartridge(RBC)? Batteries can also be damaged if the environment they are used in is too warm.

Click on the below link to know the Smart UPS Battery Charger Technology:
http://nam-en.apc.com/cgi-bin/nam_en.cfg/php/enduser/std_adp.php?p_faqid=1516

You may review the Material Safety Data Sheet for the batteries which APC use. You can download the MSDS through the below document.
http://nam-en.apc.com/cgi-bin/nam_en.cfg/php/enduser/std_adp.php?p_faqid=564

My advise to you is that replace the UPSs with new Smart UPSs if they are pretty old instead of replacing the batteries.