Smart-UPS 1400 fan recently started running all the time

[Anonymous user]

This device has been working well for a long time now. After a power outage last week, the fan is always running now. It only used to run the fan when it was charging or during a power outage or once every 2 weeks. I have left it running for over 48 hours and the fan is always running and never shuts off. I've tried different outlets and it doesn't make a difference. It doesn't make a difference if there is a load or not. The battery lights show that the battery is fully charged and the power light shows that the power is correct (not over or under). The load lights are not illuminated at all. The incorrect wiring light is not lit. The right sensitivity light on the back is lit, but not the left sensitivity light. I read another thread on this forum where they suggested that it could require servicing but there were other alternative tests that were mentioned but not elaborated on. Does anyone have any details on this? The device is in use in my home office so it's not okay for the fan to run like this all the time.

[BillP]

yeah, on this particular model, the fan should only be running if one or more of the following are true:

-UPS is on battery
-UPS is charging the battery
-UPS has >75% load
-UPS internal temp goes above 140 degrees

It seems like you've checked the basics. do you have software monitoring the UPS? you said all fiver battery charge LEDs are on indicating the battery is between 95-100% charge or whatever it is. one thing that comes to mind is perhaps the battery charge is stuck at 98% or 99% so its keeping the fan on so we could double check that. then we could double check the internal temperature of the UPS.

so if you can, i would want to install powerchute business edition with the appropriate APC serial cable which is required if you havent already. the cable should be 940-0024 or 940-1524 which is engraved on a connector.

you could also try to braindead the UPS if possible but i am not sure it will help.

to do that:

remove any communication cable if you already have it connected
turn off UPS load if present
turn off UPS and unplug from AC power
hold down the off (o) button until you hear an audible click. the fan should also go off at this time. if it doesnt, try to disconnect the batteries and leave it sitting for 8 minutes or so to achieve the same purpose.
reconnect everything and see if the fan is still on after a minute or two

[Anonymous user]

How old is the battery? The controller in SU1400NET turns on the fan when current flowing into the battery exceeds a set amount. After the battery is fully charged, the batteries are held at a constant voltage, which is around 27.6v for this UPS. There is a "leakage current" that will always flow through the battery and this increases as the battery degrades/ages.

It could be that the leakage current is now above the threshold of the fan trigger.

[Anonymous user]

i downloaded the business edition power chute software and connected a serial cable (not the official one, just one i had lying around). The software detect the UPS. I set it manually but it doesn't detect anything. It is doing something because if I stop the apc service on my computer, then the ups shuts down. I tried changing the signalling to simple signaling (and simple w/ interface expander) and those work a little better but they're backwards. When the serial cable is plugged in, the software tells me that the ups is on battery power (which it is not) and when I unplug it, it says the ups is online! I also tried "brain deading it" which didn't work/

[Anonymous user]

this is probably an old battery. i bought it on craigslist from a guy sold his server farm. Is there a way to test if the battery is leaking current with a multimeter? I have to say that when the power went out, it lasted for about 30 minutes so it seems like the batt is good. Also, should the ups tell me if the battery is going bad?

[BillP]

i can say the UPS will illuminate the replacement battery LED when the amount of voltage drop, when compared to a chart inside the UPS, is out of range against a certain load.

[Anonymous user]

that replacement LED is not eluminated

[BillP · Accepted solution]

I'm also in the "old battery" camp. It's also possible that in addition to the leak current described by KVAr, the battery could be in the early stages of thermal runaway - getting warmer and warmer. This could be helping push the temperature inside the UPS near the point where the fan would operate.

Just an idea. Might not be a bad idea to simply crack open the case while the UPS is online and pull the battery out a bit. See if it feels warm or is starting to bloat. Better to catch and replace a hot battery now than to allow it to get stuck inside the case.