Multiple older BACK-UPS models clicking from noise

[Anonymous user]

A few weeks ago in our office some of the BACK-UPS ES units would click, go on battery for a second, and report electrical noise. This began happening with increasing frequency. I replaced a couple of the batteries with new OEM ones, and thought that would do it. I also turned down the sensitivity, which made no difference. Increasingly, however, the clicking began hitting two, three workstations on separate models of BACK-UPS ES units (350/550/750) sometimes dozens of times a day. On other days, none of these would click.

We called an electrician in and they could not find anything wrong with the circuit these were on.

Finally today, after dozens of clicks and battery interruptions from electrical noise on about five different workstations to the degree that the owner's PC shut down three times, I began to detect a pattern: Users with the newer, darker and rounder model of BACK-UPS ES were not clicking at all. If I plugged in an older model with a brand new battery into their same plugs, however, those older models began clicking and dropping to battery for a second (regardless of whether they were running the PC software or not).

I am skeptical that these units could have separately suddenly become defective, but it looks like we have to replace at least eight of them. I plan to take one home tonight to see if it clicks.

Can anyone theorize why they think this suddenly happened over the course of maybe four weeks with increasing frequency? We did not add any new power-hungry devices and we are not aware of any circuit problems, although I suppose that could still be a possibility, and the newer UPS models are able to withstand it better. Any ideas?

[BillP]

By any chance, do you have any knowledge if there is some kind of electrical work being done in your area? Did the electrician checked the input frequency that is being fed into the UPS as well as the total harmonic distortion of the circuit? These two can cause the UPS to switch from Online to On Battery operation. It is possible as well that the device that is responsible to detect electrical noises has worn down already.

Let us know what you will experience with the unit that you are planning to take home.

[Anonymous user]

Hi, the unit I took home did not click onto battery at all. I took it back to the office the next day, plugged it in, and have not heard a single click in 24 hours.

We are baffled. While I only have two of the older models plugged in, neither has clicked once in 24 hours.

It could be one of the old units was somehow causing the electrical noise and that set off the older units. But it's not happening now.

We do have a solar array on our roof and have had it for years and I wonder if somehow that might not be the culprit, again the theory being these newer UPS devices have better tolerance.

I will update this thread if we make any discoveries.

[Anonymous user]

I wanted to update this issue. We worked with a local electrical company and it would cost us $4,000 to monitor our power lines. We declined to do this because the issue was isolated to older APC ups models. Our building uses solar power and it appears that these older units are not fit for solar power, period. There really is no other explanation because a) newer APC units do not have the problem, and b) the older units which have the problem in the office do not have the problem anywhere else, like our employee's homes.

So logically speaking, we need to replace all of our older APC UPS units. It would be nice to get an acknowledgement from APC that this is indeed an issue, but we don't want to to invest the time into that if they don't already know it.

[voidstar_apc]

>
...it appears that these older units are not fit for solar power, period. There really is no other explanation because a) newer APC units do not have the problem, and b) the older units which have the problem in the office do not have the problem anywhere else, like our employee's homes.

It would be nice to get an acknowledgement from APC that this is indeed an issue, but we don't want to to invest the time into that if they don't already know it.
>

It seems likely that your site has a power quality issue if the old model UPSes work fine in employee homes yet report electrical noise on-site. Unfortunately we don't know what is causing the noise, save that it appears to come and go.

Electrical noise can cause nuisance trips in any line-interactive design, including your newer BackUPS, because electrical noise can appear to be the beginning of a power outage. However different designs make slightly different decisions, so what causes one to trip may not cause the other to trip, and vice-versa.

Ideally, APC recommends fixing the source of the noise. Otherwise you can try lowering the sensitivity on UPSes that support it (I don't think your BackUPS does).

[Anonymous user]

I had the exact same problem at same time. was out of the country end of January 2013 and returned Feb 4 to find two of my APC units clicking. APC Back-UPS NS 600 tag BN600 ser 3B0635X89379 and another just like it. I have several APC units at home and in my office.
Other APC units are working fine. All attempts to get them up, changing battery, letting them charge etc, doesn't work.
So far I moved other APC units in to replace them. Opened up one unit and found nothing burned out that is visable.
One much bigger unit ( two batteries) at the office also went crazy, turns out one battery was no good. Replaced batteries and that is working ok now.

Not sure whats going on with the NS 600 units. There was a power fail while I was away. will probably buy new units to replace them since paying for repairs is not work it. But it is interesting that a bunch died at the same time. Almost as if there is some kind of kind that just times out. Would really like to get APC to give a straight answer to problem.

Also when one unit starting clicking it would cause the other unit to click. The click is the unit appearently going into and out of battery backup. Probably not good for the computers hooked up to these.

drwass2

[Anonymous user]

I put a scope on the line and it looks ok.
I wonder if some kind of CODE in the APC hit a timer wall of some type. like the Y2K problem.
At all started in Jan 2013 !!!!!!!!
I really think APC should take a good look at the problem.
Buy the way, the output signal when running on battery is square wave, nothing like a nice sine wave.
Unit seems to be in battery back up and clicks to line for a very short time (< 1sec) then goes back to battery.
What ever it is looking at to decide is in error.
drwass2

[Anonymous user · Accepted solution]

I know this thread is already a couple of months old but I hope it helps someone.  The clicking problem is a common one especially with an older UPS (more than 3 years old).  Changing batteries and lowering the sensitivity settings are only a temporary fix if it even helps at all.  The real problem is the surface mount electrolytic capacitors on their circuit board are notorious for going bad (electrically "leaky", lowered capacitance, and high ESR) which plagues many electronic products. 

We usually have at least one UPS fail in our office every time we have a power outage, brownout or power fluctuation at our campus.   I got sick of buying replacement UPS units so often so I started fixing them myself.   If you are an electronics technician like I am or a good DIYer with a soldering iron, you can attempt to fix them yourself at your own risk.  I have had 100% success rate at fixing them just by replacing the capacitors.  The plastic case is hard to pry open.  Remember to unplug and remove the batteries and discharge the big power supply caps on the circuit board first before working on the unit, some of them still hold a good charge even after the unit is unplugged from the wall for while.  If you don't have an ESR meter or capacitance meter to check the capacitors, just replace all the surface mount electrolytic capacitors (mostly 22 uF and 10 uF) with radial type electrolytic capacitors of the same capacitance and voltage (or slightly higher voltage).  Don't forget to watch the polarity of the caps when installing new ones and make sure to angle the radial caps (flat) for more clearance for the battery compartment.  There are about a dozen of these capacitors in most of the units I worked on.   Only about 4-6 of them really need changing though but when in doubt, just change all of them especially if you don't have test equipment.  The caps cost only a few cents and will you save you over $100 bucks buying a new UPS.