BX900R acting strangely with new battery, GRN and YEL LEDs blinking

[Anonymous user]

Last week this unit began beeping and the RED "Replace Battery" LED was lit so I ordered a new replacement from APC. While installing the battery I noticed:

1- a slight arcing as the final battery connection was made

2- the fan began running immediately with no AC power.

The fan was obviously running on battery power and I assumed that was the power drain that caused the arcing when connecting the battery. I then plugged the unit into an AC outlet and after a few minutes I heard some relay chattering. It sounded like a small relay and not the clunk you hear when a backup switchover occurs. The chattering was intermittent and stopped after a few minutes or so. I assumed the new battery's charge may have been low initially and it had now charged sufficiently to exceed some threshold related to charging characteristics. I didn't see or hear any other problems so I let the unit continue charging while monitoring the battery voltage (measured about 25.3 to 25.4VDC).  Sometime later I noticed the front panel GRN and YEL LEDs were both blinking about once per second or so. I checked the user manual and found no mention of this particular LED code. Also it appeared the battery voltage was dropping slowly and I waited for a while thinking this might be some kind of extended battery condition test but after several hours I decided this was probably not the case (battery voltage dropped to about 24.5VDC or so) and I disconnected the AC plug and the positive battery connector. I reconnected the battery, connected to AC and this time I heard no relay chatter but after a while I saw the same pattern on the LEDs. This pattern repeated itself several times but right now everything is reconnected and the fan is running but so far no LEDs are lit or blinking. I put everything back in the case so I can't read the battery voltage to see if it's charging or being discharged. I guess I'll know eventually if the battery runs down. Otherwise, after the recommended charging time, I'll test it with a load attached.

Does anyone know what this all means?

BTW, I replaced the battery about two years ago and for the first time went to a Batteries Plus for convenience. They claimed to be fully certified by APC for replacement batteries but I was surprised their battery only lasted 2 years (very light duty too, this UPS protects only  network modem, router and a Magic Jack Plus). The battery had also leaked a bit which was very unusual. I have quite a few APC UPS's here and have always used APC batteries in the past. I usually get 4-5 years of service and have never had a leak before. So either I have learned a good lesson here or maybe the problem is actually this UPS. I hope that is not the case since I just spent about $100 to get this new battery from APC!

[Anonymous user]

Talk about an (apparent) stroke of luck! I was about to reassemble this thing and shelve it but I took one more close look at the main PCB and on the back side I noticed one small solder pad that looked corroded. I used a magnifier and saw what appeared to be a tiny corrosion trail between two solder pads so I cleaned that area carefully an removed all traces of residue. Maybe is was a bit of the leaked battery fluid but it's hard to see how it could get on the PCB since the battery is below the PCB in normal use. Perhaps it dripped through a crack while I was exchanging batteries. At any rate I thought it was worth a try so I reattached all the wiring to the PCB, connected an ammeter and voltmeter and reconnected the battery. The difference was profound in that:

1-  there was a much small arc when the battery was connected, and

2- the fan did not run.

Also I noticed no current was flowing from the battery so this was looking pretty good. I then plugged in the AC and heard the familiar click of the relays. The fan began to run and charging current appeared. After a while the battery voltage settled around 26.3VDC and the charging current dropped to around 150mA. Then I pressed the Power button and the unit went through its normal power-up sequence and ended in the normal fashion with the GRN LED lit. Perfect! I'll check it tomorrow with loads but I'm pretty confident its working just fine again.

So the main problem may have been the Batteries Plus battery that failed and leaked. Just one tiny drip happened to fall in the wrong place and caused all this trouble. Maybe it was just bad luck but I think I'll be staying with genuine APC batteries from now on. As I mentioned previously I have always had decent lifetimes and never had a single leak when using them.

Just wanted to report the good news and possibly help someone with a similar problem someday. I still wish service info was available though.

[Anonymous user · Accepted solution]

Well it's beginning to look like another hopeless case. Today it seems to power-on and immediately go into backup mode, YEL LED lit and occasional beep. The backup portion seems to work fine, it's just not seeing the AC input, charging the battery, etc. I did check the main breaker and it's fine. Very frustrating since this is not the first time I've had to abandon an APC UPS due to a lack of service information and repair/trade options that exceed the cost of replacing it altogether. Assuming that I pulled out the main PCB for inspection and can see no signs of distress anywhere, no burned components or even any evidence of overheating anywhere on the board. Most likely it's a simple problem which could be easily fixed. Here I am with a complete shop/lab full of test equipment and TH/SMT rework tools but there's no way to justify the time and effort required to investigate further without a proper schematic or test procedure. Like I said, very frustrating.

I just can't stand throwing this stuff away either. Being an EE and R&D guy I'll probably put this one on the shelf (with a few other similar cases) just in case some of the internals might be useful someday. Doesn't make me happy though. APC seems to be a good brand overall but their support has always been lacking in this area and it does annoy me. So many of these things end up in landfills for no good reason and I don't feel like adding to the burden. At this point I may investigate splitting apart this new battery pack for use in a spare XS1000 I happen to have sitting around. Hopefully that will save the cost and hassle of trying to return or exchange this new battery.

Does anyone know if a board swap would be possible (at a reasonable cost of course)?