Symmetra 16000 shows fuel level 0%, batteries are all charged

[BillP]

We have a Symmetra 16000 running at 83% load. Recently we noticed that the fuel % level was slowly dropping, even though there weren't any power events recorded. We talked to APC, and they said we might have a bad battery. We tried pulling the batteries and measuring the output voltage on the battery modules, and they were all about 135v. When we put them back in, though, it said the fuel was 0%, and it has very slowly gone up to 5%. Any ideas what might be going sideways?

Message was edited by: ssp2pro

[BillP]

have you replaced these batteries recently? in general, yes sometimes a faulty battery that is leaking current can discharge very slowly and the UPS will see this and you'll see the charge drop slowly cause it thinks its on battery. it also usually indicates on the powerview front display that the UPS is on battery.

do you also see the on battery LED illuminated on the front display? also, do you have any external battery frames attached?

[BillP]

The oldest battery pack is 14 months old, no external frames. We do have another Symmetra 16000, and we swapped battery packs with it. The other Symmetra showed 99% charge immediately, while the first Symmetra showed 9% charge on batteries that were fully charged.
We then waited about eight hours, and the unit was jumping between 7% and 10% charge. We put it in manual bypass and did a hard reboot of the ups. It came back up showing 8% charge. We noticed we had two green lights on the master control module, so we unclipped the display on the front, in order to be able to take the plastic cover off to get a closer look. When we plugged the front display back in, it showed 99% charge. Any ideas why?

Message was edited by: ssp2pro

[BillP]

did you replace the enter SYBATT module or the batteries inside it? Depending on that answer, I can elaborate a little more on additional possibilities.

[BillP]

Well, it's happening again. The fuel level is slowly going down.
Yeah, we swapped one SYBATT with a SYBATT from another Symmetra 16000 unit we have.
I think we're going to try swapping the two panels on the units... hope it doesn't break anything else.

[BillP]

is the "on battery" LED illuminated on the powerview?

[BillP]

Well, we tried swapping the powerview panel, and it didn't make a difference
Nope, battery light is off.

[BillP]

Vin : 204.4
Vout: 209.0
Iout: 42.7

Load w/o redundancy: 83%
Load n+1 redundancy: 82%

Freq.in : 60.00hz
Freq.out: 60.00hz

Batt V: 134.9
Batt Cap: 78%
Runtime: 00hr 06min
No. of Batts: 4
No. of Bad Batts: 0

[BillP · Accepted solution]

Well, we pulled the batteries out one at a time, and they all measured ~135 statically. And then, when we rebooted the UPS, it went from 7% charge to 98% charge -- which tells me that they weren't actually discharged. Does anyone know where in the unit it finds that battery voltage? I wonder if it's being mis-reported.