SUA750XL with new batteries: ran then lost calibration - what to do next?

[Anonymous user]

I recently replaced the batteries on my SUA750XL. It charged up to 100% but had the "blinking charge level" indication, and showed estimated runtime = 0, which I know mean I needed to do a runtime calibration. I let it charge overnight.

Since I am using Linux (trying both nut and apcupsd) and use a USB cable, I couldn't find a way to run a soft calibration. (If there is a way, I would like to know it). So I did a "hard" calibration, by removing the server, connecting 250W of light bulbs (=40% load), pulling out the power, and letting it run to exhaustion - which took about 50 minutes. Then I plugged in to mains with no load and let it charge up to about 50% or so, and then added my server (which is about a 20% load). At that point it was still charging but showed a reasonable expected run time (I think it was well over an hour). So far so good.

Unfortunately I did something I was about to regret: I started a self-test (from the panel). The charge level which had been around 50% dropped to 0 instantly, the estimated runtime returned to zero, and the server shut down. When I brought the server back up, I found that it still showed 0 runtime (and was blinking again!) - i.e. it lost the calibration. It charged back to 100% but alas still was blinky.

I disabled the server software and pulled the mains. As expected, it powered the load just fine for several minutes, i.e. it had plenty of battery capacity. I plugged it in again, and now it shows 3 minutes runtime - about the amount of time I had unplugged it.

So finally, my questions:

- while it was recharging, was the calibration still considered "in progress"? and did hitting the self-test cancel it? do I just need to do it again and not screw it up this time? (i.e. let it charge all the way to 100%)? or does it sound as if something else is wrong?

- if I do need to rerun the calibration, how much damage am I doing to my brand-new batteries to cycle them twice in a couple days? if it's bad, is there any reasonable alternative?

I guess what I'm worried about is that I will re-run the calibration, then lose it again at the next self-test, because I am doing something wrong.

Thanks!

[BillP]

Did you try running another self-test after it reached 100% capacity? I honestly haven't seen what you've experienced before as it's always recommended to run a test at full capacity (though you already seem to know that now!), so odd behavior isn't surprising, though I can't really explain this one, either. Running a self-test should not clear the results of the last complete calibration, though like I've said, I've always waited until after it reached 100%. Maybe attempting that test made it incomplete.

You might need to run another calibration, but honestly, if you know you're actually getting plenty of runtime, you could probably just leave it as it is rather than run another. Like you said, that'll definitely put some decent wear and tear on the batteries, and who knows, it might fix itself when the next power outage or self-test comes along...

Also, that bar graph is only flashing because you're within 2 minutes of the low battery duration. By default, the low battery warning is at 2 minutes, so it thinks you have less than 4 minutes of runtime. If pulling the plug for a couple of minutes upped the runtime to that duration, pull it for 5 minutes (low battery warning + 2m) to at least make it stop flashing.

I'd try that self-test, assuming you haven't already, and see if it makes a difference.

[Techie_apc]

Hi Larry,

Do you have the Serial Cable that came with the UPS? If so, I would recommend you to call in the APC Customer Care Center in order to verify the Battery Constant value of the UPS, and adjust the battery constant in case if it needs to be changed. I hope that it will take care of everything.

Have a nice day!

:)

[Anonymous user]

Battery charging is complete when power consumption plateaus out. Not when it indicates 100% charge, so charge 24 hours, then...


Sometimes, APC UPSs don't like seeing voltage between ground and neutral. From my experience, it works better to cause an outage by interrupting just the hot, which can be accomplished by using a power strip with a switch. Let it fully charge, load the UPS to about half the load, then turn the switch off on the power strip. The neutral and ground remains fully connected to the building electrical system.

[MarkGinger_apc]

I am with Techie on this one. If you know the batteries are good, they hold charge, you just need to adjust the constant. If you don't know the constant off hand, give APC a call and they should reveal it to you. If they don't, post it in this forum and someone will. Changing the constant will adjust the run time to spec.


If you don't have the serial cable, you might just have to go with another calibration. Sometimes they're stubborn and require several calibrations to make it stick.

[Anonymous user]

Charge overnight, then discharge until it shuts off
Charge overnight and if then, run self-calibration

If that doesn't work adjust the constant over serial port in PROG. Ask APC for the specific value to use

Message was edited by: KVAr

[Anonymous user · Accepted solution]

I recently replaced the batteries on my SUA750XL. It charged up to 100% but had the "blinking charge level" indication, and showed estimated runtime = 0, which I know mean I needed to do a runtime calibration. I let it charge overnight.

Since I am using Linux (trying both nut and apcupsd) and use a USB cable, I couldn't find a way to run a soft calibration. (If there is a way, I would like to know it). So I did a "hard" calibration, by removing the server, connecting 250W of light bulbs (=40% load), pulling out the power, and letting it run to exhaustion - which took about 50 minutes. Then I plugged in to mains with no load and let it charge up to about 50% or so, and then added my server (which is about a 20% load). At that point it was still charging but showed a reasonable expected run time (I think it was well over an hour). So far so good.

Unfortunately I did something I was about to regret: I started a self-test (from the panel). The charge level which had been around 50% dropped to 0 instantly, the estimated runtime returned to zero, and the server shut down. When I brought the server back up, I found that it still showed 0 runtime (and was blinking again!) - i.e. it lost the calibration. It charged back to 100% but alas still was blinky.

I disabled the server software and pulled the mains. As expected, it powered the load just fine for several minutes, i.e. it had plenty of battery capacity. I plugged it in again, and now it shows 3 minutes runtime - about the amount of time I had unplugged it.

So finally, my questions:

- while it was recharging, was the calibration still considered "in progress"? and did hitting the self-test cancel it? do I just need to do it again and not screw it up this time? (i.e. let it charge all the way to 100%)? or does it sound as if something else is wrong?

- if I do need to rerun the calibration, how much damage am I doing to my brand-new batteries to cycle them twice in a couple days? if it's bad, is there any reasonable alternative?

I guess what I'm worried about is that I will re-run the calibration, then lose it again at the next self-test, because I am doing something wrong.

Thanks!