UPS diagnosis help

[Veketti]

Dear All,

I’ve got six years old UPS device Eaton Ellipse PRO 1600 with original batteries which I noticed in recent power outage shut down immediately with the grid. Load is only <60W and when I tried to power it back on, it fails to do so. Even without load it won’t turn on, it tries, but immediately shuts down. It has display and when it is connected to grid, it shows battery is full and runtime 83 minutes with that ~60W load.

It has two 12V lead acid batteries in series and as I have electric load, I tested with CC 1A load I got following figures:
Battery 1: Starting voltage 13.1V. Immediately after load applied voltage drops to 11.3V.
Battery 2: Starting voltage 13.26V. After two minutes 12.41V where the voltage drop pretty much stabilizes.

So my bet is the battery 1 is dead. But I don’t want to risk spending big money on new batteries and find out that the UPS itself is defective (I’ve had one APC UPS die already). So the question is, is this big enough proof that the culprit is the battery?

edit: feels bit odd, that is it really so that these just measure voltage of the battery and don't do any self test with load to diagnose battery health. Am I expecting too much even though this is Pro version?

Thank you in advance

[kripton2035]

I've changed a LOT of batteries on UPS (mainly eaton because it is what we sell the most) and the UPS is like new
an entry level battery is around $25-$30, and a better one around $50
for a 1600VA UPS it is worth the money.
what is to look for is the battery internal resistance, it must be below 1 ohm otherwise the battery can be considered as dead.

[Veketti]

Ok, so in this case as the load was 1A, the internal resistance of Battery 1 is 1.8 ohm and battery 2 = 0.85 ohm

Is it normal that the UPS will not turn on without load considering these battery conditions? And the second question is, is it normal that the internal diagnostics can't recognize this weak battery? I'm after that the device itself sounds to be ok or not?

[kripton2035]

even if it is labelled as a "PRO" model, no it does not detect a weak battery state, and yes it should be able to ...
yes when one battery is weak, the UPS simply does not turn on.
it should IMHO display a "change battery" on the display ... but it doesn't !
to make you buy another one ?

I also had once an online pro version, $1500 UPS (from eaton also) that went battery weak, and did not display anything too
but the batteries were specific one  very difficult to extract, and around $1000 to replace, not worth it.

[Veketti]

Great, thanks. I'll get tomorrow from local battery supplier Yuasa NPW45-12 -batteries as they seem to have those on shelf.  Fingers crossed.

[cruff]

I have an old APC 650 VA UPS that won't even respond to the control panel if a battery isn't connected. Apparently the control board is run from the battery voltage.

[Veketti]

Installed new Yuasa NPW45-12 batteries and it works wonderfully now. That cost me 80€, hope it lasts another 6 years.