I agree with everyone. I maintained and repaired Toshiba UPS Systems for several years and would bet the mortgage on batteries. Depending on a number of factors (float voltage and ripple, environment temperature, how many cycles, how deep the discharge, etc., etc.) best case expect less than 5 years, the big boys watch VRLA's closely, especially after 3 years and will change them entirely after 3-1/2 to 4 years. VRLA float voltage is maintained at approx 2.25 volts per cell or about 13.5V. They should both be reading close to that immediately after you pull them out, within a few percent of each other - first clue. What's happening is that, under load, the battery voltage very rapidly drops to the level where the UPS shuts itself down (low battery cutoff). This is a protection such that batteries can't be depleted too far which will ruin them and is happening so fast you don't realize what's going on. Headlamp bulb is a good idea, monitor the voltage, put some kind of 5A or so resistive load on a battery. It should drop to a value around 12V, then very slowly decrease with the rate accelerating with time. I suspect you will see it immediately. Make sure to clean the fan if there is one!. A cut-sheet of a VRLA battery will show you what's going on Almost assuredly the batteries. Data sheet of a VRLA battery from a safe site: https://www.farnell.com/datasheets/612553.pdf
On Fri, Jul 15, 2022 at 4:40 PM Allen Brier via BVARC <bvarc@bvarc.org> wrote: > I have a Cyberpower UPS that’s been working great for several years. I > noticed yesterday that when I had a power glitch, it died immediately. I > took it out of line and put it on my bench with no AC input. Power up and > it says it has plenty of capacity, (no AC input) but when I add a small > load to it, it dies completely. I took the batteries out and they show > 12.72 and 13.03 volts respectively. I have no way to load test the > batteries properly. > > > > Any ideas? > > > > Allen R. Brier N5XZ > > 1515 Windloch Lane > > Richmond, TX 77406 > > 713-705-4801 > > > ________________________________________________ > Brazos Valley Amateur Radio Club > > BVARC mailing list > BVARC@bvarc.org > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > Publicly available archives are available here: > https://www.mail-archive.com/bvarc@bvarc.org/ >
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