Replacement UPS on order

I own a CyberPower Value1500ELCD, rated at 900W, I think purchased in 2018. Still on the original battery, actually two batteries, each lead-acid 12V 9AH, wired in series. The mains power dropped out for a few minutes recently, and the UPS did its thing, so the batteries are still working.

Now here is the odd thing...

Being ultra safety-cautious, I always turn off the computer, then the UPS, then the mains switch. When do the reverse, flick the mains switch on, then press the UPS button, wait a moment, then the power button on the PC. The new "event" now, is my PC makes a loudish noise, the fan runs for a moment, then turns off, then a few seconds later the fan starts again and there is normal bootup -- except that the date in the CMOS has reset to January 1, 2017. This is happening everytime.

Yet, if I turn off the PC and UPS, but leave the mains switch on, next time turn on the UPS and PC, it starts up correctly.

At first I suspected the button-cell lithium battery on the PC motherboard, so replaced that. No difference.

Then I noticed that the UPS case is very hot. Under normal operation, the UPS will just be doing pass-through of the mains, and should be cool. I removed the UPS entirely, now running without a UPS, and my PC starts up as it should, perfectly OK.

I opened up the UPS and noticed that the batteries are hot. That indicated to me that the batteries are being over-charged. So maybe the batteries are failing, though as observed in recent power outage, they do still work. Right, so looked up the price of 12V 9AH batteries, AU$39.95 each from Jaycar, a local shop:

https://www.jaycar.com.au/12v-9ah-sla-battery/p/SB2487

...80 bucks, when I don't even know for sure if the batteries are the cause of the fault!!!

Looked on eBay, saw lots of cheap UPSs, and ordered this, CyberPower VP700ELCD, for AU$149 including delivery. Paid an extra AU$5 for express delivery:

https://www.ebay.com.au/itm/334624152827

OK so it's only 390W, but enough to run my PC and monitor. Doesn't say, but probably has just one lead-acid 12V 9AH battery -- that's what most of the budget UPSs have.

Yeah, that's the way it is, simpler just to buy a new UPS, rather than attempt to fix the old one. As an electronic engineer, in my younger days I would have kept the old UPS for spare parts -- lovely heatsinks in it -- but now, the batteries are going to a local battery-recycling bin and the rest of the UPS into the trash. Which is a shame.    

Tags: tech