Down in the Data Shed, all those computers are consuming power. And, of course, I use UPSes on them, so that if there's a power glitch, I don't get a load of reboots.
One of my three big UPSes (made by APC) has had a red light for some time now, and I don't know what it means. Also, it's been beeping plaintively, but only occasionally. Another one is running at 50 degrees C, which is hotter than I think it should be. So today, I spent some time sorting out power problems.
I ordered eight 12 volt batteries, and I used those to replace the dead batteries in an old 3000 watt UPS that's just been sitting doing nothing for a while. I connected it all up, and there was a flash and a bang, and I knew that this wasn't good.
So I got another old 3000 watt UPS, and put the batteries in that, and ther was no flash, and there was no bang, and it was good, and I saw it was good. Good it was.
Then I had a bit of a think, and there's some computers that don't really need to be on all the time. I mean, if there's a power cut and they go down, nothing terrible happens. So I put them directly onto the main power.
And now I have four big UPSes, and I redistributed the load so that they're only passing two or three amps (they're rated for 13). The red light has gone, it's looking good.
Encouraged by this, I dismantled two more UPSes, made by BPC (I have six of these). I can see what sort of battery they need, 12 volts 12 ah, and I can get a set of four new batteries for £70. But then I thought some more, and I decided to get another set of eight batteries for the APC that didn't go bang.
I also have a small (650 va) UPS that's been sitting in a rack for ages. I took that apart, and that also uses a 12-12 battery. So I bought one of these (they use them for mobility scooters and the like) for £17, and I'll rescuscitate that UPS.
By golly, those lead-acid batteries are heavy!