On Fri, 30 Aug 2019 13:56:09 +0100, "NY" wrote:

"T i m" wrote in message
.. .
First rule of any UPS is to check periodically that the battery is holding
its charge, and to keep the battery charged. My wife bought a UPS when she
bought a PC about 10 years ago, and we never got round to connecting or
testing the UPS for about 18 months, by which time it was out of warranty.

And flatter than a pancake I suspect?

I think the best analogy would be a bucket with a huge hole in the bottom so
it won't hold any water.

That also works. ;-)

With hindsight we should have kept the UPS and bought a new battery for it,
rather than chucking the whole thing in the skip.

But why ... ;-(

I've had to partly disassemble a UPS before to get the swollen /
corroded batteries out and the UPS itself has always been fine. ;-(

But then that may have
been money down the drain if the problem was a faulty charging circuit or a
faulty DC-to-AC inverter.

True, but nothing you couldn't have tested initially with just a
voltmeter?

If I'd still had my oscilloscope I'd have looked at the output to see what
shape of waveform was being generated and how it varied as load was applied.

Well, that could have been step two (after proving it was working in
general) and if it worked then I'd suspected it would do what it was
supposed to do? Nothing wrong with making sure of course.

But that had gone to the skip a few years earlier as I never used it - and
it was bloody big and heavy to store in the loft.

I have bought several second hand UPS's very cheap because they were
fitted with known dead batteries because I can usually cover the cost
of the UPS with the scrap value of the batteries. ;-)

I remember buying it from
a back-street Army surplus shop somewhere near Cemetery Junction in Reading
soon after I got my first job.

Not something I would expect to see in such a place.

Cheers, T i m