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Re: UPS as backup power

[Giancarlo did some experiment on an APC Backup-UPS
ES-350 rated at 350VA/200W]
My second test was more successful, the unit ran the
filter alone for 12 hours before I gave up waiting for
the thing to die and stopped the test myself and whent
to bed. In all I think it's safe to say that even
these cheap units can do a good job at keeping several
filters running during blackouts. My tanks are all in
the house and we rarely have a temperature problem
during blackouts so this works for me.

[Vallo replied]
The centrifugal pumps in the filters are rated at
~10-20W, so this isn't surprise to me at least.

Thanks guys this is most interesting.  I have plans to
hook a 350VA or 500VA to my Eheim 2028, but didn't
know 1) if the stepped sine wave would work, and 2)
how long it would run for.

My research tells me for some reason, the load vs
runtime is not linear.  For example, the chart for
ES350 (BE350U) at the APC website says:


load=200W, runtime=2 min
load=100W, runtime=8 min
load=50W, runtime=21 min

So I thought a filter at 20-25W would only run 60min
max.  But you have gotten 12+ hrs!  This is very good
news for some of us.

Maybe an EE guru can explain why.  My guess is, it has
to do with 1) Wattage rating on many equipment are
peak values so the actual consumption varies & is much
lower, 2) the UPS has to invert DC back to AC so maybe
the higher the load the less efficient it gets.

Either way the verdict is clear: try minimize the load
you put on the UPS to what you consider critical
components only.

A friendly reminder: Since most UPS use Lead-Acid
batteries (ie a car battery), logic tells me you
should keep it fully charged at all times & shouldn't
do too many of these "full drain tests".  Or you may
significantly shorten it's life & capacity, just like
if you leave the car lights on far too many times. :P

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