On Fri, Mar 3, 2023 at 7:54 AM Roger Heflin <rogerheflin(a)gmail.com> wrote:
[...]
If you read about normal UPSes they are not normally designed to run
100% duty cycle (ie on battery for days, or fixing up a low voltage
for days). So if you run yours at say 40% load it will probably
survive under the higher duty cycle, but if you run it close to 100%
load and it gets into cleaning up low voltages the UPS electronics may
not survive long (ie if fixing the voltages for hours/days).
So if they end up running in that state for long periods of time
(either because of adding bigger batteries--my UPS came with 12AH
batterys but now has external 35AH ones) and/or extended low voltages
various components may burn out.
There is also a setting on at least some UPSes that you can change so
that it does not regulate the lower voltages (wider acceptable voltage
range) and accepts those voltages as ok. I have done that with both of
my UPSes because the default setting prevents the UPSes from charging
when on a small generator, and would if the voltages was low but still
good enough cause the UPS to keep fixing the slightly low voltages and
possibly burn out.
I don't think the part about a generator is a good idea. Generators
are usually wildly out of spec for Total Harmonic Distortion (THD). A
generator under load can easily reach 15% to 20% THD. Meanwhile,
electronics usually expect 3% THD or less. So you want the signal
conditioned, and not passing directly through to the electronics.
Jeff