Subject: [Shop-talk] Boosting a UPS?

From: Mark J Bradakis <[email-masked]>
Date: Sun, 27 Jul 2014 14:08:22 -0600

It is hot here in Salt Lake. I got a small fan for my office to help keep me cool.
I plugged it into one of the non-backup outlets on the UPS that powers the Team.Net
server. Now when I turn the little fan off or on, the UPS beeps a few times. Interesting.

It could be a sign that I need to replace the UPS soon. Maybe time for a mini fund drive?
I have also heard that one can increase the capacity by wiring normal 12 volt car, motorcycle,
lawn tractor, etc. batteries into the circuit. Anyone have any experience doing so?

mjb.

ps: About the only thing I remember from all the electrical engineering classes I took
     in college is that given enough current, any circuit element can be modeled as a fuse.
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From: "Randall" <[email-masked]>
Date: Sun, 27 Jul 2014 14:00:18 -0700

> beeps a few times. Interesting.

If it is a non-backed outlet as you say, then I think this might be more a symptom of problems on the supply side.  It shouldn't be
an indication that the UPS itself, or it's batteries, are worn out or nearing overload, since the non-backed outlet is connected on
the input side internally.  Most likely though, it is just the power fail detection in the UPS picking up the sudden drop when the
fan motor is first turned on.

> lawn tractor, etc. batteries into the circuit. Anyone have 

That would only get you increased run-time (meaning longer operation without AC power).  Almost always, the load that the UPS can
carry is limited by the inverter element (that turns battery power back into AC power).  Adding a bigger battery isn't going to help
that.

I have added run-time in that fashion, but only with a UPS designed to do so and only with batteries that were similar in
construction and capacity to the originals.  Wiring up a car battery would probably work (or two of them in series if your UPS runs
on 24 volts as the larger ones do), but you might need to provide for separate charging.

As a side comment, I've had several APC "consumer" UPS units now that appear to work normally right up until they are needed.
Passes internal self test and everything, but won't carry a load without AC input.  Not a battery issue, same symptoms even with a
brand new battery.  Didn't seem to be a bad power transistor either.

So, IMO, it is worth occasionally doing a full load test where, after making sure things are backed up and saved, you yank the plug
out of the wall and see what happens.

Randall

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From: Mark J Bradakis <[email-masked]>
Date: Sun, 27 Jul 2014 17:55:25 -0600

> fan motor is first turned on.

What I need to do is shut everything off for a day, move around some hardware, rewire a few things, etc.  But the beeping
did remind me I wanted to get a higher capacity UPS as right now only two servers are on it. I know it works because during
thunderstorms we get power bumps as tree limbs shake loose wires somewhere. They last a few seconds, maybe a minute.
Right now my monitor and the networking hardware are not on the UPS. I plan to get a 500 - 700 watt unit in the near
future and run its AC supply right from the breaker box.

Yep, RealSoonNow.

mjb.

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