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Archiver > TMG > 2003-06 > 1054820704


From: Darrell Martin <>
Subject: Re: [TMG] Comment on UPS
Date: Thu, 5 Jun 2003 09:45:06 -0500 (GMT)


Greetings:

Two more comments, or comments on comments [grin].

First, whether your laptop battery will act as a UPS depends
on a few things, but a fairly new battery in good condition
in a fairly new laptop will almost certainly be fine. The
recommendation about using a surge suppressor anyway is a
good one. If you have very large numbers of "power events"
where you will be using your laptop it would probably be a
good idea to get a small UPS *anyway* and plug the laptop
into that. That's the "belt and suspenders" ("belt and
braces" to some) approach.

Second, there are two basic types of UPS's when it comes to
whether they have to "switch" to battery power. The idea is
very simple, but the terminology may differ. Some UPS units
will only switch from line power to the battery when certain
conditions occur. Typically, there is a voltage range that
is considered "acceptable", by which is meant that the UPS
can regulate the output voltage and therefore does not run
off the battery during relatively minor brownouts (voltage
sags). This can protect you from "constant" voltage alarms
and wear and tear on the UPS battery, and is particularly
useful in areas with unusually unreliable power.

The other type runs off the battery constantly. These tend
to be useful for high-end systems which might be sensitive
to power loss for even a few milliseconds. Almost all PC power
supplies have some kind of "buffer", usually a capacitor of
some kind or the equivalent but sometimes a small built-in
battery, to handle such quick power losses as a changeover
from line to battery power, so I would not recommend that a
typical TMG user should look at this as an important feature.
Note that such types of UPS also have a range of acceptable
voltages, not for the purpose of switching but for issuing
alarms and initiating automated shutdowns.

BTW, automated shutdown can be a feature on either type.
Shutdowns are managed by software on the PC, with a wired
connection, typically through USB or a serial (COM) port. A
typical TMG user is not likely to use automated shutdown
very much, but if you run programs unattended for any reason
this feature is a *must*.

Another useful feature on a UPS is a replaceable battery.

Darrell


Darrell A. Martin
a native Vermonter in exile in Illinois


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