[vox-tech] UPS and auto battery

[Ted Deppner]

On Sun, Mar 07, 2004 at 10:58:21AM -0800, Rod Roark wrote:
> the inverter, a deep cycle battery and a moderately cheap
> charger, and keep them on hand but not actually running the
> computer all the time.

I have this... a cheap "float charger" can keep a car battery charged
($15 or less at Harbor Frieght), or a car charger at $20 to $30.

> BTW do you know anything about gasoline-powered generators?
> That may be a more comprehensive solution.

Don't underestimate a car battery.  Hours of run time.  Really.  And $50
for hours and hours more (second batter) is possibly cheaper than
gasoline in a generator.

I've studied some on generaters, but have no real direct experience.  A
few items I'd raise though.  Generators can put out square waves or sine
waves.  On a computer, which their switching power supplies, this
doesn't make much difference, but sine waves are a lot nicer on
equipment in the long haul (a CRT is really the more vulnerable thing
here as compared to a computer).  Generators typically come in two major
categories, "cheap" ones that have 2 poles and run at 2 times the RPM
they need to (and thus shorten their life), and better ones that have 4
poles and run at a nice lower RPM.  (I'm thinking 900/1800 RPM or
1800/3600 RPM, but I'm not certain).  A catalog from Northern Tool has
many choices in it (http://www.northerntool.com/generators/).

Depending on your needs a $350 to $999 generator might be just fine, but
if you're interested in long life, and often use, the extra funds on a 4
pole generator will pay off.  Harbor Frieght has a small but interesting
looking selection of generators also
(http://www.harborfreight.com/cpi/ctaf/Category.taf?CategoryID=581).
More industrial looking than some of the el-cheapo stuff, but caveat
emptor.

Extra "features" like built in circuit breakers, low oil shut off, and
so forth are pretty common everywhere now if you look.  They keep a
mistake from turning into a big problem.

Lastly, lower end generators really don't do well with changing loads.
Ie, if you have 5 computers and a fridge on the generator, expect huge
voltage swings when the fridge cycles off and on.  This can burn things
out, and the voltage swings can be normous (burn out lights, blow
breakers, etc).

That's the high points from my reading and studies... I'd welcome some
real world experience from any that have it.  I've spoken with a few
people "in the boonies" who run off generators routinely for some of
this.

-- 
Ted Deppner
http://www.deppner.us/