"Jim Higgins" wrote in message
...
On Sun, 28 Aug 2005 14:37:34 -0700, in
, "Denton"
wrote:

Since I already have a station power supply, with a pair of deep cycle 12
vdc batts floating across a 35 amp power supply with a blocking diode in
the
dc plus lead, I am thinking of getting a 12 vdc to 120 vac inverter on the
battery output...to feed two desktop pc's plus two lcd monitors.

For the past couple of years I have used an APC 1500 ups to feed both pc
workstation and also am thinking of just getting another ups to feed the
second workstation...if an inverter proves to be now the best way to go.

Before I re-invent the wheel, am wondering if anyone has done this
before...thanks

Let's pretend you draw the maximum current from your 12-volt
battery that your power supply can replace. That's 12V x 35 amps
or 420 watts. Figure some losses in the inverter and the USP -
say 20% - for an output of 340 watts. Can you run the two
computers on less than 340 watts - 170 watts each? If not then
you're looking at a power deficit that would need to be made up
with an additional or larger DC power supply... that or you run
the computers thru their UPS units off wall current and only swap
over to the inverter when power fails.


Not only that, but those inverters are notoriously bad noise generators.
I've tried to use them for transmitting and gotten switching noise on the
carrier (several dB), and had lines in the monitor when trying to use a
computer.