Long Run UPS and Window Unit Air Conditioner

 I am trying to figure out what startup surge current from a window air
conditioner will do to a UPS.  If I have a unit that is rated at 1000
watts/120v, is there any method to calculate what sort of a surge I
should allow for?

Right now I have an APC 2200va unit on 48V of deep cycle batteries.  It
can operate my servers for about 5 hours.  I am considering upgrading to
a surplus 6000kva 220v unit and need to understand if it will be able to
operate my racks and a window unit for cooling.

I am curious if a 220v window unit would be a better choice for me in
this situation as it may have less surge differential and essentially
draw less current.

==============================
remove the .UCE to get me back

 

   You can only *measure* starting surge because it varies widely between
different models.   There is a device called a "hard start" that you can install
inside the unit that will reduce starting surge.  These are commonly used by the
motor home folks.


     Remember that UPS manufacturers assume a crazy power factor (usually 50%)
so that they can advertise a larger VA number.   That means that a 2200 VA unit
may only be good for 1100 actual watts.

    Honestly, I think that UPSs are a bad fit for air conditioning.  We use UPSs
not really as a power backup, but because our computers will not tolerate even
very short power interruptions.  Your air conditioning does not really mind.
Also, it would require a huge battery bank to run your AC for even an hour or
two.  It would be far better to go to Home Depot and invest in one of those
auto-start generators.


    You won't find them in 220 except for very large units.  If that is the size
AC unit you need, the UPS's you are discussing above are too small.

Vaughn

     This looks like another idea similar to my running an electric chainsaw
off my riding mower battery; great in theory, but ridiculous in real life.

 
It's worth noting that big data centers and telephone CO's, despite
often having huge UPSes onsite (often 100 kVA+), never try to run
their air conditioning from battery power.

Typical practice is to keep thermostats set a few degrees colder than
necessary, then let the AC drop out for a few minutes during a grid
outage, until the standby generator can take over and pick up its
load.

This has caused problems on a few occasions, when generators failed to
start, equipment kept running on batteries for hours and slowly cooked
itself.

--
Jordan.

 Jordan Hazen brought forth on stone tablets:

Creating and moving heat require prodigious amounts of energy.  This is
typically where the uninitiated discover how little energy is stored in
a cubic foot of battery as compared to a cubic foot of gasoline.

bob
s/v Eolian
Seattle