Call Search

New to Ham Radio?
My Profile

Friends Remembered
Survey Question

DX Cluster Spots

Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement

donate to eham
   Home   Help Search  
Pages: [1]   Go Down
Author Topic: UPS - Battery backups  (Read 1250 times)

Posts: 358


« on: March 18, 2009, 10:00:20 PM »

hey guys...,
so, what determines how long a ups will run when the power goes out..
i would think that it is the battery..
if so, has anyone tried piggy backing more batteries on their ups to see how much longer it lasts ?

just don't want to spend hundreds on a really big one.
we get lots of power outages where i live here in the high desert.


Posts: 21764

« Reply #1 on: March 19, 2009, 02:01:11 PM »

Depends on battery capacity, the load, and the nature of the load.

Most "affordable" systems can't provide much power for very long!  A typical computer UPS might power a PC for 10-20 minutes.  In some designs, if you added "infinite" battery capacity, you couldn't use the UPS too much longer because its inverter (the DC to AC part of the supply) could overheat if run much longer (continuously) than the product's original rating.

These are really for "brownouts" and short duration outages, not to sustain operation during a lengthy outage.  For that, I'd get a generator!

Posts: 229

« Reply #2 on: March 20, 2009, 02:02:00 AM »


it really depends on the size and VA/wattage rating.
I've been using APC brand UPS's for nearly 20 years
and I like their reliability factor. I can run my Icom
746 & 275H on the APC SU1000 with no problems. An APC
SU2200 XLNET allows the addition of external battery units for longer run times, from several hours to several days. Check out for additional info. You can also buy these models used from at a substantial savings. And models from the APC SU700 and higher provide sine-wave output vs modified sine-wave used in a lot of generators. Not all equipment works well with modified sine-wave output.


George ...

Posts: 3746

« Reply #3 on: March 20, 2009, 06:07:40 PM »

hi Kevin,

I use similar setup like George,
older Liebert full sine wave ups
that were removed from supermarket
point of sale systems.

great for field day, we can let the genset cool
before we refuel it.

most of the time they just need a good cleaning
to vacuum out the dust bunnies and a fresh set
of batteries.  

I got a few smaller units on ebay without batteries,
the shipping was inexpensive and I have access to
a supply of used batteries to install in the ups.

also check ebay for local seller so you can pickup.

73 james

Posts: 1042

« Reply #4 on: March 22, 2009, 02:57:20 PM »

It sort of depends on what you expect to run and how long.  I use the following, which I find reasonably affordable and simple.

For radio gear, your best best is to go 13.8 volts DC and run your station off of a battery/power supply system like a power-gate or home brew system that does the same thing - then you don't have to worry too much about your power draw.  [My downside is that my 'best' radio requires a special power supply and 50 volts - so I have to forgo it during a real emergency - so be it]

Your required battery capacity depends on your estimated outages.  In my area, we get rare outages and they seldom last longer than a few hours - I use a 100 amp/hour AGM battery that gives me at least 5 hours before I have to worry.  When the outage lasts longer, I have to fire up the generator anyway for the refrigerator, freezer, furnace and TV.  

If you need more reserve power, Trojan T-105's or T-145's are easy to find deep cycle 6 volt batteries - 220 amp hours to 260 amp hours.  These are pretty commmon golf-car batteries and are reasonably priced.

If you need AC to run a computer, the smaller home style UPS units use a single 12 volt battery, other larger ones use two in series for 24 volts.  Most of them can run about 10 minutes on internal batteries - mine has an 8 amp/hour gel-cell in it, for example.  You can substitute a much larger battery for the built-in battery.  There is a 33 amp/hour battery that is a common wheelchair battery - if you can get some used units, they are normally replaced on a schedule.  If you got a pair from the same chair, you could use them on a 24 volt unit effectively.

The down side is that these small UPS units do not restore the battery charge quickly, so if your outages are frequent AND protracted, you may have to keep a close eye on the battery charge levels.

At this point, my UPS is mainly for the minor flashes - if the power goes off, it gives me time to shut down, my internet dies w/out power anyway so I don't worry about it that much.
Pages: [1]   Go Up
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!