Re: UPS as backup power

["Giancarlo Podio" <gp at isaconsulting_com>]

Have been ill lately and lost track of many topics, I have just read all the
replies and there are some interesting comments and suggestions people have
made. I'll try to reply to what I can

Anthony Law said:
>So I thought a filter at 20-25W would only run 60min
>max.  But you have gotten 12+ hrs!  This is very good
>news for some of us....
>A friendly reminder: Since most UPS use Lead-Acid
>batteries (ie a car battery), logic tells me you
>should keep it fully charged at all times & shouldn't
>do too many of these "full drain tests".

Unfortunately I do not remember the differences in discharge rates between
lead acid and gell type batteries, however they are not linear and the less
you draw from a battery the longer it will last (non-linear). There is also
the difference between the rated AH and what you are drawing. A 50AH battery
with a 30W load will last much more than twice the time a 25AH battery would
with the same load. As someone else pointed out some of these batteries may
be sealed lead acid cells or gell type batteries. This means that no fumes
are released during charging and they can also be tilted or inverted for
short periods of time. Unfortunately these batteries do break down and when
they do they can emit fumes which I have experienced more than once, it
smells bad so it doesn't take long to realize you need to bring it outdoors.
There are escape holes for these fumes at the top of the battery, they avoid
it exploding or leaking. Another example of run times is my first test a
little while ago with a dead UPS, it would not run a PC at all, yet it ran
my canister for nearly 3 hours! It's the only reason I have not thrown it
out yet.

Josh said:
>if you are using the thing(ups power supply) as a backup why not put one of
>the cheapie on/off timers on it? if it ran 10 minutes every hour that would
>seem like plenty to me.  maybe you need more though.

The traditional use of a UPS is to have connected 24/7 so that it kicks in
automatically. If you place a timer on it this would be turning your filter
on and off at the set intervals all the time, not just during a power
outage. OTOH one could manually add a timer to the circuit if you know the
power outage is going to last more than the UPS will run for (power lines
down etc..) A good idea but may have to be a manual intervention.

Someone said:
> Also if you are interested in extending the "run
> time" of one of the small ups's you can easily replace (not
> in the cabinet)
> the current battery with a marine deep cycle
> battery

Indeed you could do this however you would also have to replace or alter the
charging circuit in order to correctly charge the new battery. In short all
you would be salvaging from the UPS unit is the DC/AC converter and sinewave
generator circuit. If anyone is interested in trying this I have various UPS
units that require new batteries, I'm getting close to throwing them out as
I have little time for them. I'm not sure what the marine batteries are like
(sealed or not) but you definetly want to use a sealed cell battery indoors.
I live near a private airport and I often buy batteries from the repair shop
there, they are extremely well made and well sealed for tilted and inverted
flight. Many electrical outlets or online stores sell all types of
batteries, choosing one is probably a bigger task than finding them.


Someone also mantioned the use of solar cells to recharge the battery. This
could work however the cost of everything might run you about the same as a
small as powered generator which could also run your heating, lighting and
most important keep those beers cold in the fridge ;-)


I just received a 2700W rack mount UPS with dead batteries for free (I paid
shipping once the dead batteries were removed). A larger UPS such as this
would probably satisfy most needs and would not need any modifications. If
you can find a cheap one on ebay with dead batteries it's worth getting.
Most people throw them out when the bateries die. APC sells a wide range of
replacement batteries however you can find the same batteries for less at
electronic outlets, it would cost me about $100 to replace the 4 batteries
in the unit I just received, not bad!

As for now the new little unit is small and easy to hide behind the tank and
I feel safer knowing my filter is backed up. Hopefully I will not experience
a blackout long enough to cause a heat issue.

Giancarlo Podio