Using an External Battery for a UPS -- Belkin 1100VA

  • Thread starter Thread starter upgrdman
  • Start date Start date
U

upgrdman

I have a Belkin 1100VA UPS that has served me very well for approx.
three years. It is still serving me well, but I'm sure the gel cell
inside is not holding a charge like it used to. I recently remembered
that I have a small "lawn and garden" type 12V wet cell laying around,
its probably a 15-20Ah battery. Would it be a bad idea to replace the
internal gel cell with this external battery?

The voltage is going to be the same, so the added capacity is the only
concern. Does anyone know if the inverter and power conditioners inside
the UPSs can handle the relatively long-term use that a 15-20Ah battery
would allow? Even better, might it be able to handle an even bigger
battery... like a 12V deep cycle 30-50Ah battery for super long run
time?

Any tips or comments are welcome,

Thank you,
--Farrell F.
 
I have a Belkin 1100VA UPS that has served me very well for approx.
three years. It is still serving me well, but I'm sure the gel cell
inside is not holding a charge like it used to. I recently remembered
that I have a small "lawn and garden" type 12V wet cell laying around,
its probably a 15-20Ah battery. Would it be a bad idea to replace the
internal gel cell with this external battery?

The voltage is going to be the same, so the added capacity is the only
concern. Does anyone know if the inverter and power conditioners inside
the UPSs can handle the relatively long-term use that a 15-20Ah battery
would allow? Even better, might it be able to handle an even bigger
battery... like a 12V deep cycle 30-50Ah battery for super long run
time?

Any tips or comments are welcome,

Thank you,
--Farrell F.
Click to expand...

Are you a smoker ?

I want to be around when you strike a match next to that thing :-)

Wet cells evolve gas when charging. The amount of gas varies with
electrode composition. UPS manifacturers are careful to use
technologies that won't fill the room with hydrogen. Lawn
and garden or automotive batteries, are expected to be used
in the "great outdoors".

http://www.battcon.com/PapersFinal2004/ODonnellPaper2004.pdf
http://www.batterystuff.com/tutorial_battery.html#3

http://nam-en.apc.com/cgi-bin/nam_en.cfg/php/enduser/std_adp.php?p_faqid=2533

"APC UPS Systems use Valve Regulated Lead Acid (VRLA) batteries.
VRLA batteries are designed to recombine hydrogen and oxygen and
emit only extremely small amounts of hydrogen under normal operating
conditions. Normal room ventilation is sufficient to remove any
hydrogen, so special ventilation is not required. The electrolyte
in a VRLA battery is not in liquid form but is immobilized. The
most common technology, termed Absorbed Glass Mat (AGM) uses a
highly porous, absorbent micro fiberglass mats that immobilize
the electrolyte and prevents it from spilling. A crack or hole
in the casing of a VRLA battery using AGM technology will not
result in a measurable electrolyte spill. Spill containment
with VRLA batteries is therefore not meaningful or appropriate."

Is the charging method on a UPS, compatible with a wet cell ?
How does a UPS detect when the battery is fully charged ?

If you wish to experiment, at a minimum, do it outdoors.
Make sure there is nothing in the vicinity that you value.
I seem to remember when I was a kid (maybe 5 years old),
my next door neighbour "redecorated" the inside of
his garage, by fooling with a car battery. Fortunately,
he wasn't inside the garage when it went off. And
neither was his car.

http://www.battery-chargers.com/charging_instructions.htm

Stick with the gell cells designed for the product.

Paul
 
i forgot about that :) ... in any case, my work uses 12V 7Ah gel cells,
and I can get a few for a decent discount. I could wire three or four
in parallel... So my only concern is if the UPS can handle charging
bigger batterys, and if the inverter and power conditioner can handle
longer usage times during a power outage.

Any ideas,

--Farrell F.
 
i forgot about that :) ... in any case, my work uses 12V 7Ah gel cells,
and I can get a few for a decent discount. I could wire three or four
in parallel... So my only concern is if the UPS can handle charging
bigger batterys, and if the inverter and power conditioner can handle
longer usage times during a power outage.

Any ideas,

--Farrell F.
Click to expand...

There are products that claim long operating times.

http://www.ups-inverter.com/inverter.html

PWM (switching) conversion allows high efficiency,
and the thing you would be worried about, is whether
the heat in the UPS has a place to go. The designer
of a UPS with fixed battery capacity (just the gell
cell in the enclosure), only has to worry about heat
during the interval that the internal battery will
last. So, assume the UPS runs at max output when
on battery, perhaps it will only run for 10 minutes.
In that 10 minutes, how hot does it get ? If the
assembly is designed, such that it stays cool for
10 minutes, it might stay cool forever. If the design
is intended to get boiling hot, knowing that the
thermal inertia of the assembly prevents danger as
long as the battery runs out in 10 minutes, then
extending the run time of such a product would be
a dumb thing to do.

If the UPS has provision, via extension cables or
bays, for adding batteries, then it may well be
designed for near-continuous operation. If the UPS
is cheap like mine, with no extension cables, and
a lack of ventilation, I would guess it would be
a bad thing to do, to make it run for hours.

To work an example, say the load is 500W, and the
conversion is 90% efficient. The output might not
be a nice sine wave, but the output could be made
in a very efficient manner. The total power draw is
500/0.90 = 555W. 500W goes to the load. 55W is
released as heat, by the PWM switching transistors
and magnetics (transformer etc). The question is
whether those 55W can be dissipated by a simple
metal plate that forms the cover for the UPS. My
*guess* would be the heat is going to build, unless
the thing has a provision for fan cooling or the
like. My APS650 appears to have no concern about
heating, as there are no vents, nor fins, no fans
to aid cooling. Either the design is very efficient
(which is not possible), or the enclosure is designed
with a limited runtime at max power as its operating
regime.

The last thing I want to do on my UPS, is destructive
testing, because I cannot afford to replace it :-)
Try to replace your battery, with the nearest equiv
capacity to the original.

In terms of power failure events here, I
see just two types. Either I have a one second
outage (switch gear failover, line slap in the wind),
or my power goes off for two hours or more (utility
recovery time after a lightning storm, or time to
replace power pole after a local drunk knocked one
over). Expecting my UPS to be comfortable for two or
three hours, considering its crappy design, is a bit
much. You can do your own testing (run on battery
for 10 minutes, unplug from AC, unplug the battery,
check for internal heat) as a means of
estimating what your chances are. Use your normal
load during the test, so that the level of heating
is consistent with the expected application,

If the UPS doesn't seem to have a cooling strategy,
and is just a sealed box, it might not be happy running
for a long time.

Now, looking at this advert:

http://www.mwave.com/mwave/viewspec.hmx?scriteria=3486084&RSKU=3486084

"Average Run Time - 4 min at half load"

that doesn't make it sound like the unit is intended
to run for a long time.

Just a guess,
Paul
 
Back
Top