using computer UPS's

[Andy Baker]

Hello,

I was wondering if anybody had experience running much larger batteries on
computer UPS (uninterruptible power supplies) I have a wood fired boiler
that only uses small circulator pumps. An outage on a full load of wood
means at the very least scaling hot water spraying out the relief valve and
all over the garage, so I'd like to avoid that. The particular UPS I'm
looking at is a beast that rates double what the circulator pumps draw (I
have no blower as it's wood fired). It's also a damn good deal at a hundred
bucks for true sine wave output. It's internal batteries are two 11 AH 12
volts in series for 24 volts. I'd like to hook my two 12V deep cycles up to
it (80 AH each) instead. Any thoughts? I have no idea how they determine
battery life or when the battery needs replacing (I replaced a 7 AH 12V one
here at work, and took the "bad" battery home where it continues to run like
a champ)

Thoughts?

Andy

 

[Steve Spence]

I built my own with a motorcycle battery, a 300 watt inverter, and a 3
stage charger. The whole thing came to less than $100, but much longer
run time than a UPS. It's a true "online" unit, not a "backup" unit, in
that the load is always powered by the inverter. I did this to cover the
short switchover between our generator and house inverter. That was
enough to cause the satellite to lose sync.

Steve Spence
Dir., Green Trust
http://www.green-trust.org

 

[SQLit]

I built my own with a motorcycle battery, a 300 watt inverter, and a 3
stage charger. The whole thing came to less than $100, but much longer
run time than a UPS. It's a true "online" unit, not a "backup" unit, in
that the load is always powered by the inverter. I did this to cover the
short switchover between our generator and house inverter. That was
enough to cause the satellite to lose sync.

Steve Spence
Dir., Green Trust
http://www.green-trust.org

I like this idea, thanks for sharing.

 

[Andy Baker]

I know a furnace doesn't really care all that much, but I'm kind of worried
about the crappy quality of the inverter's "modified sine wave" power which
is just a crappy square wave and how induction motors deal with that (power
factor issues I'm sure)

Also is the fact that... say you're drawing a 300 watt load for your online
system, your battery charger would need to put out 30 amps. I know they
exist, but it's easy to get in to high amperage situations here where your
charger just can't keep up.

A recent setup I had used a 4 pole, double throw relay. It was actuated by
the incoming line. When the coil was energized, it hooked the main up to the
furnace and all was good. When power dropped out, the coil went dead, and
the line connection went to normally open. Normally closed hooked the
furnace to the inverter, and one of the un-used poles on the relay turned
the inverter on.

Worked great for the two times that I tested it, then the MOSFETS feeding
the main transformers in the inverter EXPLODED, plus did evil things to the
chip that provided their clock signal, soooo I couldn't simply replace the
mosfets, as it would causee a shoot-thru situation and promptly blow them
up. POOF!!

Bought a new inverter. Praying for now that the power goes out when I'm home
so I can manually switch it.

Andy

 

[Steve Spence]

30 amp auto chargers are very available. If your load isn't a 24/7 load,
then a smaller charger will suffice. These MSW inverters are fine for
electronics and lighting, but motors and such would need something
better. SW inverters are available as well, for more $$$.



Steve Spence
Dir., Green Trust
http://www.green-trust.org

 

[[email protected]]

Hello,

I was wondering if anybody had experience running much larger batteries on
computer UPS (uninterruptible power supplies) I have a wood fired boiler
that only uses small circulator pumps. An outage on a full load of wood
means at the very least scaling hot water spraying out the relief valve and
all over the garage, so I'd like to avoid that. The particular UPS I'm
looking at is a beast that rates double what the circulator pumps draw (I
have no blower as it's wood fired). It's also a damn good deal at a hundred
bucks for true sine wave output. It's internal batteries are two 11 AH 12
volts in series for 24 volts. I'd like to hook my two 12V deep cycles up to
it (80 AH each) instead. Any thoughts? I have no idea how they determine
battery life or when the battery needs replacing (I replaced a 7 AH 12V one
here at work, and took the "bad" battery home where it continues to run like
a champ)

Thoughts?

Andy

Will work just fine as long as you install an extra automatic battery
charger - as the charger in the UPS is quite likely to have a problem
with the big batteries after a sustained outage.

 

[[email protected]]

I have such experience. I tried this with a ferrups UPS that I found
on a curb someplace. Put in a bigger battery. It blew the charger. I
did not care much about that, because I wanted to use the UPS as a
huge inverter, but I was a little upset.


I would certainly advise against doing it with a ferrups unit...

i

A Ferrups is extremely inefficient. The resonant core runs very warm,
even without a load.

 

[SQLit]

I know a furnace doesn't really care all that much, but I'm kind of worried
about the crappy quality of the inverter's "modified sine wave" power which
is just a crappy square wave and how induction motors deal with that (power
factor issues I'm sure)

Also is the fact that... say you're drawing a 300 watt load for your online
system, your battery charger would need to put out 30 amps. I know they
exist, but it's easy to get in to high amperage situations here where your
charger just can't keep up.

A recent setup I had used a 4 pole, double throw relay. It was actuated by
the incoming line. When the coil was energized, it hooked the main up to the
furnace and all was good. When power dropped out, the coil went dead, and
the line connection went to normally open. Normally closed hooked the
furnace to the inverter, and one of the un-used poles on the relay turned
the inverter on.

Worked great for the two times that I tested it, then the MOSFETS feeding
the main transformers in the inverter EXPLODED, plus did evil things to the
chip that provided their clock signal, soooo I couldn't simply replace the
mosfets, as it would causee a shoot-thru situation and promptly blow them
up. POOF!!

Bought a new inverter. Praying for now that the power goes out when I'm home
so I can manually switch it.

Andy

I suggest you use an latching relay. Check into the GE RR-9's and 7's.
Originally designed for lighting relays they work on 24 vdc I believe that
they are rated for 20 amps 120 or 277 v. I admit that you will need to have
an slightly more complex control circuit but you do not have the coil
holding for extended lengths of time. Also it is an good idea to have an
timer in the circuit. Changing from one source to another instantly is an
really bad idea with out synching the sources. Phase angles and all that.

I watched a guy go from utility power to generator power on an 2000 ton
chiller (5 kv) underload by pushing both transfer buttons at the same time.
After the explosion we rebuilt the switch gear and I added an 2 minute timer
in the circuit and mounted so it was un accessible if the switchgear was
hot. No more midnight nonsense.

 

[Andy Baker]

This is the UPS I'm thinking of using.

http://www.opti-ups.com/ups_detail.phtml?product_id=35

NOT a cheap piece of shit for sure! MSRP is almost $800

Andy

 

[Rob]

Ignoramus23449, I have a ferrups 1Kw, I gather as long as it
has 48v in the batts the inverter part will work? I'm thinking
of getting some bigger batts for it (it takes 4 X 31 amp), and
was wondering how the charger would fair, can you still use
it, as per normal with out the charger working?
Tanks Rob

 

[[email protected]]

This is the UPS I'm thinking of using.

http://www.opti-ups.com/ups_detail.phtml?product_id=35

NOT a cheap piece of shit for sure! MSRP is almost $800

Andy

Looks like a pretty high end unit - and a true sine wave output to
boot.
It SHOULD work, given acceptable battery charging.

 

[[email protected]]

This is a nice one, but my ferrups was an even more expensive one. It
blew anyway. Fortunately, I picked it up from garbage, effectively, so
I did not pay for it and I needed it for its inverter.

i

The Ferrups is a rather specialized unit and is/was expensive because
of the massive resonant transformer used as a voltage regulator. With
today's intelligent buck/boost Ferros are fast falling out of favor -
particularly because of their low efficiency, and particularly at low
load.

 

[John]

I have an APC 650 connected to a #27 115 AH marine/trolling battery. The
original battery was 7AH. I has only been used once for about 45
minutes. The case remained cool to the touch.

It is supplying juice to a cable modem, d-link wireless router,
a P-75 powered firewall PC, an AMD Barton 2600 PC and, one monitor.

The assembly was simple:
1. Drill a hole in the top of the plastic battery box,
2. remove the battery cover from the UPS,
3. fashion a patch cord with #10 wire with post connectors for the battery
end and blade connectors for the UPS.
4. Place the UPS on top of the battery box and secure with a
ratcheting type cargo strap,
5. Plug everything in,
6. pay your homeowner's insurance premium.