Alternative Power sources - Using APC UPSes For House Inverters

Author

Using APC UPSes For House Inverters

Too_Many_Tools

2005-08-02, 11:21 pm

I recently came into procession of a number of APC UPSes.

The models are SmartUPS 1400, SmartUPS 2200 and the Matrix 5000.

I have read that several individuals have used these for house
inverters. I would appreciate hearing how you did and what issues you
faced when you implemented them.

How does the idling current draw of the APC UPSes compare to an
inverter meant for alternate power situations like the Trace?

Thanks in advance,

TMT

Too_Many_Tools

2005-08-05, 4:21 pm

Ok, no responses...maybe I should ask the question..."What issues has
anyone had with using UPSes for a house inverter?"

Any advice?

TMT

Bruce in Alaska

2005-08-05, 5:21 pm

In article <1123265795.030815.321510@z14g2000cwz.googlegroups.com>,
"Too_Many_Tools" <too_many_tools@yahoo.com> wrote:

> Ok, no responses...maybe I should ask the question..."What issues has
> anyone had with using UPSes for a house inverter?"
>
> Any advice?
>
> TMT
>

UPS's aren't designed for longterm use, as their design criteria is for
rated power, for 30 minutes max. Typically their Inverter Heatsinks
are to small for continious use. Also their recharging circuits are
mostly designed for Trickle/Float type service as they are intended for
limited operation times, with long time spans in between. I have tried
some of the "Big Industrial" BEST 1.8Kw FrerroUPS's to run my ISP
Hardware during my winter Operations and found that a Trace 2624 MSW
Inverter is much better at keeping things running. My winter Powercycle
is, that I operate a Diesel Generator for 10 hours a day. (7Am to noon,
and 5Pm to 10Pm) This is adequate to keep all my freezers cold, charge
the Trace 4024's 1200 Amp/Hr Battery that runs the house, charge the
Trace 2624 700 Amp/Hr Battery that runs the ISP Hardware, (Sat Modem,
Router, 24 Port 10/100 Ethernet Switch, DNS Server, Mail/Web Server,
Wireless Access Points) and the Telco Switch/Microwave System Batteries.
240 Amp/Hr @ 48Vdc. When I was using the BEST, I nothing but problems
with it running out of battery and not fully recharging during Powered
operatin. Now the BEST just sits in between the Trace 2624 and the ISP
Power Buss, and keeps the 2624's transition glitches from resetting
the ISP Hardware.

Bruce in alaska
--
add a <2> before @

Jim Baber

2005-08-05, 5:21 pm

Too_Many_Tools wrote:

>Ok, no responses...maybe I should ask the question..."What issues has
>anyone had with using UPSes for a house inverter?"
>
>Any advice?
>
>TMT
>
I don't use one for a house inverter, but I have been successfully using
an APC BR1500 + (1)BR24BP
<http://www.apcc.com/resource/includ...20%281%29BR24BP>
to serve as a back up 120 VAC power supply for my oxygen concentrator.
My big concern here was a nighttime power outage while I was asleep.
This UPS allows My Inogen One to run for over 13 hours using it's own
batteries as well, in case the utility power does go out. So far the
worst Pacific Gas & Electric has managed this year has been a 9 hour
outage. (for me that is)
<http://www.apcc.com/resource/includ...20%281%29BR24BP>

nicksanspam@ece.villanova.edu

2005-08-05, 6:21 pm

Bruce in Alaska <bruceg@btpost.net> wrote:

>UPS's aren't designed for longterm use, as their design criteria is for
>rated power, for 30 minutes max. Typically their Inverter Heatsinks
>are to small for continious use...

I've heard this before, but I don't believe it, because there's nothing
inside the UPS circuitry that can store a half-hour's heat.

Nick

Too_Many_Tools

2005-08-06, 4:21 pm

Thanks to those who have responded.

Your point about UPSes not being able to run longer than their
batteries is well taken. I too have read the statement but without
supporting data to back it up.

Considering that there are thousands of UPSes for every one dedicated
house inverter, I would consider that this is an untapped source for
cheap home power for many people.

Does anyone have an article or website discussing UPS usage for home
power? Like anything else that seems simple at first, issues arise when
one tries to implement the solution.

TMT

Tim Keating

2005-08-06, 4:21 pm

On 6 Aug 2005 11:23:49 -0700, "Too_Many_Tools"
<too_many_tools@yahoo.com> wrote:

>Thanks to those who have responded.
>
>Your point about UPSes not being able to run longer than their
>batteries is well taken. I too have read the statement but without
>supporting data to back it up.

The supporting data would be the lack proper ventilation; combined
with engineering knowledge to predict the resulting failure mode of
long term operation.

I.E. No engineer is going to waste their time and compose a paper
just prove it to you that it doesn't work.

>
>Considering that there are thousands of UPSes for every one dedicated
>house inverter, I would consider that this is an untapped source for
>cheap home power for many people.

If you want longer term power that's still fairly cheap; then I
suggest you purchase Tripp-lite's.. APS 612 and higher series of
powerverters. They're designed for external battery usage and long
term operation (I.E. charger/inverters with built in cooling fans,
etc).

http://www.tripplite.com/products/inverters/index.cfm
http://www.sunelec.com/Distributors...pplittrace.html

>Does anyone have an article or website discussing UPS usage for home
>power? Like anything else that seems simple at first, issues arise when
>one tries to implement the solution.

I suspect that any low cost UPS you find will need extensive
re-engineering in order to sustain long term operation.

nicksanspam@ece.villanova.edu

2005-08-06, 6:21 pm

> I suspect that any low cost UPS you find will need extensive
>re-engineering in order to sustain long term operation.

As an electrical engineer, I disagree.

Nick

Tim Keating

2005-08-06, 8:21 pm

On 6 Aug 2005 16:53:58 -0400, nicksanspam@ece.villanova.edu wrote:

>
>As an electrical engineer, I disagree.

Disagree all you want..
Thermodynamics will dictate a rather short lifespan.

Most of UPS enclosures are plastic, or steel, both of which are
fairly good thermal insulators. When a typical UPS is producing 300
watts of AC from Batteries, it is also pumping out 50 to 100 watts of
thermal energy.

Retaining that thermal energy is generally not significant factor
if the inverter/high thermal output phase is kept to a fairly short
duty cycle.

But, when the inverter portion is operated at significant power
levels for long duty cycles. The internal temperature will build to
a point where the power semiconductors breakdown thermally.

Generally a UPS would need some form of force air cooling to run
continuously at those power levels.

nicksanspam@ece.villanova.edu

2005-08-06, 8:21 pm

Tim Keating <NotForJunkEmail@directinternet11.com1> wrote:

[color=darkred]
> Thermodynamics will dictate a rather short lifespan.

Exactly the opposite, IMO. If it can survive 10 minutes, it can survive
10 hours, since nothing inside can store heat for more than a few minutes.

Nick

Tim Keating

2005-08-06, 9:21 pm

On 6 Aug 2005 18:52:56 -0400, nicksanspam@ece.villanova.edu wrote:

>Tim Keating <NotForJunkEmail@directinternet11.com1> wrote:
>
>
>
>Exactly the opposite, IMO. If it can survive 10 minutes, it can survive
>10 hours, since nothing inside can store heat for more than a few minutes.

You're only demonstrating your ignorance of Thermodynamics..
Which is classic error for most EE's.

You can start by calculating the Thermal conductivity for each
component involved. Note: Don't forget to derate the Free air
rating of the heat sink.

nicksanspam@ece.villanova.edu

2005-08-07, 6:21 am

Tim Keating <NotForJunkEmail@directinternet11.com1> wrote:
[color=darkred]

Perhaps you are right. Suppose your 300 W UPS weighs 1 pound, excluding
battery. Say 1 Btu/F of heat capacity. You say it dissipates 50-100 watts,
eg 340 Btu/h at a 67% Ghio efficiency. On 100 F day, with no heat sinks,
it would reach 158 F (70 C, a common upper air temp limit for commercial
semiconductors) in about 1(158-100)/340 = 0.17 h, ie 10.2 minutes.

How much can your heat sinks delay that?

Nick

John Beardmore

2005-08-07, 8:21 am

In message <f41af1l9da5uqp7crirgktjc84sa801ckh@4ax.com>, Tim Keating
<NotForJunkEmail@directinternet11.com1> writes
>On 6 Aug 2005 11:23:49 -0700, "Too_Many_Tools"
><too_many_tools@yahoo.com> wrote:

> The supporting data would be the lack proper ventilation; combined
>with engineering knowledge to predict the resulting failure mode of
>long term operation.

So stick a big fan on it and don't run it too hard.

> I.E. No engineer is going to waste their time and compose a paper
>just prove it to you that it doesn't work.

Indeed, but this doesn't mean that it can never work.

> I suspect that any low cost UPS you find will need extensive
>re-engineering in order to sustain long term operation.

Of what ? Bigger fans is easy ? Better quality electrolytics ?

Cheers, J/.
--
John Beardmore

John Beardmore

2005-08-07, 8:21 am

In message <9vcaf1d3o800gue82bvv3oj37bhf48dqqd@4ax.com>, Tim Keating
<NotForJunkEmail@directinternet11.com1> writes
>On 6 Aug 2005 16:53:58 -0400, nicksanspam@ece.villanova.edu wrote:
>
>
>Disagree all you want..
> Thermodynamics will dictate a rather short lifespan.

That I really doubt !!

Though feel free to prove your point with something specific.

> Most of UPS enclosures are plastic, or steel, both of which are
>fairly good thermal insulators.

And it's how hard to fit a fan ?

And come to think of it, all but the most noddy UPSs seem to have fans
already.

> When a typical UPS is producing 300
>watts of AC from Batteries, it is also pumping out 50 to 100 watts of
>thermal energy.

Which isn't a whole lot to shift is it ?

Let's face it, this is hardly more than a typical desktop PC, and
certainly no more than a small server.

> Retaining that thermal energy is generally not significant factor
>if the inverter/high thermal output phase is kept to a fairly short
>duty cycle.

Longest time running might have more to do with it than duty cycle.

> But, when the inverter portion is operated at significant power
>levels for long duty cycles. The internal temperature will build to
>a point where the power semiconductors breakdown thermally.

Only if it's very badly designed.

> Generally a UPS would need some form of force air cooling to run
>continuously at those power levels.

Well, that's hardly a huge problem is it ?

Let's not make mountains out of molehills !

Cheers, J/.
--
John Beardmore

John Beardmore

2005-08-07, 8:21 am

In message <dd3f08$k0t@acadia.ece.villanova.edu>,
nicksanspam@ece.villanova.edu writes
>Tim Keating <NotForJunkEmail@directinternet11.com1> wrote:
>
>
>
>Exactly the opposite, IMO. If it can survive 10 minutes, it can survive
>10 hours, since nothing inside can store heat for more than a few minutes.

Even so, the components might last longer at lower temperatures, so more
cooling might be good on some units.

Cheers, J/.
--
John Beardmore

Tim Keating

2005-08-07, 9:21 am

On Sun, 7 Aug 2005 11:28:27 +0100, John Beardmore
<wookie@wookie.demon.co.uk> wrote:

>In message <f41af1l9da5uqp7crirgktjc84sa801ckh@4ax.com>, Tim Keating
><NotForJunkEmail@directinternet11.com1> writes
>
>
>So stick a big fan on it and don't run it too hard.

That's all part of the re-engineering step..
It would also include removing portions of the case.
And probably losing the UL/CSA rating.

If you have a house fire, and investigators find your specially
modified UPS started it. Your insurance company is going to make
things real ugly.

>
>Indeed, but this doesn't mean that it can never work.
>
>
>
>Of what ? Bigger fans is easy ? Better quality electrolytics ?

An what energy source are you going to use to drive the fans?
Will you end up drawing too power from Battery charging circuit and
leave it unable too establish a proper float voltage?

nicksanspam@ece.villanova.edu

2005-08-07, 10:21 am

John Beardmore <wookie@wookie.demon.co.uk> wrote:

Exactly how will thermodynamics "dictate" this? :-)
[color=darkred]
>...the components might last longer at lower temperatures, so more
>cooling might be good on some units.

Sure. Lifetimes decrease with increasing temperatures. Some engineers
measure the case temp of every IC on a board and add individual IC heat
sinks as needed to keep junction temps below 100 C.

For instance, if an IC dissipates 600 mW and its junction-to-case thermal
conductance is 20 mW/C and its case temp is 80 C, its junctions would be
80+600/20 = 110 C, so it would get its own heat sink.

Nick

Tim Keating

2005-08-07, 10:21 am

On 7 Aug 2005 04:28:45 -0400, nicksanspam@ece.villanova.edu wrote:

>Tim Keating <NotForJunkEmail@directinternet11.com1> wrote:
>
>
>Perhaps you are right. Suppose your 300 W UPS weighs 1 pound, excluding
>battery. Say 1 Btu/F of heat capacity. You say it dissipates 50-100 watts,
>eg 340 Btu/h at a 67% Ghio efficiency.
^^^^^^^^^^^^^^^^^ 75%... 400 watts DC in, 300 Watts AC out.. == 100
Watts of heat generated per hour.

340 BTU/hr is enough energy to increase the temperature of 10Lb of
H20 by 34 degrees(F) per hour. But the components of a UPS have no
where near that type of thermal capacity of pure H2O, so increase that
number by at least 4x.

I.E. Thus 340 BTU/hr increase 10lb of UPS mass by 136 Degrees(F)
per hour or 40lb of UPS mass by 34 degrees(F) per hour.

>On 100 F day, with no heat sinks,

All UPS's have heat sinks on their power semiconductors, but those
heat sinks only transfer heat away from semiconductor to the air
surrounding the heat sink inside of the UPS. The UPS case all by
itself is another layer of thermal insulation. (Adding another
derating factor to a steady state equation.)

The Junction to Ambient thermal capabilities of a typical Power
semiconductor are ~60C/watt, and Junction to Tab will be on the order
of 1 to 3C/watt. Indicating that the power semi's will require a
heat sink no mater what type of UPS you have. Typical UPS Heat sink
thermal resistance in free air will probably be no lower than
10C/watt.

Thus, attaching a fairly large internal heat sink lowers Junction
to Ambient(inside the case) from (60C/watt) down to (~12C/watt). If
4 watts of energy are being dissipated at 12C/watt, junction temp will
still be ~48C above internal case air temp.

>it would reach 158 F (70 C, a common upper air temp limit for commercial
>semiconductors) in about 1(158-100)/340 = 0.17 h, ie 10.2 minutes.

?????
One would need to know the thermal mass to calculate temp rise.

But, as demonstrated above, there are dozens of power and thermal
resistance factors to calculate. The power semi's will likely fail
long before internal case temp reaches 70C.

>How much can your heat sinks delay that?

Size and type of heat sinks are just a few of the many factors in
the overall thermal equation.

nicksanspam@ece.villanova.edu

2005-08-07, 1:21 pm

Tim Keating <NotForJunkEmail@directinternet11.com1> wrote:

>400 watts DC in, 300 Watts AC out... 100 Watts of heat generated per hour.

....100 watts per hour? :-)

> 340 BTU/hr is enough energy to increase the temperature of 10Lb of
>H20 by 34 degrees(F) per hour. But the components of a UPS have no
>where near that type of thermal capacity of pure H2O, so increase that
>number by at least 4x.

So it's unlikely that a UPS that can run for a half-hour will be unable
to run for 10 hours.

> I.E. Thus 340 BTU/hr increase 10lb of UPS mass by 136 Degrees(F)
>per hour or 40lb of UPS mass by 34 degrees(F) per hour.

Sounds like you are counting the batteries, which, if mostly lead
have little thermal capacity and little thermal connection to the
electronics, which might weigh 1 lb, for a 300 W UPS.

>
>?????

IdT = CdV.

>If 4 watts of energy are being dissipated...

You might enjoy learning the difference between power and energy.

Nick

Tim Keating

2005-08-07, 2:21 pm

On 7 Aug 2005 12:10:01 -0400, nicksanspam@ece.villanova.edu wrote:

>Tim Keating <NotForJunkEmail@directinternet11.com1> wrote:
>
>
>...100 watts per hour? :-)

So what you found a semantic error.
Here is a correction for the second half of my previous statement..

"100 Watts, yielding 341 BTU's of heat generated per hour."

>
>So it's unlikely that a UPS that can run for a half-hour will be unable
>to run for 10 hours.

Not at any significant load.. (reduced load == less heat.. )

>
>Sounds like you are counting the batteries, which, if mostly lead

No.. I detailed two scenarios.. nothing more.

>have little thermal capacity and little thermal connection to the
>electronics, which might weigh 1 lb, for a 300 W UPS.

Transformer.. Mostly Iron [444J/(Kg*K)] and some copper [385J/(Kg*K)]
which is just a small fraction of specific heat capacity of H20. [
4186J/(Kg*K) ]

>
>IdT = CdV.

Non-sequitur as applied to discussion about temperature increase of
specific UPS components. .

Are you dreaming about charging some capacitor???

>If 4 watts of energy are being dissipated...
>
>You might enjoy learning the difference between power and energy.

Another Non-sequitur..

The only thing that you've demonstrated so far is that you're NOT an
EE as you claimed in Message-ID:
<dd3816$jst@acadia.ece.villanova.edu>

Too_Many_Tools

2005-08-07, 4:21 pm

"...... I.E. No engineer is going to waste their time and compose a
paper just prove it to you that it doesn't work. ......"

Reread my original discussion....I am noting that there are MANY UPSes
that exist that could be used for a source of alternative home power.
The fact that some people are already doing it proves that it is a
viable approach. I would consider it an excellent idea for "some
engineer" to research the tradeoffs between a commonly offered UPS and
a dedicated inverter that could be used in an alternative home power
setup.

My first impressions of the alternative energy market seems to indicate
that there are many who would love to sell you expensive hardware.
Disappointedly, there seems to be little discussion of homegrown
solutions that the general public can implement using commonly
available products. Since the price of inverters have dropped
significantly because of the computer industry, I think that for a
quick and cheap solution for limited alternative home power the larger
UPSes available may make a satisfactory solution.

In an educated guess, I suspect that the idling current for UPSes might
be much larger than the inverters specifically built for home
power...but at the disadvantage of much higher cost. As a compromise, I
think larger UPSes (which are rated for continuous service) offer a
good compromise for someone who doesn't want to spend many thousands of
dollars on the alternative.

TMT

2005-08-07, 5:21 pm

In article <dd3f08$k0t@acadia.ece.villanova.edu>,
nicksanspam@ece.villanova.edu wrote:

> Tim Keating <NotForJunkEmail@directinternet11.com1> wrote:
>
>
>
> Exactly the opposite, IMO. If it can survive 10 minutes, it can survive
> 10 hours, since nothing inside can store heat for more than a few minutes.
>
> Nick
>

It isn't the "Storage" of heat that is the problem here, it is the
dissipation of the produced heat that limits most short dutycycle
devices. If you make more heat than you can dissipate, you are going to
FRY the Semiconductor switches in short order. Comsumer UPS's are NOT
designed for continious duty, and can't dissipate the generated heat
over long periods of runtime, therefor they FRY when connected to larger
battery systems, and when they run for extended runtimes......

Me this isn't "Rocket Science" but some folks think it should be...

Tim Keating

2005-08-07, 6:21 pm

On 7 Aug 2005 11:34:28 -0700, "Too_Many_Tools"
<too_many_tools@yahoo.com> wrote:

>"...... I.E. No engineer is going to waste their time and compose a
>paper just prove it to you that it doesn't work. ......"

You're quoting my text..

>
>Reread my original discussion....I am noting that there are MANY UPSes
>that exist that could be used for a source of alternative home power.
>The fact that some people are already doing it proves that it is a
>viable approach. I would consider it an excellent idea for "some
>engineer" to research the tradeoffs between a commonly offered UPS and
>a dedicated inverter that could be used in an alternative home power
>setup.

1st.
The number of UPS makes and models floating around the market is
nearly countless.
Additionally dozens of new ones introduced every month.
A few units might have schematics are available.
Who's going to pay for all that effort?? Where do you start??
Who's going to buy them, do the mods, test them, only to find out
that model has already been replaced and is no longer sold?.

2nd..
Some UPS manufacturers actually spec'd some of their higher end
Units for high duty cycles and long term operation.. Those units
usually have fans and provisions for external battery packs.

>My first impressions of the alternative energy market seems to indicate
>that there are many who would love to sell you expensive hardware.

I recommend starting out with a manufacturer like TrippLite who
make some reasonably priced Powerverter models(250$) that are designed
to run for long duty cycles.

http://www.tripplite.com/products/inverters/index.cfm

>Disappointedly, there seems to be little discussion of homegrown
>solutions that the general public can implement using commonly
>available products. Since the price of inverters have dropped
>significantly because of the computer industry, I think that for a
>quick and cheap solution for limited alternative home power the larger
>UPSes available may make a satisfactory solution.

(Decent Powerverter Prices)
http://www.sunelec.com/Distributors...pplittrace.html

Start with APS 612 or larger depending on your needs.

>In an educated guess, I suspect that the idling current for UPSes might
>be much larger than the inverters specifically built for home
>power...but at the disadvantage of much higher cost. As a compromise, I
>think larger UPSes (which are rated for continuous service) offer a
>good compromise for someone who doesn't want to spend many thousands of
>dollars on the alternative.

A typical PC UPS like a Tripplite BC500, (three Internal gel cell
6v@7amp/hr ) consumes ~11 watts, under no load. Under similar
conditions a APS912 Powerverter (900 watt continous/1800 watt 30 sec
surge) consumes ~16 watts while maintaining float voltage on a 12V
115amp/hr deep cycle battery. In the final analysis, the difference
in standby AC power consumption isn't all that great.

While the BC500 can run a loaded PC for a few minutes and takes
upwards of 24 hours to recover. The APS 912 Powerverter can power up
an entire rack(5 PC's) for several hours and takes just a few hours to
recharge the external battery.

John Beardmore

2005-08-07, 8:21 pm

In message <Me-E1253C.11451907082005@netnews.worldnet.att.net>, Me
<Me@shadow.orgs> writes
>In article <dd3f08$k0t@acadia.ece.villanova.edu>,
> nicksanspam@ece.villanova.edu wrote:

>
>It isn't the "Storage" of heat that is the problem here, it is the
>dissipation of the produced heat that limits most short dutycycle
>devices.

So let's see. You contend that it can't operate under the steady state,
but that it may take more than thirty minutes to 'fry' despite
dissipating tens of watts and having not a whole lot of thermal
capacity.

> If you make more heat than you can dissipate, you are going to
>FRY the Semiconductor switches in short order.

But IF the thermal capacity IS as small as some suggest, then the steady
thermal state will have been reached long before the batteries expire.

> Comsumer UPS's are NOT
>designed for continious duty,

Well, that's certainly limited by the batteries in normal use. This is
hardly proof that the inverters couldn't survive continuous duty.

> and can't dissipate the generated heat
>over long periods of runtime,

Well - maybe, but we only have your assertion to justify this ! What's
more, if the energy isn't being dissipated, then it MUST (to some extent
at least) be about storage, but you said "It isn't the "Storage" of heat
that is the problem here". So which is it ?

Well, it's both ! D'Oh !

> therefor they FRY when connected to larger
>battery systems, and when they run for extended runtimes......

Do you have direct personal experience of this ?

Which inverters were affected ?

Does anybody else have experience of running these inverters
successfully or otherwise ?

>Me this isn't "Rocket Science" but some folks think it should be...

No - it's not rocket science - but back of envelope calculations seem
to suggest that thermal capacity alone is not sinking the heat, and it
seems pretty likely that the steady state temperature must be closely
approached. Therefore it's likely that in well designed kit (and let's
face it, decent UPSs have fans), it IS about dissipation after the first
few minutes of operation.

Now - I could believe that inverters designed for occasional use
wouldn't use the quality of components that might be selected for
inverters intended to run 24/7, and I could believe that any set of
components would have longer service lives at lower working
temperatures, so I can agree that sticking an extra fan on might help.

There seems to be some consensus that anything beyond that needs some
proof beyond your assertion !

Cheers, J/.
--
John Beardmore

John Beardmore

2005-08-07, 8:21 pm

In message <n4ocf1d0vj75pbke3le47c838ejgp7u134@4ax.com>, Tim Keating
<NotForJunkEmail@directinternet11.com1> writes
>On 7 Aug 2005 11:34:28 -0700, "Too_Many_Tools"
><too_many_tools@yahoo.com> wrote:

> A few units might have schematics are available.

Do you have eyes ?

> Who's going to pay for all that effort??

The end user (takes pleasure in the salvage of kit).

> Where do you start??

Open the box - take a look.

> Who's going to buy them,

Who said this was a commercial enterprise ?

> do the mods, test them,

The end user.

> only to find out
>that model has already been replaced and is no longer sold?.

So ????

>2nd..
> Some UPS manufacturers actually spec'd some of their higher end
>Units for high duty cycles and long term operation.. Those units
>usually have fans and provisions for external battery packs.

I think you'll find some low end units have fans too.

>
> I recommend starting out with a manufacturer like TrippLite who
>make some reasonably priced Powerverter models(250$) that are designed
>to run for long duty cycles.
>
>http://www.tripplite.com/products/inverters/index.cfm

Yes - inverters have got cheaper too.

>
> A typical PC UPS like a Tripplite BC500, (three Internal gel cell
>6v@7amp/hr ) consumes ~11 watts, under no load. Under similar
>conditions a APS912 Powerverter (900 watt continous/1800 watt 30 sec
>surge) consumes ~16 watts while maintaining float voltage on a 12V
>115amp/hr deep cycle battery. In the final analysis, the difference
>in standby AC power consumption isn't all that great.

OK.

> While the BC500 can run a loaded PC for a few minutes and takes
>upwards of 24 hours to recover.

Yes, but it's not cooling down for 24 hours !

> The APS 912 Powerverter can power up
>an entire rack(5 PC's) for several hours and takes just a few hours to
>recharge the external battery.

Quite. So this tells us nothing about any thermal limitation on either
inverter then.

Cheers, J/.
--
John Beardmore

Tim Keating

2005-08-07, 8:21 pm

On Sun, 7 Aug 2005 23:50:13 +0100, John Beardmore
<wookie@wookie.demon.co.uk> wrote:

>In message <g4tbf1duk4lgire9oqljbuv6vusgm0c3j8@4ax.com>, Tim Keating
><NotForJunkEmail@directinternet11.com1> writes
>
>
>Well - maybe.
>

Isn't it time you stopped acting like a dumb XXX and quit trolling.

PS.. I don't sell inverters..

Tim Keating

2005-08-07, 9:21 pm

On Sun, 7 Aug 2005 23:56:23 +0100, John Beardmore
<wookie@wookie.demon.co.uk> wrote:

>Quite. So this tells us nothing about any thermal limitation on either
>inverter then.

The question was about idling current differences.. Mr. Troll..

As for thermal limitations you can figure that one out for
yourself, Mr. Dumbass troll..

vaughnsimon@att.net

2005-08-07, 9:21 pm

Tim Keating wrote: "If you have a house fire, and investigators find
your specially
modified UPS started it. Your insurance company is going to make
things real ugly."

I am really getting tired of reading this type of Internet
"wisdom". Do you know anybody who has actually burned down their house
with a modified UPS and had their insurer refuse to pay? or is this
just something you made up?

My experience is that home fire insurers even pay for totally
stupid fires.

Vaughn

John Beardmore

2005-08-07, 10:21 pm

In message <2s4df116pdkl3v62ju9c263hseltqr0fs5@4ax.com>, Tim Keating
<NotForJunkEmail@directinternet11.com1> writes
>On Sun, 7 Aug 2005 23:50:13 +0100, John Beardmore
><wookie@wookie.demon.co.uk> wrote:

>
>Isn't it time you stopped acting like a dumb XXX and quit trolling.

So you can't justify your position then.

Isn't it time you stopped making assertions when you don't really know
what you are on about ?

>PS.. I don't sell inverters..

Good !

J/.
--
John Beardmore

John Beardmore

2005-08-07, 10:21 pm

In message <0d5df1tr89kqcqrotnoakeun63muugftgh@4ax.com>, Tim Keating
<NotForJunkEmail@directinternet11.com1> writes
>On Sun, 7 Aug 2005 23:56:23 +0100, John Beardmore
><wookie@wookie.demon.co.uk> wrote:

>
>The question was about idling current differences.

No - much of this thread has been about what might limit the run time
of UPS inverters in continuous or sustained periods of use.

>. Mr. Troll..

Calling me a troll won't change what this thread has been about.

> As for thermal limitations you can figure that one out for
>yourself,

Seems most people here have some handle on the issues.

> Mr. Dumbass troll..

Ad hominem attack - the last resort of those who can't handle any
challenge to their dogma.

J/.
--
John Beardmore

Rob

2005-08-07, 11:21 pm

"Too_Many_Tools" <too_many_tools@yahoo.com> wrote in
news:1123352629.193975.283680@g44g2000cwa.googlegroups.com:

> Thanks to those who have responded.
>
>

Best thing to do is give it a shot. I currenly use an AT&T 515 UPS
(400w) to run my full size fridge when required. (Never had to use it
for more than a couple of hours at a time). Its 36v and I use 3 x 12V
battery chargers, 3 x 70 ahr batterys, and an 900w generator. Works for
me....................Rob

nospam.clare.nce@sny.der.on.ca

2005-08-07, 11:21 pm

On Sun, 7 Aug 2005 23:45:04 +0100, John Beardmore
<wookie@wookie.demon.co.uk> wrote:

>In message <Me-E1253C.11451907082005@netnews.worldnet.att.net>, Me
><Me@shadow.orgs> writes
>
>
>So let's see. You contend that it can't operate under the steady state,
>but that it may take more than thirty minutes to 'fry' despite
>dissipating tens of watts and having not a whole lot of thermal
>capacity.
>
>
>
>But IF the thermal capacity IS as small as some suggest, then the steady
>thermal state will have been reached long before the batteries expire.
>
>
>
>Well, that's certainly limited by the batteries in normal use. This is
>hardly proof that the inverters couldn't survive continuous duty.
>
>
>
>Well - maybe, but we only have your assertion to justify this ! What's
>more, if the energy isn't being dissipated, then it MUST (to some extent
>at least) be about storage, but you said "It isn't the "Storage" of heat
>that is the problem here". So which is it ?
>
>Well, it's both ! D'Oh !
>
>
>
>Do you have direct personal experience of this ?
>
>Which inverters were affected ?
>
>Does anybody else have experience of running these inverters
>successfully or otherwise ?

There are not too many UPS units more cheaply bult than the cheap APC.
One tha is, is the Upsonic.

I have torn the battery out of an old Upsonic350 and connected a cigar
lighter cord to it and ran it in my van for several years. Never
overheated it - but it was a finicky beast at the best of times, and I
got a 350 watt inverter cheap, so I pitched the old Upsonic.
>
>
>
>No - it's not rocket science - but back of envelope calculations seem
>to suggest that thermal capacity alone is not sinking the heat, and it
>seems pretty likely that the steady state temperature must be closely
>approached. Therefore it's likely that in well designed kit (and let's
>face it, decent UPSs have fans), it IS about dissipation after the first
>few minutes of operation.
>
>
>Now - I could believe that inverters designed for occasional use
>wouldn't use the quality of components that might be selected for
>inverters intended to run 24/7, and I could believe that any set of
>components would have longer service lives at lower working
>temperatures, so I can agree that sticking an extra fan on might help.
>
>There seems to be some consensus that anything beyond that needs some
>proof beyond your assertion !
>
>
>Cheers, J/.

Derek Broughton

2005-08-08, 9:21 am

Too_Many_Tools wrote:

> Ok, no responses...maybe I should ask the question..."What issues has
> anyone had with using UPSes for a house inverter?"
>
You got no responses because it's a FAQ. Google the archive - it's a bad
idea.
--
derek

Too_Many_Tools

2005-08-08, 12:21 pm

Thanks for responding....

I did google before I asked the question....and found that there has
been much discussion but no evidence that supports the claims.

If one would reread what I asked it is for anyone who has done it to
describe what issues they encountered. I am wise enough to realize that
my time is not worth reinventing the wheel if I know it already exists.
The timing of the question is because I have a number of surplus CHEAP
UPSes that are large enough to make an effort like this worthwhile.

TMT

tim

2005-08-08, 8:21 pm

Tim Keating <NotForJunkEmail@directinternet11.com1> wrote in
news:9vcaf1d3o800gue82bvv3oj37bhf48dqqd@4ax.com:

> On 6 Aug 2005 16:53:58 -0400, nicksanspam@ece.villanova.edu
> wrote:
>
>
> Disagree all you want..
> Thermodynamics will dictate a rather short lifespan.
>
> Most of UPS enclosures are plastic, or steel, both of which
> are
> fairly good thermal insulators. When a typical UPS is
> producing 300 watts of AC from Batteries, it is also pumping
> out 50 to 100 watts of thermal energy.
>
> Retaining that thermal energy is generally not significant
> factor
> if the inverter/high thermal output phase is kept to a fairly
> short duty cycle.
>
> But, when the inverter portion is operated at significant
> power
> levels for long duty cycles. The internal temperature will
> build to a point where the power semiconductors breakdown
> thermally.
>
> Generally a UPS would need some form of force air cooling to
> run
> continuously at those power levels.
>

depends on the ups. the larger aps units - 1kva and above - have
the ability to connect extra batteries in parallel for essentially
unlimited run-times depending on the loads. i happen to have one
with three very large 48v batteries i plan on setting up to run the
tv and a lamp or two when the power is off instead of having to run
the genny all the time, thus reserving the gas for keeping the frig
and freezer cold and some topping off charge on the batteries while
the genny is running. no one says one has to run a full load on
the ups all the time. the one i have is a 3kva but i only plan on
drawing at most 500w - that would give me two hours of run time
instead of 20 min even without the other two batteries.

twillmon@cybermesa.net

2005-08-09, 12:21 pm

On 2005-08-08 t3ehs2-ul6.ln1@othello.pointerstop.ca said:
>Newsgroups: alt.energy.homepower,alt.solar.photovoltaic
>Thanks for responding....
>I did google before I asked the question....and found that there has
>been much discussion but no evidence that supports the claims.
>If one would reread what I asked it is for anyone who has done it to
>describe what issues they encountered. I am wise enough to realize
>that my time is not worth reinventing the wheel if I know it
>already exists. The timing of the question is because I have a
>number of surplus CHEAP UPSes that are large enough to make an
>effort like this worthwhile.
>TMT
There's a guy in Houston, handle's "Gigawatt", used to post here over
5 years ago, who ran his house that way. He's changed to real
inverters since.

Tom Willmon
near Mountainair, (mid) New Mexico, USA

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