On Tue, 22 Nov 2005 12:55:29 -0800, "Bob Headrick"
wrote:


"Highland Ham" wrote in message
.. .

Bob , Interesting info ; can you confirm that the 18 pcs 12V battery were
in fact 9 strings of 2 batts in series (each string having a fuse )
providing 24 V ? or were all the 18 batts in parallel ?

Actually they were all in series, making it a bit nerve-wracking to replace a
battery in the string.

- Bob W7OV

216 volt battery pack??? I don't think so.

wrote:

On Tue, 22 Nov 2005 12:55:29 -0800, "Bob Headrick"
wrote:


"Highland Ham" wrote in message
.. .

Bob , Interesting info ; can you confirm that the 18 pcs 12V battery were
in fact 9 strings of 2 batts in series (each string having a fuse )
providing 24 V ? or were all the 18 batts in parallel ?

Actually they were all in series, making it a bit nerve-wracking to replace a
battery in the string.

- Bob W7OV

216 volt battery pack??? I don't think so.

Not very common on a unit as small as 2kW, but very common on units in
the double digit kw range. If he meant 20kW instead of 2kW, it almost
certainly had a high voltage battery string. Much more efficient to have
the higher voltage at much lower current to convert to the high voltage
AC. On a 20kW unit that would put your battery current in the 85A range
for a 2xxV battery string vs. 850A range for a 24V battery string.

Pete C.

On Tue, 22 Nov 2005 16:05:54 -0500, "Brent Atkerson"
wrote:

This one interests me. Wonder how many small UPSs you could run from a
truck battery (assuming using heavy enough cables between each UPS and each
battery [when needed for the 24 volt input]). I am sure you would have to
leave the vehicle running if running the UPSs for any length of time or
heavy load... Probably pretty basic questions but I am kind of interested
because I have a couple laying around and never thought of using them as an
inverter (powered by a vehicle). That would make a neat addition to a
garden tractor or something too...

Better check first if the UPS can handle a log term run of a battery. It
might be that it was designed for a short term, just to give you enough time
to power everything down properly. Longer runt time might cause some
marginal designs to overheat.



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place

On Wed, 23 Nov 2005 00:38:17 -0500,
wrote:
On Tue, 22 Nov 2005 12:55:29 -0800, "Bob Headrick"
wrote:
"Highland Ham" wrote in message
. ..

Bob , Interesting info ; can you confirm that the 18 pcs 12V battery were
in fact 9 strings of 2 batts in series (each string having a fuse )
providing 24 V ? or were all the 18 batts in parallel ?

Actually they were all in series, making it a bit nerve-wracking to replace a
battery in the string.

216 volt battery pack??? I don't think so.

No, quite possible and makes some design sense - they would not need
a heavy output transformer in the unit boosting the voltage of a 36V
or 48V battery string after converting it to a sine wave AC, as 216V
would be right around the sine wave peak voltage of 120VAC. Just run
the battery DC through two sets of power transistors to let through a
reconstituted sine wave - one for the positive half of the output
waveform, the other negative.

And it cuts the current the transistors have to pass.

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

hi very good point, many older units will not startup w/o
running from a/c power first.

Some newer APC models you can 'fool' it into
startup by pressing the test button with it offline.

Another factor, many of these older units like
the Exide, Best, Liebert and Trip Lite are
full sine wave units, a real bargian at today prices.

There was an article in QST on adapting a smaller
ups to run on an external battery. Very easy to to,
just use good fuses MaxiFuse on the leads.

Some of these newer units use microprocessors
to run the thing so if the don't power on without
batteries, they are useless except for the transformers.

73 dude




Beware that some UPSes refuse to start without A/C voltage
present. Kind of stupid, but it's reality. That could hinder their use
for emergency.

Good point bob,

my liebert unit is full sine wave, from a supermarket
pos system, just replaced all three 12v batteries
with new ones, they are in series, 36 vdc.

My work ups, exide 12kva unit used 60 batteries,
three phased in series 240vdc

dude.

Bob Headrick wrote:

"Highland Ham" wrote in message
...

Bob , Interesting info ; can you confirm that the 18 pcs 12V battery were
in fact 9 strings of 2 batts in series (each string having a fuse )
providing 24 V ? or were all the 18 batts in parallel ?

Actually they were all in series, making it a bit nerve-wracking to replace a
battery in the string.

- Bob W7OV

Yes, very possible !
Exide models as well at the other big boys Liebert etc.
use this configuration.

They use torrid transformers, very compact,
the entire assy about the size of a loaf of white bread !

The ups w batteries about 36" cubed. 12 KVA 3 phased.

dude



216 volt battery pack??? I don't think so.

No, quite possible and makes some design sense - they would not need
a heavy output transformer in the unit boosting the voltage of a 36V
or 48V battery string after converting it to a sine wave AC, as 216V
would be right around the sine wave peak voltage of 120VAC. Just run
the battery DC through two sets of power transistors to let through a
reconstituted sine wave - one for the positive half of the output
waveform, the other negative.

And it cuts the current the transistors have to pass.

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

On Sun, 20 Nov 2005 21:14:33 -0800, Too_Many_Tools wrote:

I am the "lucky" owner of a number of older UPSes.

So what can a person build out of these?

The batteries are for the most part dead but the remainder of the
components seem to be in good condition.

Any suggestions?


Sell them to FedEx? ;-)
--
Cheers!
Rich
------
"Grain grows best in ****."
-- U.K. LeGuin

On Wed, 23 Nov 2005 16:22:24 GMT, Ignoramus22022
wrote:
On Wed, 23 Nov 2005 16:13:58 GMT, Bruce L Bergman wrote:
On Wed, 23 Nov 2005 wrote:
On Tue, 22 Nov 2005 12:55:29 -0800, "Bob Headrick" wrote:
"Highland Ham" wrote:

Bob , Interesting info ; can you confirm that the 18 pcs 12V battery were
in fact 9 strings of 2 batts in series (each string having a fuse )
providing 24 V ? or were all the 18 batts in parallel ?

Actually they were all in series, making it a bit nerve-wracking to replace a
battery in the string.

216 volt battery pack??? I don't think so.

No, quite possible and makes some design sense - they would not need
a heavy output transformer in the unit boosting the voltage of a 36V
or 48V battery string after converting it to a sine wave AC, as 216V
would be right around the sine wave peak voltage of 120VAC. Just run
the battery DC through two sets of power transistors to let through a
reconstituted sine wave - one for the positive half of the output
waveform, the other negative.

And it cuts the current the transistors have to pass.

Bruce, this also sounds like a simple approach to generating 3 phase
out of DC. Without the noise and weight of rotary phase
converters. What are your thoughts on that?

Quite Plausible, but when you add the caveat of reproducing 3-Phase
power the engineering just got really complicated, and more than
likely rather expensive. And I'm NOT a high-powered electronics drive
wonk by any means, the best I could do for fixing them is look for the
obviously crispy components and swap out the blown boards - or swap
the crispy parts and diodes that fail a VOM test and see if that does
it.

With a single phase inverter, they're just doing a push-pull on one
240V lead, relative to the center tapped neutral. When you try
3-phase, there's going to be constant voltage, current and capacitance
interaction between all three sets of "hot AC" switching transistors
(or Triacs, or whatever). And the load's resistive, inductive and
capacitive components are all going to come into play.

The resulting inverter would need to be built rather robust, and be
able to overcome drive issues with brute force where finesse won't do.
Compared to that, RPC's are the KISS method. And RPC's aren't a bad
way to go, if they are well balanced and have cooling air you can tuck
them away in a closet.

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

Ignoramus22022 wrote:

On Wed, 23 Nov 2005 23:21:02 GMT, Bruce L Bergman wrote:
On Wed, 23 Nov 2005 16:22:24 GMT, Ignoramus22022
wrote:
On Wed, 23 Nov 2005 16:13:58 GMT, Bruce L Bergman wrote:
On Wed, 23 Nov 2005 wrote:
On Tue, 22 Nov 2005 12:55:29 -0800, "Bob Headrick" wrote:
"Highland Ham" wrote:

Bob , Interesting info ; can you confirm that the 18 pcs 12V battery were
in fact 9 strings of 2 batts in series (each string having a fuse )
providing 24 V ? or were all the 18 batts in parallel ?

Actually they were all in series, making it a bit nerve-wracking to replace a
battery in the string.

216 volt battery pack??? I don't think so.

No, quite possible and makes some design sense - they would not need
a heavy output transformer in the unit boosting the voltage of a 36V
or 48V battery string after converting it to a sine wave AC, as 216V
would be right around the sine wave peak voltage of 120VAC. Just run
the battery DC through two sets of power transistors to let through a
reconstituted sine wave - one for the positive half of the output
waveform, the other negative.

And it cuts the current the transistors have to pass.

Bruce, this also sounds like a simple approach to generating 3 phase
out of DC. Without the noise and weight of rotary phase
converters. What are your thoughts on that?

Quite Plausible, but when you add the caveat of reproducing 3-Phase
power the engineering just got really complicated, and more than
likely rather expensive. And I'm NOT a high-powered electronics drive
wonk by any means, the best I could do for fixing them is look for the
obviously crispy components and swap out the blown boards - or swap
the crispy parts and diodes that fail a VOM test and see if that does
it.

With a single phase inverter, they're just doing a push-pull on one
240V lead, relative to the center tapped neutral.

Right. As you know, I recently made a DC - AC inverter myself.

When you try 3-phase, there's going to be constant voltage, current
and capacitance interaction between all three sets of "hot AC"
switching transistors (or Triacs, or whatever). And the load's
resistive, inductive and capacitive components are all going to come
into play.

Yep.

The resulting inverter would need to be built rather robust, and be
able to overcome drive issues with brute force where finesse won't do.
Compared to that, RPC's are the KISS method. And RPC's aren't a bad
way to go, if they are well balanced and have cooling air you can tuck
them away in a closet.

You are right. I am going to redo my RPC into a 17.5 HP RPC. (two
motors, 10 and 7.5 HP). Right now I have a 10 HP RPC.

Someone offered me a Semikron 6 IGBT drive, with which I could make a
3 phase inverter. That sort of made me interested.

i

Get your hands on a large, like 30kw or better, used as in "please take
it out of here", three phase, online UPS from a computer room
installation. As long as you can supply adequate power to the DC bus the
inverter portion will happily generate your three phase power with no
issues with designing and inverter or trying to synchronize three
inverters or duty cycle problems. It's a DC - 3 phase AC continuous duty
inverter, ready-to-go.

Pete C.