I have about 25 UPS' I picked up at a local university sale for $30 total.
The
largest was a 2KW unit with 18 12V batteries, one of which was dead :-).
Metalworking content - after replacing the one bad battery I tested it
using my bandsaw....
- Bob Headrick
==========================
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 ?

Frank GMØCSZ / KN6WH

"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

18 x 12v = 216v with plenty current...since you are with us I assume
everything went well? ;)

TMT

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 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.

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.

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

On Tue, 22 Nov 2005 12:29:37 -0000, "Highland Ham"
wrote:


I have about 25 UPS' I picked up at a local university sale for $30 total.
The
largest was a 2KW unit with 18 12V batteries, one of which was dead :-).
Metalworking content - after replacing the one bad battery I tested it
using my bandsaw....
- Bob Headrick
==========================
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 ?

Frank GMØCSZ / KN6WH

Most likely six strings of 3, for a 36 volt system, or 3 strings of 6
for 72. a 2KW 110 volt system on 12 volts would draw close to 200
volts, on 24 close to 100, on 36 close to 60, and on 72 less tan 30
amps for 18 amps out and85% +/- efficiency.