My brain hurts from the charge rates for NiCd.

I must purify myself in the waters of Lake Minnetonka...

"1290 pack (12V, 9Ah)" now here's an actual item to look for, and I >ASS
U ME< there should be plenty of erudite discussions.

Rick Ekblaw wrote:

The key here is that the battery pack needs to put out 180W of power for
10 or 11 seconds, then it gets recharged to be ready for the next power dip.  That's a poor usage case for NiCD, which suffers from the memory effect if you don't discharge slowly and most of the way towards full discharge, but lead-acid can dump out power quickly and cycle often,
though doing that lowers the pack lifetime, it would probably need to be replaced every 3 years or so.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

9.25" (L) x 1.75" (W) 1.875" (D)

This sounds better...

Louis Ohland wrote:

My brain hurts from the charge rates for NiCd.

I must purify myself in the waters of Lake Minnetonka...

"1290 pack (12V, 9Ah)" now here's an actual item to look for, and I >ASS
U ME< there should be plenty of erudite discussions.

Rick Ekblaw wrote:

The key here is that the battery pack needs to put out 180W of power
for 10 or 11 seconds, then it gets recharged to be ready for the next
power dip.  That's a poor usage case for NiCD, which suffers from the
memory effect if you don't discharge slowly and most of the way
towards full discharge, but lead-acid can dump out power quickly and
cycle often, though doing that lowers the pack lifetime, it would
probably need to be replaced every 3 years or so.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

9.25" (W) x 1.75" (H) 1.875" (D)

Battery pack will be shorter, there's a three pin Molex plug and a short
length of cable in there...

Louis Ohland wrote:

My brain hurts from the charge rates for NiCd.

I must purify myself in the waters of Lake Minnetonka...

"1290 pack (12V, 9Ah)" now here's an actual item to look for, and I >ASS
U ME< there should be plenty of erudite discussions.

Rick Ekblaw wrote:

The key here is that the battery pack needs to put out 180W of power
for 10 or 11 seconds, then it gets recharged to be ready for the next
power dip.  That's a poor usage case for NiCD, which suffers from the
memory effect if you don't discharge slowly and most of the way
towards full discharge, but lead-acid can dump out power quickly and
cycle often, though doing that lowers the pack lifetime, it would
probably need to be replaced every 3 years or so.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

Rick, what would be the minimum rated Watt-Hour for the battery pack?
180W over 10 seconds?

Assuming a 12v battery pack...

Louis Ohland wrote:

9.25" (L) x 1.75" (W) 1.875" (D)

This sounds better...

Louis Ohland wrote:

My brain hurts from the charge rates for NiCd.

I must purify myself in the waters of Lake Minnetonka...

"1290 pack (12V, 9Ah)" now here's an actual item to look for, and I

ASS U ME< there should be plenty of erudite discussions.

Rick Ekblaw wrote:

The key here is that the battery pack needs to put out 180W of power
for 10 or 11 seconds, then it gets recharged to be ready for the next
power dip.  That's a poor usage case for NiCD, which suffers from the
memory effect if you don't discharge slowly and most of the way
towards full discharge, but lead-acid can dump out power quickly and
cycle often, though doing that lowers the pack lifetime, it would
probably need to be replaced every 3 years or so.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

Louis Ohland wrote:

Rick, what would be the minimum rated Watt-Hour for the battery pack?
180W over 10 seconds?

Assuming a 12v battery pack...

So after all of that thinking and postulating, I went back and looked at
the Announcement Letter and found:

Battery, Nicad (Internal) 6669 57F0842

so it's a NiCD pack after all. I'll bet that using it just a few times
to supply power during brief power outages killed the pack, those cells
would get HOT.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

Louis Ohland wrote:

Rick, what would be the minimum rated Watt-Hour for the battery pack?
180W over 10 seconds?

Assuming a 12v battery pack...

Louis, your battery engineer is just going to shake his head sadly at
you, as the watt-hour rating for this battery pack is going to be
irrelevant because you're not looking for it to provide continuous power
for even a minute, much less an hour. Since you want to assume a 12V
pack instead of my suggested 24V, to get to 180W you need 15A of current
coming out of that pack for the 10 or 11 seconds required -- actually a
bit more because you will have some losses involved inverting the DC
power output into AC to back-feed the PSU -- unless the battery backup
is just used to feed the DC section of the PSU, which might be the way
IBM did it.

As I think about it, feeding the DC section of the PSU is more likely
than doing the AC inversion. Since the highest output voltage is 12V, a
12V battery pack would be just fine. But you said the charger is rated
for 26V, so that would suggest a 24V battery pack. It's all getting complicated, for sure. But if you pressed your battery engineer for a watt-hour rating for this hypothetical battery pack, it would probably
be in the high single digits, maybe as much as 10 -- certainly nowhere
close to the 100+ rating of the 1290 12V SLA battery pack.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

Rick, the simplest [and slowest!] rate is c/1, a lot SIMMpler control
circuit and it makes the least heat. I've seen c/5 mentioned, much
shorter time, but more heat and it slaps the battery pack like the
naughty boy it is.

So... if you got to SEE the battery charging circuit, could you
guesstimate capacity?

The pittances we have of 26v and 40mA could mean whatever you wandt.
Measuring the output connector in the battery well -MIGHT- tell us the
actual charging voltage, which could be less than 26v. Maybe the charger
input is 26v at 40mA?

Rick Ekblaw wrote:

Louis Ohland wrote:

Rick, what would be the minimum rated Watt-Hour for the battery pack?
180W over 10 seconds?

Assuming a 12v battery pack...

So after all of that thinking and postulating, I went back and looked at
the Announcement Letter and found:

Battery, Nicad (Internal)                        6669  57F0842

so it's a NiCD pack after all.  I'll bet that using it just a few times
to supply power during brief power outages killed the pack, those cells
would get HOT.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

Louis Ohland wrote:

Rick, the simplest [and slowest!] rate is c/1, a lot SIMMpler control
circuit and it makes the least heat. I've seen c/5 mentioned, much
shorter time, but more heat and it slaps the battery pack like the
naughty boy it is.

So... if you got to SEE the battery charging circuit, could you
guesstimate capacity?

The pittances we have of 26v and 40mA could mean whatever you wandt. Measuring the output connector in the battery well -MIGHT- tell us the
actual charging voltage, which could be less than 26v. Maybe the charger input is 26v at 40mA?

OK, let's go back for another round of the guessing game. If IBM did
not go for custom-built NiCD cells, you have a few common cell sizes to
choose from: C size, sub-C size, AA size, AAA size, VARTA size pucks (3
cells stacked that are roughly a dime diameter, a bit less than an inch
long), the individual pucks used in the VARTA batteries that can stacked
to whatever length you desire in series, and then a handful of odd sizes
that largely never caught on. Given that the battery pack must fit
within a 9.25" x 1.75" x 1.875" space, if the AA size was used, they
could be in a 3x3x4 configuration and the wiring would likely be 3x4 in
series, 3 stacks of 3x4 in parallel, giving you a nominal pack voltage
of 14.4V. Each cell would likely be 600mAh meaning the pack would be
21.6 Wh.

If sub-C cells were used instead of AA, the configuration would likely
be 2x2x4 and the pack voltage would be either 9.6V or 19.2V depending on whether you wired it as 2 parallel 2x4 or every cell serial. Neither of
those choices seems likely, so I suspect the pack used AA sized cells.

Knowing that the pack has a 3 wire connection suggests positive,
negative and sense wires (most likely). It could also mean one negative
and 2 positive if the sub-C cells were used and the pack was providing
two 9.6V outputs.

You could also get into some wonky possibilities if the battery backup
was ONLY providing 5V DC power, letting the hard drive "slide" for that
10 or 11 second period of backup power, but thinking about that makes my
brain hurt.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

Rick, though I love posing possumbilities in obtuse waze, this battery
thing is past being deduced.

Let's put this on the back burner until we either have a battery pack
-OR- an actual 180W PSU so we could measure voltages and examine the
charging circuit.

Rick Ekblaw wrote:

Louis Ohland wrote:

Rick, the simplest [and slowest!] rate is c/1, a lot SIMMpler control
circuit and it makes the least heat. I've seen c/5 mentioned, much
shorter time, but more heat and it slaps the battery pack like the
naughty boy it is.

So... if you got to SEE the battery charging circuit, could you
guesstimate capacity?

The pittances we have of 26v and 40mA could mean whatever you wandt.
Measuring the output connector in the battery well -MIGHT- tell us the
actual charging voltage, which could be less than 26v. Maybe the
charger input is 26v at 40mA?

OK, let's go back for another round of the guessing game.  If IBM did
not go for custom-built NiCD cells, you have a few common cell sizes to choose from:  C size, sub-C size, AA size, AAA size, VARTA size pucks (3 cells stacked that are roughly a dime diameter, a bit less than an inch long), the individual pucks used in the VARTA batteries that can stacked
to whatever length you desire in series, and then a handful of odd sizes
that largely never caught on.  Given that the battery pack must fit
within a 9.25" x 1.75" x 1.875" space, if the AA size was used, they
could be in a 3x3x4 configuration and the wiring would likely be 3x4 in series, 3 stacks of 3x4 in parallel, giving you a nominal pack voltage
of 14.4V.  Each cell would likely be 600mAh meaning the pack would be
21.6 Wh.

If sub-C cells were used instead of AA, the configuration would likely
be 2x2x4 and the pack voltage would be either 9.6V or 19.2V depending on whether you wired it as 2 parallel 2x4 or every cell serial.  Neither of those choices seems likely, so I suspect the pack used AA sized cells.

Knowing that the pack has a 3 wire connection suggests positive,
negative and sense wires (most likely).  It could also mean one negative
and 2 positive if the sub-C cells were used and the pack was providing
two 9.6V outputs.

You could also get into some wonky possibilities if the battery backup
was ONLY providing 5V DC power, letting the hard drive "slide" for that
10 or 11 second period of backup power, but thinking about that makes my brain hurt.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)